Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
326 PM EDT Thu Apr 18 2019
Valid 12Z Mon Apr 22 2019 - 12Z Fri Apr 26 2019
...Guidance/Predictability Assessment and Weather
Highlights/Hazards...
Model variance grows quickly next week, but mainly with small-mid
scale offshore lows. GEFS/ECMWF ensembles seem reasonably
compatable early-mid next week, but even the means become quite
varied by later next week with potential renewed Pacific storm
developments to the south of the Aleutians. The WPC Alaskan medium
range product suite was mainly derived from a model/ensemble
composite blend Monday, then ensemble means thereafter amid
growing forecast spread.
However, there is decent confidence the pattern next week will be
highlighted by a deepened and meandering storm/low set to spin
heavy winds/high seas and heavy precipitation over the northern
Gulf of Alaska and southern Alaska, especially in favored terrain
early week. There will also be an additional coastal focus into
southeastern Alaska with development of a persistent and moist
onshore fetch. This will overall be supported by amplified mean
closed low/troughing aloft over the Gulf, with periodic upstream
reinforcement from upper trough energies digging down over
unsettled western/southwest Alaska and the Bering Sea. There is
also some signal for renewed storm potential over the northern
Pacific along/south of the Aleutians by mid-later next week. Given
much greater uncertainty, WPC progs only offer conservative system
representation at this time.
Schichtel
Bullet points from the WPC Days 3-7 Hazards chart can be found at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
- Heavy precipitation for parts of the Alaska Panhandle and
mainland Alaska, Sun-Mon, Apr 21-Apr 22.
- Heavy precipitation for parts of the Alaska Panhandle, Tue-Wed,
Apr 23-Apr 24.
- High winds for parts of the Alaska Panhandle and mainland
Alaska, Sun Apr 21.
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