Small Craft Advisory 138, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AST TUE FEB 6 2007

.DISCUSSION...
LOW OVER THE WESTERN BERING STILL THE DOMINANT FEATURE FOR MUCH OF
ALASKA. THE ASSOCIATED FRONT IS STRETCHING FROM EASTERN SIBERIA INTO
THE WESTERN GULF. THE LOW OVER THE BERING TO WEAKEN ALONG WITH THE
FRONT TONIGHT AND TOMORROW WRAPPING BACK INTO THE PARENT UPPER LEVEL
LOW OVER THE KAMCHATKA PENINSULA. A WEAK LOW WILL REMAIN IN THE GULF
FROM THIS FRONT BUT DISSIPATE BY THURSDAY. HIGH PRESSURE TO SHIFT
FROM THE ARCTIC OCEAN INTO THE YUKON THURSDAY.

MODELS...
MODELS INITIALIZED OK THIS MORNING. SEEMS THE GFS HAS HANDLED THE
MOISTURE AND TEMPERATURE FIELDS BETTER. ALL MODELS SEEMED TO MISS THE
MORE NORTHERN LOW IN THE NORTHWEST BERING SEA. THE MODELS ALL
INITIALIZED THESE TOO FAR SOUTH. HOWEVER...THE FRONTAL STRUCTURE OVER
SOUTHWEST ALASKA WAS OK. THE PROGRESSION OF THE SURFACE FEATURES WERE
ALL HANDLED VERY SIMILAR BY THE EUROPEAN AND NCEP MODELS THROUGH
FRIDAY. AFTER THAT TIME FRAME...EVEN THE ENSEMBLE MEAN IS QUITE
DIFFERENT OVER THE BERING THAN THE OPERATIONAL RUN OF THE GFS.

UPPER AIR...
LARGE TROUGH TO REMAIN OVER THE WESTERN BERING THROUGH THE WEEKEND.
THE BIGGEST CHANGES WILL OCCUR OVER THE MAINLAND WITH THE BREAKDOWN
OF THE RIDGE A BIT. THE HIGH CENTERED OVER THE BEAUFORT SEA TO BE CUT
OFF FROM THE RIDGE ALONG THE WEST COAST OF THE LOWER 48 WEDNESDAY. A
WEAK CLOSED TO DEVELOP OVER THE MAINLAND. THE RIDGE BUILDS BACK LATE
IN THE WEEK PUSHING THE LOW TO THE BROOKS RANGE BY SATURDAY. THE
RIDGE AXIS IS THEN SPREAD FROM THE WEST TO THE CHUKCHI SEA.

SURFACE EAST OF THE ALASKA RANGE...HIGH PRESSURE OVER THE BEAUFORT
SEA WITH A SURFACE TROUGH EXTENDING NORTHWEST TO SOUTHEAST OVER
KODIAK ISLAND. THE TROUGH TO DISSIPATE WEDNESDAY. HOWEVER...THE
MOISTURE WILL REMAIN OVER THE WESTERN GULF. THE BIG QUESTION IS HOW
MUCH WILL BE DRAWN NORTH AS THE RIDGE AXIS IS PUSHED NORTH. BELIEVE
THERE WILL BE SOME INCREASE TOMORROW WITH SOME CHANCES OF
PRECIPITATION SPREADING INLAND WEDNESDAY NIGHT OR THURSDAY. THE
DYNAMICS OF THE SITUATION ARE RATHER WEAK...SO PRECIPITATION EXPECTED
TO BE LIGHT IN MOST AREAS. THE PRECIPITATION WILL LIKELY LEAVE THE
AREA AS THE RIDGE REBUILDS IN THE AREA FRIDAY NIGHT.

WEST OF THE ALASKA RANGE...LOW OVER THE WESTERN BERING WITH A
DISSIPATING FRONT ALONG THE WESTERN COAST. THE FRONT TO TEAR APART
TONIGHT AS A SHORT WAVE RIDES NORTH ALONG IT. THE LOW TO DISSIPATE AS
WELL AS IT SETTLES UNDERNEATH THE PARENT LOW. ANOTHER UPPER LEVEL
FEATURE TO RIDE NORTH THROUGH THE CENTRAL BERING TONIGHT. THIS WILL
BRING A WEAK SURFACE REFLECTION OF PRECIPITATION AND WINDS TONIGHT
INTO THURSDAY. THIS IS DUE TO ANOTHER SHORT WAVE TROUGH MOVING OUT OF
THE DOMINANT LOW IN THE WESTERN BERING PUSHING TO THE CENTRAL BERING
AS WELL. THE SHORT WAVE IS PRECEDES A LARGE LOW INTO THE WESTERN
ALEUTIANS LATE WEDNESDAY NIGHT AND PUSHES TO THE KAMCHATKA PENINSULA
THURSDAY NIGHT. AN ASSOCIATED FRONT TO MOVE THROUGH THE BERING
THURSDAY AND TO THE BERING STRAIT FRIDAY. THE FRONT ALSO PUSHES THE
CENTRAL BERING FEATURE INLAND THURSDAY NIGHT AND FRIDAY. RIDGE BUILDS
BACK OVER SOUTHWEST ALASKA FRIDAY NIGHT. BY THIS TIME...THE ENTIRE
BERING IS IN AN AREA OF BROAD LOW PRESSURE WITH UNSETTLED WEATHER.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 120 130 170 171 172 175 176 179
FIRE WEATHER...NONE

JN FEB 07