Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 631 PM EDT Wed Sep 18 2024 Valid 12Z Sun Sep 22 2024 - 12Z Thu Sep 26 2024 ...Heavy rain for portions of the Panhandle early next week... ...Overview and Guidance Evaluation/Preferences... An active pattern will continue over the high latitudes as fall will be in full swing. Upper pattern favors strong ridging/positive height anomalies in the mid-latitudes north of Hawai'i and splitting ridging over the Bering, giving way to a deep but progressive upper low early next week. This will scrape the Aleutians on a path toward Kodiak Island and into the Gulf of Alaska as the upper trough axis settles over the mainland. By later next week, northern and southern stream energy should support another system moving across the Pacific, but models diverge on its eventual path toward the Gulf/Panhandle. The latest 12Z/18 models offered reasonable clustering for the Sun-Tue period with the ensemble means. Thus, was able to blend the GFS/ECMWF/Canadian/UKMET and deepen the progs from yesterday, now showing a sub-980mb low nearing Kodiak by late Sun/early Mon. Thereafter, the deterministic models diverge on the handling of the next upstream system, though the ensemble means were actually in good agreement with the path of a low out of the North Pacific and toward the southern Gulf of Alaska. However, individual ensemble members were divergent across the entire northeast Pacific. 12Z ECMWF was perhaps closest to the ensemble mean consensus. Over the mainland/interior, troughing will maintain itself through the week. ...Weather/Hazards Highlights... Main focus will be on the North Pacific system grazing the Aleutians and tracking near Kodiak and into the Gulf of Alaska Sun-Mon. Deep low will create a large wind field around its circulation, but perhaps gales and not quite storm force. Future model runs will offer more insight. Ahead of the system, strong influx of moisture tied back to the tropics will intersect the coast, but likely focused over the southern Panhandle into central/southern BC. WPC has outlined much of the Panhandle for potential hazardous heavy rain next Mon/Tue as the low/front approach. Several inches of rain are likely over the two-day period, especially in favored/coastal/upslope locations. The next system may bring in another surge of moisture but it may be just beyond the Hazard Outlook period. Elsewhere, precipitation should be light, though perhaps some more concentrated areas of rain/snow over the northeastern portion of the interior. Temperatures will generally be below normal for highs and slightly above normal for lows, owing to abundant cloud cover. Much more of the state will see lows below freezing, creeping closer to Southcentral/Anchorage. Fracasso 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