Small Craft Advisory 581, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT SAT AUG 3 2013

.MODEL DISCUSSION...
MODELS ARE IN GENERAL AGREEMENT ON THE WEAKENING LOW MOVING INTO
SOUTHWEST ALASKA THIS AFTERNOON...THOUGH THE NAM HANDLES THE WIND
FIELDS BEST OVER SOUTHCENTRAL ALASKA. THE GFS AND ECMWF HAVE A BETTER
HANDLE ON A DEVELOPING NORTH PACIFIC LOW WHICH BRINGS GALES TO THE
COASTAL WATERS SOUTH OF THE AK PEN ON MON.

.UPPER LEVELS...
A MODERATE VORTEX OVER EASTERN BRISTOL BAY WHICH IS ASSOCIATED WITH A
WEAKENING GALE CENTER MOVES NORTH AND WEAKENS. THE LONG WAVE TROUGH
OVER THE EASTERN BERING SEA UNDERGOES SOME FLUCTUATIONS OVER THE NEXT
COUPLE OF DAYS...HOWEVER THE OVERALL MEAN POSITION CHANGES VERY
LITTLE. GENERALLY SOUTHERLY FLOW WILL CONTINUE OVER THE MAINLAND
THROUGH MONDAY.

.SURFACE...
A WEAKENING 990S LOW OVER BRISTOL BAY IS MOVING NORTH AND WEAKENING.
THE ASSOCIATED OCCLUDED FRONT WITH SEVERAL WRAPS EXTENDING FROM THE
SW ALASKA...NORTH OF THE SUSITNA VALLEY...EASTERN COPPER RIVER
BASIN...TO THE EASTERN GULF THIS AFTERNOON. WINDY CONDITIONS WITH
STRONG GAP FLOWS WERE OBSERVED ACROSS EASTERN SW ALASKA AND
SOUTHCENTRAL. WIDESPREAD RAIN WAS OBSERVED ALONG THE FRONTAL
BOUNDARY AND IN THE VICINITY OF THE SURFACE LOW. SHOWERS WERE
OBSERVED ON THE BACKSIDE OF THE FRONTAL TROUGH.

.SHORT TERM FORECAST...

.SOUTHCENTRAL ALASKA...
BRISK WINDS AND STRONG GAP FLOWS WILL CONTINUE THROUGH THIS EVENING
ACROSS SOUTHCENTRAL ALASKA WITH STRONG PRESSURE RISES ON THE BACKSIDE
OF THE SYSTEM MOVING NORTH ACROSS THE MAINLAND. WINDS SHOULD DIMINISH
IN MOST AREAS OVERNIGHT AS PRESSURE GRADIENTS RELAX. SHOWERS ACROSS
SOUTHCENTRAL WILL DIMINISH SOME OVERNIGHT...HOWEVER THE BROAD
SOUTHERLY FLOW ALOFT WILL CONTINUE THE THREAT OF PRECIPITATION INTO
MONDAY.

.SOUTHWEST ALASKA...
WIDESPREAD RAIN AND SHOWERS ASSOCIATED WITH THE SURFACE LOW AND
FRONTAL TROUGH WILL MOVE NORTH ACROSS THE AREA TONIGHT. THE ONSET OF
SOUTHERLY FLOW ON THE BACKSIDE OF THE SYSTEM WILL LIKELY BRING LOWER
CLOUD DECKS TO COASTAL AREAS TONIGHT AND SUNDAY. THE THREAT OF
SHOWERS/RAIN WILL CONTINUE INTO MON WITH BROAD SOUTHWESTERLY FLOW
ALOFT.

ALEUTIANS/BERING SEA...
A WEAKENING LOW OVER THE NORTHERN BERING SEA MOVES TO OVER THE
EASTERN BERING SEA ON MONDAY. HIGH PRESSURE OVER THE WESTERN
ALEUTIANS/BERING SEA MOVES SLOWLY EAST THROUGH MONDAY. GENERALLY...
LOW CLOUDS ARE EXPECTED ACROSS THE AREAS WITH SOME LIGHT RAIN OR
SHOWERS MIXED WITH STRATUS OVER THE EASTERN BERING SEA IN THE
VICINITY OF THE UPPER TROUGH.

.LONG TERM FORECAST...
THE LONG WAVE PATTERN OVER THE BERING WILL DEEPEN THROUGH NEXT WEEK.
THIS SET UP WILL BRING A WETTER PATTERN WITH TEMPERATURES NEAR NORMAL
THROUGH NEXT FRIDAY.

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

RMC AUG 13