Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
425 PM EDT Mon Aug 03 2020
Valid 12Z Fri Aug 07 2020 - 12Z Tue Aug 11 2020
...Guidance Evaluation...
The WPC Alaskan medium range product suite was primarily derived
from a composite blend of the 12 UTC GFS/ECMWF/Canadian models, 12
UTC GEFS/ECMWF ensemble means and the 19 UTC National Blend of
Models days 4-8. Guidance shows a reasonably similar larger scale
pattern, but quite a bit of embedded system variance. The
composite highlights the more predictable forecast components at
the cost of some less defined systems.
...Weather Highlights/Threats and Predictability...
Potent short range Bering Sea storm energies will weaken across
the Interior Friday into the weekend, but will remain an enhanced
rain focus. Ample storm energy in this stream and with less
certainty from the northern Pacific will meanwhile transfer
downstream into unsettled northern Gulf of Alaska waters to offer
additional enhanced rains, especially over favored southern and
southeastern Alaskan coastal terrain. Substantial uncertainty
remains with subsequent offshore lows, but there is some longer
range guidance signal for an organized low to reach the Aleutians
and southern Bering Sea in about a week. Otherwise, WPC progs only
show modest development and effect pending a stronger guidance
signal with subsequent model runs.
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
Hazards:
- Heavy rain across portions of the southern coastal areas of
Alaska, Thu-Fri, Aug 6-Aug 7.
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