Small Craft Advisory 597, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
130 PM AKDT MON JUL 28 2008

.ANALYSIS AND UPPER LEVELS...A LONGWAVE TROUGH ORIENTED SE TO NW
EXTENDS FROM JUST WEST OF THE PANHANDLE INTO THE COPPER RIVER BASIN.
SEVERAL SHORTWAVES ARE ROTATING FROM EAST TO WEST AROUND THE TROUGH
INTO THE COPPER RIVER AND MAT-SU VALLEY. WEAK RIDGING IS FIRMLY IN
PLACE OVER THE EASTERN BERING WITH ANOTHER, ALBEIT MUCH WEAKER LOW IN
THE WESTERN ALEUTIANS.

.MODEL DISCUSSION...THE GFS AND NAM ARE IN DECENT AGREEMENT WITH EACH
OTHER AND AGREE WITH THE MORE CONSISTENT ECMWF THROUGH ABOUT 60
HOURS. AFTER THAT TIME...MODELS HAVE BEEN FLIP-FLOPPING WITH EACH
CONSECUTIVE RUN. THE MOST RELIABLE MODEL RUN WAS FROM THE 00Z GFS
LAST NIGHT...SO WE STUCK PRETTY CLOSE TO ITS SOLUTION WHICH REFLECTS
OUR PREVIOUS FORECAST, WITH VERY MINOR CHANGES.

.SHORT TERM FORECAST...THE SHORTWAVE OVER THE COPPER RIVER BASIN WILL
EVER SO SLOWLY DROP SOUTH THROUGH PRINCE WILLIAM SOUND LATE TUESDAY.
EXPECT PLENTY OF RAIN IN THE COPPER RIVER BASIN AND EASTERN MAT-SU
VALLEY UNTIL THAT TIME. SCATTERED SHOWERS CAN BE FOUND ON THE
PERIPHERY ACROSS THE ANCHORAGE BOWL AND COASTAL LOCATIONS. A BRIEF
PERIOD OF OFFSHORE FLOW COMMENCES AS THE SHORTWAVE DROPS SOUTH LATE
TUESDAY.

A SIGNIFICANT COLD UPPER LOW AND ASSOCIATED COLD FRONT DROPS THROUGH
THE INTERIOR APPROACHING THE ALASKA RANGE LATE TUESDAY. THIS SPELLS
PLENTY OF RAIN FOR THE KUSKOKWIM VALLEY AND THE NORTH SIDE OF THE
ALASKA RANGE. THE WESTWARD EXTENT OF THE FRONT WILL BE LIMITED DUE TO
THE PRESENCE OF THE RIDGE OVER THE EASTERN BERING. THE FRONT IS
EXPECTED TO CROSS THE ALASKA RANGE AND SPILL ACROSS SOUTHCENTRAL ON
WED. GAPS WINDS WILL BE GUSTY ESPECIALLY ACROSS KODIAK ISLAND THE THE
BARREN ISLANDS WITH THE FRONTAL PASSAGE. THE AMOUNT OF MOISTURE THAT
MAKES IT OVER THE ALASKA RANGE IS STILL IN QUESTION SO FOR NOW WE
WILL STICK WITH A SCATTERED SHOWER SCENARIO FOR ALL OF THE SOUTHERN
MAINLAND. FURTHER WEST...THE RIDGE HOLDS OVER THE EASTERN BERING WITH
PLENTY OF LOW CLOUDS AND FOG. A WEAK LOW MEANDERS ACROSS THE WESTERN
ALEUTIANS BRINGING OCCASIONAL RAIN WITH WINDS REMAINING AT OR BELOW
SMALL CRAFT ADVISORY LEVELS.

.LONG TERM FORECAST...ON THURSDAY AND FRIDAY, IT LOOKS LIKE
CONDITIONS WILL IMPROVE ON THE EAST SIDE...BUT DUE TO LOW CONFIDENCE
IN THE MODELS THIS FAR OUT, THE FORECAST IS UNCERTAIN AT BEST.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...ASHFALL ADVISORY 185.
MARINE...ASHFALL ADVISORY 170.
FIRE WEATHER...NONE.

JCA/LF