Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
534 PM EDT Fri May 31 2024

Valid 12Z Tue Jun 04 2024 - 12Z Sat Jun 08 2024

...Southern Mainland/Interior to Southeast Alaska Heavy
Precipitation Threat Tuesday/Wednesday...


...Guidance Evaluation and Preferences...

Favor a composite of well clustered 12 UTC GFS/ECMWF/Canadian
model solutions valid for Tuesday-Thursday in a pattern now with
seemingly above average predictability and detail. Opted to switch
preference to still quite compatible, but less detailed, 12 UTC
GEFS/ECMWF/Canadian ensemble means for Days 7/8 amid gradually
growing forecast spread, but especially with flow embedded surface
lows offshore over the Gulf of Alaska.

...Weather/Hazards Highlights...

A dynamic/closed upper low tracking to the south of Alaska will
lift into the eastern/northern Gulf of Alaska into
Tuesday-Wednesday. This will support a deepened surface low/system
in the Gulf of Alaska and a period of heavy precipitation and high
winds into Southeast Alaska given some enhanced ex-tropical
moisture influx. Easterly wrapping flow and impulses offer an
additional threat of heavy precipitation into eastern
SouthCentral/Alaska Range along with some enhanced rains to the
lee over the far southern Interior through at least next midweek.
Meanwhile, an upper low in the Arctic Ocean to the northwest of
the state looks to send upper low/trough energy southward into the
Bering Sea/West Coast and southeastward where there is growing
support for a deepened upper low/surface lows later next week,
while several weaker shortwaves traverse the southern side of this
mean troughing south of the Aleutians and towards the Gulf. Over
the Mainland itself, upper ridging should build warming.

Schichtel


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