Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
510 PM EST Wed Feb 26 2020
Valid 12Z Sun Mar 01 2020 - 12Z Thu Mar 05 2020
...Major Weekend Aleutians/Bering Sea Storm and Cold Interior
Temperatures...
...Guidance/Predictability Assessment and Weather
Highlights/Threats...
An upper-level high across eastern Siberia will allow for renewed
influence from Arctic shortwave energy down across much of
mainland Alaska, with another round of very cold temperatures
likely. Farther south, models and ensembles strongly agree that a
very active North Pacific storm track will offer strong potential
for a deep storm to cross the Aleutians to the southern Bering Sea
this weekend, lingering into early next week. This will bring a
major threat of hostile maritime conditions, with high winds and
heavy precipitation increasingly working to the Aleutians and the
Alaska Peninsula/Southwest Alaska. This will be supported by a
long fetch moisture plume. The 12 UTC GFS/ECMWF solutions seem
well in line with ensembles and WPC continuity.
Downstream energy transfers may support organzied triple point low
development over the northern Gulf of Alaska through early next
week. Stretching flow may support spread of moderate to terrain
enhanced heavy precipitation into southern/southeast Alaska. This
seems quite reasonable even though forecast spread and uncertainty
increases significantly next week. There also remains some
guidance signal in support of another organized low and associated
wet/unsettled weather approach up toward the Aleutians by Tuesday.
A subsequent but uncertain low track into the Gulf of Alaska and
an increasing southern/southeastern Alaskan precipitation pattern
may develop into next Wednesday/Thursday. A blend of the
reasonably consistent and compatable GEFS/ECMWF ensemble means was
coordinated with local WFOs to use for these longer time frames
amid growing model variance.
Schichtel
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
Hazards:
- High winds for parts of mainland Alaska and Aleutians, Sat-Sun,
Feb 29-Mar 1.
- Much below normal temperatures for parts of mainland Alaska,
Sat, Feb 29 and Tue-Wed, Mar 3-Mar 4.
- Much below normal temperatures across portions of mainland
Alaska, Sat-Wed, Feb 29-Mar 4.
- High significant wave heights for the coastal Aleutians,
Sat-Sun, Feb 29-Mar 1.
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