Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
640 PM EDT Mon Apr 27 2020
Valid 12Z Fri May 01 2020 - 12Z Tue May 05 2020
...Guidance/Predictability Assessment...
An upper high over northwestern Alaska will meander in place
during the first five days in May. This favors troughing from the
southern Bering along the Aleutians into the southern Gulf. The
models/ensembles have been generally stable the past several days
but have showed a bit more difference in timing today with the 12Z
GFS/GEFS quicker than the rest of the guidance out of the North
Pacific later this weekend. Farther east, in the Gulf and across
the Panhandle, the 12Z GFS was much more reasonable. The 12Z ECMWF
was favored overall which paired well with its ensemble mean, and
was used as the strong majority for the forecast next Sun-Tue. The
12Z UKMET has offered some agreement with the ECMWF in recent days
while the Canadian continues to be just a bit displaced from the
best consensus.
Focus will be over the southern Gulf/Northeast Pacific as a modest
system curls back northward and north-northwestward, blocked by
the upper high over the mainland. Its occlusion will likely push
northward through the Panhandle Saturday with perhaps a second
push as mid-level shortwaves rotate around the upper low. To the
west, old parent low will slowly fill over and just south of the
Aleutians as another system looks to enter the Bering early Mon.
Again, favored the guidance slower than the GFS which was a bit
slower than the forecast 24 hrs ago. Ensembles indicate this
system will move eastward or east-southeastward like its
predecessor several days prior.
...Weather/Threats Highlights...
Pattern remains rather unsettled for the Panhandle with multiple
waves of rain/snow near/ahead of the lead occlusion, though the
heavier rain/snow will likely be forced into British Columbia. The
Interior, by contrast, will be nearly precipitation-free owing to
the upper and sfc high. The Aleutians will see generally light
rain after Fri-Sat as the sfc low slowly weakens, and then a
renewed chance wit the next system next Mon-Tue. Temperature
anomalies will mostly hold in place with near normal readings for
most of the state but with the better chance of sustained above
average temperatures near the Bering Sea/Bristol Bay.
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
Hazards:
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