Small Craft Advisory 612, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
335 AM ADT SUN JUL 29 2007

.ANALYSIS AND UPPER LEVELS...
AT UPPER LEVELS THIS MORNING THERE IS BROAD FLAT NORTHWESTERLY FLOW
WITH A RIDGE AXIS OVER THE WESTERN ALEUTIANS. THERE ARENT REALLY
ANY SIGNIFICANT WEATHER SYSTEMS OVER OUR FORECAST AREA EARLY THIS
MORNING. AN UPPER LEVEL LOW IS PRESENT NEAR THE BERING STRAIT WITH
ANOTHER LOW AROUND THE QUEEN CHARLOTTE ISLANDS. A WEAK RIDGE/ALMOST
A COL IS PRESENT OVER SOUTHCENTRAL THIS MORNING IN BETWEEN THE
BERING STRAIT AND QUEEN CHARLOTTE LOWS. A MAJOR UPPER LEVEL LOW IS
PRESENT NEAR THE SOUTHERN END OF THE KAMCHATKA PENINSULA...AND WITH
SIGNIFICANT UPPER LEVEL JET SUPPORT THIS LOW AND AN ASSOCIATED FRONT
WILL MOVE INTO THE BERING/ALEUTIANS TODAY AND BE THE MAJOR WEATHER
PLAYER FOR THE NEXT WEEK. THE BERING STRAIT LOW WILL DRIFT SOUTH
TOWARD NOME AND LEAD TO A TRANSITION TO WEAK SOUTHWESTERLY UPPER
LEVEL FLOW FOR THE SOUTHERN MAINLAND BY TONIGHT.

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT ON THE OVERALL MAJOR PATTERN CHANGE
TAKING PLACE ACROSS THE REGION. HOWEVER...SOME ISSUES DO EXIST IN
THE DETAILS. IN PARTICULAR...THE STRUCTURE OF THE COMPLEX OF LOWS IN
THE BERING IS IN QUESTION BEGINNING ABOUT MONDAY NIGHT.
OVERALL...THIS ISNT TOO BIG OF A DEAL. ALSO...SOME UNCERTAINTY WITH
THE TIMING OF THE INITIAL FRONT FROM TUESDAY NIGHT AND BEYOND AS IT
MOVES EAST TOWARD THE GULF. OPERATIONAL GFS CONTINUES TO BE A LITTLE
FASTER THAN THE GFS ENSEMBLE MEAN AND SOME OF THE OTHER MODELS. THE
SLOWER SPEED OF THE GFS ENSEMBLE MEAN IS PROBABLY MORE REALISTIC.
OVERALL...HOWEVER...GIVEN THE BIG PATTERN CHANGE TO TAKE PLACE...THE
MODELS ARE DOING PRETTY WELL.

.SHORT TERM FORECAST...
SOUTHCENTRAL FORECAST...
SOME FAIRLY SUBTLE BUT IMPORTANT CHANGES WILL OCCUR AT UPPER LEVELS
OVER SOUTHCENTRAL BEGINNING LATER TODAY. AS THE UPPER LEVEL LOW NEAR
THE BERING STRAIT DRIFTS SOUTH TO NOME TONIGHT...A WEAK UPPER LEVEL
RIDGE AXIS WILL BUILD OVER THE COPPER RIVER BASIN. THIS MEANS A
SHIFT IN THE FLOW FROM VERY WEAK NORTHERLY TODAY TO MODERATE
SOUTHWESTERLY ON MONDAY AND TUESDAY. FIRST OFF...TODAY DOESNT LOOK
MUCH DIFFERENT THAN SATURDAY WITH AFTERNOON SHOWERS AND STORMS
EXPECTED TO FORM INLAND. WARM TEMPERATURES CAN ALSO BE EXPECTED MOST
AREAS. FOR MONDAY AND TUESDAY HOWEVER...THE SOUTHWEST FLOW WILL
BRING COOLER TEMPERATURES AND STABILIZATION FROM THE SUSITNA VALLEY
SOUTH TO COOK INLET...THOUGH THE COPPER RIVER BASIN WILL PROBABLY
STILL HAVE SOME THUNDERSTORM ACTIVITY. WILL HAVE TO WATCH FOR MARINE
STRATUS FROM HOMER UP TO ANCHORAGE WITH THIS FLOW MONDAY AND
TUESDAY. THE MARINE STRATUS AND FOG WHICH IS ALREADY PRESENT THIS
MORNING OVER MOST OF THE GULF WATERS WILL EXPAND MONDAY AND TUESDAY.

SOUTHWEST MAINLAND FORECAST...
FOG AND STRATUS TO PERSIST OVER MUCH OF THE SOUTHWEST THROUGH
TUESDAY. THE STRATUS HAS MADE IT WELL INLAND TO PLACES LIKE
SLEETMUTE AND ILIAMNA. MAIN CHANGE IN THE SHORT TERM WILL BE
INCREASING CHANCES FOR PRECIPITATION AS THE UPPER LEVEL LOW DRIFTS
SOUTH FROM THE BERING STRAIT AND NOME WITH THE FLOW SHIFTING FROM
WEST/NORTHWEST TO SOUTHWEST. NOT EXPECTING ANYTHING TOO HEAVY THOUGH
UNTIL A MAJOR FRONT BEGINS TO HIT THE KUSKOKWIM DELTA AREA FROM THE
WEST LATE TUESDAY.

BERING SEA/ALEUTIAN FORECAST...
THE KAMCHATKA LOW AND ASSOCIATED FRONT WILL BE THE MAIN WEATHER
PLAYERS FOR THE REGION. RAIN AND WIND WITH THE FRONT TO HIT SHEMYA
BY NOON TODAY...ADAK MONDAY MORNING...THE PRIBILOFS MONDAY
NIGHT...AND THE WESTERN ALASKA PENINSULA TUESDAY. AHEAD OF THE FRONT
WILL BE WEST NORTHWEST FLOW WITH WEAK SHORTWAVES BRINGING PERIODS OF
LIGHT RAIN. TONS OF STRATUS AND FOG TO PERSIST UNTIL THE FRONT GETS
NEAR.

.LONG TERM FORECAST...
AS WE HEAD INTO AUGUST...THE WEATHER IS LOOKING LIKE CLASSIC WET
AUGUST WEATHER. LOW PRESSURE TO PERSIST ACROSS THE BERING THROUGH
NEXT WEEKEND WITH AN UPPER LEVEL JET POSITIONED NEAR OR JUST SOUTH
OF THE ALEUTIANS. ONSET OF SIGNIFICANT RAIN LIKELY TO REACH THE GULF
COAST AROUND THURSDAY OR THURSDAY NIGHT. BRISTOL BAY AND THE
KUSKOKWIM DELTA SHOULD SEE RAIN FROM WEDNESDAY ONWARD. WITH THE
UPPER LEVEL JET POSITIONED NEAR OR JUST SOUTH OF THE ALEUTIANS...IT
GOES WITHOUT SAYING THAT THE ALEUTIAN/BERING REGION WILL EXPERIENCE
UNSETTLED WEATHER AS WELL.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE WARNINGS ZONES 175 AND 410.
FIRE WEATHER...NONE.

FOISY JUL 07