Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
723 PM EDT Thu Jun 30 2022
Valid 12Z Mon Jul 04 2022 - 12Z Fri Jul 08 2022
...Overview and Guidance/Predictability Assessment...
Upper pattern will slowly transition toward more troughing out of
the Bering Sea next week as the upper high over NW Canada retreats
to the southeast. This will introduce cooler temperatures to the
mainland with increased rain chances. The ensembles were in very
good agreement through the end of next week, with expected
differences in the speed and depth of the incoming trough per the
cluster analysis, but that is well within the typical spread for a
7-8 day forecast. Thus, a multi-model/ensemble blend was
sufficient for the forecast. The 12Z GFS and ECMWF paired best
with the ensemble consensus, while the 12Z Canadian was mostly in
line for the first couple of days. The 12Z UKMET diverged from the
consensus before day 4, and was not preferred.
Surface pattern will likely be devoid of any significant/robust
system, and will rather feature a lead baroclinic boundary
progressing eastward in tandem with the upper trough, with a wave
of low pressure possible along the front south of the Aleutians
that may lift toward the AKPen and Southcentral late next week.
Deterministic models differ on its strength but favor a weak area
of low pressure as of the latest cycle. With increased uncertainty
in these details by next Thu/Fri, incorporated about a 50%
weighting of the ensemble means to balance the deterministic
GFS/ECMWF. Confidence is above average overall. 19Z NBM was a good
starting point for the sensible weather grids.
...Weather and Hazard Highlights...
Well above normal temperatures at the start of the period (Mon Jul
4) over eastern Interior locations will trend back toward more
typical values by midweek as cooler temperatures spread eastward
from the Bering. By late in the period, much of the mainland will
see below normal temperatures. 70s and low 80s will be replaced by
upper 50s to around 70 degrees through the period.
Dry weather will prevail for the first half of the period as the
upper ridge axis moves through. By midweek, rain chances will
increase as southwest flow brings in more moisture from the North
Pacific. Slowly-moving frontal boundary just southeast of the
Aleutians may enhance rainfall over Kodiak into the southeastern
Kenai Peninsula to Prince William Sound, depending on the trough
orientation/strength and surface front. Regardless, most of the
state will see some welcome rain next week.
Fracasso
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
Hazards:
No significant hazards are expected over Alaska during this
forecast period.
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