Small Craft Advisory 698, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT WED SEP 11 2013

.ANALYSIS AND UPPER LEVELS...
THERE IS AN UPPER LEVEL LOW OVER THE CENTRAL ALEUTIANS WITH A
SURFACE LOW CENTERED JUST TO THE EAST. ANOTHER LOW IS OVER EXTREME
NORTHEAST RUSSIA. THERE IS A SHORT-WAVE TROUGH OVER SOUTH CENTRAL
ALASKA MOVING TO THE NORTHEAST. THERE IS AN UPPER LEVEL RIDGE
BUILDING INTO THE WESTERN BERING SEA.

.MODEL DISCUSSION...
THE NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH 84 HOURS.
THERE IS A BIT OF A SPLIT IN MODEL SOLUTIONS AFTER 60 HOURS...WITH
THE GFS AND ECMWF HAVING A SLIGHTLY SLOWER SOLUTION THAN THE
NAM...UKMET AND GEM. THIS IS FAIRLY MINOR...AND WITH THE GFS AND
ECMWF SOLUTIONS IN AGREEMENT CONFIDENCE IN THE FORECAST IS FAIRLY
HIGH.

.SHORT TERM FORECAST...
FOR SOUTH CENTRAL AND SOUTHWEST ALASKA...THE TROUGH OVER SOUTH
CENTRAL ALASKA WILL EXIT TO THE NORTH LATE THIS EVENING. THE CENTRAL
ALEUTIAN LOW WILL MOVE EAST AND FRONTAL PRECIPITATION WITH THIS
SYSTEM WILL REACH SOUTHWEST ALASKA LATE TONIGHT AND SOUTH CENTRAL ON
THURSDAY. THE UPPER LOW ITSELF WILL MOVE INTO THE FAR WESTERN GULF
THURSDAY NIGHT. AT THE SAME TIME THE RUSSIAN LOW WILL MOVE EAST...AND
ENTER NORTHWEST ALASKA FRI MORNING. THESE TWO LOWS WILL MOVE EAST
TOGETHER (THOUGH NOT PHASING UP) AND BOTH BE ALONG 150 DEGREES WEST
LONGITUDE SATURDAY MORNING. THE ALEUTIAN LOW IS CURRENTLY FAIRLY
STRONG...BUT WILL WEAKEN AS IT MOVES EAST AND INTO THE GULF.

THE BERING SEA HIGH WILL FOLLOW THESE LOWS..AND WILL HAVE MIGRATED
INTO SOUTHWEST ALASKA ON FRIDAY AND INTO SOUTH CENTRAL ON SATURDAY.
THIS WILL BRING IN A DRYING TREND FOR THE END OF THE WEEK.

FOR THE BERING SEA AND ALEUTIANS...WINDY CONDITIONS ARE EXPECTED
ACROSS THE CENTRAL ALEUTIANS TONIGHT WITH THE NORTHWEST FLOW BEHIND
THE EXITING LOW. THESE WINDS WILL WEAKEN AND MOVE EAST ACROSS THE
EASTERN ALEUTIANS AND BERING SEA ON THURSDAY. THE NEXT (MUCH WEAKER)
SYSTEM WILL MOVE INTO THE WESTERN BERING SEA AND WESTERN ALEUTIANS
ON THURSDAY...BUT SLOW DOWN CONSIDERABLY AND POSSIBLY ONLY MAKE IT
TO THE CENTRAL BERING/ALEUTIANS ON SATURDAY.

.LONG TERM FORECAST...
THE RIDGE WILL SLOWLY MOVE EAST ACROSS SOUTHERN ALASKA DURING THE
WEEKEND INTO EARLY NEXT WEEK. SOUTH CENTRAL ALASKA WILL LIKELY
REMAIN DRY THOUGH MONDAY. SOUTHWEST ALASKA COULD SEE SOME SHOWERS ON
SUNDAY AND A BETTER CHANCE OF RAIN ON MONDAY AS WESTERLY FLOW ALOFT
RETURNS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING 172.
         GALE WARNING 130 132 150 155 160 165 170 175 179.
FIRE WEATHER...NONE.

LUDWIG SEP 13