Small Craft Advisory 316, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
155 PM AKDT MON APR 14 2014

.ANALYSIS AND UPPER LEVELS...
SKIES HAVE CLEARED OVER MUCH OF SOUTHCENTRAL AS HIGHER PRESSURE
AND OFF SHORE FLOW HAS BECOME MORE DOMINANT OVER THE AREA. A
DISSIPATING FRONTAL SYSTEM HAS MOVED JUST SOUTH OF THE GULF AND
CONTINUES TO WEAKEN...AS IT BECOMES MORE ELONGATED BY THE 125 KT
JET TO THE SOUTH. A FRONTAL SYSTEM OVER THE SOUTHWEST COAST
DISSIPATES...ENDING THE PRECIPITATION OVER THE LOWER KUSKOKWIM
DELTA. DECREASING CLOUDS HAVE BEEN OBSERVED OVER THE BRISTOL BAY
AREA AND LOWER KUSKOKWIM VALLEY...AS ONSHORE FLOW FROM THE
SOUTHEAST BEGINS TO WEAKEN. AN UPPER LEVEL TROUGH RESIDES OVER
MUCH OF THE WESTERN AND CENTRAL BERING. CURRENT OBSERVATIONS SHOW
WET AND WINDY CONDITIONS PERSISTING OVER THE WESTERN AND CENTRAL
ALEUTIANS...AS A LARGE COMPLEX LOW COVERING MUCH OF THE WESTERN
AND CENTRAL BERING ADVECTS WARMER MOIST NORTH PACIFIC AIR OVER THE
AREA.

&&

.MODEL DISCUSSION...
MODELS REMAIN IN GOOD AGREEMENT WITH THE EVOLUTION OF UPPER LEVEL
FEATURES THROUGH THE SHORT TERM...BUT SEEM TO STRUGGLE WITH SOME
SMALLER FEATURES AT THE SURFACE. MODELS ARE SHOWING THE BERING
SEA SYSTEM MERGING INTO ONE LARGE LOW CENTER...WHILE A WEAKER
CIRCULATION SITS IN THE GULF. BOTH SYSTEMS LACK THE JET SUPPORT
NEEDED FOR FURTHER DEVELOPMENT SO THEY WILL STAGNATE OVER THE NEXT
COUPLE DAYS. THE GFS AND NAM LOCK INTO A MORE EASTERLY SOLUTION
OF THE BERING SEA LOW TUESDAY MORNING. THE EC SEEMS TO BE AN
OUTLIER REGARDING THIS SYSTEM...KEEPING THE LOW CENTER CLOSER TO
THE WESTERN BERING TUESDAY MORNING. THE FORECAST CHALLENGE FOR THE
WEST WILL BE THE TIMING AND STRENGTH OF THE WINDS OVER THE
CENTRAL AND EASTERN ALEUTIANS ASSOCIATED WITH THE COMPLEX LOW
MOVING INTO THE BERING THIS EVENING. THE MODELS ARE ALSO
STRUGGLING WITH THE PLACEMENT AND STRENGTH OF THE WEAKER SYSTEMS
OVER THE GULF FROM TUESDAY NIGHT THROUGH THE END OF THE SHORT
TERM. MODELS HAVE BEEN STRUGGLING WITH THE MESO-CIRCULATION
CURRENTLY IN THE GULF OF ALASKA...MAKING IT SLIGHTLY CHALLENGING
TO FORECAST CLOUD COVERAGE OVER THE GULF AND SOUTHCENTRAL. VISIBLE
AND WATER VAPOR SATELLITE IMAGERY HAVE DEPICTED THESE WEAK
CIRCULATIONS QUITE WELL. HOWEVER...EVEN THE HIGHER RESOLUTION
MODELS ARE HAVING TROUBLE CAPTURING THESE SMALLER CIRCULATIONS.
GIVEN THE AFOREMENTIONED DISCREPANCIES AND DIFFERENCES BETWEEN THE
MODELS...FORECAST CONFIDENCE REMAINS AROUND AVERAGE FOR THIS
PACKAGE.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...THE MESO-SCALE LOW IN THE NORTHERN GULF WILL
CONTINUE TO MOVE SOUTH AND WEAKEN TONIGHT. THIS WILL DELAY THE
CLOUD COVER IN THE PRINCE WILLIAM SOUND AREA MOVING WESTWARD INTO
SOUTH CENTRAL ALASKA. HOWEVER CLOUDS WILL INCREASE OVERNIGHT AS
SOUTHEAST FLOW ALOFT FORCES THEM INTO THE AREA. PRECIPITATION WILL
BE MOSTLY RELEGATED TO THE NORTH GULF COAST AND PRINCE WILLIAM
SOUND. A FEW SHOWERS MAY CREEP OVER THE MOUNTAINS INTO SOUTH
CENTRAL ALASKA TOMORROW MORNING.

SOUTHWEST ALASKA...
A RESIDUAL FRONTAL BOUNDARY OVER THE KUSKOKWIM DELTA AND WESTERN
BRISTOL BAY IS KEEPING CLOUDS IN THAT REGION. THERE SHOULD BE A
FEW BREAKS IN THE CLOUDS BEFORE AN APPROACHING FRONT BRING MORE
MOISTURE TO THE REGION BY TUESDAY NIGHT.

BERING SEA/ALEUTIANS...
THE COMPLEX LOW IN THE CENTRAL ALEUTIANS WILL PUSH INTO THE
CENTRAL BERING SEA BY TOMORROW. THERE WILL BE SOME GUSTY EAST TO
SOUTHEAST WINDS IN CONJUNCTION WITH THE OCCLUDED FRONT AHEAD OF
THE LOW. PRECIPITATION IN THIS ARE WILL BE MOSTLY RAIN. THE COLDER
AIR IS ROTATION AROUND THE SOUTHWEST PORTION OF THE SYSTEM WHICH
WILL KEEP SOME SNOW SHOWERS WEST OF ADAK THIS EVENING...SPREADING
EASTWARD OVERNIGHT.

&&

.LONG TERM FORECAST...
THE OVERALL PATTERN WILL NOT CHANGE MUCH UNTIL THE WEEKEND. THE
UPPER LEVEL TROUGH WILL PERSIST IN THE BERING SEA WITH THE UPPER
HIGH IN THE YUKON. THIS WILL PRODUCE EASTERLY FLOW ALONG THE
NORTHERN GULF COASTLINES WITH THE CHANCE FOR SHOWERS AS THE NORTH
PACIFIC SURFACE LOW FILLS AND EVENTUALLY DISSIPATES LATER IN THE
WEEK. THE SOUTHWEST ALASKA WILL HAVE OFFSHORE FLOW WITH THE BERING
AND ALEUTIAN CHAIN HAVING NORTHEASTERLY FLOW. THE EASTERN BERING
SEA WILL HAVE A WEAK TROUGH GENERATING SHOWERY PRECIPITATION WITH
STRATUS BY END OF THIS WEEK THROUGH THE WEEKEND. THIS WEEKEND THE
HIGH LOOKS TO RETROGRADE WESTWARD AS THE THOUGH BEGINS TO MOVE TO
THE SOUTHEAST. THIS WILL CAUSE SOME CLEARING AGAIN FOR A GOOD PART
OF MAINLAND ALASKA. &&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...174 176
FIRE WEATHER...NONE.

TP APR 14