Small Craft Advisory 555, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM ADT TUE JUN 26 2007

.MODEL DISCUSSION...MODELS IN GENERAL AGREEMENT IN EASTERN DOMAIN
THROUGH FRI. MAIN DIFFERENCES ARE OUT WEST WITH LOW COMPLEX OVER THE
ALEUTIANS. NAM/UKMET/GFS POSITIONS INITIALIZED WELL...NAM WAS A
LITTLE TOO DEEP ON PRESSURE THOUGH. NAM AND UKMET MODELS TEND TO GO
WITH ONE DEEPER CENTER AND MOVE IT TO NUNIVAK ISLAND THU MORNING. THE
GFS GOES WITH TWO WEAKER CENTERS. ALTHOUGH FEEL THAT THE GFS FORECAST
OF TWO CENTERS IS PROBABLY A MORE REALISTIC SOLUTION...GFS ENSEMBLE
SHOWS A FAIRLY HIGH DEGREE OF UNCERTAINTY. 12Z FORECAST PACKAGE WENT
CLOSER TO NAM/UMKET SOLUTION. FOR NOW WILL STICK WITH EARLIER
FORECAST PACKAGE WITH HANDLING OF LOWS. GOOD NEWS IS THAT MOVEMENT
AND TIMING OF FRONTAL TROUGH IS SIMILAR IN MODELS.

.ANALYSIS
.EAST...GENERAL PATTERN IS FOR THE THERMAL TROUGH TO CONTINUE OVER
THE INTERIOR AND HIGH PRESSURE TO REMAIN OVER THE GULF OF ALASKA OVER
THE NEXT COUPLE OF DAYS. STABILITY INDICES INDICATE AFTERNOON AND
EVENING CONVECTION LIKELY OVER SOUTHCENTRAL NORTH OF KENAI PEN AND
COPPER RIVER BASIN THROUGH THU. LOOKS LIKE BEST SHOT FOR
THUNDERSTORMS OVER THE SUSITNA VALLEY...TALKEETNA MOUNTAINS...AND
COPPER RIVER BASIN. MARINE STRATUS ALONG THE NORTHERN GULF BROKE UP
FAIRLY WELL THIS MORNING...HOWEVER EXPECT IT WILL REFORM TONIGHT.
CONCERN IS THAT WITH HIGH PRESSURE OVER THE GULF...MAY SEE A WEAK
MARINE PUSH UP COOK INLET OVER THE NEXT DAY OR SO. IF IT DOES
OCCUR...THEN COULD DELAY AFTERNOON CONVECTION IN THE ANCHORAGE BOWL.
EXPECT FAIRLY BRISK SEABREEZES ALONG COASTAL LOCALS OVER THE NEXT DAY
OR SO.

UNSTABLE CONDITIONS WILL CONTINUE OVER SOUTHCENTRAL AND COPPER RIVER
BASIN INTO THE WEEKEND WITH THERMAL TROUGH OVER THE MAINLAND. HIGH
PRESSURE BUILDS ALONG THE NORTH GULF COAST...SO MAY SEE STRENGTHENING
SEABREEZES OVER COOK INLET AND KNIK WINDS EARLY IN THE WEEKEND.

.WEST...A FAIR DEGREE OF UNCERTAINTY STILL EXISTS WITH COMPLEX OVER
THE ALEUTIANS. CURRENT SAT IMAGERY AND AVAILABLE OBSERVATIONS
INDICATES THAT LOW CENTER HAS PUSHED NORTH OF ADAK AROUND NOON TODAY.
EXPECT CENTER SHOULD HOLD IN THE 990S AS IT MOVES TOWARD SW
AK...CENTER LIKELY TO WEAKEN TO THE UPPER 990S/LOWER 1000S MB THU
NEAR NUNIVAK. ASSOCIATED FRONTAL TROUGH APPROACHING THE EASTERN
ALEUTIANS/PRIBILOF ISLANDS MOVES TO NEAR THE DELTA COAST/WESTERN AK
PEN WED AFTERNOON...THEN WEAKENS AS IT MOVES INLAND OVER SW
AK/EASTERN BRISTOL BAY WED NIGHT/THU. EXPECT WINDS AND MIXING IN
ADVANCE OF FRONT AND WITH LOW CENTER WILL BREAK UP EXTENSIVE LOW
STRATUS OVER THE EASTERN BERING SEA/SW COAST.  HIGH PRESSURE BUILDS
BACK OVER THE WESTERN AND CENTRAL BERING SEA THU AND FRI.

UNSTABLE CONDITIONS WITH BREAKS OVER THE NORTHERN/EASTERN KUSKOKWIM
VALLEY THIS EVENING MAY BE ENOUGH FOR ISOLATED THUNDERSTORM ACTIVITY.
SHOULD BE MORE STABLE WITH COOLING TEMPS IN LOWER LAYERS AND WARNING
AT 500MB WED/THU. CONDITIONS BECOME MORE OVER INTERIOR SW AK FRI/SAT
WITH COLD BREAKS AND STRENGTHENING THERMAL TROUGH.

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

RMC JUN 07