Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 655 PM EST Wed Mar 06 2024 Valid 12Z Sun Mar 10 2024 - 12Z Thu Mar 14 2024 ...General Overview... Considerably colder temperatures are expected for much of the western mainland and portions of the Interior that will persist into early next week. Meanwhile, a low pressure system system is forecast to track south of the Aleutians and into the northern Gulf on Friday, with increasing prospects for precipitation across the Southern Coast, Southeast Alaska, and adjacent mountain ranges into the weekend. A deep surface low over the western/central Aleutians on Friday is expected to produce a triple point low that will likely reach the Gulf over the weekend, but may take a more southern track compared to the previous low. A third low pressure system may follow behind this for next Tuesday across the Gulf. ...Guidance Evaluation and Preferences... The current run of guidance had an increase in spread in terms of timing, location and depth of individual systems, particularly those tracking across the Aleutians an Gulf of Alaska. Overall there was a small southward shift with the synoptic pattern along with an uptick on the moisture these systems will be be tapping into by the end of the extended period. The progression of the next strong low in the general vicinity of the Aleutians and Gulf was mostly defined by a compromise of the GFS, CMC and the ECMWF which are all hinting a wetter, deeper system for the Panhandle and southern coast. The WPC preferred model blend began with a general consensus of the CMC/GFS/UKMET/ECWMF and then included the GEFS mean and EC ensemble mean by the middle period while dropping the UKMET. This approach stayed near continuity with the previous WPC Alaska forecast. ...Weather/Hazards Highlights... Most of Southeast Alaska and portions of the southern coast will be in an active wet pattern through the extended period as a few surface lows and frontal systems affect the region. Precipitation (rain and mountain snow) should extend back into the Southeast Coast/AK Peninsula and portions of the mainland under general unsettled flow/troughing, but not as heavy. Pacific moisture streaming in will be increasing over the Panhandle by the end of the forecast period which will likely lead to increased coverage of rain. Additionally, this pattern may coincide with a warm up in temperatures which may lead to snow melt increasing the potential for runoff across the Panhandle. Multi-day accumulations will generally be in the 2 to 4 inch range, with locally higher amounts possible. The Aleutians should stay wet and unsettled for much of the forecast period as several systems move through the region. Colder air will filter into portions of northern and western Mainland behind a cold front resulting in below average temperatures for early March into next weekend. Widespread subzero lows are expected for western and northern portions of the mainland, with perhaps some -30s across the normally colder locations of the North Slope. Campbell 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