Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
619 PM EST Fri Nov 15 2019
Valid 12Z Tue Nov 19 2019 - 12Z Sat Nov 23 2019
...Very Stormy Alaskan Pattern Next Week...
...Guidance/Uncertainty Assessment...
Ensemble and model guidance seems fairly well clustered through
much of next week with the overall larger scale pattern evolution
aloft and for the most part, a number of potentially
deep/well-organized and heavy weather focusing embedded systems
within the flow. Forecast confidence is building for these deep
lows. The WPC product suite was primarily derived from a composite
blend of the 12 UTC GFS/ECMWF and 12 UTC GEFS/NAEFS/ECMWF ensemble
means. The blending process typically weakens offshore lows too
much, so these systems were manually adjusted to better fit a
patterm with seemingly good continuity and model upper support.
This forecast strategy was collaborated with the local Alaskan
forecast offices.
...Weather Highlights/Threats...
A leading deep surface low will track from the Aleutians/southern
Bering Sea to southwest/western Alaska Tuesday-Wednesday, then
gradally weaken inland Thursday. A second system follows on its
heels mid to late next week. Both systems offer a significant
maritime threat for high winds/waves, with moisture expected to
wrap onshore to sustain some threat of locally heavy
precipitation/winds in proximity to and well ahead of the deep
lows/frontal systems across the Gulf of Alaska and into southern
and southeast Alaska where the heaviest precipitation is expected.
The inland threat will focus over favored mountains and coastal
terrain.
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 precipitation across portions of the Alaska Panhandle and
mainland Alaska, Mon-Thu, Nov 18-Nov 21.
- High winds across portions of the Aleutians, Wed-Thu, Nov 20-Nov
21.
- High significant wave heights for coastal portions of the
Aleutians, Mon-Wed, Nov 18-Nov 20.
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