Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
626 PM EDT Wed Sep 29 2021
Valid 12Z Sun Oct 03 2021 - 12Z Thu Oct 07 2021
...Pattern Overview and Guidance/Predictability Assessment...
An active weather pattern can be expected during the extended
forecast period across the Alaska domain with two large storm
systems. The first will be a weakening low over the northern Gulf
this weekend, followed by a ridge axis building in from the north
Pacific. The second system will be the extratropical version of
what is now Typhoon Mindulle and this is forecast to cross the
Bering early next week, with a trailing low likely behind this
along with a reinforcing cold front.
Model guidance is initially well clustered with the Gulf system
for the weekend and also for the arriving extratropical low
through Monday night. The CMC is stronger and faster with a cold
front south of the Aleutians by Tuesday, whilst still comparable
with the parent surface low over the Bering. By the end of the
forecast period next Thursday, there is considerable model spread
regarding a potential triple point low forming over the Gulf
region, so leaning more towards the ensemble means seems prudent
for days 7 and 8.
...Weather/Hazard Highlights...
The heavy precipitation associated with the weakening Gulf low is
forecast to abate in intensity by Sunday morning across the
Panhandle region, although gusty onshore winds are likely to
persist until Sunday night when the pressure gradient lessens
further. A period of dry weather can be expected for most of the
state on Monday before precipitation associated with the Bering
Sea storm arrives across western Alaska by Tuesday. The main
concern will be strong winds and very rough seas across the
Aleutians and extending up the Alaska coast towards Nome.
Moderate to heavy snow can be expected for portions of the
Interior by the middle of next week as the moisture surge moves
inland. Temperatures are expected to initially be quite chilly
for most of the state through Tuesday before a slight moderating
trend ensues ahead of the Bering Sea storm system across the
western half of the state.
Hamrick
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Sat, Oct 2.
- High winds across portions of the Alaska Panhandle and mainland
Alaska, Sat, Oct 2.
- High winds across portions of mainland Alaska and the Aleutians,
Mon-Tue, Oct 4-Oct 5.
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