Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 653 PM EST Fri Feb 28 2025 Valid 12Z Tue Mar 04 2025 - 12Z Sat Mar 08 2025 ...Aleutians/North Pacific lows may bring enhanced precipitation and gusty winds into southern coastal areas of Mainland Alaska next week... ...Overview... An upper ridge stretching northwest from Canada into Southeast Alaska and the Mainland into Tuesday-Wednesday will gradually be pushed east as upper troughing develops from Pacific and Arctic energies combining. Possibly several surface lows supported by the troughing aloft and moist Pacific inflow will allow for rounds of precipitation to affect the southern coast, likely heaviest in the Kenai Peninsula, and expanding into Southeast Alaska mid-late week. Strong winds may also be a threat especially over maritime areas at times. Additionally, northerly flow on the backside of the lows may produce gusty winds through the Bering Strait to St. Lawrence Island and farther south through the Aleutians and Alaska Peninsula. Then by late next week, mean upper ridging will track through the Aleutians/Bering Sea with another upper/surface low sneaking into the Aleutians behind it. The forecast pattern will favor widespread above normal temperatures aside from more moderate readings over the far western mainland early-mid week. ...Guidance Evaluation and Preferences... Model and ensemble guidance is in generally good agreement with the pattern described above. Guidance struggles more with the smaller scale details of the embedded vort maxes and surface lows though. The surface pattern is likely to be complex through Tuesday-Wednesday with multiple low centers across the northern Pacific to Aleutians and Alaska Peninsula and southern Bering Sea, which all have model spread. Finally by Day 6/Thursday 12Z there is some model agreement in consolidation of the lows, particularly from the GFS and ECMWF runs that indicate surface lows in the 970s in Bristol Bay and in the Gulf of Alaska. The UKMET was farther south while the CMC had two lows in the Gulf at that time. There is some signal for the Gulf low to move into Southcentral and weaken by Friday. Farther north, there is some uncertainty with how an upper low near the Chukchi Sea may drift south Wednesday-Thursday. In particular the UKMET and to some extent the CMC have the core of the low tracking south while the GFS and ECMWF keep it north. Regardless, the feature should provide some Arctic energy to the Aleutians to Alaska Peninsula upper low to form the broader trough atop western Alaska moving east. Models are in good agreement in principle with the trough deepening and shifting east, while an upper ridge pushes through the Aleutians Friday-Saturday. There is also currently rather good consensus for an upper low and potentially a strong surface reflection to reach the western Aleutians by Day 8/Saturday. The WPC forecast favored a blend of mainly deterministic models and especially the GFS and ECMWF early in the period. As the period progressed, increased the proportion of ensemble means, but was able to maintain a slight majority of deterministic models as the pattern became dominated by synoptic scale features that were fairly agreeable for a Day 7-8 forecast. ...Weather/Hazards Highlights... Multiple surface lows and sufficient moisture with Pacific inflow will maintain a few days of moderate to locally heavy precipitation along the southern coast of the state from the Alaska Peninsula and Kodiak Island toward the Kenai Peninsula and Prince William Sound. The heaviest amounts are likely to be in the favored southern part of the Kenai Peninsula, with multiple days of moderate to heavy precipitation potentially leading to hazardous conditions. The focus for precipitation is likely to expand into Southeast Alaska around Thursday as the more consolidated surface low moves east. Precipitation chances are forecast to wane by late week as the trough aloft pushes through. The northern Pacific and vicinity surface lows may also cause periods of moderate to strong winds for the Gulf and perhaps even spreading into coastal areas Wednesday-Thursday. Periods of light snow are also possible farther north, especially in the western Mainland, through Tuesday-Wednesday as energy drifts southward. This could also cause brisk to strong northerly winds through the Bering Strait and St. Lawrence Island and possibly cause some maritime hazards. Deep layer northerly flow is likely across the Aleutians to Alaska Peninsula Thursday-Saturday on the backside of the trough. Then, by next Saturday the next low approaching the Aleutians may lead to strong southerly winds and precipitation chances there. Much of Alaska will remain much milder than normal through next week. The Mainland can expect temperatures 10 to 20 degrees above average with highs a few degrees plus or minus 40F in Anchorage and Fairbanks Tuesday-Thursday. The far western Mainland may start near to a bit cooler than normal before warming up, while Southeast Alaska can expect temperatures generally 10 to 15 degrees above normal. Cooler weather likely arrives by next Saturday with the northerly flow behind the trough. 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