Area Forecast Discussion
Issued by NWS Fairbanks, AK
Issued by NWS Fairbanks, AK
260 FXAK69 PAFG 202243 AFDAFG Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 243 PM AKDT Fri Sep 20 2024 .SYNOPSIS... The decaying wave to the southeast of the Mainland is going to continue to propagate towards the east with only some residual showers associated with it over the eastern half of the state. A weak mesolow over the Interior is also continuing to provide some weak instability, enough for there to be a few light showers in and around the vicinity of the White Mtns. There will be a developing arctic trough, which will deepen and allow for some colder air advection from the North Slope to progress southward and could bring about some snow to around 1000 ft within the Interior and possibly even down to the valley floor for some locations this weekend. Meanwhile, an occluded low pressure system moving into the Gulf early next week, and the arctic trough remaining in place, will keep the chance of rain/snow showers going through the mid part of next week. There could be a potentially significant system impacting the region the following weekend. && .DISCUSSION... Upper Levels and Analysis... Overall high pressure has dominated most of the region, with only a weak low centered north of Utquiagvik of around 1011 mb, and some overall weak troughing over the North Slope keeping a few light showers still in place, mainly over the Brooks Range. This will begin to increase in intensity going into the morning tomorrow as the trough begins to deepen. There will be a major shortwave trough with an associated upper level low moving into just south of the Fox Islands, of around 970 to 975 dam, which will occlude and move into the Gulf. The GFS has another low developing from this system and undergoing cyclogenesis as it does and will deepen to 966 dam just south of false pass, but then will fill from there as it enters the Gulf going into Monday morning. The EC does not have this deepening as much and keeps the progression moving slightly more to the north and hugging the coastline of the northern Gulf, which aligns more with the other deterministic models. Generally, weak troughing will continue to be present over the Mainland through the mid part of next week. Forecast and Model Discussion... A general blend of the deterministic models was utilized to bring up PoPs more over the North Slope, given that there is higher levels of moisture in place and what is shown in the NBM. This has increased the probability of more rain/snow showers for this evening for this locations and especially increasing chances of shower activity for the W Brooks Range by the early morning hours tomorrow. Snow levels will continue to come down as there will be colder air sliding southward into the Interior, although with wet bulb temperatures being as high as they are, the chance of snow making it down to the valley floor of the Interior is not likely, although there could be some areas which this occurs going into the overnight hours on Saturday if there is enough clearing. The central and W Brooks Range will likely receive at least a foot of snow for some of the higher elevations through Sunday afternoon, which the best shot of accumulating snowfall during the morning hours tomorrow. The overall pattern of weak instability, and low pressure to the south early next week, will likely keep shower activity going for much of the Mainland through the mid part of the following week, mainly for the eastern half. Central and Eastern Interior... Light showers will begin to increase by tomorrow morning and temperatures will continue to drop as colder air is advected from the north. It is possible that there could be some snow making it down to the valley floor for some locations, although the snow level looks to drop down to around to around 500-1000 for most locations. There could be some snowflakes mixing in for the Fairbanks area, yet will likely have no accumulating snow, perhaps only on grassy surfaces. The best chance of this looks to be Saturday night though Sunday morning. Spotty rain/snow showers will continue to be possible through the mid part of next week. West Coast and Western Interior... Occasional light rain showers will be possible over the coastal regions through this evening, but will diminish by tomorrow as an arctic trough digs into the Interior and brings more of a northeasterly wind component to the area. This will help to keep things mostly dry through the rest of the weekend. The northeasterly winds will also be quite brisk on Sunday, and generally between 15 to 30 mph. With the colder air advection, temperatures will steadily continue to drop off and be on an overall downtrend through the mid part of next week. North Slope and Brooks Range... With an arctic front moving across the region this weekend, and the arctic low shifting more to the south, there will be much heavier and more accumulating snow to the central and W Brooks Range. Eventually, rain mixing with snow in the lower levels will become all snow above 1000 feet. Models have been relatively consistent with this and the totals still look to be around 6 to 12 inches, especially for the Anaktuvuk Pass. Some locations of the plains north of the Brooks Range may also receive some heavier snowfall totals, which is why this was also included in the Winter Storm Warning. The weak troughing will keep the possibility of snow showers going into the mid part of next week, although the intensity of these showers should wind down as the week progresses. Extended Forecast Days 4-7... Looking beyond Monday night, there looks to be a slight uptick in the probability of rain/snow showers for the Interior as a stronger low pressure system moves in south of the area into the Gulf. There could be some gusty winds occurring within the Windy and Isabel passes as this low moves closer to the Alaska Range, although it looks like everything will remain below criteria for the time being, although this could change if the low strengthens. The possibility of showers will not be as likely over the W Interior with drier winds in place. The colder temperatures will still be locked in place, especially north of the Brooks Range, and a majority of the showers are expected to be over the eastern half of the Mainland during this period in the forecast. Coastal Hazard Potential Days 3 and 4...None. && .HYDROLOGY... && .AFG WATCHES/WARNINGS/ADVISORIES... AK...Winter Storm Warning for AKZ809. PK...None. && $$ Steward