Scientific Forecaster Discussion
Southcentral and southwest Alaska forecast discussion
National Weather Service Anchorage Alaska
200 PM akdt Tuesday Mar 11 2014
Analysis and upper levels...
the mean trough position is located just west of Mainland Alaska.
The central upper low in this trough is centered over the northern
Bering Sea. There is a short-wave trough pushing through northward
through south central Alaska...and another over just southwest of
southwest Alaska. There is a low south of the western Aleutians
moving east...pushed along by a nearly zonal jet stream across the
the numerical models are in good agreement through 36 hours
(wednesday afternoon) with just some minor disagreements on
location/strength of low that will be south of the Alaska Peninsula
later Wednesday. Divergences then become larger through the rest of
the forecast (to 84 hours or Friday afternoon). Confidence in the
over-all pattern is good...offset by the uncertainty of the smaller
details gives a forecast confidence of near normal.
Short term forecast...
for south central Alaska...the short-wave trough over the area will
slowly move through tonight.The short-wave off the southwest coast
will push into south central Wednesday morning and then through the
area Wednesday afternoon. These will bring a good chance of
precipitation with rain/snow changing to mostly snow by morning with
cold air from southwest Alaska wrapping around the low. Total
precipitation amounts will be fairly light for most areas as the
moisture is somewhat limited.
The main front associated with the next low...currently south of the
western Aleutians...will push into south central Alaska on Wednesday
afternoon. This will bring a slug of decent precipitation to coastal
areas...with more limited precipitation inland due mainly to
downslope factors. Winds will increase again along Turnagain Arm and
higher elevations...possibly approaching warning levels. This system
will continue to affect the area through Friday.
For southwest Alaska...decent chances of precipitation will continue
through tonight...then taper off behind the southwest coast
short-wave as it moves through the area. Frontal precipitation will
move into southern portions of the area Wednesday afternoon and
spread north through Wednesday night. This system will merge with
the northern Bering upper low...which will slowly slide southeast
through Friday. As a result...good chances of precipitation and
fairly cold temperatures will continue to affect the area through
public...High Wind Warning 101.
Marine...Storm Warning 119 155.
Gale Warning 120 125 130 131 132 138 150 160 165 170 172
176 177 178 180.
Heavy freezing spray 160 179 180.
Ludwig Mar 14