Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 648 PM EST Sun Feb 26 2023 Valid 12Z Thu Mar 02 2023 - 12Z Mon Mar 06 2023 ...Overview... For the latter part of this week, a trough aloft and a couple of surface low pressure systems consolidating in the Gulf of Alaska will help produce precipitation across the Alaska Peninsula into the Panhandle, though the heaviest amounts are likely to be in the short range period. Precipitation could fall as snow even to coastal areas of the Panhandle, with rain and snow showers both possible across the Peninsula. Gusty to high winds are possible on the backside of the lows, in favored gap wind areas of the Peninsula into Kodiak Island and the Kenai Peninsula along with the surrounding waters and islands. Then by next weekend, upper ridging looks to move into the Aleutians first and then set up across the mainland. This should cause initially colder than average temperatures to moderate and direct the storm track across the Aleutians and western Alaska. ...Model Guidance/Predictability Assessment... Model guidance shows reasonably good agreement today with the larger-scale features of the forecast. Models indicate a surface low will persist over the Gulf of Alaska at the start of the period Thursday, while another low tracks quickly from Bristol Bay across the Alaska Peninsula to merge with the Gulf low by early Friday. These show good consensus overall. Meanwhile the track/strength of a trough in the upper levels moving across the mainland also remains pretty agreeable in the guidance. Thus for the first part of the period, the WPC forecast was based on a blend of the deterministic 12Z ECMWF/GFS/CMC/UKMET, with the blending process serving to smooth out any small differences. Models also show fairly good consensus with an upper ridge building behind this trough, first across the Aleutians and Bering Sea and shifting into the mainland by the weekend, with Bering Sea troughing behind. There are some mainly minor timing and amplitude differences mostly well within reason of the spread at forecast lead times of 6-8 days. The main exception was the 12Z CMC, as by early next week it shows energy breaking down the northern part of the ridge and making its way into the mainland. The CMC ensemble also indicated considerable spread for the northern part of the ridge. However, GFS and EC runs as well as the bulk of their ensemble members show the ridge holding on. While it remains possible that energy will round the ridge and serve to suppress it, it seemed prudent given the strength of the ridge and the full suite of model guidance to lean away from the CMC solution. At the surface, the upper pattern will direct the low track north-northeasterly across the Aleutians likely this weekend while a mean low sets up over far eastern Russia as well. The timing for the former low looks to be in better agreement today, slower than yesterday's ECMWF. All this considered, gradually incorporated more ensemble mean guidance and eliminated the UKMET and CMC for a fairly even blend of the GFS/GEFS mean/ECMWF/EC mean by days 7-8. ...Weather/Hazards Highlights... Low pressure at the surface in the Gulf of Alaska and a mean upper trough will provide support for precipitation (mainly snow) to continue across the Panhandle, though with lighter amounts than in the short range period. Additionally, a surface low quickly passing across the Alaska Peninsula on Thursday could cause some light to modest rain and snow showers there. Northwest of the mean Gulf low, high winds are a concern around Thursday-Friday across the Alaska Peninsula eastward into Kodiak Island and the Kenai Peninsula with strong offshore flow. A drying trend is likely across the Panhandle by the weekend as upper ridging moves into the mainland, directing cold and dry northerly flow into the region. Meanwhile western Alaska can expect more active conditions for next weekend as low pressure and frontal systems could affect the Aleutians into the western mainland. While the details are yet to be determined, it seems likely that the western mainland could see a couple rounds of at least light snow this weekend into early next week, while precipitation across the Aleutians to Alaska Peninsula could be enhanced at times as surface lows help to focus moisture. Temperatures across the Panhandle are likely to be below normal in terms of highs for the latter part of this week, and lows and highs could continue to drop there into next weekend given northerly mean flow ahead of the upper ridge. Elsewhere, a somewhat progressive pattern will lead to some temperature swings. High temperatures in particular will drop considerably across the mainland eastward Thursday-Saturday with the bout of upper troughing. But by the weekend, the western part of the state is expected to moderate to above normal underneath the ridge, reaching much of the mainland by next Monday. Some highs above freezing look possible across the Alaska Peninsula and into the southwestern mainland. 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