Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
301 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 days next week, 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.
There is though still decent confidence the pattern over the next
week will be highlighted by a deepened and meandering storm/low
set to spin heavy winds/high seas and heavy precipitation next
week over the northern Gulf of Alaska and southern Alaska,
especially in favored terrain. There may also be additional
coastal focus into southeastern Alaska with potential triple point
developments and moist onshore fetch. This will overall be
supported by amplified mean closed low/troughing aloft, 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