Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
430 PM EDT Sun Sep 22 2019
Valid 12Z Thu Sep 26 2019 - 12Z Mon Sep 30 2019
An increasingly amplified upper-level pattern is forecast to
dominate much of Alaska and the Bering Sea during the medium range
period. A dissipating occluded systems will spread some rain down
the Alaska Panhandle, with snow tapering off over the inland
sections of southern Alaska on Thursday. Model guidance is in
excellent agreement that a significant upper-level ridge will
build northward toward southern Alaska for the rest of the week.
This will allow a conduit of moisture to spread northward from a
cut-off low in the central Pacific into southwestern Alaska later
this week, possibly continuing into early next week. Global
models continue to show run-to-run variability on how fast the
cut-off low will move toward southwestern Alaska, leading to
uncertainty with respect to the timing of the precipitation. The
ECMWF has been on the fast side, while the latest 12Z run shows an
even faster arrival time. Apt to lean toward the 00Z EC mean to
handle the uncertainty. Therefore the WPC grids for Alaska were
derived based on a consensus of the 00Z ECMWF, 00Z EC mean, 06Z
GEFS mean, and 12Z GFS, with more weights given to the 00Z EC
mean. Precipitation should not be excessively heavy at a
particular instance but periods of rain can be expected to persist
late this week into the weekend across southwestern Alaska.
Nevertheless, storm total rainfall amounts could exceed 2 inches
by the weekend.
Kong
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