Small Craft Advisory 424, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM ADT MON MAY 12 2008

.MODEL DISCUSSION...
HE MODELS REMAIN IN VERY GOOD AGREEMENT AND DONT ANTICIPATE ANY
SIGNIFICANT CHANGES TO THE FORECASTS.

.ANALYSIS AND UPPER LEVELS...
THE MAJOR FALL LIKE STORM NOW PUSHING A FRONT INLAND ALONG THE GULF
COAST OF ALASKA HAS GOOD MOISTURE CONTENT IN THE FRONT AS EVIDENCED
BY THE MODERATE TO HEAVY RAIN ALONG THE COAST AND RAIN ALONG THE LEE
SIDE OF THE CHUGACH EVEN WITH THE STRONG DOWNSLOPE WINDS. THE TROUGH
IN THE EASTERN INTERIOR ALONG WITH THE RIDGING BETWEEN THE TROUGH AND
THE INCOMING FRONT IS ACCELERATING THE WIND. EXPECT THE TROUGH TO
INTENSIFY THIS EVENING AS THE FRONT JUMPS THE COASTAL MOUNTAINS AND
ALASKA RANGE. THIS COMBINED WITH AN AMPLIFYING RIDGE ALONG THE NORTH
GULF COAST WILL KEEP THE SOUTH WIND BLOWING ACROSS THE COPPER RIVER
BASIN INTO SOUTH CENTRAL ALASKA. THE MAJOR CONCERN WITH THIS SCENARIO
IS THE SOUTH TO EAST WIND ACROSS THE SOUTH CENTRAL REGION AND THE
COPPER RIVER BASIN TO THE NORTHEAST END OF THE KUSKOKWIM VALLEY ALONG
WITH LOW HUMIDITY.

.SHORT TERM FORECAST...
THE RAIN ALONG THE NORTH GULF COAST IS EXPECTED TO DECREASE IN
INTENSITY TONIGHT AS THE FRONT PUSHES INLAND. THE ONSHORE FLOW WILL
HOWEVER KEEP CONDITIONS MOIST ALONG THE COASTAL ZONES. INLAND OF THE
COASTAL MOUNTAINS THE INCREASED CLOUD COVER AND MOISTURE WILL HELP
ALLEVIATE THE FIRE WEATHER CONCERN ALTHOUGH CONDITIONS WILL STILL BE
DANGEROUSLY CLOSE TO RED FLAG WARNING CRITERIA. ACROSS THE ALASKA
RANGE THE STRONG DOWN SLOPE IS DRYING CONDITIONS AND WE WILL NEED TO
KEEP AN EYE ON THE MCGRATH AREA FOR RED FLAG CONDITIONS.
SOUTHEASTERLY FLOW WILL KEEP THE PRECIPITATION IN A DOWNSLOPE PATTERN
UNTIL EARLY TUESDAY MORNING WHEN WINDS TURN MORE SOUTHERLY. SHOWERS
WILL PERSIST THROUGH WEDNESDAY AS THE UPPER LEVEL TROUGH SLOWLY MOVES
THROUGH THE REGION.

THE NEXT LARGE LOW IS ON TAP TO MOVE INTO THE SOUTHWEST GULF OF
ALASKA WEDNESDAY. THIS STORM MOST LIKELY WILL BRING ANOTHER SHOT OF
STRONG WIND AND AREAS OF RAIN THE THE GULF COAST AREAS.

THE MAIN LOW IS CROSSING THE ALASKA PENINSULA AND SPLITTING TO TWO
CENTERS WITH THE PRIMARY CENTER MOVING TO THE WEST NORTHWEST AS A
WEAKER LOW MOVES ALONG THE BERING COAST TO THE DELTA LATE TONIGHT. AS
THE SURFACE GRADIENT RELAXES ACROSS THE SOUTHWEST MAINLAND THE
DOWNSLOPE DIMINISHES AND THUS ALLOWS FOR MORE PRECIPITATION. WE HAVE
ADJUSTED THE FORECAST TO REFLECT THE EXPECTATION OF MORE RAIN TONIGHT
AND TUESDAY.

BERING AND ALEUTIANS WILL STAY IN THE WESTERLY FLOW AND THE TYPICALLY
SHOWERY CONDITIONS ASSOCIATED WITH THAT FLOW PATTERN. THE COLD AIR IS
EXPECTED TO REMAIN OVER THE PRIBILOFS KEEPING THE PRECIPITATION
MAINLY SNOW OVER THE AREA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 132 175 176
FIRE WEATHER...NONE

SAM MAY 08