Gale Warning 156, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKST THU FEB 5 2009

.ANALYSIS AND UPPER LEVELS...
AT THE SURFACE A 1000 MB LOW IS LOCATED OVER PRINCE WILLIAM
SOUND...WITH A FRONT EXTENDING SOUTH THROUGH THE GULF OF ALASKA. A
982 MB LOW IS LOCATED JUST EAST OF SAINT MATTHEW ISLAND. A FRONT
EXTENDS OFF OF THIS LOW SOUTHWARD THROUGH THE CENTRAL ALEUTIANS. A
1000 MB LOW IS DEVELOPING IN THE SOUTHWESTERN GULF OF ALASKA.

IN THE UPPER LEVELS...A TROUGH AND WEAKENING CLOSED LOW ARE OVER THE
BERING SEA. A LOW AMPLITUDE RIDGE IS OVER THE GULF OF ALASKA AND
EASTERN MAINLAND. A 145 KT JET STREAK STRETCHES THROUGH THE
SOUTHWESTERN GULF OF ALASKA.

.MODEL DISCUSSION...
MODELS ARE IN DECENT AGREEMENT THROUGH THE FIRST 48 HOURS...BUT
DIFFERENCES BEGIN TO ARISE AFTERWARD. MAIN DIFFERENCES PERTAIN TO THE
STRENGTH AND POSITION OF A LOW DEVELOPING IN THE NORTH PACIFIC...AND
ITS SUBSEQUENT EVOLUTION BY THE START OF NEXT WEEK. DIFFERENCES ALSO
EXIST REGARDING THE EVOLUTION OF THE LOW CURRENTLY DEVELOPING IN THE
SOUTHWESTERN GULF OF ALASKA. MINIMAL CHANGES WERE MADE TO THE
EXISTING FORECAST PACKAGE PAST 60 HOURS...WITH A BLEND OF THE GFS/NAM
SOLUTIONS IN THE SHORT TERM.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...
THE WEAK LOW IN PRINCE WILLIAM SOUND IS DISSIPATING WHILE MOVING INTO
THE COPPER RIVER BASIN. LIGHT SNOW SHOWERS ASSOCIATED WITH THIS LOW
ARE STILL AFFECTING SOME AREAS...BUT ARE WIDELY SCATTERED IN NATURE.
AS THE AFOREMENTIONED LOW DEVELOPING IN THE GULF OF ALASKA MOVES
NORTHWARD...RAIN AND SNOW SHOWERS WILL MOVE BACK INTO COASTAL
PORTIONS OF SOUTHCENTRAL THIS AFTERNOON. KODIAK ISLAND WILL SEE AN
ADDITIONAL SHOT AT PRECIPITATION SATURDAY AS AN UPPER LEVEL TROUGH
SWINGS THROUGH THE WESTERN MAINLAND. TRANQUIL CONDITIONS WILL BE THE
RULE ACROSS THE REMAINDER OF THE AREA...WITH MAINLY CLOUDY SKIES AND
SEASONABLE TEMPERATURES THROUGH THE WEEKEND.

.SOUTHWEST...
SCATTERED SNOW SHOWERS WILL PERSIST ACROSS THE KUSKOKWIM
VALLEY...KUSKOKWIM DELTA...AND BRISTOL BAY AREAS TODAY AS THE LOW
NEAR SAINT MATTHEW MOVES INLAND. SNOW CHANCES WILL INCREASE ACROSS
ALL OF SOUTHWEST ALASKA FRIDAY NIGHT INTO SATURDAY AS SYNOPTIC
FORCING INCREASES IN RESPONSE TO AN UPPER LEVEL TROUGH MOVING OVER
THE AREA. EXPECT CONDITIONS TO IMPROVE ON THE BACKSIDE OF THE TROUGH
AS WEAK HIGH PRESSURE BUILDS INTO BRISTOL BAY SUNDAY MORNING.

.BERING SEA AND ALEUTIANS...
BRISK WINDS AND SCATTERED SNOW SHOWERS WILL CONTINUE TODAY ACROSS THE
ISLANDS. A FRONT WELL AHEAD OF A DEVELOPING NORTH PACIFIC LOW WILL
BEGIN IMPACTING THE WESTERN ALEUTIANS THIS AFTERNOON...BRINGING
WIDESPREAD RAIN AND SNOW WITH STRONG SOUTHERLY FLOW. THIS FRONT WILL
MOVE ACROSS THE CENTRAL AND EASTERN ALEUTIANS SUNDAY.

.LONG TERM FORECAST...
WHILE MODEL AGREEMENT IS POOR IN THE EXTENDED...STILL EXPECT TROUGH
CURRENTLY OVER THE BERING SEA TO SWING THROUGH MAINLAND ALASKA WITH
WEAK RIDGING BUILDING OVER THE ALEUTIANS AND BERING SEA THROUGH
MONDAY. MODELS DO AGREE ON BRINGING A LOW INTO THE BERING SEA EARLY
IN THE WEEK...WITH ANOTHER LOW MOVING INTO THE GULF OF ALASKA DURING
THE SAME TIME FRAME.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...STORM 175 176
         GALE 132 150 155 160 165 170 171 172 179
         HEAVY FREEZING SPRAY 155 165 179
FIRE WEATHER...NONE

NRH FEB 09