Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
644 PM EST Wed Mar 04 2020
Valid 12Z Sun Mar 08 2020 - 12Z Thu Mar 12 2020
...Overview and Guidance/Predictability Assessment...
A broad upper level ridge will be situated over the Aleutians and
the Gulf region to begin the forecast period on Sunday, with a
positively tilted trough and a surface low reaching the Aleutians
and the Gulf region by the early part of next week. Surface high
pressure continues to govern the weather pattern over the northern
Interior region and the Arctic Coast. A second low pressure
system likely begins approaching the Bering Sea region on
Wednesday.
The 12Z models and ensemble means were in generally good agreement
to start. The main feature of interest will be a low over the
Bering Sea that will cross the Aleutians and traverse the northern
Gulf region. The EC mean is initially a little farther to the
northwest, but becomes closer to the model consensus by day 5 and
6 once it reaches the northern Gulf. More noteworthy differences
appear by Wednesday with the ECMWF tracking the low quicker along
the Panhandle region while the GFS and ensemble means are slower
with its progression. It remains the case that the ensembles were
in better agreement than the deterministic guidance, and therefore
a greater weighting towards the means by this time period was
incorporated. A weaker storm system will likely cross the Bering
by next Wednesday, although confidence on the details is limited
at this time with the GFS suggesting a more southern track and the
ECMWF well to the north.
...Weather Highlights/Threats...
Precipitation is expected to increase across the Panhandle region
by Monday and into Tuesday with the Gulf low slowly approaching
from the west. Precipitation could be locally heavy with enhanced
moisture convergence, especially for windward terrain.
Temperatures will continue to be frigid for the northern third of
the state with subzero highs expected north of the Brooks range.
Hamrick
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
Hazards:
- Heavy precipitation across portions of the Alaska Panhandle to
the coast sections of southern Alaska, Sun-Tue, Mar 8-Mar 10.
- Heavy snow across portions of southern Alaska, Mon, Mar 9.
- Much below normal temperatures across portions of eastern
mainland Alaska, Sat, Mar 7.
- Much below normal temperatures across portions of western
mainland Alaska, Mon-Tue, Mar 9-Mar 10.
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