Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 649 PM EST Sat Dec 02 2023 Valid 12Z Wed Dec 06 2023 - 12Z Sun Dec 10 2023 ...Overview... As the period begins Wednesday, a surface low is forecast to be gradually weakening over the Gulf of Alaska, spreading some lingering precipitation across Southcentral into Southeast Alaska as well as some gusty wind potential along the southern coastal areas. Then by the latter half of next week, a northern stream upper low with likely some surface reflection looks to track southeastward into the Bering Sea and over western parts of Alaska. ...Guidance Evaluation and Preferences... Model and ensemble agreement with the 12Z cycle was reasonably good for the early part of the period. Models show good clustering in placement and gradual weakening of the Gulf surface low Wednesday-Thursday. The details of the upper low and energetic shortwaves and the associated surface lows moving from Siberia southeast into the northern Bering Sea/western Alaska are a bit more nebulous. The 12Z CMC looks to be on the northern side with the centroid and the northern extent of the upper low/trough even by Thursday or so compared to the consensus of other guidance. In general a multi-model deterministic blend was able to be used for the early-mid medium range period. Models diverge more by Saturday/Day 7 as the established upper low pattern varies with shortwaves coming through and the resulting surface lows. The 12Z ECMWF was particularly aggressive at digging energy on the southwestern side of the upper low atop the Alaska Peninsula and vicinity. Meanwhile the 12Z GFS spun up a strong surface low near Southeast, unlike its other runs, ensemble members, and other guidance that showed a low much farther west in the Gulf. Considering the variability of the deterministic guidance, quickly transitioned to a blend of over half GEFS and EC ensemble means by Days 7-8. ...Weather/Hazards Highlights... By midweek the surface low over the Gulf should be weakening, some lingering moderate precipitation is possible, possibly locally heavy in the Yakutat area. Some enhanced winds are also a threat with the low. The highest winds likely will phase into the short range period but with some northerly/northeasterly gap winds likely remaining from around the Alaska Peninsula to Cook Inlet. Lighter precipitation may continue across the southern coast into Thursday. As surface and upper lows move southeast through the eastern Bering/western Alaska, they will spread rain/snow to the Aleutians and some snow to the Alaska Peninsula into the southern Mainland, but with totals generally on the lighter side. Light snow accumulations are expected over northern areas in the interior to the Brooks Range. Additional enhanced precipitation chances for Southcentral and Southeast are possible by late next week into the weekend as these lows come in and as another low may be drawn north through the northern Pacific into the Gulf. The Brooks Range and North Slope should maintain above average temperatures through next week, with highs staying above 0F for the most part. However, some pockets of below normal temperatures are likely to traverse southwestern areas into Southcentral, with temperatures within a few degrees of average in between. Tate 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