Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
309 PM EDT Mon Oct 14 2019
Valid 12Z Fri Oct 18 2019 - 12Z Tue Oct 22 2019
...Guidance/Predictability Assessment...
Guidance differences have increased some compared to the last few
days with respect to small-mid scale weather focusing systems
despite a still reasonably similar and energetic larger scale
pattern evolution through medium range time scales. Prefer to
still include some model with ensemble guidance for better detail
and greater system strengths consistent with average
predictability, but highly favorable upper trough/jet energy in an
active/stormy pattern. The 12 UTC GFS/00 UTC ECMWF overall seem
most compatable with GEFS/ECMWF ensembles. Accordingly, the WPC
Alaskan medium range product suite was derived from a composite
blend, weighing ensembles greater by day 7/8 amid growing system
uncertainty. This solution maintains decent WPC continuity as
collaborated with the Alaskan NWS forecast offices.
...Weather/Hazards Highlights...
It remains the case that the infusion of the extratropical remains
of former western Pacific super typhoon Hagibis into the Bering
Sea well offshore Alaska will prolong unsettled weather as the
system meanders under a closed upper trough. Unsettled conditions
will persist from the Aleutians to southwest Alaska underneath in
strong flow. Expect more modest conditions into western Alaska on
the periphery of a lead and lingering low spinning over the
eastern Bering Sea, with max supporting energies tranferring into
the Gulf of Alaska. Meanwhile, these 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. There also remains a good guidance signal for two
additional deepening low approaches from the south of the
Aleutians northeast across the Gulf of Alaska next weekend into
next week in a continuing stormy pattern. This again offers a
threat of heavy precipitation for southern/southeastern Alaska
into early next week.
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
Alaska Hazards:
- Heavy precipitation for the Alaska Panhandle and southern
Alaska, Sun-Mon, Oct 20-Oct 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