Small Craft Advisory 119, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKST TUE FEB 3 2009

CORRECTED FOR WARNING TABLE

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL LOW IS LOCATED OVER INTERIOR ALASKA WITH A TROUGH
EXTENDING SOUTHEAST THROUGH WESTERN CANADA. ANOTHER UPPER LEVEL LOW
IS LOCATED OVER THE SOUTHWEST BERING. WEAK TRANSITORY RIDGING EXISTS
BETWEEN THESE UPPER LEVEL LOWS...CENTERED OVER THE ALASKA PENINSULA.

AT THE SURFACE...A 961 MB LOW IS LOCATED NEAR SHEMYA. AN OCCLUDED
FRONT EXTENDS FROM THE LOW THROUGH THE ALASKA PENINSULA. A TRIPLE
POINT LOW IS DEVELOPING 50 NM SOUTHEAST OF SAND POINT ALONG THE
AFOREMENTIONED OCCLUDED FRONT. ELSEWHERE...WEAK HIGH PRESSURE IS
LOCATED OVER INTERIOR ALASKA.

.MODEL DISCUSSION...
MODELS CONTINUE TO STRUGGLE THIS AFTERNOON...PARTICULARLY REGARDING
THE STRENGTH AND LOCATION OF THE TRIPLE POINT LOW FORMING IN THE
GULF. MODEL UNCERTAINTY ALSO ARISES CONCERNING THE LOW EVOLUTION IN
THE BERING SEA BY 36 HOURS...OR 00Z THURSDAY. THE 12Z GFS WAS USED
FOR CONSTRUCTING THE AFTERNOON PACKAGE THROUGH 00Z FRIDAY...WITH A
FOCUS ON THE 12Z ECMWF AFTERWARD.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...
THE AFOREMENTIONED TRIPLE POINT LOW WILL BE THE MAIN PLAYER ACROSS
SOUTHCENTRAL ALASKA AND KODIAK ISLAND THROUGH THE SHORT TERM. SNOW
WILL BEGIN OVERSPREADING KODIAK THIS EVENING AS THE LOW MOVES
NORTHEAST INTO THE CENTRAL GULF. PRECIPITATION IS EXPECTED TO BEGIN
MIXING WITH RAIN TOMORROW...BUT MODERATE SNOW ACCUMULATIONS ARE
POSSIBLE. SNOW ASSOCIATED WITH THIS LOW WILL BE OVERSPREADING COASTAL
AREAS TONIGHT THROUGH WEDNESDAY...BECOMING SCATTERED IN NATURE BY
LATE WEDNESDAY. ACCUMULATIONS ARE HIGHLY DEPENDENT ON THE EVENTUAL
TRACK OF THE LOW...WITH A TRACK FURTHER SOUTH LIMITING ACCUMULATIONS
ALONG COASTAL AREAS. A FRONT WELL AHEAD OF THE BERING SEA LOW WILL
BEGIN SPREADING SNOW FURTHER INLAND ON THURSDAY.

.SOUTHWEST...
A SERIES OF FRONTS EXTENDING FROM THE LOW IN THE BERING SEA WILL
RESULT IN WIDESPREAD CHANCES FOR SNOW ACROSS SOUTHWEST ALASKA THROUGH
THURSDAY. PRECIPITATION WILL BE INCREASING NORTHWARD AND EASTWARD
OVER THE NEXT SEVERAL DAYS...WITH MODERATING TEMPERATURES AS WELL.
THE TRIPLE POINT LOW FORMING EAST OF SAND POINT WILL BRING A RAIN
SNOW MIX FOR THE ALASKA PENINSULA THROUGH WEDNESDAY...BEFORE CHANGING
BACK TO ALL SNOW BY THURSDAY.

.ALEUTIANS AND BERING SEA...
SCATTERED RAIN AND SNOW SHOWERS...ALONG WITH WITH STRONG WINDS...WILL
CONTINUE TO AFFECT THE ALEUTIANS AND PRIBILOFS THROUGH THURSDAY. AS
THE LOW MOVES TOWARD THE EAST THROUGH THURSDAY...COLD AIR ON THE BACK
SIDE OF THE LOW WILL CHANGE PRECIPITATION BACK TO ALL SNOW.

.LONG TERM FORECAST...
UPPER LEVEL FLOW IS EXPECTED TO BECOME AMPLIFIED AGAIN LATER IN THE
WEEK...WITH A TROUGH SETTLING OVER ALASKA. DETAILS ON THE EVOLUTION
OF THIS TROUGH ARE QUESTIONABLE...AS MODEL GUIDANCE DISAGREES ON HOW
LONG THE TROUGH MAY STAY ENTRENCHED. GENERALLY EXPECT SEASONAL
TEMPERATURES WITH PERIODS OF UNSETTLED WEATHER TO PERSIST ACROSS THE
REGION AS WE MOVE INTO NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 150 155 160 165 170 185
         STORM 172 175 176
         HEAVY FREEZING SPRAY 130 140 141
FIRE WEATHER...NONE

NRH FEB 09