Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
707 PM EDT Mon Jun 21 2021
Valid 12Z Fri Jun 25 2021 - 12Z Tue Jun 29 2021
...Rainy conditions forecast for Aleutians, Alaskan Peninsula,
Kenai Peninsula, and southeast AK/panhandle later this week...
...Guidance/Predictability Evaluation...
General model consensus shows a mean upper trough over the
Aleutians and southwest portions of the Mainland, with embedded
cyclonic circulations through most of the extended. There is the
typical spread in some of the specifics regarding timing, strength
and placement, but overall is in fair to good agreement. The WPC
Alaskan medium range product suite was a composite blend of 12Z
GFS/ECWMF/CMC/UKMET with light weighting of the 12Z GEFS mean/00Z
EC mean.
This blend yielded maintained a rather deep cyclone for June to
impact the eastern Aleutians to the Alaskan Peninsula late this
week before it gradually weakens and meanders gradually west
northwest into the southern Bering Sea over the weekend. Strong
integrated water vapor transport downstream from this storm
supports locally heavy rain from the Kenai peninsula over to
southeast AK/panhandle. This pattern is also favorable for
portions of the North Slope and surrounding locations to maintain
increased cloud cover and chances for rain near a stationary
frontal boundary. The potential for rain will linger into the
weekend before this boundary weakens.
A new cyclone is expected to develop at the base of the Bering Sea
trough in the north Pacific, impacting the adjacent Aleutians, up
to and including the AK peninsula next Monday, bringing another
round of wind and showers to these regions. Also during the course
of the extended period, temperatures are forecast to be above
seasonal average-- especially across the Panhandle as the ridge
over the north Pacific Ocean persists. Elsewhere, temperatures
will largely be near normal or slightly cooler than average.
Campbell
Hazards
- Heavy rain across portions of the Alaska Panhandle and mainland
Alaska, Thu-Sat, Jun 24-Jun 26.
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