Small Craft Advisory 473, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
1240 PM AKDT SUN JUL 10 2011

.ANALYSIS AND UPPER LEVELS...A CUT-OFF LOW REMAINS PARKED OVER THE
NORTHERN BERING SEA. A RIDGE CENTERED NEAR 41N 157W EXTENDS UP
INTO THE GULF OF ALASKA AS WELL AS EASTERN PORTIONS OF SOUTHCENTRAL
ALASKA. ACTIVE WEATHER IS CENTERED IN THE CORRIDOR IN BETWEEN FROM
THE CENTRAL ALEUTIANS NORTHEASTWARD TO SOUTHWEST ALASKA. A WEAK
UPPER LEVEL WAVE HAS BEEN PRODUCING SHOWERS AS IT CROSSES SOUTHWEST
ALASKA THIS MORNING...BUT IT IS QUICKLY EXITING TO THE NORTH.
THIS UPPER WAVE HAS ALSO BROUGHT CLOUDS INTO THE WESTERN HALF OF
SOUTHCENTRAL BUT LITTLE IN THE WAY OF PRECIP. THE PRIMARY FOCUS OF
THE FORECAST TODAY IS A 994 MB LOW SOUTH OF THE CENTRAL ALEUTIANS
WHICH IS EXPECTED TO TRACK RAPIDLY OFF TO THE NORTH-NORTHEAST.

.MODEL DISCUSSION...MODELS ARE IN GOOD AGREEMENT WITH SYNOPTIC
FEATURES. THE PRIMARY CHANGE TO THE EXISTING FORECAST IS SLOWER
MOVEMENT OF FRONT INTO SOUTHWEST ALASKA TONIGHT INTO MONDAY ALONG
WITH SLIGHTLY WEAKER WINDS ALONG THIS FRONT. OTHERWISE...FORECASTS
ARE GENERALLY ON TRACK.

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...SOUTHWEST FLOW WILL MAINTAIN MOSTLY CLOUDY
SKIES ACROSS THE WESTERN HALF OF SOUTHCENTRAL TONIGHT INTO MONDAY.
THE UPPER RIDGE WILL AMPLIFY SLIGHTLY OUT AHEAD OF THE SYSTEM
MOVING INTO THE BERING SO RIDGE WILL NOSE ITS WAY BRIEFLY OVER
COOK INLET TO SUSITNA VALLEY CORRIDOR. THIS MAY PRODUCE ENOUGH
CHANGE IN FLOW TO PRODUCE OCCASIONAL BREAKS IN THE CLOUDS.
CONDITIONS WILL QUICKLY DETERIORATE LATE MONDAY AFTERNOON THROUGH
MONDAY NIGHT AS THE FRONT FROM THE BERING ARRIVES ALONG WITH
CORRESPONDING UPPER LEVEL WAVE. WITH A CONTINUED DEEP LAYER OF
SOUTHWEST FLOW EXPECT WIDESPREAD RAIN ACROSS THE REGION. ALL OF
THIS WILL EXIT TUESDAY AFTERNOON THROUGH TUESDAY NIGHT. HOWEVER...
ADDITIONAL WEAK IMPULSES EMBEDDED WITHIN THE UPPER LEVEL FLOW WILL
MAINTAIN MOSTLY CLOUDY SKIES AND A CHANCE OF SHOWERS AS WE HEAD
THROUGH MID WEEK.

BERING SEA/ALEUTIANS/SOUTHWEST ALASKA...THE UPPER JET WILL DRIVE
THE LOW SOUTH OF THE ALEUTIANS RAPIDLY NORTH-NORTHEASTWARD...
BECOMING CENTERED UNDER THE NORTHERN BERING UPPER LOW MONDAY NIGHT.
RAIN AND WINDS WITH THE LOW AND ALONG THE FRONTAL SYSTEM WILL
SPREAD QUICKLY ACROSS THE EASTERN BERING AND ALASKA PENINSULA
TONIGHT AND INTO SOUTHWEST ALASKA ON MONDAY. SOUTHWEST ALASKA WILL
BEGIN TO DRY OUT TUESDAY THOUGH WITH CONTINUED ONSHORE FLOW AND WEAK
UPPER LEVEL IMPULSES MOVING THROUGH CONDITIONS WILL REMAIN RATHER
CLOUDY WITH A CHANCE OF SHOWERS. A WEAK INVERTED TROUGH WILL
POSITION ITSELF ALONG THE EASTERN ALEUTIANS AND SOUTHERN ALASKA
PENINSULA TUESDAY BEFORE SHIFTING SOUTH WEDNESDAY. A SURFACE HIGH
WILL THEN DOMINATE THE SOUTHERN BERING AND ALEUTIANS MID TO LATE
WEEK. THIS TIME OF YEAR THAT USUALLY RESULTS IN CLOUDY SKIES LIGHT
WINDS AND AREAS OF FOG.

.LONG TERM FORECAST...SYNOPTIC FLOW LOOKS FAIRLY ZONAL FROM THE
BERING SEA TO SOUTHERN MAINLAND AND GULF OF ALASKA LATE THIS WEEK
INTO NEXT WEEKEND. THERE DOESN'T APPEAR TO BE ANY MAJOR FEATURES
OF NOTE UNTIL A PACIFIC LOW APPROACHES THE ALEUTIANS HEADING INTO
THE WEEKEND. UNDER THIS WEAK FLOW REGIME EXPECT SOME SUN EACH DAY
OVER MAINLAND ALASKA ALONG WITH A CHANCE OF DIURNAL SHOWERS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING...155 165 170 172 180.
FIRE WEATHER...NONE.

SEB JUL 11