Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 616 PM EDT Sat Sep 28 2024 Valid 12Z Wed Oct 02 2024 - 12Z Sun Oct 06 2024 ...Strong winds, significant waves, and some moderate to heavy rainfall expected to accompany a strong storm system into the Panhandle Monday-Tuesday... ...Overview... A strong low, which is expected to bring gusty winds and moderate to locally heavy rainfall early next week, should be moving into the Panhandle and weakening by the start of the period on Wednesday. After this, the pattern should remain fairly progressive as another surface low or two track from Bristol Bay into the Gulf and towards the Panhandle, but likely much weaker than the early week system. By next weekend, a strong surface low into the Bering will be slow to move as a blocky ridge builds over western Canada. This low may bring some impactful weather to parts of the southwest or western coast region, but still with a lot of uncertainty in hazards. ...Guidance Evaluation/Preferences... Models overall show good agreement with the large scale pattern through the period, but plenty of uncertainty in the details. There are also some timing differences with the series of weak lows into the Gulf mid week, but a blend of the 12z deterministic guidance seems to serve as a good starting point for the beginning of the period. By Thursday and beyond, a strong surface low (possibly a central pressure as low as 950 to 960mb) looks to track into the Bering Sea, and models for a few days now have shown good consensus on the existance of this system, but continue to wobble on the exact track and placement. This seems to be dependent on how strong a ridge builds downstream over western Canada. Best guess now is this system will track east towards Nunivak Island before turning more southward and weakening. By next Sunday, the guidance shows this system in or near Bristol Bay. Lastest cluster of ensembles shows some potential for a triple point low to track into the Gulf late weekend, but latest deterministic runs have backed off on the earlier timing of this. Preferred a blend of the ensemble means with the 12z GFS, ECMWF, and CMC for this system which mitigates the smaller scale differences while still keeping a sufficiently strong system. ...Weather/Hazards Highlights... The early week surface low into the southern Panhandle region of Southeast Alaska will bring with it maritime hazards, rainfall, and gusty winds, but should be waning by the start of the period. After this, the remainder of the Southeast/Southern Coast area should remain generally unsettled with light rain expected as another weaker system or two passes from Bristol Bay into the Gulf mid week. A large and deeper storm system should enter the Bering Sea later next week, with increasing rain chances along the West Coast and through the Aleutians into next weekend. Given a sufficiently deep system, storm to hurricane force winds and high waves are likely over the Bering Sea, but hazardous impacts across land areas and coastal western Alaska are more uncertain, though some coastal flooding and gusty winds are possible depending on how deep the low is as it approaches Alaska. In a broad sense, cooler than normal high temperatures are likely over southern parts of Alaska and warmer than normal temperatures are likely for the northern two-thirds of the Mainland during the period. 40s to low 50s are forecast for highs in most lower elevation areas, with an overall warming trend as next week progresses. Santorelli Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range Alaskan products including 500mb, surface fronts/pressures progs and sensible weather grids can also be found at: https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html