Small Craft Advisory 311, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKDT SUN MAY 1 2011

.MODEL DISCUSSION...MODELS CONTINUE TO DO FINE FOR THE FIRST HALF OF
THE WEEK. MAJOR WEATHER ITEMS ARE HANDLED IN A SIMILAR MANNER IN EACH
MODEL. IN THIS PATTERN MORE SUBTLE FEATURES MAY HAVE GREATER IMPACT
ON THE FORECAST AND THE NAM OVER LAND WILL LIKELY DO THE BEST IN THIS
REGARD.

.ANALYSIS AND UPPER LEVELS...A RATHER COMPLEX UPPER LEVEL PATTERN
OVER THE FORECAST AREA TODAY AS A BROAD UPPER LEVEL TROUGH SITS OVER
MOST OF THE MAINLAND PART OF THE STATE WITH A SEPARATE CUT OFF LOW
SOUTH OF THE CENTRAL ALEUTIANS. THERE IS ALSO A HIGH AMPLITUDE UPPER
LEVEL RIDGE EXTENDING OUT OF THE PACIFIC AND OVER THE ALASKA
PENINSULA INTO THE EASTERN BERING SEA. IN ADDITION THERE IS ANOTHER
UPPER RIDGE RIDING UP THE SOUTHEAST ALASKA COAST TO THE ALCAN BORDER.

THE JET STREAM AT 250 MB LOOKS A BIT SERPENTINE AS IT MEANDERS UP AND
DOWN AND AROUND THESE FEATURES TODAY. THIS PATTERN WILL SETTLE DOWN
OVER THE NEXT TWO DAYS RETURNING THE JET STREAM TO A MORE ZONAL DUE
WEST TO EAST PATTERN BUT IT WILL REMAIN WELL SOUTH OF THE FORECAST
AREA.
MAJOR SURFACE SYSTEMS ARE CONFINED TO THE SOUTHEASTERN GULF WITH A
LOW THAT WILL HEAD INTO SOUTHEAST ALASKA LATE TOMORROW AND AND
ELONGATED WEATHER FRONT ALONG THE ALEUTIAN ISLANDS.

.SHORT TERM FORECAST...WITH A BROAD UPPER LEVEL TROUGH OVER MAINLAND
ALASKA AND SOME DAYTIME HEATING THE ENVIRONMENT IS FAVORABLE FOR THE
DEVELOPMENT OF SHOWERS OVER AND NEAR THE MOUNTAINS THIS EVENING AND
AGAIN MONDAY AFTERNOON AND EVENING FOR ALL OF THE MAINLAND AREAS OF
THE FORECAST AREA.
LOW LYING AREAS WILL BE AT RISK FOR THE DEVELOPMENT OF FOG ONCE AGAIN
TONIGHT AS TEMPERATURES RAPIDLY FALL AFTER THE SUN SETS.

.LONG TERM FORECAST...WHILE THERE IS SOME UNCERTAINTY IN THE LONG
TERM MODELS WHAT DOES SEEM LIKELY IS THAT THE STORM TRACK WILL REMAIN
OVER THE ALEUTIAN ISLANDS AND INTO THE GULF OF ALASKA THROUGHOUT THE
WEEK. THIS WILL KEEP MAINLAND ALASKA IN WEAK UPPER LEVEL FLOW WITH
AFTERNOON SHOWERS OVER THE MOUNTAINS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 175 176.
FIRE WEATHER...NONE.

MAY 11