Small Craft Advisory 787, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT TUE OCT 8 2013

.ANALYSIS AND UPPER LEVELS...
THE PATTERN OVER ALASKA/BERING SEA CONTINUES TO BE FAIRLY
PROGRESSIVE. THERE IS A VERTICALLY STACKED LOW OVER ALASKA CENTERED
OVER EASTERN NORTON SOUND...WITH A COLD FRONT STRETCHING SOUTHWEST
FROM THE GULF COAST ALMOST TO THE MIDWAY ISLANDS. THERE IS AN UPPER
LOW CENTERED JUST WEST OF THE WESTERN ALEUTIANS. A SHORT-WAVE RIDGE
IS IN BETWEEN THESE TWO SYSTEMS.

.MODEL DISCUSSION...
THE MODELS ARE IN GOOD AGREEMENT EARLY ON...THEN BEGIN TO SHOW SOME
SPREAD LATER ON. THE MAIN ISSUES ARE HOW THEY HANDLE THE
EXTRA-TROPICAL TRANSITION OF TYPHOON DANA AND ALSO A LOW MOVING INTO
THE SOUTHEAST GULF OF ALASKA. BOTH OF THESE ARE ISSUES FOR AFTER 60
HOURS. FOR THESE TWO FEATURES...MODELS ARE COMING INTO BETTER
AGREEMENT THAN THEY HAVE BEEN...WITH BOTH SYSTEMS NOW PREDICTED TO
BE WEAKER THAN WHAT THE 00Z ECMWF HAD. ALL THIS CONSIDERED...THE
FORECAST CONFIDENCE IS HIGHER THAN AVERAGE EARLY ON...THEN NEAR TO
BELOW AVERAGE AFTER 60 HOURS (THURSDAY AFTERNOON AND BEYOND).

.SHORT TERM FORECAST...
THE ALASKA LOW WILL BROADEN AND SPLIT TONIGHT. THE EASTERN PORTION
OF THE LOW WILL FORM ALONG THE NORTH GULF COAST TONIGHT ALONG THE
TRIPLE POINT. THIS LOW WILL RIDE THE PROGRESSIVE FLOW INTO THE
PANHANDLE WEDNESDAY MORNING. STRONG WINDS WILL DEVELOP IN THE
NORTHERN GULF WITH THE SURFACE PRESSURE RISES BEHIND THIS LOW. THE
WESTERN PORTION OF THE LOW WILL MOVER MORE SLOWLY INTO NORTHERN
ALASKA. THE LOW WEST OF THE ALEUTIANS WILL RAPIDLY ACROSS THE BERING
SEA AND ALEUTIANS TONIGHT REACHING SOUTHWEST ALASKA LATER ON
WEDNESDAY. THE SHORT-WAVE RIDGE WILL BE PUSHED INTO SOUTH CENTRAL ON
WEDNESDAY NIGHT...SLOWING DOWN INTO THURSDAY AS THE UPPER LOW MOVES
NORTHEAST INTO NORTHWEST ALASKA. THE LOW WILL THEN PUSH INTO SOUTH
CENTRAL ON THURSDAY AND DISSIPATE ON FRIDAY. FAST FLOW WILL CONTINUE
FURTHER SOUTH AND WEST...BRINGING ANOTHER LOW INTO/ACROSS THE
ALEUTIANS THURSDAY INTO FRIDAY. AS MENTIONED ABOVE...THE MODELS ARE
NOT CURRENTLY DOING TO WELL WITH THIS RECENTLY TRANSITIONED TROPICAL
SYSTEM.

FOR SOUTH CENTRAL ALASKA...PRECIPITATION WILL WIND DOWN TONIGHT AS
THE UPPER LOW SPLITS AND MOVES EAST. THE STRONG WINDS BEHIND THIS
LOW WILL WEAKEN WEDNESDAY NIGHT WITH THE ARRIVAL OF THE SHORT-WAVE
RIDGE. PRECIPITATION CHANCES WILL INCREASE AGAIN ON THURSDAY AND
THURSDAY NIGHT AS THE NEXT SYSTEM MOVES IN...THEN TAPER OFF ON
FRIDAY AS IT DISSIPATES.

FOR SOUTHWEST ALASKA...STRONG WINDS ARE EXPECTED THIS EVENING AS
SURFACE PRESSURE RISES PUSH STRONGLY INTO WESTERN ALASKA BEHIND THE
LOW. ALSO EXPECTING SOME SHOWERS WITH THE ONSHORE FLOW. A BRIEF
BREAK IN THE WINDS/RAIN EARLY WEDNESDAY WITH THE PASSAGE OF THE
SHORT-WAVE RIDGE. THE NEXT SYSTEM WILL PUSH INTO SOUTHWEST ALASKA
LATER WEDNESDAY INTO THURSDAY. ONSHORE FLOW WILL CONTINUE ON FRIDAY
FOR SOME LINGERING SHOWERS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING 120 130 131 178.
         GALE WARNING 119 129 132 136 137 138 139 141 150 155 160
                   165 170 172 173 174 175 176 177 179 180 181.
FIRE WEATHER...NONE.

LUDWIG OCT 13