Brisk Wind Advisory 56, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AST THU DEC 28 2006

.DISCUSSION...

SYNOPTIC PATTERN OVER THE AOR THIS MORNING IS DOMINATED BY A DEEP
STACKED LOW OVER THE CENTRAL GULF OF ALASKA WHOSE MID/HIGH CLOUD
SHIELD IS OVERSPREADING MUCH OF THE STATE. PAIH RADAR SHOWING THE
PRECIP SHIELD ASSOCIATED WITH THE WARM FRONT IS MOVING ONSHORE ALONG
THE NORTH GULF COAST WHERE PRECIP IS FALLING AS RAIN ALONG THE
IMMEDIATE COAST WITH SNOW FARTHER INLAND FROM THE COAST IN THE COLDER
LOW LEVEL AIR AT SEWARD AS WELL AS ACROSS THE SOUTHERN PORTIONS OF
THE KENAI PENINSULA. FARTHER WEST...NORTHERLY FLOW/COLD AIR ADVECTION
ACROSS THE EASTERN BERING SEA IS BRINGING SNOW SHOWERS AND BREEZY
CONDITIONS TO THE PRIBILOFS AND THE AKPEN WITH BLOWING SNOW REDUCING
VISIBILITIES IN THE PRIBILOFS. A WARM FRONTAL BAND IS SEEN ON IR
IMAGERY PUSHING NORTH TOWARDS THE WESTERN AND CENTRAL ALEUTIANS NORTH
OF A WELL DEFINED BAROCLINIC ZONE SOUTH OF THE ALEUTIANS ALIGNED
ROUGHLY ALONG 47N ANCHORED BY A LOW OVER THE NORTH PACIFIC NEAR 43N
155E.

FORECAST SOUTH AND EAST OF THE ALASKA RANGE...MODELS ARE IN GOOD
AGREEMENT WITH BRINGING THE GULF LOW INTO THE PRINCE WILLIAM SOUND
AREA THIS AFTERNOON. STORM FORCE WINDS ARE EXPECTED ACROSS MARINE
ZONE 120 THIS MORNING BUT SHOULD SUBSIDE THIS AFTERNOON AS THE FRONT
MOVES INLAND AND THE LOW CENTER PULLS CLOSER TO LAND.  AREAS
IMMEDIATELY ALONG THE COAST SHOULD SEE PRECIP FALL MOSTLY AS RAIN
TODAY WITH SOME MIXING WITH SNOW OCCURRING FARTHER INLAND AT
LOCATIONS INCLUDING PORTAGE AND SEWARD. SNOW FALLING IN THOMPSON PASS
IN COMBINATION WITH STRONG WINDS WILL BRING BLIZZARD CONDITIONS THERE
TODAY. ONSET OF SNOW IN THE ANCHORAGE BOWL WILL MOST LIKELY BE
DELAYED UNTIL THE AFTERNOON HOURS AS TIME WILL BE NEEDED TO SATURATE
THE SIGNIFICANT DRY LAYER INDICATED IN THE 12Z PANC SOUNDING. SNOW
OVER KODIAK ISLAND SHOULD TAPER OFF IN THE AFTERNOON AS THE LOW AND
THE MAJORITY OF THE MOISTURE PULLS AWAY TO THE NORTH AND EAST OF THE
ISLAND.

PRECIP WILL CONTINUE TONIGHT AS THE LOW MAKES LANDFALL WITH RAIN
CHANGING OVER TO SNOW LATER IN THE NIGHT ALONG THE COAST WITH COLD
ADVECTION DROPPING TEMPS BACK BELOW FREEZING OVERNIGHT. THIS COLD
ADVECTION COULD ALSO SERVE TO ENHANCE SNOWFALL ACROSS THE ANCHORAGE
BOWL. CURRENTLY GOING WITH 2 TO 4 INCHES IN ANCHORAGE WHICH MAY NEED
TO BE ADJUSTED UP OR DOWN DEPENDING ON HOW FAR EAST THE LOW ACTUALLY
MOVES INTO PRINCE WILLIAM SOUND. SNOW SHOULD ALSO BEGIN IN EARNEST
TONIGHT IN VALDEZ PROPER AS THE LOW MOVES ONSHORE AND EASTERLY FLOW
IS REPLACED BY SOUTHERLY FLOW WITH SNOW ALSO MOVING INTO THE COPPER
RIVER BASIN. SNOWY WEATHER SHOULD PERSIST ACROSS MUCH OF SOUTHCENTRAL
THROUGH SATURDAY NIGHT AS THE LOW CONTINUES TO FILL IN PLACE OVER
SOUTHCENTRAL WITH ADDITIONAL ENHANCEMENT FROM A STRONG 500MB
SHORTWAVE THAT MOVES THROUGH THE AREA SATURDAY NIGHT.

LOOK FOR A BRIEF BREAK IN THE ACTION FOR SOUTHCENTRAL ON SUNDAY AS A
SHORTWAVE RIDGE MOVES ACROSS SOUTHCENTRAL. PRECIP SHOULD RETURN TO
THE REGION BY SUNDAY NIGHT AS YET ANOTHER STORM SYSTEM ROLLS UP INTO
THE GULF OF ALASKA. THE MORE WESTERLY TRACK OF THIS SYSTEM COULD
SIGNAL A WARM UP...PARTICULARLY TO THE EAST OF ANCHORAGE AS SOUTHERLY
FLOW/WARM AIR ADVECTION DEVELOPS ACROSS THE AOR. IN THE EXTENDED...
LITTLE CHANGE IN THE OVERALL PATTERN AS THE LONGWAVE TROUGH REMAINS
ENTRENCHED OVER THE STATE. GIVEN THE GENERALLY UNSETTLED PATTERN...
CHANCE POPS ARE IN ORDER FOR MUCH OF NEXT WEEK.

FORECAST FOR MAINLAND SOUTHWEST AK...AN UPPER LEVEL TROUGH MOVES INTO
THE KUSKOKWIM VALLEY TODAY AND TONIGHT ALLOWING FOR SCATTERED SNOW
SHOWERS. A SHORTWAVE RIDGE MOVES ACROSS BRISTOL BAY SATURDAY...
BRINGING A BREAK IN THE SHOWER ACTIVITY. SHOWER ACTIVITY RETURNS TO
BRISTOL BAY ON SUNDAY AS A STRONG LOW MOVES SOUTH OF THE AKPEN WHILE
NORTHEASTERLY FLOW KEEPS THE KUSKOKWIM VALLEY AND DELTA DRY AND COLD.
AN UPPER LEVEL LOW DROPS INTO THE EASTERN BERING/KUSKOKWIM DELTA BY
TUESDAY...REINTRODUCING A CHANCE OF SHOWERS INTO THE FORECAST.

FORECAST FOR FOR THE BERING SEA AND THE ALEUTIANS...A HIGH WIND
WARNING IS IN EFFECT FOR THE WESTERN ALEUTIANS WITH A WATCH FOR THE
CENTRAL ALEUTIANS AS THE WARM FRONTAL BAND PUSHES INTO THE CHAIN AND
THE PARENT LOW/PRESSURE GRADIENT DEEPENS IN RESPONSE TO UPPER LEVEL
FORCING ALONG WITH LOW LEVEL WARM ADVECTION. THIS LOW MOVES EAST TO
THE SOUTH OF THE ALEUTIANS SPREADING WIND AND SNOW ACROSS MUCH OF THE
CHAIN THROUGH THE WEEKEND. SNOW SHOWERS SPREAD ACROSS THE BERING SEA
IN THE COLD ADVECTION IN THE WAKE OF THE LOW THROUGH THE WEEKEND AND
THE EARLY PART OF NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 131
         HIGH WIND WARNING 191
         HIGH WIND WATCH 187
MARINE...STORM 120 130 132 172 175 176
         GALE 121 125 150 170 171
         HEAVY FREEZING SPRAY 160 185

WOOD DEC 06