Small Craft Advisory 332, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKDT THU APR 16 2009

.ANALYSIS AND UPPER LEVELS...
BIG PICTURE IS A STACKED LOW IN THE GULF WITH HIGH PRESSURE RIDGE
OVER THE BERING. AN UPPER LOW WEST OF THE KAMCHATKA PENINSULA MAKING
A OMEGA TYPE PATTERN. SHORT WAVE TROUGHS ARE ROTATING AROUND THE LOWS
IN THE GULF AND WEST OF KAMCHATKA. THESE ARE BRINGING STRONGER WINDS
AND SOME AREAS OF PRECIPITATION TO THE WESTERN ALEUTIANS AND AROUND
THE GULF COAST OF ALASKA. VERY MINIMAL AMOUNTS OF PRECIPITATION TO
REACH INLAND LOCATIONS IN SOUTH CENTRAL ALASKA. A MODERATE PRESSURE
GRADIENT RESIDES BETWEEN THE BERING HIGH AND GULF LOW. THE RESULT IS
GUSTY NORTHERLY WINDS ACROSS THE EASTERN BERING SEA AND ALONG THE
WESTERN COAST.

.MODEL DISCUSSION THROUGH LONG TERM...
MODELS ARE IN VERY GOOD AGREEMENT THROUGH SUNDAY WITH THE OVERALL
PATTERN OF TROUGH RIDGE TROUGH. THE TIMING AND ACTUAL BREAKDOWN OF
THIS FLOW STARTS TO TAKE PLACE MONDAY AND IS DEBATABLE ON THE PUSH OF
THE RIDGE EASTWARD. THE GFS IS A BIT FASTER WITH PUTTING THE RIDGE
OVER THE MAINLAND. THIS IS TYPICAL THOUGH AND PREFER A SLOWER EC
SOLUTION. OVERALL...NOT THAT MUCH DIFFERENCE BUT THE SLOWER PUSH OF
THE RIDGE IS PREFERRED. IN THE SHORTER TERM...THE NAM AND GFS
DISAGREE ON THE LITTLE FEATURES ROTATING AROUND THE GULF LOW. THIS IS
THE BASIS OF DIFFERENCES AT THE SURFACE AS WELL. PREFER THE MORE
BROAD BRUSH AFTER TODAY SINCE TIMING CAN BE DIFFICULT.

IN DETAIL...A SHORT WAVE IS MOVING OFF THE ALASKA PENINSULA TODAY AND
RE-ENFORCING THE GULF LOW. ANOTHER SHORT WAVE TO COME OUT OF THE
ARCTIC TOMORROW AND FEED INTO THE GULF LOW AS WELL SATURDAY. EACH
WAVE BRINGS SOME COLD AIR AND WITH IT AN INCREASE IN THE PRESSURE
GRADIENT FROM THE GULF LOW AND BERING HIGH PRESSURE.

.SHORT TERM FORECAST...
.SOUTH CENTRAL...THE LOW COMPLEX IN THE GULF OF ALASKA TO FEED THE
GULF COASTAL COMMUNITIES CLOUDS AND RAIN THROUGH TONIGHT. THE
PRECIPITATION ACTIVITY TO BECOME MORE SCATTERED IN NATURE AFTER
TONIGHT. THE TIMING OF INCREASED WINDS OR PRECIPITATION WILL BE
DIFFICULT DUE TO THE NUMEROUS SHORT WAVES ROTATING AROUND THE LOW IN
THE GULF. THE CURRENT WAVE ROTATING AROUND THE LOW TO BRING SOME
ORGANIZED RAIN AND SNOW ALONG THE COAST TO KODIAK ISLAND TONIGHT. THE
WINDS WILL ALSO BE STRONG ENOUGH FOR GALE WARNINGS. AFTER THIS...MOST
SHORT WAVES ARE ANTICIPATED TO BE WEAKER. MOST INLAND LOCATIONS WILL
BE PARTLY CLOUDY. HOWEVER...THE COPPER RIVER BASIN COULD SEE SOME
SHOWERS IN THE SOUTHEAST FLOW AT TIMES. THIS WILL LIKELY BE CONFINED
TO SOUTH AND EAST OF GULKANA.

.SOUTHWEST...DRY CONDITIONS TO PERSIST THROUGH TOMORROW IN SOUTHWEST
ALASKA EXCEPT IN THE AKPEN. THE NORTHERLY FLOW TO KEEP CLOUD COVER
AND SHOWERS ON THE BERING SIDE OF THE AKPEN AND EXTREME EASTERN
ALEUTIAN ISLANDS. A SHORT WAVE TROUGH TO PUSH SOUTH THROUGH THE
MAINLAND FRIDAY AFTERNOON BRINGING A FEW SHOWERS AND POSSIBLY AN
INCREASE IN WIND SPEED. THE PRESSURE GRADIENT CURRENTLY BRINGING SOME
GUSTY NORTH WINDS TO RELAX A BIT AS THE LOW IN THE GULF WEAKENS THEN
PICK UP A BIT AGAIN TOMORROW.

.BERING SEA AND ALEUTIANS...HIGH PRESSURE OVER THE BERING WITH SOME
CLOUDINESS ALONG THE EASTERN ALEUTIANS IN NORTHERLY FLOW. THE HIGH
PRESSURE TO REMAIN THROUGH THE NEXT FEW DAYS. GUSTY NORTHERN WINDS TO
REMAIN IN THE EASTERN BERING AS LOW PRESSURE REMAINS IN THE GULF.
HOWEVER...THE LOW IN THE GULF WEAKENS OVER TIME. THE ONLY ORGANIZED
PRECIPITATION ACTIVITY WILL BE WITH A FRONT PARKED OVER THE WESTERN
ALEUTIANS. THE FRONT WILL PULSE AS WEAK SHORT WAVE TROUGH RIDE
THROUGH IT THE NEXT COUPLE DAYS. WINDS WILL BE NEAR OR ABOVE GALE
FORCE THE NEXT COUPLE DAYS. THE FRONT WILL PUSH EASTWARD BEGINNING
SUNDAY.

.LONG TERM FORECAST...
RIDGE IN THE BERING AND LOW IN THE GULF TO REMAIN THROUGH SUNDAY. THE
LOW WEST OF KAMCHATKA TO MOVE EAST SUNDAY AND INTO THE WESTERN
BERING. THIS WILL PUSH THE FRONT THAT WAS PARKED OVER THE WESTERN
ALEUTIANS IN TO THE CENTRAL ALEUTIANS MONDAY AND TO THE WEST COAST
TUESDAY. THE LOW IN THE GULF TO PUSH INTO CANADA DURING THIS TIME
FRAME. IN GENERAL...THE BERING TO GET WETTER WHILE THE MAINLAND DRIES
OUT A BIT. THE RIDGE TO STAY OVER THE MAINLAND THROUGH WEDNESDAY.
BROAD SOUTHWEST FLOW TO BE OVER THE MAINLAND LATER NEXT WEEK WITH AN
AREA OF LOW PRESSURE IN THE BERING.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE...120 130 132 176
         HEAVY FREEZING SPRAY...179
FIRE WEATHER...NONE

JN APR 09