Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
550 PM EST Wed Nov 20 2019
Valid 12Z Sun Nov 24 2019 - 12Z Thu Nov 28 2019
Lower amplitude flow will be punctuated by a fairly robust Bering
Sea system next week. Some shifts in the recent model guidance
were handled by a blend of the 12Z GFS/ECMWF/UKMET to start. To
the south, there remains disagreement on how to handle a digging
trough that will likely split off an upper low, but may allow its
northern part to slide eastward toward/south of Hadai Gwaii.
For the Bering system, models have nudged a bit quicker overall to
bring the system toward the western coastline by early Tuesday.
Parent low may have a better chance of lifting northward given the
flow across the mid-latitudes that would be flatter/quicker with a
weaker sfc low. This may bring stronger southerly winds northward
toward the Seward peninsula than forecast 24 hrs ago. Introduced a
hazard area in light of the increased probabilities. Still expect
some portion of the front to slide into the Gulf next Wed/Thu and
move east on a rather zonal flow.
Southern system may stay south enough to not even affect the
southern Panhandle next Tue, with most of the energy lingering as
a closed low in the central Pacific. This would allow for a drier
period for the Panhandle after the initial trough Sun/Mon weakens.
Blend of the non-12Z Canadian guidance served well to start, with
a trend toward the 12Z ECMWF/GEFS mean and 00Z ECMWF ensemble
mean. 12Z ECMWF may be too aggressive with a piece of the
mid-latitude trough that moves into the Gulf but the 12Z GFS may
be too weak. Blended solution was used to mitigate future changes.
Fracasso
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 precipitation across portions of mainland Alaska, Mon-Tue,
Nov 25-Nov 26.
- Heavy precipitation across portions of mainland Alaska, Tue-Wed,
Nov 26-Nov 27.
- High winds across portions of mainland Alaska, Mon-Tue, Nov
25-Nov 26.
- High significant wave heights for coastal portions of mainland
Alaska, Mon-Tue, Nov 25-Nov 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