Small Craft Advisory 212, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT SUN MAR 20 2011

.ANALYSIS AND UPPER LEVELS...
THE DECAYING CENTER OF YESTERDAY'S POWERFUL LOW PRESSURE SYSTEM IS
LOCATED NEAR NUNIVAK ISLAND AND IS RAPIDLY TRACKING NORTHWARD TOWARDS
SAINT LAWRENCE ISLAND. THE CENTRAL PRESSURE HAS RISEN TO AROUND 970
MB...BUT THIS STORM IS STILL BRINGING STORM FORCE WINDS TO THE
EASTERN BERING AND THE COAST OF SOUTHWEST ALASKA. THE ASSOCIATED
WEATHER FRONT IS NEARLY STATIONARY IN THE WEST CENTRAL GULF AND IS
SHEARING APART AS THE LOW AND THE UPPER LEVEL JET MOVE FURTHER AWAY
FROM EACH OTHER. THIS FRONT IS BRINGING SNOW SHOWERS TO THE INTERIOR
OF SOUTHWEST ALASKA AND RAIN SHOWERS TO KODIAK AND THE SOUTHERN KENAI
PENINSULA. CLOUDS ARE SPREADING AHEAD OF THIS SYSTEM ACROSS THE KENAI
PENINSULA NORTHWARD TO THE SOUTHERN SUSITNA VALLEY. STRONG GAP WINDS
ARE ALSO BLOWING IN TURNAGAIN AS A RESULT OF THE LOW LOCATED IN THE
EASTERN BERING. THE REST OF SOUTHCENTRAL REMAINS CALM UNDER A RIDGE
OF HIGH PRESSURE.

.MODEL DISCUSSION...
THERE IS A GENERAL CONSENSUS AMONG THE MODELS WITH THE TRACK AND
STRENGTH OF THE WANING EAST BERING SEA LOW...WITH ALL GUIDANCE
SOLUTIONS GRADUALLY WEAKENING THE SYSTEM AND BRINGING IT THROUGH THE
BERING STRAIT ON MONDAY MORNING. THERE IS FAR LESS AGREEMENT IN THE
POSITION OF THE NEXT BERING SEA LOW ALREADY TAKING SHAPE WEST OF
SHEMYA. THIS IS DUE TO THE COMPLEX NATURE OF THE LOW AND THE
PROGRESSIVE FLOW OF THE UPPER LEVEL JET...NEITHER OF WHICH THE MODELS
HANDLE WELL. THE MODELS ARE AT LEAST SOMEWHAT CONSISTENT IN BRINGING
THE MEAN CENTER OF THE LOW INTO THE EASTERN BERING BY TUESDAY
MORNING. IN THE UPPER LEVELS...THE MODELS ARE IN DECENT SYNOPTIC
AGREEMENT THROUGH THE MIDDLE PART OF THE WEEK...ALTHOUGH THE GFS
BECOMES SIGNIFICANTLY FASTER THAN THE EC OUT PAST THURSDAY AND
FRIDAY.

.SHORT TERM FORECAST...
SOUTHCENTRAL...PRIMARY FORECAST CONCERN TODAY WILL BE THE SLOW
PROGRESS OF THE WEATHER FRONT CURRENTLY AFFECTING KODIAK ISLAND AS IT
MOVES NORTHWARD TO THE KENAI PENINSULA. THE NORTHERN PORTION OF THE
FRONT WILL CONTINUE TO PROGRESS THROUGH THE INTERIOR. THE PORTION
OVER THE GULF SHOULD STALL AND WEAKEN OVER THE NORTHERN GULF TONIGHT
AND MON AS A TRIPLE POINT CENTER DEVELOPS NEAR KODIAK. MODERATE
PRESSURE GRADIENTS AHEAD OF THE FRONT ARE PRODUCING A CLASSIC DRY
DOWNSLOPE PATTERN FROM THE WESTERN KENAI NORTH TO THE MATANUSKA
VALLEY THIS AFTERNOON AND ARE EXPECTED TO CONTINUE INTO TONIGHT. THE
MAIN AREA OF PRECIPITATION WILL BE OVER WESTERN COOK INLET AND
WESTERN SUSITNA VALLEY. EXPECT PRESSURE INDUCED GAP FLOW ACROSS THE
THE MATSU AND TURNAGAIN ARM.. GRADIENTS WILL RELAX SOME OVERNIGHT. A
SECONDARY FRONTAL TROUGH MOVES TO OVER THE WESTERN GULF ON TUE. THIS
FRONT SHOULD BE WEAKER...SO NOT MUCH WIND OR PRECIPITATION IS
EXPECTED. HIGH PRESSURE OVER THE COPPER RIVER BASIN WILL CONTINUE DRY
CONDITIONS THROUGH TUE...THOUGH MAY SEE A FEW CLOUDS.

SOUTHWEST AND BERING SEA...THE WEAKENING STORM CENTER NEAR NUNIVAK
ISLAND THIS AFTERNOON CONTINUES TO RACE TOWARD THE BERING STRAIT.
WINDS ARE BECOMING MORE SOUTHERLY ACROSS THE MAINLAND AND WILL
CONTINUE TO DIMINISH THROUGH THIS EVENING AS THE LOW PULLS AWAY.
HEAVY WET SNOW AND RAIN OVER THE DELTA COAST AND BRISTOL BAY AREA
SHOULD DIMINISH LATER THIS AFTERNOON. BY THIS EVENING EXPECT SOME
MARINE STRATUS AND SHOWERS TO PUSH ONSHORE AS FLOW BECOMES
SOUTHWESTERLY OVER THE SOUTHWEST MAINLAND.

A WEATHER FRONT MOVING TO THE EASTERN BERING SEA MON BRINGS RENEWED
RAIN AND SNOW AND GUSTY WINDS TO SW ALASKA.

.LONG TERM FORECAST...PROGRESSIVE WEATHER PATTERN TO PERSIST FOR THE
FORESEEABLE FUTURE ACROSS THE ALASKAN AOR. THE MOST ACTIVE WEATHER
LOOKS LIKE IT WILL BE CONFINED MAINLY TO THE BERING SEA REGION FOR
THE FIRST HALF OF THE WEEK. HOWEVER BY MIDWEEK A MORE SIGNIFICANT LOW
WILL TRACK PARALLEL TO THE ALEUTIANS AND DROP INTO THE SOUTHERN GULF.
AT THIS TIME IT APPEARS THIS LOW WILL STAY FAR ENOUGH SOUTH TO HAVE
ONLY MINIMAL IMPACTS ON SOUTHCENTRAL...BUT THIS WILL NEED TO BE
MONITORED WITH FUTURE MODEL RUNS. TEMPERATURES ACROSS THE ENTIRE
REGION WILL REMAIN SEASONABLY WARM...WITH PERIODS OF SUNSHINE
CONFINED MAINLY TO INLAND AREAS OF SOUTHCENTRAL.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 155 170 172 175 176 179 180
FIRE WEATHER...NONE.

RMC/KS MAR 11