Anchorage Ski Outlook

1.22.2020 
Thurs – Fricold, dry, gap winds (high confidence).
Temps dropping again. Inversions in the usual spots (East Anchorage, Portage, Granite, etc). Some fog. Gap winds in channeled terrain like Whittier, Seward, Turnagain Arm, the Mat Valley, Peters Hills, and especially Thompson Pass. Sheltered ski terrain should be protected from the wind.

Weekend: cold, cloudy/showery near coast (moderate confidence).
More cold temps. Some clouds/showers near coast, with a storm possibly arriving Sunday. Inversions. Gap winds in channeled terrain. Sheltered terrain should be protected from the wind.

Early Next Week: cool temps, snowfall near coast (low confidence).
Temps will moderate slightly as storms brush up against the Gulf of Alaska. Areas close to the coast will get some snow; while the inland stays drier. No rain concerns.

Dirty Details
There is excellent agreement between the different models that temperatures will drop and skies will clear over the next couple of days as shown by looking at the forecasts for Kickstep on Meteoblue:


Going into the weekend, a small low in the Gulf of Alaska will produce some clouds and possibly showers, more so closer to the coast. On Windy that low is quite visible:


For early next week there is poor agreement on timing and strength of storms that could bring snow. Whether and when the coastal mountains get snow depends on if the lower pressure systems going thru the Gulf get close enough. Looking at recent ensemble model runs for precipitation next week, they are very inconsistent on how much snow we'll get:


However, there is good agreement that the interior will stay dry as is shown by GFS model run-to-run output for the Susitna Valley:


Finally, as noted in this afternoon's forecast discussion, cold temperatures are likely to stick around for at least another week or two.

Last Week
Our last week is well summarized by the weather record at Sunburst. First, cold temps were pushed out as the wind direction shifted from the north to south.


Then, winds, temps, and humidity peaked with the arrival of the Sunday/Monday storm. It generally has to be windy to snow at Turnagain as most precip there is orthographic where the wind lifts relatively warm air over the Chugach:


Even more wringing out of moisture is produced when the wet/warm air is lifted over cold air. This helped to bring snowfall to Anchorage this week:


Today the Anchorage has been stuck under low clouds because there wasn't enough wind to push out the clouds. Meanwhile its been sunny up above:


Places that had enough wind (like Whittier) to scoop out the low clouds have been sunny too:


Archived Outlook - 1.15.2020 
Thurs – Fri: cold, dry, gap winds (high confidence).
Cold temps (but not as cold as its been) will persist with inversions in the usual cold spots. Gap winds in channeled terrain like Whittier, Seward and especially the Mat Valley and Thompson Pass.

Weekend: moderating temps, approaching storm (moderate confidence).
Temps will moderate as high pressure leaves our region. Clouds will arrive ahead of the late Sunday/Monday storm. This storm will favor the coastal areas and there should be no rain concerns.

Early Next Week: moderate temps, snow (low confidence).
After the Sunday/Monday storm wraps up, more snowfall is likely. Timing, strength, and location of the snowfall is uncertain, but at this point it looks like both the coast and interior could get snow. Significant rain concerns are unlikely.

Dirty Details
Cold and clear weather remains over our region. The notable change is that the Mat Valley winds have really kicked up. These winds are stronger than the light gap wind that we have been feeling because they are reinforced by strong upper level northeasterly winds and are impacting Hatcher Pass.


This weekend the weather finally begins to change as the high pressure weakens and moves northeast:


This will bring increasing temps, and will allow a storm to push into Southcentral late Sunday/Monday. This storm will favor areas closer to the coast. Following this storm, more snowfall is likely moving forward in the week. Timing, strength, and location of the snow is up in the air. Below are the precipitation forecasts from the different models for early next week. Their lack of agreement leads to high uncertainty in snowfall, especially for Hatcher.


Last Week
Another awesome week for Southcentral skiers! The cold and clear weather has continued with amazing snow and midwinter light like here on Cornbiscuit the other day:


Inversions continue to be strong, with Sunburst 30 degrees warmer than Granite the other day. Remember, without an inversion, temperatures in a dry atmosphere would decrease at a rate of 3.5 F per 1,000 feet as opposed to INCREASING at 9.3 F per 1,000 feet!


As expected, the winds have jumped up a bit. Particularly notable has been the Mat Valley getting in on the action. Hatcher generally was spared until yesterday, but up high everywhere has seen some wind like Lynx Peak on Saturday:


Archived Outlook - 1.8.2020 
Thurs – Fri: cold, dry (high confidence).
Cold temps will persist with inversions in the usual cold spots. Valley fog is likely. Gap winds in channeled terrain like Whittier, Seward and especially Thompson Pass.

Weekend: temps increasing, light snow near coast (moderate confidence).
Temperatures will increase over the weekend, snow is possible near the coast Sunday into Monday. No rain concerns. Inland will remain dry. Gap winds in channeled terrain decreasing over weekend.

Early Next Week: dry, moderately cold (moderate confidence).
Temps will generally hold from the weekend. Gap winds in channeled terrain like Whittier, Seward and especially Thompson Pass. Temperature inversions and valley fog in the usual spots.

Dirty Details
We have a few more days of cold weather before temps increase slightly as an small storm brushes against our region later this weekend. This storm has consistently trended later over model runs as can be seen in GFS precipitation output for the Kenai Mountains:


At the same time it has also trended south as shown in this cool modeled precipitation trend animation from Tropical Tidbits:


Moral of the story is that the storm's main impacts will be some cloud cover and possibly light snow near the coast later in the weekend.

Next week will be back to more of the same as cold, dry weather continues in our zone. There is good model agreement that early next week will be dry:

Source: Meteoblue

Looking farther out, it is possible that the dry weather will continue through the work week.

Last Week
Another awesome week for Southcentral skiers! As expected we've been in a period of cold and clear weather. The snow and midwinter light have been amazing, like they were here on the Pinnacle on Saturday:

Photo: Dmitry Surnin

This weather pattern has had some distinct and interesting phenomena. For one, inversions have been strong, with folks seeing temps around -20 F on their way to go skiing. Granite Creek had a particularly notable inversion the other day:


These temp inversions form at night and are driven by cold, dense air flowing downhill while any warmth that is left at the surface escapes into the atmosphere. Without clouds to act as an insulating blanket more energy can escape into the atmosphere. And without winds there isn't much to mix out the inversions. Here's an old textbook graphic of the process:


Another consequence of our cold and clear temps is that snowpacks are faceting. Y'all probably remember this process from avy school, but just like everything else in the world, faceting is driven by gradients. The difference between the relatively warm/wet air in the snow and the cold/dry atmospheric air produces a pressure gradient that drives water vapor through the snowpack and causes snow metamorphism. Avalanche.org has a good description and fun animation of the process:


Finally, gap winds are impacting our region as cold air flows from the interior towards a low in the Gulf. Thompson Pass is experiencing the strongest winds with the NWS forecasting winds up to 40 mph and winds chills as low as -55!! Thompson Pass often experiences the worst of these gap winds because the temperature gradient between the cold Copper River Basin and the warm coast is so large and over a relatively small distance. Like I said, gradients rule us!

Archived Outlook - 1.1.2020 
Thurs – Fri: clearing, cold (high confidence).
Cold temps will persist with inversions in the usual cold spots (East Anchorage, Portage, Granite Creek, etc). Valley fog is likely.

Weekend: cold, mostly dry (high confidence).
Saturday will be clearer with light snow possible near the coast on Sunday. Cold temps will persist with inversions in the usual cold spots. Valley fog is likely. Gap winds are possible in channeled terrain like Thompson Pass, Whittier, and Seward.

Early Next Week: cold, dry (moderate confidence).
Cold temps will persist with inversions in the usual cold spots. Valley fog is likely. Gap winds are possible in channeled terrain like Thompson Pass, Whittier, and Seward.

Dirty Details
After an exciting and active period of weather, the storm track is finally moving to our south and leaving behind cold and dry weather.


During this period, lows passing thru the Gulf of AK will bring some clouds, wind, and minor snowfall to our region. This is especially true closer to the Prince William Sound.

As is the case here when its dry and cold, gap winds could be an issue. These winds can be visualized as water behind a reservoir (cold, dense, high pressure air from the interior) going thru a gap in the dam (wind thru Thompson Pass) and flowing downhill (towards relatively warm and low pressure air in the Gulf of AK). Here's a cool figure from UBC illustrating this:


The gap winds for this period actually look pretty minor, but will be most significant for Seward, Whittier, and Thompson Pass. If the gap winds are worse than expected and impact our main ski areas, the key to skiing during these conditions is to get away from the gaps. For example, gap winds flowing through Turnagain Pass can leave unstable wind slabs on Tincan Proper, while the Library has no slab formation.

This weather pattern could last awhile. Recent GFS model runs for precipitation for the Kenai Mountains show lots of zeros thru next week:


Last Week
Wow! What a week! It started out with expected cold and moist air that brought us blower dendrites. Then, temperatures jumped with the arrival of warm air from the south. By 3 AM yesterday Anchorage had already broken the record temp for December 31! The Anchorage area was significantly warmer than Turnagain Pass due to Chinook winds crashing down on us over the Chugach Mountains. Called "Snow-Eater" by the Blackfeet these warm winds are caused by air that has dropped some of its moisture and rapidly warms as it descends over the mountains. Chinooks are common on the dry-side of mountains all over the Western US such as the Rockies, Sierras, and Cascades. Here's a cool figure of the phenomenon from Accuweather.


Then, our New Years cold front arrived and temperatures dropped rapidly. Its pretty cool to see the distinct onset of dropping temperatures with the arrival of the cold air in our local weather stations:


Archived Outlook - 12.25.2019 
Thurs – Fri: cold, windy in channeled terrain (high confidence).
The remainder of the work week will be quiet. Temperatures will bottom out (with inversions) on Friday morning before beginning to warm as the next storm arrives Friday afternoon.

Weekend: stormy favoring the coast, cool temps (low confidence).
Snowfall will continue thru the weekend as multiple storms pulse thru. The mountains close to Prince William Sound will be favored, with Valdez looking to do best. Certainty in the timing and strength of these pulses is low. No rain concerns. Colder inland.

Early Next Week: stormy, moderate temps (low confidence).
Snowfall will continue in our zone. Confidence in timing, strength, and location of snowfall is low. Valdez looks to do best with Girdwood, Hatcher, and the Anchorage Front Range all possibly doing well. No rain concerns. Colder inland.

Dirty Details
Thursday will bring significant winds to our channelized terrain as cold, dense air from the interior flows downhill towards the departing low pressure in the Gulf of Alaska. These winds will impact Turnagain Arm, Turnagain Pass, Seward, Whittier, and Valdez as seen on Windy:


On Friday afternoon the next storm hits our mountains. This storm won't be huge, but the cold air should help to wring out a good amount of low density snow that will help to build up the snowpack at low elevations. Additional waves should arrive on Saturday and again Sunday. There is low confidence in these storms due to poor agreement between models as shown in the varying precipitation forecasts for Kickstep:

Source: Meteoblue.

Going into next week, forecast confidence is low. The highest confidence is for the Valdez area where models are showing agreement on continued snowfall:

Source: Meteoblue.

I'm going to get myself into trouble with this, but looking out into late next week there is the chance of drying weather. This is shown in GFS model output (each column is one model run) of the water equivalent forecast for the Kenai Mountains:


Again, this is a LONG time out. And there is disagreement between model runs about when and if drying will occur. If it does, expect plunging temps, winds in channeled terrain, and rapidly faceting snow.

Last Week
Christmas came early last week with an absolutely incredible weather window at Turnagain. Not only was the snow good, it was stable, and sunny. It blows me away just how good our backcountry skiing can be. Here's Connor Johnson on Friday ripping spines in the golden hour:


The clouds came in earlier on Sunday than I expected. In retrospect, this should have been reflected in a lower confidence for my weekend forecast. On the bright side, the clouds brought a refresh of blower snow for the beginning of this week. That blower snow is a function of temperature and humidity, as shown in the chart below:


The huge dendrites at the top of the figure are formed when cold, moist air coming off of places like the Great Salt (or the Sea of Japan) dumps feet of low density snow in Little Cottonwood Canyon (or Hokkaido). Turnagain often experiences the denser dendrites on the left side of the figure due to warmer air from the Gulf of Alaska. Our recent colder temperatures are much better for producing that cold smoke we crave!

Archived Outlook - 12.18.2019 
Thurs – Fri: dropping temps, clearing skies, windy in channeled terrain (high confidence).
Temperatures drop as winds switch from blowing off of the ocean to out of the Arctic. The usual suspects like Granite Creek and East Anchorage will have temp inversions. Moderate winds through gaps especially Seward, Thompson Pass, and the Copper River. Limited fog is possible.

Weekend: cold, clear, windy in channel terrain (high confidence).
Temps continue to drop. Inversions persist. Outflow winds continue. Limited fog possible.

Early Next Week: moderating temps, dry inland, light snow near coast (low confidence).
Temperatures will moderate as low pressure enters the Gulf of AK. Confidence about precipitation timing and amount is low. But, expect light precipitation and low rain/snow lines for Turnagain/Girdwood.

Dirty Details
Temperatures will start to drop tomorrow as the wind direction finally switches from bringing warm air off the north Pacific to bringing cold, dry air from the Arctic. This is nicely shown on Windy's upper atmosphere wind forecast for Friday:


There is high confidence in this clear/cold weather because there is good run-to-run model agreement and good agreement between models. We can see the agreement between models for Kickstep on Meteoblue:


These cold temps will bring outflow winds. How strong the winds are is the uncertainty for skiers through the weekend. The winds are driven by cold, dense, high pressure air from the interior flowing "downhill" towards the relatively warm, low density, air over the Gulf of Alaska. They are lazy and follow corridors to the coast. For this weekend, areas that will be most affected are Thompson Pass, Cordova, Seward, and the Matanuska Valley. Turnagain Pass will be impacted to a lesser extent. The key to avoiding these winds is to get away from the paths they like to take. Areas that will see the most wind are shown below with Windy's wind accumulation parameter:


Early next week areas close to the coast will likely see snowfall and the associated rising temps of warmer air off the Pacific. There is low model agreement about this both in terms of strength and timing, but don't expect anything big. Meanwhile, there is high confidence that inland will stay dry as shown by the consistent zero-precipitation forecast for the Susitna Valley:


Last Week
Our region has been in a repeating pattern of weak storms in the Gulf of AK bringing moderate snow to Turnagain and coastal areas. This pattern is visible on the Sunburst weather station record as sustained northeasterly winds and high relative humidity:


Despite the series of storms that have hit the Kenai Mountains, there is no snow down low. A quick look at the below-average Kenai SNOTELs tells the story of the warm weather we have been experiencing:


Meanwhile the inland has stayed dry. This precipitation gradient between the coast and the inland is due to downsloping, which is nicely explained in this figure I edited from the Teton Valley News:


Temperatures have also slowly been trending down:


As skies continue to clear, and winds switch to the north that downward temperature trend is about to significantly accelerate!

Archived Outlook - 12.11.2019 
Thurs – Fri: moderate temps, moderate precip near coast, dry inland (high confidence).
Moderate precipitation will fall at Turnagain Pass and closer to the coast while the inland stays dry. The rain/snow line will be near the road at Turnagain. The high peaks of Turnagain will receive 2 feet of snow with minimal accumulation at the road.

Weekend: moderate temps, moderate precip near coast, dry inland (moderate confidence).
Saturday will be in between storms before another storm arrives for Sunday. The rain/snow line will be near the road. The inland will be downsloped and dry.

Early Next Week: moderate temps, dry inland, potentially drying (low confidence).
Sunday's western PWS storm will likely continue into Monday, with clearing/drying possible Tuesday into Wednesday. The inland will be dry. Temperatures should drop a bit.

Dirty Details
There is high confidence in dry weather over the interior of our region over the next week as exemplified by consistent GFS run-to-run model output for Talkeetna:


While the interior is downsloped, areas closer to the coast will pick up precipitation as is clearly seen in the long-term water equivalent forecast for our zone. As is classic when the wind blows from the southeast, areas closest to the western Prince William Sound do the best.


The exact timing and strength of the Sunday/Monday storm is uncertain due to disagreement in timing/strength between the models:


There is good agreement that over the next week temperatures will slowly drop as can be seen by the Meteoblue model ensemble graph for Turnagain Pass:





Last Week
The last week started with rising temps as the flow direction shifted from north to south over our zone. Areas closest to the coast clouded up first followed by Hatcher Pass by the weekend. The weekend was stormy as multiple warm storms produced rain/snow close to the coast (Portage/Turnagain/Girdwood/Seward) while inland got wind, wind, wind. Monday's big storm left relatively warm temps in its wake. The before, during, and after are exemplified nicely in the Marmot Wx Station:


At Hatcher the weekend's story was wind slabs on top of the surface hoar formed by our last period of cold, clear, and high humidity. This led to lots of skier triggered avalanches. I was briefly caught in one before self-arresting, and so did everyone's friend Edskimo:

Meanwhile, areas closer to the coast were getting hammered with copious amounts of precipitation and high snow lines. Rain on snow produced big peaks in area hydrographs, like this one on Sixmile Creek:


Temperatures have remained warm into the work week as southerly onshore flow has persisted:


Archived Outlook - 12.4.2019 
Thurs – Fri: rising temps, skies becoming cloudy (high confidence).
Temperatures will rise as the wind direction shifts from the north. With this shift expect cloud cover to increase and snow showers by the end of the work week.  Areas closest to the Prince William Sound (PWS) will be impacted the most.

Weekend: stormy, warm, windy (moderate confidence).
Precipitation will begin in earnest on Saturday night favoring areas closest to the PWS with the interior in the shadow. Rain lines will rise to the alpine for Turnagain/Girdwood/Seward. All areas will be windy.

Early Next Week: stormy, warm, windy (moderate confidence).
The stormy pattern favoring areas closest to the PWS will continue. Rain lines will be high. All areas will be windy.

Dirty Details
There is good agreement between the models that the next series of storms will arrive to the Gulf Coast late on Saturday. This is exemplified by model output of accumulated precipitation for Kickstep Mountain at Turnagain Pass:


By Monday morning the peaks above Turnagain/Girdwood/Seward will receive 3+ feet of snow. There will be tight elevation gradients with lower elevations receiving wet/heavy snow and rain. Storminess will continue (and will continue to favor the coastal zones) into next week. However, timing of next week's storms is lower as can be seen by the difference between the models. For example, model output for Kickstep Mountain:


Timing is uncertain, but its going to precipitate a lot. 10 day forecasts are never great, but here is the 10 day snowfall forecast from the ECMWF. Its classic for southeast flow. The western PWS will get copious precip. The Neacolas and Tordrillos also do well. Meanwhile, the Anchorage Front Range and Talkeetnas will be in the shadow of the High Chugach.


Last Week
The arrival of last week's warm, wet, and windy storm was visible as rising temps (and wind, and humidity), on area weather stations:


By early this week the Hatcher Pass SNOTEL was approaching the SWE content that it normally peaks at each May:


Independence Mine is now at 311% of median (w/ Tony D reporting 8 feet of snow at Birthday Pass!!!), the Peters Hills are at 264% of median, and the Anchorage Front Range is even a bit above average. Like we discussed last week, these warm storms really hit the Kenai hard, and although the SNOTELS down there did pick up to two inches of water, it fell as rain down low.

As the storms cleared early this week, calmer winds, clear skies, and cold temps arrived. However, humidity remained high. Clear skies, cold temps, and high humidity are a great recipe for surface hoar formation.


Archived Outlook - 11.27.2019 
Thurs – Fri: stormy, windy, warm temps (high confidence).
The advertised storm is already upon us; precipitation and winds will peak tonight/tomorrow. The rain line will rise above the Turnagain Pass road level; there will be no rain concerns for Hatcher. On Friday, lighter precipitation will continue closer to the Prince William Sound, while Hatcher will see clouds/snow showers. Storm totals for Hatcher and the Turnagain/Girdwood alpine will exceed 3 feet and could reach 5 feet. The Peters Hills, Thompson Pass, and Anchorage Front Range will do well.

Weekend: cloudy to stormy, moderate temps (moderate confidence).
Saturday will be a cloudy and showery in-between day before another storm moves in Saturday night. This storm will favor areas closer to the Prince William Sound with 9" to 18" of snow and less as you move away from the coast. The weekend storm should not have high rain line issues.

Early Next Week: stormy to clearing, cooling temps (high confidence).
The weekend storm will move out of our area on Monday. Behind it temperatures will dramatically fall and skies will clear. Expect moderate outflow winds.

Dirty Details
There is high confidence about our Thanksgiving storm due to good agreement both between different models and from run-to-run. For example, below is consistent run-to-run QPF (multiply X10 to estimate snowfall) model output for the mountains around the Western Prince William Sound (source wxweb.meteostar.com).


And, good agreement between models as exemplified by model output for the Hatcher Pass (source meteoblue.com).


This big, wet, warm storm is courtesy of a giant tap of tropical moisture getting lifted by the jet stream over the cold air in place in our mountains. Because this storm is blowing in from the southwest, it will allow all areas to receive snowfall (source Windy.com).


On Friday, the upper level wind direction will shift to the southeast, which allow precipitation to continue for mountains around the Western Prince William Sound, but will put Hatcher in the shadow of the Chugach Mountains:


The weekend's storm will not be as strong or as warm partly because it will not have the same jet stream support as the Thanksgiving storm; the jet stream will be to our south and it will be blowing from the west instead of the south.


Early next week temperatures will drop and skies will trend clearer as the Sunday storm leaves our area and cold, dry air from the north moves in. There is high confidence in this dry, cold period as seen in strong run-to-run GFS model agreement in the QPF output for the Kenai Mountains:


Last Week
After last weekend at Hatcher its hard for us skiers in Southcentral AK to be anything but stoked about how the season is starting out. With huge stellar dendrites falling from the blue sky and blower snow it felt like Japan! Here's a favorite weekend moment of mine:


The Hatcher Pass SNOTEL is at 250% of its median SWE for this date (median for March 8th)! The Thompson Pass SNOTEL is doing even better at 330% of median SWE!!! The Kenai Mountains and Girdwood Valley which are particularly susceptible to rain have struggled with SWE at area SNOTELS as low as 7%. But, hopefully that's about to turn around too!

Archived Outlook - 4.24.2019
Thurs – Fri: cloudy to clearing, cool, wind in favored terrain (high confidence).
Clouds tomorrow, especially near the Prince William Sound, where snow will also fall. Expect warming and clearing into Friday with cold nights. There will be some wind tonight/tomorrow along the Anchorage Front Range, Turnagain Arm, Whittier, and Seward.

Weekend: sunny, warm days, cool nights, calm (high confidence).
Dry weather will be well established over our region. With strong spring sun and clear nights, afternoons will be warm and mornings will be cold. The sun will have a strong impact on solar aspects, while high north aspects will harbor cold snow.

Early Next Week: cloudy to clearing, snow showers possible, warm (moderate confidence).
Southcentral will be on the edge of a storm in western Alaska on Monday. As such, clouds to light snow are possible. When the sun comes out expect immediate warming and solar impact to snow.

Dirty Details
Spring is re-arriving in Southcentral Alaskal this time probably for good. Along with it comes intense solar warming and clear, cold nights. But, first we have one more day of cloudy weather. This cloudy weather it courtesy of a weak low in the Gulf of Alaska. As the short term precipitation forecast shows, this storm will heavily favor the western PWS:


With cooler air in place, the snow that falls near the coast will be light and have low rain/snow lines. On Friday and going into the weekend clearing will arrive in full force. There is high confidence in this forecast because of strong run-to-run model consistency:

Kenai Mountains QPF Forecast


On Monday we will see some clouds and possible light snow as a storm over western Alaska bumps up against us. If the storm shifts a little east we will see light snow; if it stays west we'll just see clouds. Here is how the storm is currently forecast to track:


Sun will return on Tuesday and dry weather should stick around for the rest of the work week.

Last Week
The last week has been awesome, bringing snow (and low rain/snow lines) to all of our mountains. The low rain/snow lines have been courtesy of a cold air feed from western Alaska:


This cold air is also what allowed snow to fall on Monday with so little wind. Often snowfall in our region is orographic, which is where winds smash moisture against the mountains. This produces lift, then precipitation, but also windboard. One look at the Anchorage Front Range and you can see how the snow fell without wind. Its caked up there; for example, last night in upper Middle Fork:


This storm came on the tail end of other storms that first favored Hatcher, then the western Chugach mountains, then the western Prince William Sound mountains. Here's what it looked like in the western Chugach on Saturday:

Photo: Dmitry Surnin

Interestingly, late April 2018 also saw an extremely stormy period. Actually, that was way stormier - it snowed 20 feet in the Alaska Range. But, in a time of year that is climatologically one of the driest, stormy patterns are always a bit of a surprise!

Archived Outlook - 4.17.2019
Thurs – Fri: partly cloudy to weak storm, mild temps, light wind (high confidence).
On Thursday evening another storm will arrive favoring Hatcher Pass and the Anchorage Front Range. This storm will be weaker and quicker than last night's storm. Temperatures will drop into Friday.

Weekend: stormy, mild temps, windy in favored areas (high confidence).
Initially snowfall will favor Hatcher Pass and the Anchorage Front Range before switching to areas near the PWS on Saturday night. Temperatures will rise on Sunday with the rain/snow line at or above the road at Turnagain; additionally winds will increase along the Anchorage Front Range and Turnagain Arm.

Early Next Week: light snow to possible clearing, mild temps (low confidence).
There will likely be some light snow for all mountains of our region on Monday. Tuesday is up in the air, there maybe additional snowfall or clearing. There are signs of clearing towards the middle of the week.

Dirty Details
Clouds are clearing this evening as the storm that's been over us weakens and moves to the west. Its departure is visible on the Kenai radar:

Over the last 36 hours this storm brought intense snowfall in a thin line from the Anchorage Front Range up through Hatcher Pass. The Indian Pass SNOTEL picked up an inch of SWE while Hatcher Pass picked up 2+ feet of snow; the Kenai Mountains and Girdwood were left high and dry. Pretty cool to see the rapid accumulation on the Marmot webcam:

On Friday night, upper atmosphere winds will blow up the Cook Inlet from the southwest, bringing another shot of precipitation to Hatcher Pass and the Anchorage Front Range:

On Saturday afternoon, wind direction will shift to the SE effectively turning off precipitation for the Upper Cook Inlet mountains for the rest of the weekend:

Looking into the next work week, particularly Tuesday, uncertainty goes way up. For example below are the model precipitation forecasts for Hatcher Pass. On Sunday, the models consistently agree in dry weather, as opposed to Monday and Tuesday where timing and strength of precipitation has little agreement between models.

Archived Outlook - 4.3.2019
Thurs – Fri: partly cloudy, mild temps, calm (high confidence).
Light snow near the Prince William Sound on Thursday night followed by clearing Friday. Expect minimal accumulations near the coast and dry inland.

Weekend: snow near coast, mild temps, windy in favored areas (moderate confidence).
Moderate snow for areas closer to the PWS with the inland remaining dry. Saturday is likely stormier. Total weekend snowfall will be about 1 foot for the Girdwood and Turnagain alpine with rain at sea level and low elevations. Expect winds in channeled terrain.

Early Next Week: snow near coast, mild temps, windy in favored areas (low confidence).
Moderate snow for areas closer to the PWS with the inland remaining dry. Total snowfall will be 1-2 feet for the Girdwood and Turnagain alpine; with rain at sea level and low elevations. Expect winds in channeled terrain.

Dirty Details
A pattern shift is finally underway after our glorious period of spring weather and sending conditions. Many new and classic lines/routes went down - nice work folks! The change in the weather can be felt as cooler air is blown in by upper atmosphere winds from the northwest:

This weekend, areas closer to the PWS will see moderate snowfall, while the inland side of the Chugach (and the Talkeetnas) remain dry. It will be windy thru the channeled terrain of the road corridors (Turnagain Arm, Whittier, Thompson Pass, and Seward) as high pressure from the interior flows through the gaps towards the low pressure over the ocean. There is good agreement between the models for Saturday's snowfall, with deteriorating agreement on Sunday (shown is Turnagain Pass forecast):

Early next week looks to be more of the same with snowfall for coastal areas. Confidence in this forecast decreases on Tuesday. From Sat - Tues precipitation will be limited because the storm-conveyor-belt jet stream will be to the south:

It is possible that a stronger system with support from upper atmosphere winds will arrive on Wednesday.

Last Week
High pressure was well established over Alaska as seen in the classic clockwise-spinning upper atmosphere winds:

The high pressure brought sunny days, clear nights, and distinct diurnal temperature swings seen in the weather stations:

We also saw record setting heat with three broken or tied high temperature records in Anchorage (50, 49, and 50 degrees F), and a high of 44 degrees F at Sunburst on Sunday!

Archived Ski Outlook - 3.27.2019
Thurs – Fri: mostly cloudy, warm, calm (high confidence).
Cloudy skies and calm winds will continue into Friday. With insulating cloud cover nights will stay warm. Mountain snow showers are possible Thursday night. Expect clearing late Friday.

Weekend: sunny, warm, calm (high confidence).
High pressure will be firmly established overhead. It will bring clear skies, cool mornings, and intense solar warming in the afternoon. Along with calm winds will come mild temperature inversions in the mornings.

Early Next Week: sunny, warm, calm (high confidence).
High pressure will continue for Southcentral AK. Again, we will see intense sun, cool mornings, and calm winds. The pattern is likely to stick around thru at least the work week.

Dirty Details
The period begins with cloudy skies as a storm in the Bering pushes up against the high pressure over our region. By Friday night clearing begins as high pressure reasserts itself. There is good agreement between the four models for late week cloudiness and weekend clearing:

Going into next week, there is excellent agreement that the pattern will continue. Below is forecast precipitation for the Kenai Mountains. Each column represents output from an individual GFS model run (runs every six hours).

Last Week
From Wednesday thru Friday, 4.7 inches of SWE (snow water equivalent) fell at the Alyeska SNOTEL. That's equivalent to 50+ inches of snow in the alpine!!! Moving away from the Prince William Sound, less and less snow/rain fell:
 - Alyeska SNOTEL: 4.7 inches
 - Turnagain SNOTEL: 2.3 inches
 - Summit SNOTEL: 0.5 inches
 - Indian Pass: 0.6 inches
 - Hatcher Pass: 0.0 inches

This precipitation gradient is typical of Prince William Sound storms where the interior side of the Chugach Mountains remains much dryer. Last Friday's radar loop clearly shows the storm smashing into the Chugach from the southeast and dissipating as it passes over the mountains:


Over the weekend the pattern continued, with areas closest to the PWS receiving the most precipitation:
- Alyeska SNOTEL: 1.5 inches
 - Turnagain SNOTEL: 1.0 inches
 - Summit SNOTEL: 0.2 inches
 - Indian Pass SNOTEL: 0.2 inches
 - Hatcher SNOTEL: 0.2 inches

Since it started snowing on March 8th, 11.0 inches of SWE have been recorded at the Turnagain SNOTEL, and 12.9 inches at the Alyeska SNOTEL. That equates to well over 100 inches of snow in the alpine with significantly more above Portage and Whittier (and why there are giant glaciers there).

As forecast, clearing began over our region on late Sunday with warm high pressure established by Monday. On Wednesday afternoon Granite Creek reached 58 degrees!!! Wednesday was cloudy as southerly flow in southwest Alaska brought moisture over us. This can be seen in today's water vapor imagery:

Archived Ski Outlook - 3.20.2019
Thurs – Fristormy, windy, warm (high confidence).
The next in a series of storms is already impacting our region with the next storm arriving on Friday. Like a broken record, these storms will favor areas closer to the western Prince William Sound with high rain/snow lines and FEET of snow for the Turnagain/Girdwood alpine. The Chugach Front Range will see high winds from these storms; Hatcher will also see some wind.

Weekend: stormy, windy, warm (high confidence).
Storminess will continue into the weekend. Again this will favor areas closer to the western Prince William Sound with high rain/snow lines and FEET of snow close to the coast. The Chugach Front Range will see high winds from these storms. Clearing will begin late Sunday.

Early Next Week: clearing, warm, strong sun effect, calm (high confidence).
There is high confidence in the arrival of high pressure and clearing skies around Monday. With the long days, high sun angle, and warm air mass in place, expect significant solar heating on the south half of the compass. Calm winds and clearing skies will lead to strong valley inversions. High pressure looks to stick around for awhile.

Dirty Details
The next storm is already upon us. Its arrival can be seen on the Middleton Radar, and as increasing temperatures and winds at the local weather stations. Once this storms finishes tomorrow, it will be followed by another one on Friday. There is high confidence in these events due to consistent results both between different models as well as from one model run to the next. These storms will continue to bring high rain/snow lines as warm, moist air is carried north from the panhandle. This extremely warm air produced temperatures of 70 degrees in SE Alaska yesterday, and a record high of 61 in Cordova today.

There will be a brief break in precipitation on Saturday before the next storm moves in late Saturday. This should be the final storm before high pressure begins to move into our region. Like all of our recent storms, this last one will favor the mountains around the western PWS. Forecasted total snowfall for the next week shows areas that are favored by this southeasterly storm track (and correspondingly, areas that have very large glaciers).

After the Sunday storm high pressure finally starts to develop for southcentral Alaska! As seen in the figure below, the arrival of high pressure is accompanied by the shift south of the storm-conveyor-belt that is the jet stream.

There is good model consistency that drier and sunnier weather will stick around through the end of work week.

Last Week
Between Wednesday morning and Saturday morning, 4.0 inches of SWE (snow water equivalent) fell at the Turnagain Pass SNOTEL. That's equivalent to 40+ inches of snow in the alpine!!! Moving away from the Prince William Sound, less and less snow/rain fell:
 - Center Ridge SNOTEL: 4.0 inches
 - Alyeska SNOTEL: 2.5 inches
 - Summit Cr SNOTEL: 1.4 inches
 - Indian Pass: 0.6 inches
 - Hatcher Pass: 0.0 inches

Temperatures rose reaching 35 degrees F at Center Ridge on Friday. Winds were strong throughout the zone, even gusting to 50 mph at Hatcher Pass. The Middleton Radar showed the storm crashing into the western PWS on Friday:

Temperatures continued to warm over the weekend as storms brought more warm air from the Pacific Ocean into our region. The figure below shows last weekend's upper level winds carrying this warm subtropical air north


Over the weekend, temperatures reached 40 degrees at Granite Creek, and precipitation continued to favor areas closest the the western Prince William Sound. Weekend precip totals:
 - Center Ridge SNOTEL: 1.4 inches
 - Alyeska SNOTEL: 0.6 inches
 - Summit Cr SNOTEL: 0.3 inches
 - Indian Pass: 0.3 inches
 - Hatcher Pass: 0.0 inches

By Tuesday we finally got the weather window that I mentioned last week. With clearing skies, the temperatures dropped before beginning to rise again with the arrival of the next storm and associated warm air from the ocean. Last week's temperature record shows the warming and cooling with each weather event:

Archived Ski Outlook - 3.13.2019
Thurs – Fristormy, warm (high confidence).
The storm that is already impacting our region will continue into Friday. Another storm will arrive immediately on its heels. These storms are very similar. Areas closer to the western Prince William Sound (Whittier & Seward) will see the most precip with each storm bringing FEET of snow to the Turnagain/Girdwood alpine. The rain/snow line will rise over the storm to at/above the Turnagain Pass road level. The Chugach Front Range will see high winds from these storms; Hatcher will likely also see wind.

Weekend: stormy, warm (high confidence).
The Friday storm will continue into Saturday before being following by ANOTHER powerful storm. Again, areas closer to the western PWS will see the most. The rain/snow line will be high. The Chugach Front Range will see high winds, as will Hatcher to a lesser extent.

Early Next Week: stormy, warm, possible breaks in storminess (moderate confidence).
More western Prince William Sound storms look to be in the lineup. There is less certainty about the exact timing of the storms, and there may be a breaks, but expect more of the same: areas closer to the western PWS favored for precip, high rain/snow lines, and high winds in the Chugach Front Range. Continued storminess is likely for the long term.

Dirty Details
The first of a series of storms is slamming into the western Prince William Sound. This is very visible on the Middleton Island Radar:

Mountains closer to the western Prince William Sound see the most snowfall from this kind of storm (Whittier & Seward) as moisture slams into the mountains from the southeast. Behind this storm there are more storms in the pipeline; these are clearly visible in the model output:

The next storm (Low #2) will arrive Friday. It will be very similar to the last one. More western PWS storms arrive over the weekend. They will bring high rain/snow lines and abundant precip as they carry warm moisture from the Pacific Ocean. Areas in the lee of the Kenai and Chugach Mountains will be downsloped. Below is a nice graphic from the Teton Valley News explaining downsloping (and why Whittier averages more precip than Anchorage):

Long term there is no sign of the stormy pattern letting up. The 10 day forecast for the mountains above Seward is calling for a preposterous 200+ inches of snow. Long term forecasts are notoriously inaccurate, but you get the idea.

Last Week
Snowfall began in our mountains on Thursday afternoon. Areas closer to the western Prince William Sound saw the most with Turnagain/Girdwood picking up 1-2 feet of snow by Saturday morning and with high winds in the Chugach Front Range.

A stormy weekend favored the western Prince William Sound. This time the rain/snow line reached the road at Turnagain Pass. Weekend storm totals for the Turnagain/Girdwood alpine were generally 1-2 feet. The Chugach Front Range saw less snow, but high winds. The Friday and weekend storms were both clearly visible as peaks in the wind record at the Sunburst Weather Station:

Monday saw light snowfall in Turnagain/Girdwood due to continued moist onshore flow visible on the Middleton Island Radar:

Additionally, Hatcher picked up about 6 inches on Monday afternoon/night due to moist winds blowing up the Cook Inlet. This was about 6 hours earlier than I forecast. Up inlet flow shown on Monday's Kenai Radar Loop:

Archived Ski Outlook - 3.6.2019
Thurs – Fricloudy to stormy, warm (high confidence).
Snowfall will begin in our mountains on Thursday afternoon, increasing on Friday. Areas closer to the western Prince William Sound will see the most (Whittier & Seward). The Turnagain and Girdwood alpine will see 1-2 feet of snow by Saturday morning. Precipitation should remain all snow at the Turnagain Pass road level, though there could be a rain/snow mix at sea level. The Chugach Front Range sees less snow, but high winds for this kind of storm.

Weekend: stormy, warm (high confidence).
Precipitation will again favor areas closer to the western Prince William Sound; this time there will be rain concerns. The rain/snow line could easily reach the road at Turnagain Pass, though it shouldn't rise to the alpine. Saturday will be stormier; weekend storm totals for the Turnagain/Girdwood alpine will be 15 - 30 inches. Again, the Chugach Front Range sees less snow, but high winds for this kind of storm.

Early Next Week: cloudy to snowy (low confidence).
Monday will be an in between period with clouds and light snow before another storm arrives on Tuesday. This storm will favor the mountains around the Cook Inlet including Hatcher, the Chugach Front Range, the Peters Hills, and the Alaska Range. Another storm looks to arrive in our region on Wednesday.

Dirty Details
There is good consistency from model run-to-run and between models about the timing and strength of the Thursday/Friday storm. Additionally, recent model runs have trended the storm stronger. The figure below shows the good consistency between the models. The NAM forecasts higher winds because it is higher resolution. Forecast is for Kickstep.

Like the Thurs/Fri storm, this weekend's storm will favor the mountains around the western Prince William Sound. This is clearly seen in the 5 day snowfall forecast. The Tordrillos/Neacolas, Seward, and mountains above Port Wells do particularly well with this kind of storm.

Monday will be a transition day before the arrival of the next storm on Monday night. This storm currently looks to favor the mountains around the Cook Inlet with upper atmosphere winds blowing up the inlet from the southwest. Given that its 6 days away, there is good model run-to-run consistency for this storm. GFS SWE forecast for the Susitna Valley shows this consistency:

Last Week
Springlike high pressure remained over our region last Thursday and Friday bringing with it calm winds and HOT temps; the Sunburst weather station even reached 47 degrees!

Over the weekend an extremely weak storm passed over us bringing clouds and snow showers. Although accumulations were insignificant, visibility was greatly reduced. Here's what visibility was like on Sunday in the Chugach Front Range:


As forecast, sunny skies returned on Monday. Tuesday was overcast, but snowfall was limited to the Susitna Valley. Model runs leading up to Tuesday had trended this event weaker and weaker.

Archived Ski Outlook - 2.27.2019
Thurs – Frisunny, calm, warm (high confidence).
Springlike high pressure remains well established over our region bringing with it calm winds and warm temps. Without winds to scoop it out, high pressure will cause valley fog and temperature inversions. Expect sun impact on solar aspects.

Weekend: partly sunny to cloudy, calm, warm (high confidence).
Expect some clouds and possible snow showers without significant accumulations, Sunday will be cloudier. With nightly cloud cover don't expect fog to develop or strong nightly temperature inversions. The sun won't soften solar aspects.

Early Next Week: partly sunny to snowy, moderate temps (low confidence).
There is moderate confidence that Monday will be at least partly sunny. Confidence drops on Tuesday with a possible storm - exact timing and strength of this storm are uncertain. Do not expect huge snowfall numbers, or snow/rain line issues. It doesn't currently look like the storm will favor the Prince William Sound vs. the Cook Inlet Mountains.

Dirty Details
Wind forecasts show the high pressure still established and spinning in the Gulf of AK.


But, by Friday the high pressure begins to move southeast and out of our region. This weekend the high pressure breaks down allowing a very weak storm to pass over us with snow showers possible. This is exemplified in the figure below showing spotty precip for Kenai Mountains in model runs over time:

Models have trended the Tuesday storm later (see below). There is also good agreement between models that Monday will be at least partly sunny. There is poor run to run model consistency on the strength of the storm, except that it doesn't look huge. Currently, upper atmosphere winds look to be out of the south, which would allow snowfall for both the Prince William Sound and the Cook Inlet Mountains. On the other hand, SE or SW flow would favor the PWS or the Cook Inlet, respectively.

Last Week
Last Wednesday night's storm went south, brushed our region, and rapidly exited. Snow totals were low and favored areas closer to the PWS. Following the quick storm were the gap winds Thursday decreasing by Friday. Thompson Pass saw the worst winds while northern areas like Hatcher were spared.

By the weekend springlike high pressure was over our region with strong inversions, calm winds, and warm sun. Strong solar warming has been very evident in the diurnal temp swings observed at the Sunburst Wx Station:


Inversions at Turnagain Pass produced temperature swings of almost 35 degrees from the top of Sunburst to the Johnson Pass chest freezer:

Archived Ski Outlook - 2.20.2019
Thurs – Fri: stormy -> windy -> sunny (high confidence).
Tonight's storm will exit our region tomorrow followed by strong winds. Snow totals will generally be less than 12" and will favor areas closer to the Prince William Sound. Winds will decrease on Friday to be replaced by warm sunshine. Expect the worst winds along the highway corridors (Chugach Front Range, Turnagain Arm, Turnagain Pass, Seward, Whittier, Thompson Pass). These winds hit channeled terrain and the Front Range the worst.

Weekend: sunny, calm, warm (high confidence).
Springlike high pressure will be well established over our region bringing with it calm winds and warm temps. Without winds to scoop it out, high pressure will cause valley fog and temperature inversions. Expect strong sun impact on solar aspects.

Early Next Week: sunny, calm, warm (moderate confidence).
The warm high pressure is likely to persist into next week. Expect strong sun affect, valley fog, and temperature inversions.

Dirty Details
Tonight's storm will exit our region tomorrow. With its quick passage and minimal support from upper atmosphere winds, don't expect huge snow totals. Cold air should squeeze a bit more fluffy snow out of the atmosphere. As the storm moves east, strong winds will blow from high pressure towards the low pressure of the departing storm. These winds will decrease on Friday as the low moves on and upper level winds decrease. Tomorrow's winds draining through gaps to the coast are shown below:


Models are very consistent in the establishment and persistence of the high pressure ridge over our region. This is exemplified in the figure below showing zero forecast precipitation for the Kenai Mountains in model run after run. Model time is in Greenwich Mean Time (Zulu), subtract 9 hours to get local AK time.

Last Week
Temps dropped with the strong arctic winds last Wednesday - Thursday; they bottomed out Thursday night before warming Friday with solar heating and the arrival of warmer air from the southwest.


Weekend snowfall initially favored the Kenai before switching to the Cook Inlet. By Sunday night the the mountains had picked up a foot of snow. Southwesterly upper level winds persisted thru Monday which continued snowfall in the mountains around the upper inlet. Monday's Kenai radar shows moisture flowing up the inlet.


Snowfall distribution for Sat - Mon is typical of SW upper winds enhanced by cold air. SNOTELs recorded 0.7" of SWE for Turnagain, and 2" for Alyeska, the Chugach Front Range, Hatcher Pass, and the Peters Hills. Multiply SWE by 10 to approximate snowfall. The SNOTELS are at lower elevations, more snow will have fallen at higher elevations.

Archived Ski Outlook - 2.13.2019
Thurs – Fri: clear, cold, windy, no sun effect (high confidence). Winds will be the strongest tonight, temperatures will be coldest on Thursday night. Expect the worst winds along the highway corridor (Chugach Front Range, Turnagain Arm, Turnagain Pass corridor, Seward, Whittier, Portage). These winds hit channeled terrain and the Front Range the worst.

Weekend: warm, stormy (high confidence). Storm totals will likely be less than a foot, snow will begin during the day Saturday, Sunday looks to be snowier (particularly for Hatcher), all southcentral ski zones will see accumulation. Rain/snow line will be at/near sea level. Temperatures will warm thru weekend.

Early Next Week: moderate temps, light snowfall, some sun (low confidence). A small storm front will pass thru our region on Monday night, it will likely clip the Kenai Mountains, and will bring cloud to the rest of the zone.  With moderate temps there will be sun effect on steep south faces when the sun comes out.

Dirty Details
The ongoing strong winds are due to cold, dense air from the interior flowing “downhill” towards the low in the Gulf of AK. These winds are being strengthened by strong upper atmosphere winds blowing out of the arctic and dragging cold air with them. These winds are lazy and favor passes, gaps, and channeled terrain as they funnel to the coast. The figure below shows these upper winds carrying these strong Arctic air south:


On Saturday, a storm front will ride southwesterly upper atmosphere winds into Southcentral. A second low will follow on its heels Sunday. For both of these systems, upper level flow will be from the southwest. Upper level southwest winds allow snowfall for Hatcher Pass and the Chugach Front Range, as opposed to upper level southeast winds which favor snowfall for the Kenai/Girdwood and generally turn off snowfall for Hatcher/Front Range. This upper level wind setup is shown below:


Early week next the storm track will move to our south, turning off significant precipitation to our zone. A storm riding the storm track will likely clip our region on Monday night. Confidence is low because each model run has not consistently predicted the timing or impact of this system on our region, but have generally trended our precipitation forecast down - it is unlikely to be significant. The figure below shows how consecutive model runs are forecasting SWE (snow water equivalent) for the Kenai Mountains early next week.  Model time is in Greenwich Mean Time (Zulu), subtract 9 hours to get local AK time.

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