Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
653 PM EDT Mon Jun 28 2021
Valid 12Z Fri Jul 02 2021 - 12Z Tue Jul 06 2021
...Unsettled weather expected from portions of the Aleutians to
the South-Central Coast...
...Overview and Guidance/Predictability Evaluation...
The extended range begins Friday with an initially deep upper low
lifting north over the AK Pen region, and weakening into the
Bering Sea. This occurs as the next upper low deepens and drops
south into the western Aleutians. Eastward progress of these lows
should be halted by an upper level ridge axis over eastern Alaska
and western Canada. There continues to be some bit of dispersion
amongst the guidance concerning a few shortwaves rounding the base
of the mean trough with the 12z GFS the strongest with one such
wave entering the Gulf early next week and low pressure swinging
into southern Alaska. The deterministic GFS, ECMWF, and CMC plus
the means, created a good starting point for early in the period.
Thereafter, removed the 12z GFS in favor of more of the ensemble
means which are a good middle ground solution with some placement
issues on the next Bering Sea closed low days 6 and 7.
...Weather/Threats Highlights...
Unsettled weather will continue into Friday from eastern parts of
the Aleutians into the AK Peninsula and Kodiak island with periods
of showers, some locally moderate to heavy, and gusty winds as a
frontal boundary moves into and weakens across the region.
Moisture should also extend northward into parts of the western
mainland bringing rainfall to the region during the weekend,
though placement of any potential heavy rainfall remains
uncertain.
As upper level ridging remains fairly persistent across eastern
Alaska, especially the first half of the period, east-central AK
should be the warmest with highs in the 70s and 80s. Elsewhere
across Alaska should be near or below normal underneath mostly
cloudy skies and mean upper level troughing.
Santorelli
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
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