Small Craft Advisory 830, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT WED OCT 23 2013

.ANALYSIS AND UPPER LEVELS...
THERE IS A LARGE UPPER LOW CENTERED OVER THE CENTRAL ALEUTIANS. A
RAPIDLY DEEPENING LOW IS CURRENTLY SOUTH OF THE EASTERN ALEUTIANS
AND ALASKA PENINSULA AND MOVING NORTH. A SMALL LOW CENTERED JUST
WEST OF YAKUTAT IS MOVING ONSHORE. ANOTHER LOW IS JUST SOUTHEAST OF
THE KAMCHATKA PENINSULA AND MOVING EAST-SOUTHEAST TOWARD THE BASE OF
THE ALEUTIAN UPPER LOW.

.MODEL DISCUSSION...
THE NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT. THE ECMWF AND GEM
ARE STILL FURTHER EAST...FASTER...AND A LITTLE STRONGER WITH THE LOW
MOVING INTO THE BERING SEA LATE TONIGHT THAN THE GFS AND NAM. THE
ECMWF/GEM IS THE PREFERRED SOLUTION WITH THIS SYSTEM. THE MODELS ARE
CLOSE ENOUGH THAT THE CONFIDENCE IN THE FORECAST IS HIGHER THAN
NORMAL. THERE IS A BIT OF A LARGER SPREAD WITH THE SYSTEM MOVING
INTO THE ALEUTIANS AND ALASKA PENINSULA LATE FRIDAY INTO SATURDAY
BUT THE MODELS SEEM TO HAVE THE BASIC DYNAMICS CORRECT...AND FEEL
THAT THEY WILL BEGIN TO CONVERGE IN SUBSEQUENT MODEL RUNS.

.SHORT TERM FORECAST...
THE YAKUTAT LOW WILL MOVE INLAND THIS EVENING. ACCUMULATING SNOW IS
EXPECTED OVER THE EASTERN COPPER RIVER BASIN...ENDING BY LATE
EVENING. OTHERWISE SOUTH CENTRAL ALASKA WILL BE DRY TONIGHT.

THE RAPIDLY DEVELOPING LOW THAT IS CURRENTLY SOUTH OF THE EASTERN
ALEUTIANS AND ALASKA PENINSULA WILL MOVE INTO THE BERING SEA LATE
TONIGHT. SIGNIFICANT (WARNING LEVEL) WINDS ARE EXPECTED ACROSS THE
ALASKA PENINSULA BOTH WITH THE WARM FRONT THIS EVENING AND THEN WITH
THE "WRAP AROUND" TIP OF THE OCCLUSION THURSDAY MORNING AND INTO THE
AFTERNOON. PRECIPITATION AND WINDS (BELOW WARNING LEVEL) WITH THE
LEADING FRONTAL BAND WILL PUSH INTO SOUTHWEST ALASKA LATE TONIGHT
AND THURSDAY MORNING...THEN INTO SOUTH CENTRAL THURSDAY MORNING INTO
THURSDAY AFTERNOON. THE DEVELOPMENT OF A "TRIPLE POINT" LOW ALONG
THE FRONT WILL HELP TO KEEP WINDS SPEEDS ALONG TURNAGAIN ARM BELOW
WARNING LEVELS.

THE LOW WILL THEN TAKE A TURN TOWARDS THE NORTHWEST WHILE WEAKENING.
WEATHER OVER SOUTHERN ALASKA WILL DIMINISH LATE THURSDAY NIGHT AND
FRIDAY. A SHORT-WAVE RIDGE WILL BUILD OVER SOUTHERN ALASKA ON FRIDAY
NIGHT AND SATURDAY.

BY FRIDAY AFTERNOON THE LOW THAT WAS NEAR KAMCHATKA WILL BE SOUTH
OF THE CENTRAL ALEUTIANS. THIS SYSTEM WILL THEN DEVELOP INTO THE
DOMINANT LOW IN THE AREA...WITH PRECIPITATION AND WINDS SPREADING
ACROSS THE ALEUTIANS AND ALASKA PENINSULA THROUGH SATURDAY
AFTERNOON.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 181.
MARINE...STORM WARNING 155 165 172 179 180 185.
         GALE WARNING 119 120 125 129 130 131 132 136 137 138 150
                     160 170 171 173 174 176 177 178 181.
FIRE WEATHER...NONE.

LUDWIG OCT 13