907
FXAK02 KWNH 182115
PMDAK

Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
414 PM EST Sat Jan 18 2025

Valid 12Z Wed Jan 22 2025 - 12Z Sun Jan 26 2025

...Heavy precipitation across southeast Alaska and the Alaska
Panhandle...


...General Overview with Model Guidance Assessment...
The general flow pattern features an approaching upper trough
trying to split around and partially erode ridging across eastern
AK and northwest Canada.  This should maintain periods of enhanced
onshore flow across southeast AK and the AK Panhandle, keeping
them wet from mid next week through next weekend.  Detail issues
remain, such as whether or not the trough trying to erode the
downstream ridge in the eastern portion of the domain remains
phased or splits in two.  Hedged towards the idea of the trough
splitting with a concept of an upper low near the AK
Panhandle/Aleutians late in the forecast periods.  The pressures,
winds, 500 hPa heights, fronts, PoPs, and QPF were primarily based
on the 12z runs of the UKMET, Canadian, GFS, and ECMWF, with some
12z NAEFS/00z ECMWF ensemble mean included later on to deal with
the usual detail issues, in this case with the upper trough.  The
remainder of the grids were based more towards the 19z NBM.


...Weather/Hazards Highlights...
The main story will be the heavy precipitation across southeast AK
and the AK Panhandle, with local amounts in the 5-10" range
forecast between mid next week and next weekend.  As the upper
trough slowly edges into western AK, a prolonged period of heavy
snow is possible.  The eastern interior will be driest, more under
the remnant ridging.  Due to the general amplified pattern over
North America (ridge western continent and trough eastern
continent), temperatures will be well above average across the
state, with 20-30F warm anomalies common early on for the west and
10-20F positive anomalies common in eastern AK and the AK
Panhandle early on/mid next week.  The warm anomalies should
slowly erode with time as the upper level trough either makes
headway across western AK, or splits.  Should it split in a more
pronounced fashion, the forecast would cool down across the North
Slope and interior as we get closer to the time of verification on
later model runs/succeeding days as the cold front moving across
AK could pick up its forward progress to the east and southeast.

Roth


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

$$