Area Forecast Discussion
Issued by NWS Fairbanks, AK
Issued by NWS Fairbanks, AK
252 FXAK69 PAFG 182227 AFDAFG Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 227 PM AKDT Wed Sep 18 2024 .DISCUSSION... .SYNOPSIS... A powerful occluded low is moving inland over Bristol Bay this morning. That low shifts east today and eventually clouds and shower chances increase over the Alaska Range and Southern Interior into Thursday night. An arctic trough will bring colder air and accumulating snow chances to the Brooks Range and Arctic beginning Thursday. The arctic trough will dig south this weekend bringing colder air and chances for snow even down into the Interior. .DISCUSSION... Upper Levels and Analysis... A strong occluded low pressure system of around 530 dam is transiting eastward across the Kenai Peninsula and will continue to fill as it propagates across the Prince William Sound by later this evening. There is also a weak shortwave transitioning slowly across the NW Arctic. Winds will continue to weaken across the eastern Alaska Range through the evening as the low pressure to the south continues to pull away. Models have begin to show more of a stronger trough deepening over the Mainland by this weekend, which will allow for much colder temperatures to be advected in from the north. Forecast and Model Discussion... As the low to the south further weakens as it moves into the Gulf of Alaska, the loosening gradient will allow winds to will continue to weaken over the E Alaska Range. The weak troughing is expected to keep the chances of rain going across most of the Mainland and Interior region later this evening and through Thursday. There will be a stronger through moving in this weekend, which will allow for colder air advection from the North Slope and bring the chance of snow down in the Interior, especially by Saturday night. GFS has continued to have a better and more reliable handle of this and will continue to be blended in more. Temperatures will likely continue to trend below the seasonal average into early next week. Central and Eastern Interior... With residual moisture in place and weak troughing, the possibility of on and off showers will continue over portions of the Mainland, and this will likely prevail through Friday. There will likely be snowfall accumulations across the Alaska Range, especially for elevations around 2000 ft and above tonight. The colder air moving in this weekend could support snowfall down to the valley floor of the Interior, and especially light accumulations around 1000 ft and above. It is more likely to see accumulating snow by Saturday night. West Coast and Western Interior... There will still be the possibility of light showers across the West Coast and Interior all the way into the late week with continued flow being more westerly. There could be snowfall across the western Brooks Range by later in the week and though the weekend as the trough deepens from the north. There will be some drier air moving in on Friday, and also though into Saturday as more northerly winds become predominant will the deepening low across the North Shore. Extended Forecast Days 4-7... With the deepening trough over the Mainland this weekend, and much colder temperatures expected as a result, it could allow for some of the first snowfall to make it down into the Interior, even for the lower elevations. Models, and particularly the GFS, have also been trending towards the arctic trough this weekend of becoming stronger as it moves across the Brooks Range and then setting setting up over the Central and Eastern Interior through Tuesday of next week. The ECMWF has also continued to align more with this solution and also agrees with the trend towards a colder airmass advection which may support measurable snowfall down to the valley floor of the Interior this weekend. .Coastal Hazard Potential Days 3 and 4...None. .HYDROLOGY... Rainfall of 0.5 to 0.75 inches fell over the YK Delta and Lower Yukon Valley/Middle Kusko Valley the last 24 hours. Smaller stream and larger stem river rises are occurring, but will not be significant. Elsewhere, no concerns as rivers are running low due to fairly low snow levels. && .AFG WATCHES/WARNINGS/ADVISORIES... AK...None. PK...Small Craft Advisory for PKZ801. Small Craft Advisory for PKZ803-852. Small Craft Advisory for PKZ804. Small Craft Advisory for PKZ805. && $$