Small Craft Advisory 480, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKDT SAT JUN 13 2009

.MODEL DISCUSSION...MODEL INITIALIZATIONS REASONABLE. FORECAST TREND
WITH SYNOPTIC FEATURES ARE IN GENERAL AGREEMENT THROUGH MON
AFTERNOON. MODEL CONSISTENCY OF LOW COMPLEX SOUTH OF THE ALEUTIANS/AK
PEN BEYOND MON CONTINUES TO BE PROBLEMATIC. WILL MAKE ADJUSTMENTS TO
CURRENT GRIDS THROUGH MON AFTERNOON. GRIDS WILL NOT BE MODIFIED
BEYOND THIS POINT DUE TO LOW CONFIDENCE AND A HOPE TO MAINTAINING
SOME CONSISTENCY IN CURRENT FORECAST PRODUCTS.

.UPPER LEVELS...
LOW OVER THE GULF MOVES TO THE EASTERN GULF AND WEAKENS MON AFTERNOON
AS A RIDGE BUILDS OVER THE MAINLAND. CURRENT SATELLITE IMAGERY
INDICATES A FAIRLY EXTENSIVE AREA OF CLOUDS ALONG A DEFORMATION AXIS
EXTENDING FOR WESTERN CANADA TROUGH THE MATANUSKA VALLEY. THIS ZONE
MAY WEAKEN SOME AND DRIFT SE THROUGH TONIGHT. LOW CENTER SOUTH OF THE
CENTRAL ALEUTIANS DRIFTS SE AND INTENSIFIES THROUGH MON. THE
ASSOCIATED TROUGH ELONGATES EAST WITH A CENTER DEVELOPING WELL SOUTH
OF THE AK PEN SUN NIGHT AND MOVING NORTH MON. A TROUGH MOVING ACROSS
EASTERN RUSSIA SAT NIGHT DIGS SOUTH TO THE THE CENTRAL BERING SEA MON
AFTERNOON.

.SURFACE SHORT TERM FORECAST...

.EAST...A WEAK LOW OVER THE SOUTHERN GULF OF ALASKA MOVES SLOWLY EAST
AND DISSIPATES ON MON. SOME WEAK RIDGING SHOULD CONTINUE ALONG THE
NORTH GULF OVER THE WEEKEND. THE THERMAL TROUGH OVER THE INTERIOR
DROPS SOUTH AND INTENSIFIES MON. THIS SHOULD ENHANCE AFTERNOON AND
EVENING CONVECTION THROUGHOUT THE EAST WITH THUNDERSTORM POTENTIAL
OVER THE COPPER RIVER BASIN AND SUSITNA VALLEY.

PRECIPITATION STILL A LITTLE IN QUESTION FOR TONIGHT AS DEFORMATION
ZONE PUSHES SOUTHEAST ACROSS SOUTHCENTRAL. EXPECT WILL SEE SHOWERS OR
RAIN OVER MUCH OF THE EAST TONIGHT...HIGHER POPS PROBABLY OVER THE
COPPER RIVER...THOUGH THE 18Z RUN OF THE NAM IS A LITTLE LESS
AGGRESSIVE. AREAS OF LOW CLOUDS AND SOME FOG WILL LIKELY START THE
DAY MON...BUT SHOULD SEE BREAKS IN CLOUDS WITH POTENTIAL FOR SOME
SHOWERS.

.WEST...THERMAL TROUGH OVER THE SW INTERIOR WEAKENS AS COOLER AIR
MOVES IN AT LOWER LEVELS. THIS WILL LIMIT AFTERNOON CONVECTION TO
SHOWERS OVER THE INTERIOR. THUNDERSTORM POTENTIAL INCREASES ACROSS
THE LOWER KUSKOKWIM VALLEY MON AFTERNOON AS WARM AIR INTRUSION IN THE
LOWER LAYERS INTENSIFY THE THERMAL TROUGH. STRATUS AND FOG WILL
CONTINUE TO BE A AVIATION CONCERN ALONG COASTAL SW ALASKA AS A LIGHT
GENERALLY ONSHORE FLOW PERSISTS THROUGH MON MORNING. MODELS ARE STILL
HAVING DIFFICULTY RESOLVING THE LOW COMPLEX DEVELOPING SOUTH OF THE
ALEUTIANS/AK PEN SUN AND MON...SO CONFIDENCE IS FAIRLY LOW.
HOWEVER...NO MATTER WHERE THE LOW CENTERS END UP...SHOULD SEE
INCREASING EASTERLY FLOW ACROSS THE ALEUTIANS SUN AND MON AND ALONG
THE AK PEN MON.

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

RMC JUN 09