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 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:
Last Week
High pressure was well established over Alaska as seen in the classic clockwise-spinning upper atmosphere winds:
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:
Thurs – Fri: stormy, 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:
Thurs – Fri: stormy, 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):
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:
Thurs – Fri: cloudy 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 – Fri: sunny, 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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