Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
150 PM EDT Sun Oct 13 2019
Valid 12Z Thu Oct 17 2019 - 12Z Mon Oct 21 2019
...Guidance/Predictability Assessment...
Model differences remain with embedded small-mid scale weather
focusing systems despite a reasonably similar larger scale pattern
evolution through medium range time scales. Prefer to include some
model with ensemble guidance for better detail and greater system
strengths consistent with average predictability, but highly
favorable trough/north Pacific jet energy support aloft in an
active/stormy pattern. The 12 UTC GFS/00 UTC ECMWF seem most
compatable with GEFS/ECMWF ensembles, so the WPC product suite was
derived from a composite blend. This solution maintains good WPC
continuity as collaborated with the Alaskan NWS forecast offices.
...Weather/Hazards Highlights...
The infusion of the potent extratropical remains of western
Pacific super typhoon Hagibis into the Bering Sea well offshore
western Alaska will prolong unsettled weather as the system
meanders under a closed upper trough, with moderate precipitation
working into western Alaska. Meanwhile, system energies will
consolidate over the Gulf of Alaska into late week and support
deepened low developments that will threaten maritime interests
and bring enhanced precipitation into southern and southeast
Alaska. The lead system may also tap tropical moisture from the
remnants of Tropical Storm Ema that is now west of Hawaii.
Predictability is lower at longer time frames, but there is still
a growing guidance signal for additional deepening low approach
from the south of the Aleutians northeast across the Gulf of
Alaska next weekend in a continuing stormy pattern.
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
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