Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
641 PM EDT Wed Jun 28 2023
Valid 12Z Sun Jul 2 2023 - 12Z Thu Jul 6 2023
...Synoptic Overview and Sensible Weather...
A strong upper low just south of the eastern Aleutians Sunday
morning is forecast to lift northward across the Alaska Peninsula
and then Bristol Bay by late Monday. A second upper low is
expected to develop over the western Bering around this time and
then pivot around the decaying upper low near southwestern Alaska.
East of the big upper trough will be a downstream ridge axis
extending across northeastern mainland Alaska into the Yukon
Territory. Much of the eastern Gulf region should also be under
an upper ridge axis.
The storm system lifting north across the Alaska Peninsula Sunday
into early Monday is expected to produce heavy rain across the
windward terrain from Kodiak Island to the Kenai Peninsula and
portions of the Chugach Mountains, and then improving conditions
going into Tuesday. Temperatures are expected to be mild across
much of the Interior, with highs reaching well into the 70s and
even some lower to middle 80s possible across the Yukon Flats.
Readings mainly in the 60s are expected for the North Slope, and
upper 40s to lower 50s near the Arctic Coast.
...Guidance Evaluation/Preferences...
The 12Z model guidance suite is in good overall agreement on most
synoptic scale features for the upcoming weekend and into Monday,
so a general model blend suffices as a starting point in the
forecast process. Going forward into the middle of next week, the
CMC is northwest of the model consensus with the second closed low
near the Aleutians, but the agreement on its position is improved
compared to yesterday's forecast. By next Thursday, the ECMWF is
considerably stronger with a polar low north of the Bering Strait,
but otherwise reasonably close to the ensemble means elsewhere.
The use of the ensemble means increased to about 50% by next
Thursday.
Hamrick
Hazards:
- Heavy rain across portions of the Alaska Peninsula and the Kenai
Peninsula, Sun-Mon, Jul 2-Jul 3.
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