Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
711 PM EDT Mon Mar 23 2020
Valid 12Z Fri Mar 27 2020 - 12Z Tue Mar 31 2020
...Colder for much of the Interior...
Troughing will settle over the Interior during the medium range
period as upper ridging noses into the Bering Strait late this
weekend. A complicated evolution of a splitting upper low south of
Kamchatka may be coming into better agreement in the latest 12Z
deterministic models, and perhaps leading the ensemble means that
were straddled among differing solutions (and thereby much less
detailed). Though the past few days of runs have been fairly
inconsistent in how the unraveling upper low evolves, what has
been consistent has been the upper ridge/trough couplet across the
region by the weekend into next week. Aside from the 12Z UKMET
(too slow or too fast over different areas), the
GFS/ECMWF/Canadian provided a good starting point that still shows
an incoming system through the Bering Sea on Friday as an arctic
front dives southward toward the Alaska Range. That will settle
into the Gulf Saturday with another system south of the Aleutians
moving eastward. That western system has trended stronger but
should still remain just south of the island chain. Still
relatively low confidence there but likely much less impact to the
region than the prior system.
For next Sun-Tue, the 12Z Canadian moved the upper ridge much
farther eastward than the GFS/ECMWF and ensemble means (and
continuity) and was not preferred. Otherwise, trended toward much
more ensemble weighting as the upper ridge/high potentially breaks
off into the Beaufort Sea, allowing westerly flow across the
Bering and AKPEN. Elsewhere, the Interior will be generally drier
and remaining cold (temperatures 10-20 deg below normal) except
for the North Slope. The Panhandle will see the most
precipitation--one to three inches area-wide with more amounts
farther south near the main low or triple point of the several
systems.
Fracasso
Hazards:
- Much below normal temperatures across much of northern Alaska,
Fri, Mar 27.
- Much below normal temperatures across much of central, southern,
and eastern Alaska, Sat-Mon, Mar 28-Mar 30.
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
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