Small Craft Advisory 612, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT WED AUG 14 2013

.MODEL DISCUSSION...
INITIALIZATIONS WERE REASONABLE. FORECAST SOLUTIONS BECOME MORE
PROBLEMATIC TOWARD THE END OF THE SHORT AS THE UPPER CENTER BROADENS
AND DROPS INTO THE GULF OF ALASKA. MODELS THEN STRUGGLE WITH
PLACEMENT OF SURFACE CENTERS OVER THE GULF. CONFIDENCE ON POSITIONING
OF LOW CENTERS IN THE GULF IS NOT EVERY HIGH...THOUGH THERE WILL
CERTAINLY BE LOW PRESSURE. SO BLENDED OFFICIAL GRIDS TOWARD THE ECMWF
WITH THE NET RESULT WAS AN INCREASE IN THE E AND SE FLOW IN THE GULF.
THE MODELS WHERE IN FAIR AGREEMENT IN THE BERING SEA.

.ANALYSIS AND UPPER LEVELS...
.500 MB...
THIS MORNING WATER VAPOR IMAGERY SHOWS A WEAK TROUGH EXTENDING SE
ACROSS KODIAK ISLAND WITH A SECONDARY TROUGH OVER COASTAL SW ALASKA
AND THE AK PEN. THE PRIMARY SURFACE LOW IS EVIDENT OVER THE EAST
CENTRAL BERING SEA WITH STRONG NEAR ZONAL FLOW OVER THE NORTH
PACIFIC.

THE WAVE NEAR KODIAK WILL WEAKEN AS IT MOVES ACROSS SOUTHCENTRAL
TONIGHT. THE SECONDARY WAVE NEAR BRISTOL BAY/AK PEN MOVES N AND E
INTO SW ALASKA/SOUTHCENTRAL ON THU...CONTINUING INLAND THROUGH THU
NIGHT. A DEVELOPING WAVE ROTATING AROUND THE SOUTHERN PERIPHERY THE
THE BERING SEA LOW ELONGATES IN A E-SE DIRECTION OVER THE GULF FRI.
THE BERING SEA CENTER MOVES TO THE AK PEN ON FRI THEN SOUTH FRI
NIGHT/SAT. THE RIDGE BUILDS OVER THE WESTERN BERING SEA THROUGH SAT.

.SHORT TERM FORECAST...
MARINE STRATUS BROKE UP SOME OVER THE GULF AS THE FLOW SHIFTED MORE
SW TO W. THE MARINE STRATUS WAS FAIRLY WIDE SPREAD ACROSS COOK
INLET/ANCHORAGE BOWL...AND MATSU THIS MORNING/AFTERNOON. A WAVE
MOVING ACROSS SOUTHCENTRAL TONIGHT MAY KICK OFF A FEW SHOWERS INLAND
AND A LITTLE LIGHT RAIN ALONG THE WESTERN GULF. HOWEVER THE MARINE
STRATUS WILL ONCE AGAIN BE THE DOMINATE FEATURE OVER THE GULF AND
COOK INLET/ANCHORAGE/MATSU TONIGHT AND THU. A SECONDARY WEAK WAVE
MOVES INTO SOUTHCENTRAL ON THU AND MAY BRING A FEW SHOWERS. A FRONTAL
TROUGH MOVING INTO THE GULF FRI WILL BRING INCREASED CHANCES OF RAIN
ALONG THE COASTS AND SHOWERS INLAND. E TO SE FLOW WILL ALSO INCREASE
OVER THE GULF OVER THE NEXT COUPLE OF DAYS.

.SW ALASKA...
SHOWERS EVIDENT ACROSS MUCH OF SW ALASKA THIS AFTERNOON WILL CONTINUE
TO SPREAD WITH UPPER TROUGH TONIGHT. PROBABLY WILL SEE SOME LOWER
CLOUDS ALONG THE COASTAL AREAS TONIGHT BEHIND WITH SOUTHERLY FLOW.
UPPER WAVES WILL CONTINUE UNSETTLED WEATHER WITH SHOWERS ACROSS THE
REGION ON THU. STABILITY INDICES SHOULD BE LOW ENOUGH THAT FORCING
WITH UPPER WAVES COULD TRIGGER THUNDERSTORMS OVER THE KUSKOKWIM
VALLEY THU AFTERNOON AND EVENING. TEMPS WILL COOL AND RAIN WILL
SPREAD TO THE SOUTHERN COASTS ON FRI WITH THE APPROACH OF THE NEXT
FRONT.

ALEUTIANS/BERING SEA...
STRONG WESTERLY WINDS AND SCATTERED SHOWERS WILL CONTINUE INTO
THURSDAY MORNING FOR THE CENTRAL AND WESTERN ALEUTIANS AS THE LOW
REMAINS NEARLY STATIONARY TO THE NORTH OF THE CHAIN. WINDS WILL
FINALLY BEGIN TO TREND DOWN DURING THE DAY ON THURSDAY AS THE LOW
BEGINS TO MOVE OFF TO THE EAST...BRINGING ANOTHER ROUND OF STEADIER
RAIN TO THE EASTERN ALEUTIANS AND AK PEN.

.LONG TERM FORECAST...
A COOLER AND WETTER PATTERN WILL RETURN TO SOUTHCENTRAL AK LATE IN
THE WEEK AS THE LONGWAVE TROUGH SHIFTS EASTWARD OVER MAINLAND ALASKA
AND THE BERING LOW MOVES INTO THE NORTHEASTERN PACIFIC. UPPER LEVEL
RIDGING WILL BUILD OVER THE BERING AS THE LOW DEPARTS TO THE
EAST...BRINGING AN INCREASE IN FOG AND STRATUS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALES 172 175.
FIRE WEATHER...NONE.

RMC AUG 13