Area Forecast Discussion - SouthCentral and SouthWest


FXAK68 PAFC 252355
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
355 PM AKDT WED MAY 25 2016
.ANALYSIS AND UPPER LEVELS...
An upper level ridge currently dominates the eastern and central
Bering and southwest mainland. Fog and stratus cover much of the
Bering and continues to push into the southwest mainland due to
persistent westerly flow. The Alaskan Range is preventing this
stratus from surging eastward. As a result, fairly mild conditions
are occurring across south central Alaska today with just a thin
veil of cirrus clouds. Meanwhile a well organized low pressure
system is centered in the western Aleutians near Shemya. An
associated low level jet is bringing gusty winds and steady rain
to the central Aleutians.

&&
.MODEL DISCUSSION...
Models remain in relatively good agreement in the short term as
the upper level ridge continues to amplify and push westward.
Models show more disagreement towards the long term as an upper
level wave over the eastern gulf pushes westward into south
central on Sunday.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)..
A building ridge over the eastern Bering and southwest Alaska
will amplify into Southcentral through Friday. A moisture
connection to a large western Bering low is spreading high clouds
over Southcentral, but this moisture tap will diminish by Friday,
allowing for clearing skies and continued warming temperatures.
With rapidly building high pressure inland, this will allow for
the development of a northerly offshore pressure gradient. All
areas of Southcentral will warm up including coastal locations.
Showers will be possible along the Talkeetna Mountains, Wrangell
Mountains, and Alaska Range through Thursday before clearing out.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...
Cloud cover and showers over the area will begin to diminish this
evening in advance of approaching ridging from the Bering Sea.
This ridging will move overhead and strengthen on Thursday,
allowing for sunny skies, warming temperatures, and light winds.
Ridging will then persist into Friday, leaving allowing
interior temperatures to continue to warm into the 70's with weak
offshore flow and sunny skies.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...
Most of the activity over the region will remain confined to the
western Bering/Aleutians as a weakening gale force front will
continue to remain nearly stationary over the area this evening.
This will bring a few strong wind gusts to mainly the Adak area
this evening before winds and rain will diminish throughout the
region as the associated low moves northward into the northwest
Bering and dissipates. As this happens, winds throughout the
region will fall below small craft by Friday morning...and remain
there into this weekend with clearing skies.

&&

.LONG TERM FORECAST (Days 3 through 7)...
On Day 3, models remain in fair agreement with a pair of weak lows
over the Aleutians and a northwest to southeast orientated ridge
over the Western Gulf of Alaska. Starting late on Day 3, models
begin to diverge with a fairly weak-flow pattern developing over
the region. Models are unanimous in developing a surface low on
Sunday southwest of Shemya, but the model agreement ends there
with the GFS developing a low that meanders just south of the
Western Aleutians through the end of the period before washing out
and the EC aggressively developing a 980 mb low that migrates into
the Southcentral Bering Sea. With this wide spread, the extended
forecast settled heavy on WPC Guidance, which was mainly based on
the 00Z EC Ensemble with some 00Z EC deterministic data. 

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Gale Warning 173 175 176.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...en
SOUTHCENTRAL ALASKA...ja
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...dek
LONG TERM...rf