Alaska Extended Forecast Discussion National Weather Service College Park MD 611 PM EDT Sun Oct 26 2025 Valid 12Z Thu 30 Oct 2025 - 12Z Mon 03 Nov 2025 ...Heavy Mountain Snow and Lower-Elevation Rain Expected Late Week Along Much of the Gulf Coast... ...Synoptic Overview... In the upper levels, a large upper level trough will be the focus allowing for a series of impressively deep lows to turn out of the Pacific and into the Gulf through the first half of the period, resulting in widespread and long-duration mountain snow and low- elevation rain along the Gulf Coast. An upper level low near Bristol Bay on Thursday will merge with a fast moving shortwave trough over the Aleutians as it rounds the southern side of the low and moves the entire trough over the western Gulf. As the shortwave turns north, it will support deep surface cyclogenesis, resulting in a low that likely dips below 950 mb for a short time Friday. As the attendant 500 mb low becomes as strong as 500 dm, expect extreme instability all across the Gulf, likely resulting in thunderstorm activity as the leading front plows into the Gulf coast Thursday into Friday. The rest of the period through the weekend will feature this low weakening almost as fast as it strengthened, while drifting northwest to the northwestern Gulf, near Kodiak and the Kenai Peninsula, then sitting in place while filling further. Elsewhere, expect a long- duration ocean- effect rain/snow shower event along the AKPen and eastern Aleutians as polar air moves over the relatively warm Bering. Strong gap winds are likely through the AKPen. The weather will be much more tranquil across the northern half of the state as relatively benign easterly flow remains in place throughout the period. ...Guidance Evaluation and Preferences... Agreement among the primary guidance has improved significantly from 24 hours ago, with good agreement in the upper levels, primarily between the 00Z EC and the 12Z GFS, through about 00Z Sunday. After that significant differences arise as a strong shortwave races down the Aleutians in the GFS, while that same feature in the EC is much slower and weaker. Thus, ensembles were preferred for the later days 7 and 8 period on Sunday and Monday. The 12Z EC came in much stronger with the low in the Gulf, dipping well into the 940s at peak intensity, but also much further west than the preferred solution. ...Weather/Hazards Highlights... The leading front of the deep 950 mb low in the central Gulf on Friday will plow into much of the Gulf Coast Thursday and Thursday night. Expect heavy mountain snow and lower-elevation rain with frontal passage. Along-front easterly flow into the Kenai and Chugach mountains of the eastern Kenai Peninsula will result in the same hazardous weather. The heavy precipitation hazard was therefore expanded west to include much of Southcentral's Gulf Coast. Brief periods of high winds are likely through the Panhandle, the inner channels, and the higher elevations along the Gulf Coast, as well as through the gaps in the AKPen and eastern Aleutians due to the strong return northerly flow. As mentioned above, extreme instability between the 500 dm low aloft and the relatively warm mid-40s Fahrenheit SSTs will support thunderstorms with the rain and subsequent upslope into the mountains with the leading occluded front. && Wegman 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