Southcentral and southwest Alaska forecast discussion
National Weather Service Anchorage Alaska
300 PM akdt Wednesday may 22 2013
Analysis and upper levels...
High pressure continues to hold firm over the central Gulf extending
north into southcentral Alaska this afternoon. A few weak
disturbances are rotating north and east from the Alaska Peninsula to
southwest Alaska bringing periods of rain to the southwest Mainland
and skirting southcentral with some light showers...otherwise just
mostly cloudy conditions over southcentral.
Out west...upper level low remains over the west-central Bering with
a nearly stacked surface front with embedded weak surface lows. A
second front extends south across the eastern Bering and will move
north through the Mainland tonight.
Model discussion...
Models are in good agreement synoptically. There are some speed
differences with respect to a moderate strength low forecasted by
models to move north from the Pacific Ocean toward the central and
eastern Bering Sea late Thursday through Saturday. The GFS and NAM
models are slower while the European and Canadian global models are
faster. The slower GFS solution was preferred for this forecast
package.
Short term forecast...
Southcentral...
High pressure will win out over most of southcentral and keep most of
the active shower activity confined to the Susitna Valley and Kodiak
Island...with a few showers affecting the western Kenai Peninsula and
perhaps some isolated showers in the vicinity of Anchorage and
Matanuska Valley. Otherwise...just middle to high level cloudiness
expected over the region the next couple of days before a return to
sunnier and drier conditions toward the weekend. Temperatures will
continue their slow trend upwards most days...especially so for the
Copper River basin.
Southwest Mainland...
Upper level trough will push a front through the region tonight with
much drier conditions behind it for Thursday into Friday...especially
inland.
Bering Sea/Aleutians...
Low stratus...patchy light rain or drizzle...and light winds will
continue across most of the Bering through Thursday. An increase in
winds and rain will result from low pressure strengthening as it
approaches the central and eastern Aleutians from the south-southwest
late Thursday and then moves into the Bering Sea on Friday. Some low
end gale-force winds are possible with the front along the northern
edge of the system affecting the Alaska Peninsula...eastern
Aleutians...and central and eastern Bering Sea late Thursday through
Friday.
Long term forecast...
A more typical climatological pattern for may has emerged and will
result in normal to above normal temperatures for southern Alaska
this weekend through early next week. With the increased sunshine and
instability will come an increased chance for diurnal showers to form
over the mountain ranges especially toward the interior by the
weekend. The unsettled areas will be the climatologically favored
areas this time of year...the Bering Sea extending east into the
North Pacific south of the Gulf of Alaska.
Aer/alu...watch/warning summary
public...Flood Warning...152
marine...none.
Fire weather...Fire Weather Watch 141 for low relative humidity.
Cirrocumulus may 13
