Small Craft Advisory 844, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 AM ADT SAT SEP 16 2006

.DISCUSSION...

...SUMMARY...
THE MAIN SURFACE LOW THIS MORNING NEAR COLD BAY WILL SHEAR APART AND
WEAKEN TODAY...WITH A NEW SURFACE LOW PRESSURE DEVELOPING BY THIS
AFTERNOON NEAR THE MAIN UPPER LEVEL LOW AND UPPER JET SUPPORT IN THE
SOUTHERN GULF OF ALASKA. THIS LOW WILL BE FAR ENOUGH SOUTH TO HAVE
MINIMAL EFFECTS AS FAR NORTH AS THE MAINLAND FOR SUNDAY. THE NEXT
BIG WEATHER MAKER FOR THE STATE WILL BE AN INTENSIFYING LOW PRESSURE
MOVING FROM WEST TO EAST THROUGH THE ALEUTIANS FROM TONIGHT INTO
EARLY NEXT WEEK. THIS LOW HAS THE LIKELIHOOD OF PRODUCING STORM
FORCE WINDS AS IT MOVES THROUGH THE CENTRAL AND EASTERN ALEUTIANS
SUNDAY NIGHT INTO MONDAY.

...MODELS...
CONTINUING TO GO MOSTLY WITH GFS OVER NAM/WRF FOR THE FORECAST. OVER
THE NORTHERN GULF OF ALASKA...GFS INITIALIZED MUCH BETTER WITH
POSITION OF THE RAIN BAND. NAM/WRF WAS TOO FAR SOUTH AND WEST WITH
THE RAIN AND TOO STRONG WITH THE INFLUENCE OF THE RIDGE OVER EASTERN
ALASKA. BEYOND THIS INITIAL HICCUP IN THE NAM/WRF...MODELS AGREE
FAIRLY WELL WITH THE LOW OVER THE GULF OF ALASKA AND THE DRYING OUT
OF THE MAINLAND SUNDAY INTO EARLY MONDAY. REGARDING THE UPCOMING
MAJOR ALEUTIAN LOW...GENERALLY SPEAKING...MODELS ARE IN DECENT
AGREEMENT. AS HAS OFTEN BEEN THE CASE RECENTLY...0Z NAM/WRF IS THE
ODD MODEL OUT...AS IT IS SLOWER AND WEAKER THAN THE
GFS...UKMET...AND ECMWF. GFS HAS BEEN QUITE CONSISTENT ITS
SOLUTION...AND FORECAST OUT WEST REFLECTS GFS FAIRLY CLOSELY.
CONSIDERABLE UNCERTAINTY DOES EXIST...HOWEVER...AS TO WHERE THE LOW
GOES AFTER IT REACHES THE VICINITY OF THE ALASKA PENINSULA TUESDAY.

...SOUTHCENTRAL ALASKA/KODIAK ISLAND FORECAST...
STILL A GOOD PLUME OF RAIN THIS MORNING STRETCHING FROM THE GULF OF
ALASKA AND MIDDLETON ISLAND UP INTO PRINCE WILLIAM SOUND. BY THIS
EVENING...THIS BAND WILL BECOME MORE EAST WEST ORIENTED AS THE RIDGE
EDGES IN FROM THE NORTHEAST...AND ANY AREAS TO THE NORTH OF EASTERN
PRINCE WILLIAM SOUND AND ANCHORAGE THAT HAD BEEN RECEIVING RAIN WILL
DRY OUT. THE SOUTH SIDE OF THE KENAI PENINSULA WILL KEEP RECEIVING
RAIN INTO TONIGHT...HOWEVER. ALSO...THE PRESSURE GRADIENT TODAY WILL
NOT BE AS STRONG...MEANING WINDS WILL NOT BE AS STRONG IN AREAS LIKE
THE TURNAGAIN ARM AND PALMER. STILL...THE WINDS WILL BE BLOWING IN
THE FAVORED AREAS. MOST OF SOUTHCENTRAL WILL DRY OUT ENTIRELY BY
SUNDAY WITH PARTLY CLOUDY SKIES...WITH THE EXCEPTION OF KODIAK. THE
NEXT SYSTEM WILL BEGIN TO AFFECT THE AREA LATE MONDAY.

...SOUTHWEST MAINLAND ALASKA/ALEUTIAN ISLANDS/BERING SEA FORECAST...
EVEN THOUGH THE LOW NEAR COLD BAY THIS MORNING WILL SHEAR APART AND
WEAKEN TODAY...A TROUGH AXIS WILL REMAIN AROUND THE SOUTHWEST COAST
INTO SUNDAY...MEANING CONTINUED MOIST SOUTH TO SOUTHEAST FLOW FOR
THE SOUTHWEST MAINLAND AND CONTINUED RAIN CHANCES INTO SUNDAY.
HOWEVER...WITH WEAK DYNAMICS AND GENERALLY DOWNSLOPE FLOW...TOTALS
ARE EXPECTED TO BE LIGHT. A WEAK AND BRIEF RIDGE OF HIGH PRESSURE
WILL MOVE FROM WEST TO EAST ACROSS THE ALEUTIANS INTO TONIGHT AHEAD
OF A STRONG LOW PRESSURE. THIS LOW PRESSURE WILL IMPACT THE CENTRAL
ALEUTIANS ON SUNDAY...THE EASTERN ALEUTIANS SUNDAY NIGHT AND
MONDAY...AND THE SOUTHWEST MAINLAND BEGINNING MONDAY AFTERNOON. THE
WESTERN ALEUTIANS WILL SEE ONLY MINOR EFFECTS FROM THIS LOW.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALES 170 171 172 AND 499.

FOISY SEP 06