Small Craft Advisory 841, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM ADT WED OCT 10 2007

.ANALYSIS AND UPPER LEVELS...

PLANETARY UPPER LEVEL TROUGH EXTENDING FROM EASTERN RUSSIA TO THE
ROCKIES THIS AFTERNOON...WITH EMBEDDED LOWS OVER THE WESTERN BERING
AND PRINCE WILLIAM SOUND. A SURFACE LOW IS DIRECTLY BENEATH THE UPPER
BERING LOW...WITH ANOTHER SURFACE LOW CENTERED OVER THE SOUTHEAST AK
PANHANDLE. A SMALLER LOW IS SOUTH OF PRINCE WILLIAM SOUND. A WEAK
RIDGE COVERS SOUTHWEST AK AND THE AK PEN. A WEATHER FRONT EXTENDS
ACROSS THE NORTHERN BERING TO THE EASTERN ALEUTIANS.

.MODEL DISCUSSION...

MODELS ARE IN GENERALLY GOOD AGREEMENT...WITH A TRIPLE POINT LOW
DEVELOPING ON THE BERING FRONT TONIGHT INTO THU. THIS LOW THEN
CROSSES THE AKPEN THU AND REDEVELOPS IN THE GULF THU EVENING. FROM
THAT POINT THE LOW DRIFTS NORTHEAST...REACHING PRINCE WILLIAM SOUND
FRI AFTERNOON AND NIGHT. THE FORECAST LEANS HEAVILY TOWARD THE
GFS...ALTHOUGH THE GFS...NAM...UKMET...AND ECMWF ALL BRING THE LOW TO
THE SAME PLACE.

.SHORT TERM FORECAST...

IN THE WEST...THE BERING LOW AND ASSOCIATED FRONT WILL KEEP SHOWERY
PRECIP OVER THE ALEUTIANS THROUGH THU. AT THAT POINT THE MAIN LOW
DRIFTS EAST AND PRECIP DIMINISHES FROM THE WEST THROUGH FRI WITH
GALES ACROSS THE ISLANDS. THE NEXT KAMCHATKA LOW AFFECTS THE WESTERN
ALEUTIANS WITH RAIN AND GALES FRI NIGHT THROUGH SAT.

OVER SOUTHWEST AK...LIGHT SNOW WILL END THIS EVENING OVER THE
KUSKOKWIM VALLEY AS A WEAK UPPER WAVE DISSIPATES. THE FRONT ACROSS
THE BERING WILL BRING RAIN SHOWERS TO COASTAL SECTIONS OF THE AKPEN
EARLY THU. THESE WILL MOVE INLAND...REACHING PARTS OF THE KUSKOKWIM
VALLEY THU NIGHT. MIGRATION OF THE SURFACE LOW AND COLDER AIR ACROSS
THE AKPEN WILL KEEP SOME SNOW SHOWERS OVER THE AREA INTO THE WEEKEND.

SOUTH AND EAST OF THE AK RANGE...GENERALLY DRY CONDITIONS WILL
PERSIST UNTIL REMNANTS OF THE BERING FRONT MOVE TOWARD THE NORTH GULF
COAST LATER ON THU. THIS WILL BRING RAIN TO KODIAK AND THE COAST THU
THROUGH THE WEEKEND. BY LATE FRI SOME RAIN WILL MOVE INLAND AS THE
TRIPLE POINT LOW MOVES INTO THE GULF. AT THIS POINT MODELS BRING THE
LOW TO PRINCE WILLIAM SOUND FRI NIGHT INTO SAT. 1000-850 MB
THICKNESSES SHOW THIS TO BE ALL RAIN FOR SAT...WITH COLDER AIR HUNG
UP ALONG THE ALASKA RANGE.

.LONG TERM FORECAST...
IN THE WEST THE NEXT KAMCHATKA LOW MOVES TO BRISTOL BAY BY MON. THIS
SYSTEM IS STILL WARM SO RAIN WILL SPREAD ACROSS THE ALEUTIANS AND
BERING THROUGH THIS PERIOD. OVER SW AK....A DRY BREAK BETWEEN SYSTEMS
WILL OCCUR SAT NIGHT INTO SUN...AND THEN THE BERING FRONT WILL BRING
RAIN ALONG THE COAST AND SOME SNOW TO THE KUSKOKWIM VALLEY MON. FOR
SOUTH AND EAST OF THE AK RANGE...THE PRINCE WILLIAM SOUND LOW BEARS
WATCHING. CURRENT PROGNOSIS IS FOR COLD AIR TO MOVE INTO THE SUSITNA
VALLEY AND SOUTH CENTRAL FOR A BIT OF SNOW SAT NIGHT INTO SUN...BUT
IT IS WAY TOO EARLY FOR ANY CONFIDENCE IN SUCH A SOLUTION. STAY
TUNED.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALES 172 175 176 185
FIRE WEATHER...NONE

DS OCT 07