Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
539 PM EDT Wed Aug 24 2022
Valid 12Z Sun Aug 28 2022 - 12Z Thu Sep 01 2022
...Multi-day heavy rainfall threat for Southeast Alaska...
...Guidance/Predictability Assessment...
The 12 UTC GFS/ECMWF/Canadian/UKMET solutions now seem fairly well
clustered and reasonable for at least days 4/5 (Sunday/Monday) and
a composite seems to weed out the less predictable smaller scale
differences, bolstering forecast confidence. The still compatible
and reasonable GEFS/ECMWF ensemble means seem to then provide
better run to run consistent solutions into the longer term day
6-8 time frame than the models amid slowly growing forecast
spread. This plan maintains good WPC product continuity in an
active and amplified pattern. This includes a collaborated and
well depicted in guidance weekend to early next week heavy
rainfall threat for Southeast Alaska with fueling influence from
deep remnant moisture from current west Pacific Typhoon Tokage.
...Sensible Weather and Potential Hazards...
An active weather pattern for Alaska and vicinity is likely well
into next week. There remains a strong guidance signal indicating
that an amplified/closed upper low/trough and regenerating surface
lows/frontal systems will settle and refocus a main multi-day
storm focus over the Gulf of Alaska and into Southeast Alaska
Sunday through next midweek.
Additional storm energies will meanwhile consolidate well upstream
next week over the Bering Sea and work toward western/southwestern
Alaska by late period. There is more uncertainty with the complex
development of these individual systems, but overall offer a
threat for enhanced winds/waves and rainfall.
Schichtel
Hazards:
- Heavy rain across portions of the Alaska Panhandle and mainland
Alaska, Sat-Weds, Aug 27-Aug 31.
Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook 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