Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
802 PM EDT Wed Jul 17 2024
Valid 12Z Mon Jul 22 2024 - 12Z Fri Jul 26 2024
...Somewhat wet pattern for the Aleutians and portions of the
Southeast Coast into the Panhandle...
...Overview...
A surface low pressure tracking north into the Gulf weakens as it
approaches the Panhandle region. This may spread some moisture
into at least the Panhandle, but models have backed off on any
sort of heavy rain threat. An upper ridge building eastward over
the mainland will promote a warmer trend for temperatures over
most areas aside from the Southcentral coast and Panhandle leading
to some of the hottest temperatures so far this season for several
locations. Along the southern periphery of progressive high
latitude flow, a mean frontal boundary may set up near the
northern coast early next week. Finally, a deep-layer low will
make gradual progress from the northwestern Pacific through the
western Aleutians and into the central Bering Sea, spreading a
broad area of rain across the region and perhaps eventually into
the southwestern mainland.
...Guidance Evaluation/Preferences...
The latest guidance continue to have a good handle on the synoptic
pattern, favoring deeper closed lows over the Bering and eastern
Gulf of Alaska. As noted the past few runs, the details on the
exact placement have varied but within the normal envelope of
spread for the longer range period. Consensus favors a somewhat
slower eastward progression of both the Gulf and Bering lows.
Followed continuity by starting with equal weighting of the
GFS/ECWMF/CMC/UKMET through Tuesday morning; beyond that, dropped
the UKMET and added the GEFS and EC ensemble means gradually to
help mitigate the smaller scale differences while also keeping
operational input to add detail where feasible.
...Weather/Hazards Highlights...
Most of the guidance depicts a surface low pressure system lifting
towards the Southern Coast and Panhandle region that will usher in
lighter QPF amounts each day. A northwestern Pacific low drifting
into the Aleutians and Bering Sea along with associated fronts
will spread areas of rainfall gradually eastward across the region
during the period. The leading edge of this moisture may reach
into the southwestern mainland. This system (along with the
northeastern Pacific low) may produce some brisk winds but with
speeds likely staying well below hazardous criteria.
Expect increasing coverage of above normal readings by the weekend
as an upper ridge builds over the mainland, but the Panhandle and
parts of Southcentral may see greater persistence of below normal
highs. Parts of the Mainland/Interior will have some of the
hottest temperatures of the season so far during this period,
rising into the upper 80s to lower 90s. The hot temperatures are
likely to stick around for at least 3-4 days. Southwestern areas
may also trend back below normal with the arrival of some
clouds/rainfall. Negative anomalies for min temperatures should be
more moderate early next week.
Campbell
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