Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
139 PM EDT Sat Oct 12 2019
Valid 12Z Wed Oct 16 2019 - 12Z Sun Oct 20 2019
Guidance continues to show stormy flow near Alaska. The better
clustering of model and ensemble forecasts at medium range time
scales offers some improved forecast confidence, but differences
remain with embedded small-mid scale weather focusing systems.
Prefer to include model with ensemble guidance for better detail
and greater system strengths consistent with predictabilityand
highly favorable trough/north Pacific jet energy support aloft.
The 12 UTC GFS/00 UTC ECMWF seem suprisingly compatable with each
other and ensembles and the WPC product suite was derived from
this composite blend. This maintains good WPC continuity.
The infusion of the potent extratropical remains of super typhoon
Hagibis into the Bering Sea well offshore western Alaska will
prolong unsettled weather as the system meanders under a closed
mean upper trough, but with modest precipitation working onshore
into western Alaska. Meanwhile, system energies will consolidate
over the Gulf of Alaska into mid-late next week and support
deepened low developments that will threaten maritime interests
and pump enhanced precipitation into southern and southeast
Alaska. Upstream,re-newed storm developments underneath the Bering
Sea meandering Hagibis extratropical low will meanwhile threaten
the Aleutians and southwest Alaska/Akpen next midweek with highly
unsettled conditions. This system is stated to work ernestly into
the Gulf of Alaska in the wake of the lead system, with similar
results. Predictability is lower at longer time frames but there
is a growing guidance signal for additional deepening low approach
from the north Pacific to the south of the Aleutians downstream to
the Gulf of Alaska in about a week 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