Small Craft Advisory 744, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT THU SEP 26 2013

.ANALYSIS AND UPPER LEVELS...
THE DOMINANT WEATHER FEATURE IS A POWERFUL LOW OVER THE EASTERN
BERING SEA MOVING JUST SOUTH OF DUE EAST. THE UPPER LOW IS CENTERED
JUST WEST OF NUNIVAK ISLAND WITH THE SURFACE LOW AHEAD OF IT
CENTERED JUST SOUTH OF NUNIVAK ISLAND. THE WARM FRONT STRETCHES FROM
ABOUT CHIGNIK SOUTHWARD. THE COLD FRONT IS ROUGHLY ALONG THE ALASKA
PENINSULA AND ALEUTIAN CHAIN...WITH THE OCCLUDED FRONT ALONG THE
SOUTHWEST COAST OF MAINLAND ALASKA. THERE IS ALSO A WEAKENING LOW
OVER SOUTH CENTRAL ALASKA THAT IS MOVING SLOWLY EAST.

.MODEL DISCUSSION...
THE NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT. THERE ARE SOME
DIFFERENCES IN HOW THEY HANDLE SMALL-SCALE DETAILS IN THE LOW THAT
MOVES FROM THE BERING INTO THE GULF (MAINLY DUE TO A SLIGHT SPLIT IN
LOW LEVEL FLOW)...BUT NOT ENOUGH TO CAUSE FORECAST PROBLEMS. THERE
IS A GREATER DIFFERENCE IN HOW THEY HANDLE A LOW MOVING INTO THE
ALEUTIANS ON SATURDAY AND SUNDAY. THE GFS IS A NICE "MIDDLE GROUND"
ON THIS LOW AND MATCHES THE INHERITED FORECAST WELL...SO IT WAS THE
PREFERRED SOLUTION.

.SHORT TERM FORECAST...
FOR SOUTH CENTRAL AND SOUTHWEST ALASKA...THE WEAKENING LOW WILL
CONTINUE TO PROVIDE SOME SHOWERS TONIGHT WILL HAVE DISSIPATED BY
FRIDAY MORNING. THE BERING LOW WILL MOVE ACROSS SOUTHWEST ALASKA
TONIGHT AND THEN CROSS KODIAK ISLAND AN PUSH INTO THE GULF OF ALASKA
FRIDAY MORNING. WINDS WITH THIS SYSTEM ARE QUITE STRONG...ESPECIALLY
SOUTH OF THE SURFACE LOW ALONG THE ALASKA PENINSULA. THIS LOW ALSO
HAS A NICE MOISTURE TAP INTO A FORMER TROPICAL SYSTEM NEAR JAPAN SO
PRECIPITATION OVER SOUTHWEST ALASKA AND COASTAL AREAS OF SOUTH
CENTRAL SHOULD BE PRETTY DECENT...THOUGH THE FAST SPEED OF THIS
SYSTEM WILL LIMIT TOTAL STORM ACCUMULATIONS. INLAND PORTIONS OF
SOUTH CENTRAL WILL NOT SEE VERY MUCH RAIN AS THE BULK OF THE
MOISTURE AND DYNAMICS STAYS OVER/NEAR THE GULF.

BY SATURDAY THE LOW WILL HAVE MOVED WELL SOUTHEAST OF SOUTHERN
ALASKA. SOME RESIDUAL UPPER LEVEL "TROGHINESS" WILL KEEP SOME
MOISTURE OVER THE AREA ON SATURDAY AND SUNDAY.

FOR THE BERING SEA AND ALEUTIANS...WINDY CONDITIONS WILL CONTINUE
OVER THE EASTERN BERING SEA AND EASTERN ALEUTIANS THROUGH FRIDAY AS
THE MAIN LOW PUSHES INTO THE GULF AND THE SURFACE PRESSURE FILLS
BEHIND IT. WINDS WILL SUBSIDE OVER THE CENTRAL AND WESTERN
ALEUTIANS/BERING SEA. THE NEXT SYSTEM WILL MOVE INTO THE WESTERN AND
CENTRAL ALEUTIANS LATE FRIDAY AND INTO SATURDAY. THIS IS THE FORMER
TROPICAL SYSTEM MENTIONED ABOVE. THIS SYSTEM WILL WORK ITS WAY INTO
THE EASTERN ALEUTIANS ON SUNDAY. THIS SYSTEM LOOKS LIKE IT WILL BE
WEAKER THAN THE CURRENT ONE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 181.
MARINE...STORM WARNING 150 155 160 165 180.
         GALE WARNING 120 125 130 132 138 140 170 171 172 176 179.
FIRE WEATHER...NONE.

LUDWIG SEP 13