Small Craft Advisory 191, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
445 PM AKST FRI MAR 1 2013

.ANALYSIS AND UPPER LEVELS...
BROAD UPPER LEVEL TROUGHING REMAINS IN PLACE OVER MUCH OF THE REGION
THIS AFTERNOON...WITH A CLOSED UPPER LOW DRIFTING SLOWLY NORTHWARD
OVER EASTERN RUSSIA AND A POTENT NORTH PACIFIC LOW MOVING EASTWARD
APPROXIMATELY 150 MILES SOUTH OF ATKA. THIS SYSTEM CONTINUES TO BRING
SNOW AND STRONG WINDS TO PARTS OF THE WESTERN AND CENTRAL
ALEUTIANS...LIKELY PRODUCING BLIZZARD CONDITIONS BETWEEN KISKA AND
ADAK...WITH THOSE CONDITIONS POISED TO SPREAD EASTWARD OVER THE
CENTRAL ALEUTIANS AND PRIBILOFS THIS EVENING AS THE SYSTEM PROGRESSES
TO THE EAST. A WEAK UPPER TROUGH AND ASSOCIATED SURFACE LOW MOVING
INLAND OVER THE NORTH GULF COAST IS SPREADING SNOW SHOWERS OVER MUCH
OF SOUTHCENTRAL AK...WITH SOME RAIN MIXING IN ALONG THE COAST.

.MODEL DISCUSSION...
MODELS REMAIN IN REASONABLE AGREEMENT THROUGH THE SHORT TERM WITH
RESPECT TO OVERALL SYNOPTIC FEATURES. THE STRONG LOW JUST SOUTH OF
THE ALEUTIANS WILL CONTINUE TO TRACK EASTWARD THROUGH SATURDAY AS IT
BEGINS TO SLOWLY WEAKEN...THEN DIVE SOUTHEASTWARD INTO THE NORTHEAST
PACIFIC ON SUNDAY AS IT ENCOUNTERS AN UPPER LEVEL RIDGE BUILDING OVER
THE SOUTHERN MAINLAND AND A 150 KT UPPER LEVEL JET DIGS ALONG ITS
WESTERN PERIPHERY. MODEL SOLUTIONS BEGIN TO DIVERGE EARLY NEXT WEEK
AS THE GFS AND NAM KEEP THE RIDGE CENTERED OVER THE NORTHERN GULF
COAST WHEREAS THE EC HAS THE HIGH LOCATED FURTHER EAST OVER THE
PANHANDLE. UTILIZED THE GFS SOLUTION FOR NOW AS IT HAS DISPLAYED
GREATER RUN TO RUN CONSISTENCY.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
SNOW SHOWERS ONGOING ACROSS SOUTHCENTRAL AK WILL TAPER OFF TONIGHT AS
AN UPPER LEVEL RIDGE BEGINS TO BUILD IN OVERHEAD. RIDGING WILL REMAIN
ESTABLISHED THROUGH THE EARLY PART OF THE WEEK...YIELDING GENERALLY
CALM CONDITIONS AND PARTLY CLOUDY SKIES WITH THE EXCEPTION OF KODIAK
ISLAND. A FRONT ASSOCIATED WITH THE LOW AFFECTING THE ALEUTIANS WILL
REACH THE WESTERN GULF BY SATURDAY EVENING AND THEN STALL AND WEAKEN
AS IT ENCOUNTERS THE RIDGE AND THE LOW RETREATS INTO THE NORTHEAST
PACIFIC. THIS WILL RESULT IN GUSTY WINDS ALONG WITH A MIX OF RAIN AND
SNOW OVER KODIAK ISLAND BEGINNING SATURDAY NIGHT AND PERSISTING INTO
THE EARLY PART OF THE WEEK.

SOUTHWEST ALASKA...
CALM CONDITIONS AND CLEAR SKIES WILL PERSIST INTO TONIGHT AS UPPER
LEVEL RIDGING BUILDS OVER THE SOUTHWEST MAINLAND. SNOW WILL THEN
RETURN TO COASTAL PORTIONS OF BRISTOL BAY AND THE KUSKOKWIM DELTA ON
SATURDAY AS THE FRONT ASSOCIATED WITH THE ALEUTIAN LOW APPROACHES THE
THE COAST. SNOW WILL BE ACCOMPANIED BY STRONG WINDS ALONG COASTAL
PORTIONS OF BRISTOL BAY...LEADING TO THE POTENTIAL FOR AREAS OF
BLOWING SNOW. SNOW WILL TAPER OFF WITH WINDS GRADUALLY SUBSIDING ON
SUNDAY AS THE LOW MOVES AWAY FROM THE AREA AND INTO THE NORTHEAST
PACIFIC.

ALEUTIANS/BERING SEA...
BLIZZARD CONDITIONS WILL OVERSPREAD THE CENTRAL ALEUTIANS THIS
EVENING AND PERSIST THROUGH THE DAY ON SATURDAY AS SNOW COUPLED WITH
HURRICANE FORCE NORTHERLY WINDS ON THE BACKSIDE OF THE LOW LEAD TO
SIGNIFICANTLY REDUCED VISIBILITIES. BLIZZARD CONDITIONS WILL ALSO
SPREAD TO THE PRIBILOFS THIS EVENING AS WINDS INCREASE WITH THE
ARRIVAL OF THE FRONT. STRONG SOUTHEASTERLY WINDS WILL CONTINUE INTO
SATURDAY OVER THE EASTERN ALEUTIANS AND AKPEN AS THE LOW PUSHES
EASTWARD. HOWEVER...TEMPERATURES WILL REMAIN WARM ENOUGH FOR A
RAIN/SNOW MIX OVER THESE AREAS...ALLOWING VISIBILITIES TO REMAIN HIGH
ENOUGH TO LIMIT ANY BLIZZARD CONCERNS. CONDITIONS WILL IMPROVE OVER
THE ALEUTIAN CHAIN FROM WEST TO EAST ON SATURDAY INTO SATURDAY NIGHT
AS THE LOW MOVES OFF TO THE EAST AND THEN SOUTHEAST INTO THE NORTHERN
PACIFIC. THE BREAK WILL BE SHORT LIVED AS THE NEXT LOW MOVES INTO THE
WESTERN BERING ON SUNDAY...WITH A FRONT SPREADING PRECIPITATION OVER
THE CHAIN FROM WEST TO EAST SATURDAY NIGHT INTO SUNDAY NIGHT.

.LONG TERM FORECAST...
THE UPPER LEVEL RIDGE BUILDING INTO SOUTHCENTRAL AK TONIGHT WILL
REMAIN IN PLACE THROUGH THE EARLY PART OF THE WEEK...RESULTING IN
DRIER AND RELATIVELY BENIGN CONDITIONS OVER MUCH OF THE SOUTHERN
MAINLAND. THE NEXT SYSTEM TRACKING THROUGH THE BERING WILL THEN HELP
TO BREAK DOWN THE RIDGE BY THE MIDDLE OF THE WEEK...BRINGING AN
INCREASED CHANCE OF PRECIPITATION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 187 191 195
         HIGH WIND WARNING 185
MARINE...GALE WARNING 132 138 150 160 165 179 180
         STORM WARNING 155 170 172 176
         HURRICANE FORCE WIND WARNING 175
         HEAVY FREEZING SPRAY 175 176 179
FIRE WEATHER...NONE

CB MAR 13