Small Craft Advisory 919, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
150 PM ADT THU NOV 1 2007

.ANALYSIS AND UPPER LEVELS...A STRONG VERTICALLY STACKED LOW JUST
NORTHEAST OF KODIAK ISLAND EARLY THIS AFTERNOON IS TRACKING
NORTHWARD TOWARD SEWARD. THE SURFACE PRESSURE HAS BOTTOMED OUT AND
IS BEGINNING TO SLOWLY RISE. WIDESPREAD GALE FORCE WINDS ARE BEING
OBSERVED ACROSS THE GULF COASTAL WATERS WHILE THE TYPICAL STRONG
GAP WINDS ARE PROMINENT OVER LAND. THE REMNANTS OF THE OCCLUDED
FRONT ARE NOW MOVING INLAND ACROSS SOUTHCENTRAL TOWARD THE ALASKA
RANGE. WITH FAIRLY WARM AIR IN PLACE ACROSS MUCH OF THE REGION RAIN
IS THE PREDOMINATE PRECIPITATION TYPE. SNOW IS FALLING AT HIGHER
ELEVATIONS NEAR THE COAST SUCH AS THOMPSON PASS AND TURNAGAIN PASS.
DOWNSLOPING IS RESULTING IN LITTLE OR NO PRECIPITATION FOR INLAND
LOCATIONS. A SURFACE TROUGH EXTENDS FROM THE LOW CENTER NORTHWESTWARD
OVER INTERIOR BRISTOL BAY AND INTO THE KUSKOKWIM VALLEY. A BAND OF
PRECIPITATION IS CENTERED NEAR THIS AXIS...MAINLY IN THE FORM OF
RAIN IN BRISTOL BAY AND SNOW AS YOU HEAD NORTH ALONG THE ALASKA
RANGE. THIS PRECIPITATION BAND WILL TRANSLATE NORTHEASTWARD AS THE
LOW TRACKS NORTHWARD. AN UPPER LOW IS SITTING NEARLY STATIONARY
OVER THE KUSKOKWIM DELTA. BEHIND THIS LOW...ON THE BACK SIDE OF THE
UPPER TROUGH...COLD ADVECTION IS OCCURRING ACROSS MOST OF THE BERING
SEA RESULTING IN SHOWERS. A RIDGE IS BUILDING OVER THE FAR WESTERN
BERING SEA AHEAD OF A SHORT-WAVE DROPPING OUT OF RUSSIA. WEST PACIFIC
SATELLITE IMAGERY SHOWS A LONG FETCH OF MOISTURE BEING TRANSPORTED
FROM ABOUT 20N ALL THE WAY UP TO THE KAMCHATKA PENINSULA.

.MODEL DISCUSSION...NAM AND ECMWF INITIALIZED BEST ON THE LOCATION
OF GULF LOW WITH THE GFS/UKMET TOO FAR NORTH AND WEST. THE 18Z MODEL
POSITIONS ARE ALL TOO SLOW AND A BIT TO THE WEST. MODEL SOLUTIONS DO
ALL TRACK THE LOW NORTH-NORTHEAST ACROSS WESTERN PRINCE WILLIAM SOUND
TONIGHT. BASED ON LATEST SATELLITE IMAGERY THIS SEEMS REASONABLE.
HOWEVER...WILL MAKE ADJUSTMENTS TO SPEED UP THE TRACK OF THE LOW.
OTHERWISE...SHORT-TERM MODEL SOLUTIONS ARE IN FAIR AGREEMENT AND
NO MAJOR CHANGES WILL BE MADE.

.SHORT TERM FORECAST...

SOUTHCENTRAL...THE BEST AREA OF LIFT WILL BE JUST AHEAD OF THE LOW
CENTER TONIGHT WHICH WILL BRING WIDESPREAD PRECIPITATION...POSSIBLY
HEAVY AT TIMES...TO THE PRINCE WILLIAM SOUND REGION. DOWNSLOPING
WINDS WILL CONTINUE EAST OF THE LOW TRACK SO THAT THE COPPER BASIN
WILL REMAIN MOSTLY DRY WITH ALL THE PRECIPITATION HANGING UP ALONG
THE COAST. THOMPSON PASS WILL REMAIN ALL SNOW AND COULD RECEIVE UP
TO A FOOT OF SNOW OVERNIGHT. LIGHT PRECIPITATION CAN BE EXPECTED WEST
OF THE LOW TRACK OVER THE WESTERN KENAI PENINSULA...ANCHORAGE...AND
THE MATSU. IT WILL TAKE A WHILE FOR ENOUGH COLD AIR TO ADVECT IN AND
CHANGE PRECIPITATION TO ALL SNOW. THE TIMING OF THE COLD AIR AND END
OF PRECIPITATION IS TRICKY. RIGHT NOW IT LOOKS LIKE PRECIPITATION
WILL CHANGE TO SNOW AFTER MIDNIGHT FOR COOK INLET REGION AND TAPER
OFF TOWARD MORNING. SO THERE MAY BE SOME LIGHT ACCUMULATION. AS THE
REMNANTS OF THE LOW TRACK INLAND FRIDAY SNOW WILL SPREAD TO NORTHERN
SECTIONS OF SOUTHCENTRAL...UP ALONG THE ALASKA RANGE. MODELS SHOW A
SECONDARY WEAK UPPER LOW FORMING OVER THE SOUTHERN SUSITNA TONIGHT
AND MOVING TO THE KENAI FRIDAY. MEANWHILE...THE UPPER LOW OVER THE
KUSKOKWIM DELTA WILL TRACK INTO THE GULF LATE FRIDAY. SO A CHANCE
OF SHOWERS WILL CONTINUE ACROSS THE REGION THROUGH FRIDAY NIGHT.
DRYING WILL OCCUR ON SATURDAY AS EVERYTHING MOVES OFF TO THE EAST
AND A RIDGE BUILDS IN FROM THE WEST.

SOUTHWEST ALASKA...AREAS OF SNOW ON BACK SIDE OF LOW (ALONG REMAINS
OF OCCLUSION) WILL CONTINUE THROUGH TONIGHT OVER INTERIOR SOUTHWEST
ALASKA. ALONG THE COAST THERE MAY BE A FEW SNOW SHOWERS AS THE UPPER
LOW OVER THE KUSKOKWIM DELTA MOVES SOUTHEASTWARD ACROSS BRISTOL BAY
TONIGHT THROUGH FRIDAY MORNING. THE UPPER TROUGH WILL GRADUALLY MOVE
OFF TO THE EAST FRIDAY NIGHT AND SATURDAY...RESULTING IN DRYING
ACROSS THE REGION. A FRONT WILL APPROACH THE SOUTHWEST COAST LATE
SATURDAY WITH PRECIPITATION AND WIND LIKELY BY SATURDAY NIGHT.

BERING SEA/ALEUTIANS/AKPEN...SNOW SHOWERS WILL CONTINUE ACROSS THE
EASTERN BERING TONIGHT AND THEN TAPER OFF FROM WEST TO EAST FRIDAY
AS UPPER RIDGE MOVES IN FROM THE WEST. THE NEXT SYSTEM LOOKS
IMPRESSIVE WITH ABUNDANT MOISTURE TRANSPORT AND EXCELLENT UPPER
LEVEL SUPPORT. EXPECT STORM FORCE WINDS AS THE FRONT REACHES THE
ALEUTIANS LATE TONIGHT INTO FRIDAY MORNING. COLD ADVECTION ON THE
BACK SIDE OF THE LOW WILL ALSO BRING SOME STORMS INTO THE WESTERN
ALEUTIANS FRIDAY AFTERNOON AND NIGHT. THE FRONT WILL WEAKEN AS IT
CROSSES THE BERING SEA/ALEUTIANS FRIDAY AND SATURDAY WITH PARENT
LOW REMAINING OVER THE WESTERN BERING.

.LONG TERM FORECAST...MEDIUM RANGE MODELS INDICATE A LARGE COLD CORE
LOW SETTING UP OVER THE BERING SEA FOR THE EXTENDED FORECAST PERIOD.
DETAILS ARE CERTAINLY IN QUESTION...BUT THIS PATTERN USUALLY LEADS
TO UNSETTLED WEATHER ACROSS THE ENTIRE FORECAST AREA AS MULTIPLE
SYSTEMS/WAVES ROTATE AROUND THIS MAIN CIRCULATION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALES 120 130 132 150 155 160 180 170 171 172 179 185.
         STORMS 175 176.
FIRE WEATHER...NONE.

SEB NOV 07