Small Craft Advisory 863, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKST SUN NOV 3 2013

.ANALYSIS AND UPPER LEVELS...AN UPPER TROUGH STRETCHES ACROSS EASTERN
RUSSIA AND THE WESTERN PACIFIC...WITH A LOW CENTER OVER THE WESTERN
ALEUTIANS. THIS TROUGH WILL SWING ACROSS THE BERING SEA OVER THE NEXT
COUPLE DAYS. ANOTHER TROUGH OVER THE EASTERN GULF OF ALASKA IS MOVING
EASTWARD...LEAVING HIGH PRESSURE TO BUILD INTO MUCH OF THE MAINLAND
TODAY. THE MAIN AREAS OF PRECIPITATION ARE ALONG THE FRONT IN THE
WESTERN AND CENTRAL ALEUTIANS AS WELL AS OVER THE COPPER BASIN AND
GULF OF ALASKA AS THE GULF LOW MOVES OFF TO THE SOUTHEAST.

.MODEL DISCUSSION...MODELS CONTINUE TO HANDLE STRONG LOW OVER THE
WESTERN ALEUTIANS VERY WELL. THE GFS REMAINS THE PREFERRED SOLUTION
THROUGH WEDNESDAY MORNING. THE ECMWF BECOMES THE PREFERRED SOLUTION
FROM WED MORNING AND ON...SHOWING A SLIGHTLY SLOWER PROGRESSION
NORTHWARD INTO THE NORTHWEST BERING BY INTO WED AFTERNOON.

CLOSER TO SOUTHCENTRAL...MODELS APPEAR TO BE IN FAIR AGREEMENT WITH
THE LOW IN THE EASTERN GULF AS IT PROGRESSES SOUTHEASTWARD AND
DISSIPATE BY WED EVENING. DRIER NORTHERLY OFFSHORE FLOW ACROSS THE
WESTERN SLOPES OF THE CHUGACH AND KENAI MOUNTAIN RANGES CAN BE
EXPECTED ON THE BACK END OF THIS PASSING LOW...CONTINUING TO KEEP
LITTLE TO NO PRECIPITATION IN THE FORECAST FOR THE ANCHORAGE AREA
THROUGH WED MORNING. MODELS CONTINUE TO SHOW A SLIGHT DISAGREEMENT
WITH THE NEXT FRONTAL PASSAGE OVER THE GULF AND SOUTHCENTRAL. GFS
SEEMS TO BE THE MIDDLE GROUND SOLUTION BETWEEN THE WEAKER AND
SLIGHTLY SLOWER (REGARDING THE LOW FORMATION) NAM SOLUTION...AND THE
STRONG AND FASTER (REGARDING LOW FORMATION AND TIMING ON THE FRONT
CROSSING THE GULF) ECMWF SOLUTION. THE GFS BRINGS THE FRONT INTO THE
WESTERN GULF WEDNESDAY EVENING AND STARTS TO DECOUPLE THURSDAY
EVENING AS IT MOVES OVER THE EASTERN GULF.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...THE UPPER TROUGH OVER THE EASTERN MAINLAND WILL
CONTINUE TO MOVE EASTWARD TONIGHT...GRADUALLY CLEARING SKIES IN ITS
WAKE. THIS AREA WILL BE UNDER THE INFLUENCE OF HIGH PRESSURE UNTIL
THURSDAY AFTERNOON THROUGH THURSDAY NIGHT...WHEN THE FRONT FROM THE
WESTERN BERING LOW SWINGS NORTHWARD THROUGH THE GULF. WINDS WILL
INCREASE THROUGH THE USUAL GAPS AS THE FRONT APPROACHES...AND COLD
AIR WILL MOVE SOUTHWARD INTO THE AREA. THIS WILL BRING BETTER CHANCES
FOR THE PRECIPITATION TYPE BEING SNOW RATHER THAN RAIN ACROSS THE
AREA THURSDAY AND THURSDAY NIGHT.

SOUTHWEST MAINLAND...
DECREASING CLOUDS ARE EXPECTED OVER MUCH OF THE AREA AS HIGH PRESSURE
CONTINUES TO BUILD OVER SOUTHWEST MAINLAND THROUGH WED MORNING.
WINDIER AND WETTER CONDITIONS CAN BE EXPECTED WITH THE NEXT FRONTAL
PASSAGE WEDNESDAY MORNING...WITH STRONG WINDS AND INCREASING SEAS
ALONG MUCH OF THE WESTERN COAST FROM CAPE NEWENHAM NORTH. A WINTERY
MIX IS EXPECTED WITH THE PRE-FRONTAL PUSH OF THIS SYSTEM...THEN A
TRANSITION TO A RAIN/SNOW MIX WITH THE FRONTAL PASSAGE. ON THE BACK
END OF THE FRONT...GUIDANCE INDICATES A COLD POOL DIGGING INTO THE
EASTERN BERING AND TRANSITIONING OVER THE WESTERN COAST BEGINNING
LATE THURSDAY MORNING. THIS WILL BRING A WINTERY MIX BACK TO THE
SOUTHWEST COAST AND SNOW SHOWERS TO THE SOUTHWEST INTERIOR. STRONG
WESTERLY FLOW DEVELOPS ACROSS THE BERING THURSDAY MORNING AND INTO
THE WEEKEND. THE LARGE SWELL GENERATED BY THE CYCLONE WILL BE
REINFORCED BY THIS STRONG WESTERLY FLOW...AND WILL LIKELY GENERATE A
STORM SURGE ALONG THE SOUTHWEST MAINLAND FROM CAPE NEWENHAM NORTH.
THE COASTAL FLOOD WATCH WILL BE UPGRADED TO A WARNING FOR THIS VERY
REASON AND WILL CARRY A SIMILAR START TIME AS THE PREVIOUSLY ISSUED
WATCH.

BERING SEA/ALEUTIANS/AKPEN...
HIGH WINDS TO HURRICANE FORCE WILL CONTINUE TO BATTER THE WESTERN
ALEUTIANS THROUGH EARLY WEDNESDAY AS THE LOW CENTER MOVES INTO THE
WESTERN BERING. GUIDANCE CONTINUES TO INDICATE THAT THE SYSTEM WILL
GO THROUGH A SECOND INTENSIFICATION PHASE LATE WEDNESDAY MORNING AS
MID LEVEL COLD AIR ADVECTS INTO THE SYSTEM. THIS COLD AIR ALOFT
RAPIDLY ADVANCES INTO THE BACK OF THE LOW AND GENERATES EXTREMELY
POWERFUL WINDS APPROACHING 100 MPH IN GUSTS NEAR SHEMYA TONIGHT.
WINDS ASSOCIATED WITH THIS CYCLONE WILL REMAIN STRONG ENOUGH TO
WARRANT A HIGH WIND WARNING ISSUANCE FOR THE PRIBILOF ISLANDS FOR
TONIGHT. MARINERS ARE URGED IN THIS AREA TO TAKE PRECAUTIONS FOR
POWERFUL WINDS AND WAVE HEIGHTS TO 40 FEET OR MORE ACROSS THE BERING
SEA.

.LONG TERM FORECAST...A SECOND LOW WILL MOVE THROUGH THE BERING SEA
OVER THE WEEKEND. THIS LOW WILL BE MUCH WEAKER THAN THE CURRENT
BERING LOW...HOWEVER IT WILL CAUSE SOUTHWEST WINDS AND SEA SWELLS TO
CONTINUE ACROSS THE SOUTHERN BERING THROUGH THIS TIME.
OTHERWISE...THERE ARE SOME SMALL CHANCES FOR PRECIPITATION OVER THE
WEEKEND ACROSS SOUTHCENTRAL ALASKA BUT NO SIGNIFICANT STORMS ARE ON
THE HORIZON AT THIS TIME.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING...187 191 195.
         COASTAL FLOOD WARNING...155 161.
MARINE...HURRICANE 178 185 411 412 413.
         STORM 170 172 173 174 175 176 177 179 180 181 414.
         GALE 130 131 132 150 155 160 165 171 351 352.
FIRE WEATHER...NONE.

SCHRECK