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