Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
620 PM EDT Wed Jun 16 2021
Valid 12Z Sun Jun 20 2021 - 12Z Thu Jun 24 2021
...Guidance/Predictability Evaluation...
The WPC Alaskan medium range product suite was primarily derived
from a composite blend of relatively well clustered guidance of
the 12Z GFS/CMC/ECMWF, along with some previous WPC continuity and
00Z ECMWF. Guidance forecast spread continues to indicate above
normal predictability on the synoptic scale pattern. Some more of
the GEFS and EC means was incorporated for next Wednesday and
Thursday to account for increasing model spread by this time.
...Weather/Threats Highlights...
The first storm system during this forecast period is expected to
affect the Gulf of Alaska region on Sunday, which will likely
produce unsettled maritime conditions along with periods of rain
from the Alaskan Peninsula to the southeast panhandle. A stronger
storm system builds south of the Aleutians and should track slowly
to the east for the beginning to middle part of next week. This
would result in an emerging maritime and regional threat to
monitor as an occluded surface low will most likely impact areas
from the Aleutians to the Alaskan Peninsula in a potentially much
wetter pattern toward the middle of next week for coastal areas.
The weather pattern is expected to become more amplified by the
Tuesday to Thursday time period as an upper level ridge builds in
across eastern Alaska, which is in response to the meandering
upper level gyre over the Aleutians. This will result in warm
temperatures across much of the Interior next week, especially for
those areas that have mostly clear skies.
Hamrick
Hazards:
No significant hazards are expected over Alaska during this
forecast period.
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