Small Craft Advisory 178, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKST SUN FEB 24 2013

.MODEL DISCUSSION...
GUIDANCE IS IN FAIRLY GOOD AGREEMENT THROUGH 84 HOURS. THERE ARE
SOME SMALL DIFFERENCES IN TIMING OF THE SURFACE LOWS AND
PRECIPITATION FIELDS...WITH GENERALLY THE GFS BEING FASTER WITH BOTH
FIELDS THAN THE ECMWF AND NAM. HOWEVER...THE GFS AND ECMWF (AND
UKMET AND GEM GLOBAL) ARE IN GOOD ENOUGH AGREEMENT TO LEND
CONFIDENCE TO THE FORECAST...WHILE THE NAM SEEMS TO BE A BIT OF
AN OUTLIER.

.ANALYSIS AND UPPER LEVELS...
FAIRLY ZONAL FLOW EXISTS ACROSS THE NORTH PACIFIC OCEAN. A SERIES
OF LOWS IN THIS FLOW WILL AFFECT SOUTHERN ALASKA OVER THE NEXT FEW
DAYS. THE GENERAL PROGRESSION OF THESE SYSTEMS IS TO SLIDE ALONG
ALONG OR JUST SOUTH OF THE ALEUTIANS AND THEN NORTHEAST INTO THE
GULF OF ALASKA. THE FIRST SYSTEM IS JUST EAST OF KODIAK AND IS
MOVING TO THE NORTHEAST AND WEAKENING. ANOTHER LOW IS SPINNING UP
SOUTH OF THE AKPEN/EASTERN ALEUTIANS WITH AN EAST/NORTHEAST
TRAJECTORY. ANOTHER SYSTEM THAT WILL EVENTUALLY AFFECT THE ALEUTIANS
IS FORMING ABOUT 1000 MILES SOUTHWEST OF WESTERN ALEUTIANS.

.SHORT TERM FORECAST...
THE KODIAK LOW WILL REACH THE GULF COAST TONIGHT AND DISSIPATE
MONDAY MORNING. THIS WILL CONTINUE TO BRING PRECIPITATION TO SOUTH
CENTRAL ALASKA TONIGHT...MAINLY FOR COASTAL AREAS...BUT SOME SHOWERS
WILL MOVE INLAND.

THE SECOND SYSTEM WILL CONTINUE TO WIND UP AND MOVE NORTHEAST. THIS
WILL BRING POSSIBLE BLIZZARD CONDITIONS TO THE AKPEN TONIGHT AND
MONDAY...AND TO THE BRISTOL BAY AREA MONDAY. THE MAIN LOW WILL MOVE
INTO THE GULF LATER MONDAY/MONDAY NIGHT. THIS SYSTEM WILL BE LARGER
THAN THE PREVIOUS ONE...BUT ALSO CENTERED FURTHER SOUTH.
PRECIPITATION AND WINDS FROM THIS SYSTEM WILL MOVE INTO SOUTH
CENTRAL ALASKA MONDAY AND TUESDAY. WITH ITS MORE SOUTHERLY TRACK
PRECIPITATION WILL BE MOSTLY CONFINED TO COASTAL AREAS EVEN MORE SO
THAN THE PREVIOUS SYSTEM. THIS LOW WILL REMAIN IN THE GULF AND
WEAKEN TUESDAY NIGHT AND WEDNESDAY.

THE SYSTEM SOUTHWEST OF THE WESTERN ALEUTIANS WILL CONTINUE TO
DEVELOP AND WILL MOVE INTO THE WESTERN ALEUTIANS MONDAY AFTERNOON.
THIS LOW WILL BE QUITE LARGE BY THIS TIME AND THE SURFACE PRESSURE
WILL BOTTOM OUT AROUND 970 MB. THE SYSTEM WILL MOVE INTO THE CENTRAL
ALEUTIANS BY MONDAY EVENING AND THE EASTERN ALEUTIANS TUESDAY. THIS
SYSTEM WILL THEN SLOW DOWN AND WEAKEN TUESDAY NIGHT AND WEDNESDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WATCH 161 181.
MARINE...STORM WARNING 150 155 172 175.
         GALE WARNING 120 130 132 160 165 170 176 185.
         HEAVY FREEZING SPRAY 130 140 150 155 165 170 171 179.
FIRE WEATHER...NONE.

LUDWIG FEB 13