Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
601 PM EDT Sun Jun 28 2020
Valid 12Z Thu Jul 02 2020 - 12Z Mon Jul 06 2020
...Guidance/Predictability Assessment...
The WPC Alaskan medium range product suite for day 4/Thursday was
primarily derived from a blend of reasonably well clustered
solutions from the 12 UTC GFS/ECMWF/Canadian. Opted after
collaboration with Alaskan offices to switch to an ensemble mean
forecast plan days 5-8 in a period of rapidly growing system
forecast spread/uncertainty. The 00 UTC ECMWF ensemble mean
overall provided system developments more in line with a
compromise of the varied models than the 12 UTC GEFS mean, but
continuity is not stellar in either case.
...Overview and Weather/Hazard Highlights...
A weakening system will be in the process of ejecting over the
North slope and eastern Interior Thursday. Upstream, a Bering Sea
system will also work inland to western/northwest AK Thursday and
produce some organized rains. The weakening system will work
inland and force another front eastward across the North Slope and
Interior Friday, again with a chance to channel moisture and
generate unsettled and showery conditions with passage.
Meanwhile, a deeper low will lift slowly across the Bering Sea
Friday-next Monday and present a maritime wind/wave hazard. A lead
weather focusing front will be slow to shift over the Aleutians
toward western/southwest AK and the AKpen, with eastward motion
inhibited by a warming mainland upper ridge building over the
extended holiday weekend.
Schichtel
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