Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 752 PM EDT Sun Mar 13 2022 Valid 12Z Thu Mar 17 2022 - 12Z Mon Mar 21 2022 ...Overview... The most notable feature over Alaska for the medium range period will be an upper low meandering slowly southeastward over the Alaska Peninsula as the period begins Thursday, shifting into the Gulf of Alaska through late week. A potent upper-level shortwave diving southward across the Bering Sea as well as energy along an active storm track across the northeastern Pacific will serve to redevelop and reinforce the closed low through early next week. This pattern will support a series of surface low pressure systems and bring a sustained period of inclement weather through the Panhandle and occasionally up into the southern coasts for much of the week. ...Guidance/Predictability Assessment... Overall model guidance has rather good agreement for a medium range Alaska forecast throughout most of the period. The upper low appears well handled by the guidance as an initially closed system over the Alaska Peninsula Thursday, with some question of whether it will be open or closed during a transition period on Friday as it begins to interact with potent energy dropping south across the Bering Sea. A multi-model blend of the 12Z deterministic guidance (GFS/ECMWF/CMC/UKMET) worked well for days 4-5, with the blend serving to smooth out the relatively small individual model differences. The feature is likely to close off once again over the weekend as energy consolidates, though with some differences in its position (how far east/west) Saturday as it drifts. Then guidance now has the core of the low retrograding back west of Kodiak Island by Sunday due to additional energy interaction from the northeastern Pacific, and hovering Monday over the Gulf. The overall meandering and energy interactions aloft as well as the associated surface low pressure systems vary somewhat from model to model, but this general idea is the same amongst guidance with clear outliers not really seen for today's forecast. With these minor differences, the WPC forecast phased in some of the GEFS/EC ensemble means while maintaining some operational guidance in the blend for strength of systems for the latter part of the period. The overall trend looks to be slower/farther west with the upper low lingering by days 7-8 compared to yesterday, as the northern Pacific energy serves to reload the low. ...Weather/Hazard Highlights... Much of the mainland should see dry conditions during the period, though perhaps with increasing snow showers by next weekend in the eastern mainland, as precipitation is expected to focus along southern parts of Alaska given the northern Pacific storm track. The Panhandle in particular should see rounds of enhanced precipitation, with the heaviest amounts in the medium range period currently expected on Friday with the deepest of the Gulf surface lows. The precipitation will linger across the Panhandle with rounds of increasing and decreasing intensity depending on location of the surface lows and the orientation of the upper trough/low--so Saturday could see a relative lull before amounts pick up early next week. While precipitation does not appear to be very intense, recent heavy rain/snow across the area could make it more sensitive to additional impacts. In addition, brisk winds are expected with the approach of Friday's surface low with some gusty winds possible across the Panhandle. On the other side of the lows, periods of breezy northerly winds are expected over the Aleutians, along with some chances of snow showers. Colder than average high temperatures are forecast for much of Alaska given troughing aloft, with highs generally 10-20F below normal for mid-March across the southwestern mainland and Alaska Peninsula on Friday and Saturday as a reinforcing cold front comes through. These cooler temperatures will spread into much of the interior as well. However, low temperatures should be closer to normal with some areas even above normal for lows. The North Slope will be the main area that can expect near to above normal temperatures for highs as well as lows, along with possibly the southeastern mainland. Meanwhile, the Panhandle should see below normal highs through the period and a mix of above and below normal lows. 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