Southcentral and southwest Alaska forecast discussion
National Weather Service Anchorage Alaska
500 am akdt Sat may 25 2013
Analysis and upper levels...
Broad upper level trough over the Bering this morning with an
embedded low over the eastern Aleutians. Another closed off low is
over the southern Gulf of Alaska. Sharp upper ridges are centered over
Kamchatka and the alcan. The jet is following a near zonal great
Circle Route well south of Alaska. At the surface...a large low
pressure center is just south of the eastern Aleutians. Surface high
pressure is over the extreme western Bering....and most of Mainland
Alaska.
Model discussion...
Models are in agreement that the low south of the Aleutians will move
over Dutch Harbor and then retrograde past the pribilofs where it
will linger into the middle of next week. But before this
happens...when the low is near Dutch Harbor...it will spin off an
initial triple point low this evening that remains south of the akpen
and moves directly east. This will then consolidate into the main
triple point low south of Kodiak Island on Sunday. An easterly wave
will move along the northeastern flank of the triple point and bring
precipitation on Sunday to the north Gulf Coast...and areas just
across the chugach range. The thermal trough will remain in the
vicinity of the Alaska Range during this period...so some convection
may develop there on Sunday. High pressure will then build over the
northern Gulf Monday into Tuesday. The forecast utilizes the GFS and Gem in
the short term and transitions to wpc guidance in the extended.
Short term forecast...
In the west...small craft and gale force winds will accompany the low
over the eastern Aleutians. As the parent low retrogrades past the
pribilofs...rain or showers will persist through the beginning of the
week.
For southwest Alaska...as the low moves into the Bering rain will affect
coastal areas through sun. The remnants of the easterly wave will
then bring more showers across the Alaska and Aleutian ranges into early
next week.
Southeast of the Alaska Range will be dry except for sun into Monday when
the easterly wave brings rain to the coast. Some showers will also
cross the chugach and Kenai ranges into Sun night. Warm and dry
conditions then return for the early part of next week.
Long term forecast...
The west will be dry..but SW Alaska will have showers by middle week as the
thermal trough drops south into the area. These will also affect
southcentral.
Aer/alu...watch/warning summary
public...none
marine...gales 150 155
fire weather...red flag 141 will be issued later this morning
Ds may 13
