Gale Warning 503, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKDT TUE JUL 7 2010

.ANALYSIS AND UPPER LEVELS...A COMPLEX UPPER LEVEL LOW PRESSURE
SYSTEM EXISTS ACROSS MUCH OF THE EASTERN BERING SEA  AND WESTERN
MAINLAND ALASKA. A NEW UPPER LEVEL LOW CONTINUES TO STRENGTHEN
NORTHWEST OF ADAK...WHILE A SHORTWAVE ASSOCIATED WITH A WEAKENING LOW
OVER CHIGNIK STRETCHES INTO THE NORTH PACIFIC.  TO THE EAST...A WIDE
UPPER LEVEL RIDGE STRETCHES ALONG THE WESTERN CANADIAN COAST.

.AT THE SURFACE...A DECENT BAROCLINIC ZONE STILL STRETCHES FROM THE
NORTH PACIFIC AND ACROSS THE GULF OF ALASKA TOWARDS YAKUTAT.
SATELLITE IMAGERY THIS MORNING IS INDICATING THAT A SURFACE LOW IS
BEGINNING TO FORM ALONG THIS BAROCLINICITY UNDERNEATH THE UPPER LEVEL
SHORTWAVE 450 MILES SOUTHEAST OF KODIAK CITY. MEANWHILE TO THE
EAST...SURFACE PRESSURE IS BENEATH THE UPPER LEVEL RIDGE.

.MODEL DISCUSSION...MODELS ARE FINALLY IN MUCH BETTER AGREEMENT TODAY
ON THE PROGRESSION OF THE SURFACE LOW SOUTH OF KODIAK ISLAND TOWARDS
THE BARREN ISLAND ALTHOUGH THERE IS STILL DISAGREEMENT ON THE
INTENSITY OF THIS LOW. THE ECMWF IS THE CLEAR OUTLIER SO A BLEND OF
THE REST OF THE MODELS WAS USED FOR THE SHORT TERM. IN THE LONG
TERM...THE MODELS ARE BECOMING MORE DIVERGENT THAN THEY WERE EARLIER
IN THE WEEK SO THERE IS LESS CERTAINTY. THE GFS HAS THE MOST
CONSISTENT SOLUTION AND WAS USED FOR THE LONG TERM FORECAST.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...STEADY RAIN IS EXPECTED TO IMPACT MUCH OF
SOUTHCENTRAL TODAY BY THIS AFTERNOON AS A LOW SOUTH OF KODIAK ISLAND
QUICKLY PROGRESSES TO THE NORTHEAST TOWARDS THE BARREN ISLANDS.
ALTHOUGH ANCHORAGE AND THE WESTERN KENAI PENINSULA WILL BE
DOWNSLOPED...SHOWERS ARE STILL POSSIBLE THIS AFTERNOON INTO THIS
EVENING. MODELS INDICATE THAT THE HEAVIEST RAIN WILL FALL ALONG THE
EASTERN KENAI PENINSULA AND SEWARD COULD RECEIVE SEVERAL INCHES OF
RAIN TODAY.

.SOUTHWEST...A WEAKENING UPPER LEVEL LOW WILL PROGRESS TO THE
NORTHEAST TODAY ACROSS BRISTOL BAY. AS A RESULT...SHOWERS WILL IMPACT
MUCH OF THE SOUTHWEST MAINLAND TODAY. A SHORTWAVE MOVING ACROSS THE
REGION THURSDAY EVENING WILL BRING THE CHANCE FOR SCATTERED SHOWERS
BUT MORE STEADY RAIN IS LIKELY FRIDAY AFTERNOON AS A FRONT PROGRESSES
THROUGH.

.BERING SEA AND ALEUTIANS...SHOWERS ARE POSSIBLE ACROSS MUCH OF THE
ALEUTIANS TODAY AS A DEVELOPING UPPER LOW NORTHWEST OF ADAK MOVES
SOUTHWESTWARD ACROSS THE ALEUTIAN ISLANDS. A SEPARATE SURFACE LOW
WILL APPROACH THE ALEUTIAN FROM THE SOUTH BY LATE TONIGHT AND BRING
STEADY RAIN TO THE CENTRAL ALEUTIANS. ITS ASSOCIATED FRONT WILL KEEP
RAIN IN THE FORECAST FOR THE EAST AND CENTRAL ALEUTIANS INTO FRIDAY.

.LONG TERM FORECAST...UPPER LOWS WILL CONTINUE TO MOVE ACROSS THE
FORECAST REGION...CREATING MOIST AND COOL CONDITIONS ACROSS THE AREA.
MODELS ARE HINTING THAT A MORE SUBSTANTIAL RIDGE MAY BUILD AFTER 10
DAYS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...STORM WARNING 170 172 175
         GALE WARNING 120 155
FIRE WEATHER...NONE

ELN JUL 10