Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
324 PM EDT Fri May 03 2019
Valid 12Z Tue May 07 2019 - 12Z Sat May 11 2019
Ensembles still show upper ridging currently south of the Gulf of
Alaska to remain in place through most of next week, but have now
all shifted to show the ridge breaking down around next Friday.
The deterministic models have also showed this trend (or likely
have led the way of their ensembles) but with increased spread in
the surface waves along the wavy front moving slowly eastward
through the Gulf. Trying to time/track these embedded features has
been difficult and preferred to rely on a best consensus of the
12Z GFS/00Z ECMWF and their ensemble means given the changes of
the weaker features. Still expect several waves of low pressure to
ride northward along the boundary into, at first, southwestern
Alaska then into Southcentral before the whole front finally moves
eastward into the Panhandle around next Friday. This would allow
the next system to move toward the Aleutians next Fri/Sat but the
ensemble spread was large. Consensus approach yielded a position
near the forecast yesterday which was prudent for now. To the
north, non-ECMWF models take the small upper low in the Yukon near
or into far northeastern Alaska before turning back to the east,
and preferred to maintain this thinking rather than the westerly
track of the 00Z ECMWF.
Temperatures will increase over most of the state but high
temperatures may be tempered over Southcentral due to the cloud
cover. Precipitation will focus over the western side of Cook
Inlet eastward to Prince William Sound but with a bit more
progression eastward later in the week than indicated yesterday.
Still, locally heavy rain may be possible (elevation snow)
especially Tue/Wed dependent on the orientation of the
lower/mid-level flow and track of surface waves along the front.
In-house ensemble suggests 3-5 inches (local max 6"+) over the
eastern Kenai peninsula into PWS.
Fracasso
Bullet points from the WPC Days 3-7 Hazards chart can be found at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
- Heavy precipitation across portions of mainland Alaska, Tue-Wed,
May 7-May 8.
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