Small Craft Advisory 656, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
150 PM AKDT THU SEP 16 2010

.ANALYSIS AND UPPER LEVELS...A BLOCKING HIGH CENTERED OVER PRINCE
WILLIAM SOUND CONTINUES TO DOMINATE ALASKA MAINLAND WEATHER. AS A
RESULT SUNNY SKIES COVER MUCH OF THE INTERIOR AND KODIAK ISLAND.
HOWEVER...THE LIGHT WINDS BENEATH THIS RIDGE ARE ALLOWING STRATUS TO
PERSIST WITHIN COOK INLET AND PORTIONS OF PRINCE WILLIAM SOUND.
STRATUS IS ALSO LINGERING ALONG PORTIONS OF THE BERING COAST AND
VALLEYS OF THE MAINLAND SOUTHWEST. MEANWHILE AN OCCLUDED CYCLONE
SOUTH OF ADAK CONTINUES TO WEAKEN. ITS ASSOCIATED FRONT BROUGHT PEAK
WINDS OF CLOSE TO 40 KT TO DUTCH HARBOR AND LIGHT RAIN THIS MORNING.

.MODEL DISCUSSION...MODELS ARE CURRENTLY IN GOOD AGREEMENT THROUGH
THE WEEKEND DUE TO THE INTENSITY OF THE RIDGE OVER MAINLAND ALASKA.
HOWEVER...THE GFS AND ECMWF ARE SHOWING MORE DISAGREEMENT IN THE
MANIFESTATION OF THE BERING LOW AS IT DISSIPATES OVER THE WEEKEND. IN
THE LONG TERM...MODELS ARE GENERALLY KEEPING HIGH PRESSURE OVER
MAINLAND ALASKA INTO THE MIDDLE OF NEXT WEEK.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...FOG AND STRATUS ARE EXPECTED TO LINGER IN THE INLET
OVER THE NEXT FEW DAYS AS WINDS ALOFT REMAIN LIGHT AND DO NOT ALLOW
MIXING BETWEEN THE SHALLOW MOIST MARINE BOUNDARY LAYER AND THE DRY
INVERSION ABOVE. MODELS ARE INDICATING THAT THE FOG WILL BEGIN TO
DIMINISH BY SATURDAY AS NORTHERLY WINDS BRING DRIER AIR THROUGH THE
INLET. THE INVERSION ALOFT WILL ALSO WEAKEN BY SATURDAY WHICH WILL
ALLOW FOR MORE MIXING.

.SOUTHWEST...
PATCHY FOG AND STRATUS IS POSSIBLE AGAIN TONIGHT IN THE KUSKOKWIM
DELTA WITH MORE FOG ALONG THE BERING COAST. HOWEVER...FOG IS EXPECTED
TO BE LESS DENSE TONIGHT DUE TO THE APPROACH OF AN UPPER LEVEL
SHORTWAVE INTO THE REGION WHICH WILL BRING SOME HIGH AND MID LEVEL
CLOUDS. A FRONT ASSOCIATED WITH THE LOW SOUTH OF ADAK WILL TRY TO
MOVE WESTWARD ACROSS THE ALASKA PENINSULA BUT WILL WEAKEN
DRAMATICALLY AND STALL AS IT ENCOUNTERS STRONG HIGH PRESSURE OVER THE
WEEKEND. SO RAIN IS EXPECTED TO OCCUR MOSTLY ACROSS THE WESTERN
ALASKA PENINSULA.

.ALEUTIANS...A LOW SOUTH OF ADAK WILL SLOWLY MOVE EASTWARD BUT
DISSIPATE OVER THE NEXT FEW DAYS. ITS ASSOCIATED FRONT WILL CONTINUE
TO BRING THE CHANCE OF SHOWERS TO THE EASTERN ALEUTIANS INTO
SATURDAY. A NEW LOW PRESSURE SYSTEM WILL APPROACH THE THE WESTERN
ALEUTIANS BY LATE SATURDAY NIGHT.

.LONGTERM...MODELS ARE INDICATING THE HIGH PRESSURE WILL REMAIN
DOMINANT OVER MAINLAND ALASKA THROUGH THE MIDDLE OF NEXT WEEK WHICH
WILL CONTINUE TO KEEP THE MAJORITY OF THE REGION RAIN FREE. MODELS
ARE NOW INDICATING A POSSIBLE PATTERN CHANGE BY THE END OF NEXT WEEK
AS LOW PRESSURE SYSTEMS BEGIN TO RETURN TO MAINLAND ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING...170 171 176
FIRE WEATHER...NONE.

ELN SEP 10