Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
727 PM EDT Thu May 27 2021
Valid 12Z Mon May 31 2021 - 12Z Fri Jun 4 2021
***Heavy rain likely for portions of southern Alaska***
...Overview and Guidance Evaluation...
The weather pattern from Memorial Day through the first few days
of June will be featured with a broad upper level gyre situated
over the southern Bering and eastern most Aleutians/northern Gulf,
with multiple shortwave perturbations pivoting around it along
with associated frontal boundaries. A narrow upper level ridge
axis should extend across the Interior and northwest Alaska with a
stationary frontal boundary across the north-central portion of
the state. In terms of the models, there appears to be better
than average deterministic agreement through early Wednesday,
mainly owing to the amplified pattern in place. The 12Z CMC is
closer to the consensus (but not available in time for the
fronts/pressures forecast) compared to the 00Z run. By the end of
next week, the 18Z GFS is farther east than the better clustered
CMC/ECMWF with the main upper low over the Gulf region. The WPC
forecast was primarily derived from a blend of the 12Z
ECMWF/GFS/00Z UKMET through Tuesday, and then a slight increase in
the ensemble means for Wednesday through Friday.
...Weather/Threats Highlights...
The persistent low pressure and onshore flow from the Alaska
Peninsula to the southeast panhandle region is expected to produce
multiple rounds of moderate to locally heavy rainfall for coastal
areas and nearby mountain ranges. Some locations could receive a
few inches of rainfall next week, especially across
topographically favored areas. Some showers can also be expected
across portions of the Interior, mainly for the middle of the
week. Temperatures are expected to reach the 60s and low 70s
across much of the Interior for highs, and remaining quite chilly
north of the Brooks range where highs should remain in the 30s and
40s.
Hamrick
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:
- Heavy rain across portions of the Alaska Panhandle and mainland
Alaska, Sun-Tue, May 30 - June 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