Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
359 PM EDT Sun Jul 14 2019
Valid 12Z Thu Jul 18 2019 - 12Z Mon Jul 22 2019
An upper low slowly moving eastward through the Arctic Ocean will
be the main focus for the interior/northern areas of the 49th
state. This will gradually introduce lower heights to much of the
mainland north of Southcentral as heights build through the Bering
Sea. An upper low will exit the Panhandle Thursday but lingering
troughing will be maintained south of the Gulf. The
models/ensembles largely handle this evolution well but detail
differences plagued the deterministic models in recent runs.
However, the 12Z GFS and 00Z ECMWF offered enough compatibility to
be used in the blend with the 00Z ECMWF ensemble mean. The recent
GEFS means have been less consistent across the north with the
incoming troughing, flattened by spread in the members. Given the
relative stability and trend (to more troughing) in the ECMWF
ensemble mean, a blend with the GFS/ECMWF offered a good starting
point. To the south, GFS runs from 24 hrs ago have abandoned the
more robust surface wave development late next week but the 12Z
GFS again showed such development early next week. By then, this
may be plausible given the pattern shift but was only depicted as
a weak wave well south of the region.
Pattern favors near to above average temperatures in offshore flow
early in the period over Southcentral but near/below average
across the North Slope and Panhandle due to lowering heights
(north) and precipitation (both areas). Though the heaviest
precipitation may be over the Panhandle, the North Slope could see
the heaviest relative precipitation given the lower climo values.
Elsewhere, the Alaska Range will see scattered showers with
enhancement as the baroclinic zone approaches.
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
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