Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
350 PM EDT Thu May 23 2019
Valid 12Z Mon May 27 2019 - 12Z Fri May 31 2019
Model guidance continues to show decent agreement on the synoptic
evolution in and around Alaska through the medium range period.
The upper-level pattern continues to favor a blocking ridge over
mainland Alaska and into the Northeast Pacific, steering occluded
cyclones toward the central and eastern Aleutians where they
gradually weaken and dissipate. Despite large spread in the model
solutions downstream across the Northeast Pacific into the west
coast of North America, model ensembles show very good agreement
on an occluded cyclone to meander in the vicinity of central to
eastern Aleutians for a good part of next week. This will allow
unsettled weather to continue across much of the Aleutians into
the southern part of mainland Alaska, where heavy rain is possible
near the immediate coast. The blocking ridge over the Northeast
Pacific should begin to nudge eastward as the next occluded
cyclone approaches the central Aleutians from the south early
next week. A consensus of the 00Z EC mean and the 06Z GEFS
together with a small amount of the 12Z GFS and 00Z ECMWF were
used to generate the WPC grids for Alaska for Days 7-8. The
operational solutions generally place the center of the cyclone
farther south of the Aleutians than their ensemble means. The
blend of these models yielded solutions that agree very well with
yesterday's WPC forecasts. The resulting cyclone center meanders
from central to eastern Aleutians through the middle of next week
into Friday. More operational solutions from the 12Z GFS and 00Z
ECMWF were incorporated for Days 4-6.
Kong
Hazards:
-Heavy precipitation across portions of mainland Alaska, Sat-Tue,
May 25-May 28.
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