Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
553 PM EDT Thu Jul 23 2020
Valid 12Z Mon Jul 27 2020 - 12Z Fri Jul 31 2020
...Overview and Guidance Evaluation...
Complicated pattern evolution in the northern stream/high
latitudes continues to plague model/ensemble consistency. Farther
south across the north central Pacific, seems that the guidance is
staring to come into better agreement, but still lacks a
good/solid consensus. Approach to the forecast was to use a broad
consensus, despite the differences, to start with a trend toward
only the ensemble means by next Wed. The deterministic models
clustered either quicker or slower than the ensemble means across
the Aleutians, and NW or SE of the ensembles over the
Arctic/Beafort. This suggested that the intermediate ensemble mean
consensus was desirable especially later in the period which
should minimize changes to the forecast.
...Weather Highlights/Threats...
Affects of the upper/sfc low in the Arctic/Beaufort will depend on
its proximity to the North Slope, and today's forecast was a bit
closer/stronger than 24 hrs ago. Thus, chances of breezy and
showery weather have increased for the North Slope and Brooks
Range early next week. To the south, locally heavy rain is
possible along and north of the Alaska Range Monday as the Gulf
upper low pulls away. Some squashed ridging moving in from the
west should dry out the interior a bit Tue-Thu. Frontal boundary
to the north will slowly press southward, bringing an increased
chance of showers and some storms with it. Temperatures will
generally be below normal over much of the state owing to the
upper trough/low and near to below normal heights and 850mb
temperatures, with the exception over southwestern areas where
brief ridging will pass through Tuesday.
Fracasso
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 rain across portions of the Alaska Panhandle and mainland
Alaska, Sun, Jul 26.
- Heavy rain across portions of mainland Alaska, Mon, Jul 27.
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