Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
245 PM EST Sat Feb 23 2019

Valid 12Z Wed Feb 27 2019 - 12Z Sun Mar 03 2019

Strong upper high will only slowly nudge eastward next week into
next weekend as the storm track remains through the Bering Sea
into the Arctic. Models/ensembles agree on the longwave evolution
but still differ on staying power of the upper high (prefer the
ECMWF ensemble which maintains it longer) and the speed of the
Bering systems (which has been woefully inconsistent).

Preferred a blend of the 12Z GFS with the 00Z ECMWF and 00Z ECMWF
ensemble mean which clustered fairly well with the lead system in
the Bering on Wednesday (though continued quicker than the
previous two days' forecasts) which will head north across
northeastern Russia into the Arctic as its cold front gets hung up
along the western coastline from the AKPen through Seward
Peninsula into the Chukchi Sea. By the weekend, still prefer the
ECMWF ensemble mean which was generally stronger with the upper
high than the GEFS mean and was preferred back into the Bering
with what looks to be a rather robust system for next Sat/Sun. All
models over the past 2-3 cycles have shown a sub ~980mb system
nearing the western Aleutians late in the period.

Most of the state will remain precipitation-free under the upper
high with rain/snow confined to the Aleutians and into western
Alaska. Temperatures will be mostly above average but likely quite
variable through the interior due to inversions in the thermal
profile with little mixing. The greatest temperature anomalies
will likely occur across the North Slope into northwestern Alaska
where temperatures may exceed 25-35 deg F above average owing to
sustained southerly flow over lower/flatter elevations.
Temperatures over the Panhandle may be slightly below average due
to northeasterly/easterly flow out of Canada, especially next
weekend as the upper high slips northward and allows a cool push
of air to leak southwestward out of the Yukon.

Fracasso


WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can be found at:

http://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
http://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
http://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html