Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 713 PM EST Fri Mar 11 2022 Valid 12Z Wed Mar 16 2022 - 12Z Sun Mar 20 2022 ...Overview... All of the model guidance continue to support the general idea that a compact shortwave trough over the Arctic Ocean will dive south across mainland Alaska Tuesday, reaching the Alaskan Peninsula by early Wednesday as it evolves into a closed low. The closed low will then interact with an active storm track across the northeastern Pacific to bring a sustained period of inclement weather through the Panhandle and occasionally up into the southern coasts for much of the workweek. ...Guidance/Predictability Assessment... The ensemble means show very good agreement on the aforementioned synoptic evolution in the vicinity of Alaska through the medium-range period. The deterministic runs exhibit larger run-to-run variability regarding how far west/east the upper low will track through the Alaskan Peninsula on Wednesday. Nevertheless, the spread is quite reasonable given the forecast lead time. Toward the end of the forecast period, model consensus indicates that the upper low should drift eastward into the Gulf of Alaska as it interacts with various low pressure systems that are forecast to track through the northeastern Pacific. An omega block will appear to set up across the Aleutian toward northeastern Siberia by the end of next week. The GFS and GEFS (especially the 12Z run) are fast with placing this block farther east than the ECMWF, EC mean, and the CMC mean. Therefore, the slower 06Z GEFS was used in place of the 12Z GEFS for Days 7-8. The WPC forecast grids for Alaska were based on 40% from the 12Z ECMWF/00Z EC mean, 40% 12Z GFS/12Z GEFS, and 20% from the 12Z CMC/CMC mean for Days 4-6, transitioning to include more of the ensemble means for Days 7-8 as well as replacing the GEFS with the 06Z run as mentioned above. The results look very compatible to continuity. ...Weather/Hazard Highlights... Much of the mainland should see dry conditions during the period, as precipitation is expected to focus along southern parts of Alaska given the northern Pacific storm track. The Panhandle in particular should see steady precipitation becoming heavier on Tuesday ahead of a stronger albeit weakening low pressure system. Heaviest amounts are expected to occur on Wednesday. Although the precipitation does not appear to be very intense through the period, recent heavy rain/snow across the area could make it more sensitive to additional impacts. The precipitation will tend to linger through late next week across the Panhandle with perhaps a gradual downward trend as the low slowly weakens. In addition, brisk winds are expected with the approach of the low with gusty winds. On the other side of the low, breezy northerly winds are expected over the Aleutians by later in the week. A transition to colder than average temperatures is forecast next week for much of Alaska with troughing aloft. This will particularly be true in terms of highs, which could be 10-30F below normal for mid-March. The North Slope will be the main area that can expect near to above normal temperatures. Meanwhile, the Panhandle should see below normal highs through the period and a mix of above and below normal lows. Kong - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Wed, Mar 16. 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