Small Craft Advisory 102, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKST THU JAN 29 2009

.ANALYSIS AND UPPER LEVELS...

ALOFT...A STRONG SHORTWAVE CONTINUES TO DIG SOUTHWARD INTO ALASKA
FROM THE ARCTIC OCEAN THIS MORNING AS IT TRIES TO MOVE AROUND THE
BASE OF A STRONG LOW CURRENTLY OVER NORTHWESTERN CANADA.  STRONG
RIDGING REMAINS ENTRENCHED OVER MOST OF WESTERN NORTH AMERICA AND A
STRONG RIDGE IS ALSO LOCATED ACROSS NORTHEASTERN RUSSIA AND WESTERN
BERING. NORTHERLY FLOW WITH ORIGINS OVER THE NORTH POLE CONTINUES TO
PUSH COLD AIR SOUTHWARD OVER THE BERING SEA AND ALONG THE WEST COAST.
A BAGGY UPPER LOW OVER THE ALASKA PENINSULA CONTINUES TO MOVE TOWARDS
THE NORTHERN GULF.

AT THE SURFACE...A 991 MB LOW CURRENTLY OVER THE NORTHEASTERN PART OF
THE ALASKAN PENINSULA IS CONTINUING ITS TREK UP COOK INLET DURING THE
DAY TODAY...WITH LIGHT OVERRUNNING PRECIP CURRENTLY ENCOMPASSING MOST
OF SOUTHCENTRAL AHEAD OF THIS LOW.  WEAK SURFACE RIDGING PERSISTS
ACROSS MOST OF THE NORTHERN HALF OF THE STATE...THE WESTERN AND
NORTHERN BERING SEA...AND THE CENTRAL ALEUTIANS.  A LOW IS WEST OF
SHEMYA...AND A LARGE AND COMPLEX DOUBLE-BARRELED LOW PRESSURE SYSTEM
IS DEVELOPING ABOUT 600 MILES SOUTH OF SHEMYA.

.MODEL DISCUSSION...

MODELS ARE IN GOOD AGREEMENT BRINGING THE AKPEN LOW TO THE NORTHERN
GULF/PRINCE WILLIAM SOUND AREA BY THU NIGHT AND LEAVING A TROUGH IN
THAT AREA THROUGH SAT AFTERNOON. DIFFERENCES IN FORECAST SOLUTIONS
ARE MORE EVIDENT WITH THE DOUBLE-BARRELED LOW SOUTH OF SHEMYA. THIS
FEATURE IS NOT DEPICTED AS TWIN LOWS BY THE EC...AND WHILE THE MODELS
COME TOGETHER WITH A SINGLE LOW SOUTH OF THE EASTERN ALEUTIANS IT WAS
DECIDED TO GO TOWARD THE SLIGHTLY MORE NORTHERLY TRACK OF THE GFS AS
IT BRINGS THE LOW ALONG THE ALEUTIANS ON SAT. IN GENERAL THE FORECAST
LEANS TOWARD THE GFS SOLUTION.

.SHORT TERM FORECAST...

IN THE WEST...AREAS OF SNOW SHOWERS ON NORTHWEST FLOW WILL PERSIST
THROUGH THE END OF THE WEEK. AT THAT POINT SNOW WILL SPREAD ACROSS
THE ALEUTIANS AS LOW PRESSURE APPROACHES DUTCH HARBOR EARLY SAT AND
THEN MOVES TOWARD THE GULF EARLY NEXT WEEK.

FOR SOUTHWEST AK...LOW PRESSURE TRACKING FROM THE AKPEN TO PRINCE
WILLIAM SOUND TODAY AND TONIGHT WILL KEEP SNOW OVER THE
AREA...ESPECIALLY ALONG THE ALASKA AND ALEUTIAN RANGES. AS CONDITIONS
IMPROVE NEAR THE MOUNTAINS...A WEAK UPPER LEVEL TROUGH WILL BRING
SOME SNOW SHOWERS TO THE KUSKOKWIM ZONES FRI. DRY CONDITIONS WILL
THEN PERSIST THROUGH EARLY NEXT WEEK...EXCEPT FOR SOME SNOW OVER THE
AKPEN ASSOCIATED WITH THE ALEUTIAN LOW MOVING ALONG THE CHAIN.

SOUTH AND EAST OF THE AK RANGE...LIGHT SNOW WILL CONTINUE ACROSS THE
AREA THROUGH FRI...WITH LESSER AMOUNTS CONTINUING EAST OF THE
TALKEETNAS THROUGH SAT. AT THAT POINT THE ALEUTIAN LOW MOVES INTO THE
GULF AND BRINGS ANOTHER ROUND OF SNOW TO COASTAL AREAS AND THE COPPER
RIVER BASIN BY EARLY NEXT WEEK.

.LONG TERM FORECAST...

A NORTH PACIFIC LOW AND ASSOCIATED FRONT WILL BRING SNOW AND THEN
RAIN TO THE ALEUTIANS THROUGH THE FIRST HALF OF NEXT WEEK. WEAK
RIDGING WILL KEEP SOUTHWEST AK DRY DURING THE SAME STRETCH. SOUTHEAST
OF THE AK RANGE WILL HAVE DRY CONDITIONS WEST OF THE TALKEETNAS
THROUGH THE MIDDLE OF THE WEEK WITH SNOW ALONG THE COAST AND COPPER
RIVER BASIN.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALES 120 132 138 140 150 155 160 172 175
         STORMS 130
         HEAVY FREEZING SPRAY 130 138 140 141 160 165 179
FIRE WEATHER...NONE

DS/CC JAN 09