Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
328 PM EDT Mon May 13 2019
Valid 12Z Fri May 17 2019 - 12Z Tue May 21 2019
Troughing is favored over the Gulf of Alaska through the period
with ridging nosing into eastern/northeastern Alaska this weekend
into next week. Aside from one main area of low pressure, many
smaller shortwaves will rotate around the broad circulation along
50N which will generally confine precipitation to southern coastal
areas. The ensemble means have been much more consistent
(especially the ECMWF ensemble mean) with the overall pattern as
the short wavelength features are inherently hard to predict this
far out. Daily changes to the forecast have been mitigated via the
ensembles and generally the nearest deterministic model(s). 12Z
GFS/FV3-GFS and 00Z ECMWF were in good agreement to start as the
best-modeled system turns toward the far southern Gulf waters
Saturday. Consensus now has the low stalling then shifting back
southeastward rather that wrapping back northwestward into the
Gulf. Thereafter, another weaker system will travel well south of
the area as the upper trough changes shape and allows higher
heights to push northwestward out of the Yukon into eastern
interior areas. Back to the west, ridging toward the eastern coast
of Kamchatka may allow for some height falls to slip southeastward
into the Bering but the 00Z ECMWF appeared much too aggressive
compared to the ensemble consensus.
Temperatures should rise through the period especially through the
interior, into the 60s to the low 70s while 50s/60s are forecast
for coastal areas. Precipitation will generally be light with no
direct mid-latitude moisture connection as it will be focused into
SW Canada and the Pacific Northwest.
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
No significant hazards are expected over Alaska during this
forecast period.
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