Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
657 PM EST Wed Feb 1 2023
Valid 12Z Sun Feb 5 2023 - 12Z Thu Feb 9 2023
...Pattern overview and Weather/Hazard Highlights...
The main focus in the extended forecast will be the approach of a
strong low from the North Pacific that'll head in the general
direction of Kodiak Island and the Kenai Peninsula late Sunday and
into Monday. There is the potential for widespread gale to storm
force winds over the open waters, and strong gusty winds for the
coastal areas. Strong onshore flow could easily result in some
coastal flooding at times of high tide. There remains a decent
signal for heavy coastal rain and mountain snow from the Kenai
Peninsula to the Chugach Mountains, with an inch or two of
rainfall near the coast. Strong gap winds are also a possibility
depending on how the low tracks. In terms of temperatures, the
greatest negative anomalies are expected from the Brooks Range to
the Arctic Coast, where readings could be up to 25 degrees below
early February averages Sunday through Tuesday, before a gradual
moderation trend ensues across this region. A trend to milder
conditions is likely across southern Alaska owing to increased
onshore flow.
...Model Guidance/Predictability Assessment...
The models are generally in good agreement across most of the
Alaska domain on Sunday across most of the domain, and are coming
into better agreement with respect to the big storm system moving
in from the North Pacific. The CMC remains on the eastern side of
the guidance, and the GFS a bit west of the consensus. There has
also been a trend for a stronger low with central pressures
possibly getting below 960 mb by 00Z Monday based on the UKMET,
ECMWF, and GFS. As the low weakens near the coast Monday night,
the CMC loses ensemble and GFS/ECMWF support for a trailing low
over the southern Gulf on Tuesday that reaches the southeast
Panhandle Tuesday night, and this scenario appears unlikely.
Model spread increases further going into Tuesday and beyond
across the North Pacific. The fronts/pressures forecast was
hedged more in the direction of the GFS/ECMWF through Tuesday
owing to the more substantial differences noted with the CMC. For
the middle of the week, more of the ensemble means were
incorporated into the forecast process.
Hamrick
Hazards:
- Heavy precipitation across portions of south-central mainland
Alaska, Sun, Feb 5.
- High winds across portions of south-central mainland Alaska,
Sun, Feb 5.
- Much below normal temperatures across portions of northern
mainland Alaska, Sat-Sun, Feb 4-Feb 5.
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