Gale Warning 608, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 PM AKDT WED SEP 22 2010

UPDATED GALE WARNINGS

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL OMEGA HIGH WHICH HAS HELD STEADFAST ACROSS THE
MAINLAND FOR THE PAST TWO WEEKS IS FINALLY BREAKING DOWN AS IT GETS
PINCHED OFF OVER SOUTHCENTRAL BY TWO LOW PRESSURE SYSTEMS. WHILE THE
EASTERN LOW IS CENTERED OVER THE NORTHWEST TERRITORY....A BROAD
SHORTWAVE EXTENDING WESTWARD FROM THE LOW ENCOMPASSES THE YUKON
TERRITORY AND FAR EASTERN ALASKA AND IS SLOWLY SAGGING SOUTH AND WEST
ACROSS THE MAINLAND. UNDERCUTTING THE HIGH FROM THE WEST IS A SHARP
TROUGH OF LOW PRESSURE THAT COVERS MUCH OF THE BERING SEA...WITH
MULTIPLE EMBEDDED LOWS LOCATED OVER THE PRIBILOFS AND THE FAR WESTERN
BERING. THIS SYSTEM IS CURRENTLY UNDER THE LEFT FRONT QUADRANT OF A
175 KT JET ALONG THE 50N PARALLEL...WHICH WILL AID IN THE RAPID
INTENSIFICATION OF THE LOW IN THE NEXT TWO DAYS.

AT THE SURFACE...A BROAD AREA OF LOW PRESSURE IS SITUATED OVER THE
SOUTHERN BERING SEA...WITH TWO SMALL BUT TIGHT 980 MB LOWS TRANSITING
ACROSS THE CENTRAL AND WESTERN ALEUTIANS ALONG THE NORTHERN PERIPHERY
OF THE UPPER LEVEL JET. THE WESTERN LOW IS WEAKENING AS IT BECOMES
OCCLUDED WHILE THE EASTERN LOW HAS JUST RECENTLY DEVELOPED ALONG THE
TRIPLE POINT OF THE OLD LOW. FURTHER EAST...A 987 MB LOW IS WEAKENING
WELL SOUTH OF THE GULF AND SHOULD BE ABSORBED BY THE SYSTEM MOVING IN
FROM THE ALEUTIANS TOMORROW. A WEAK SURFACE TROUGH OVER SOUTHCENTRAL
BROUGHT AREAS OF CLOUDS TO THE MAT-SU VALLEY AND ANCHORAGE BOWL THIS
MORNING...BUT THESE HAVE ALREADY PUSHED SOUTH OVER THE KENAI
PENINSULA.

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT SYNOPTICALLY SPEAKING...THOUGH SOME
AMBIGUITY EXISTS AS TO THE EXACT STRENGTH AND TRACK OF A NEW AND
VIGOROUS TRIPLE POINT LOW THAT IS CURRENTLY DEVELOPING NEAR THE
CENTRAL ALEUTIANS. THE GENERAL CONSENSUS BETWEEN THE MODELS IS TO
BRING THE LOW ABOUT 500 MILES SOUTH OF KODIAK BY THURSDAY NIGHT
BEFORE WRAPPING IT INTO THE GULF BY SATURDAY. THE CENTRAL PRESSURE OF
THE STORM IS SOMEWHAT LOWER IN THE GFS AND EC SOLUTIONS AS COMPARED
TO THE NAM...BUT THIS DISCREPANCY IS SIGNIFICANTLY LESS COMPARED TO
PREVIOUS RUNS. THE MODELS TYPICALLY HAVE A HARD TIME PINPOINTING THE
DETAILS OF SUCH PROGRESSIVE STORMS UNTIL THEY ACTUALLY DEVELOP...AND
THIS SYSTEM IS NO EXCEPTION.

.SHORT TERM FORECAST...
.SOUTHCENTRAL ALASKA...THE CURRENT TRIPLE POINT LOW OVER THE CENTRAL
ALEUTIANS DIVES SOUTHWARD AND RAPIDLY INTENSIFIES BY FRIDAY
MORNING...REACHING A MINIMUM CENTRAL PRESSURE OF 948 MB 500 MILES
SOUTH OF MIDDLETON ISLAND. THE LOW WILL THEN GRADUALLY FILL AS IT
BECOMES OCCLUDED AND TRACKS INTO THE CENTRAL GULF LATE SATURDAY AT
970 MB. THE LOW CONTINUES TO FILL AND MEANDERS ALONG THE NORTH GULF
COAST INTO THE BEGINNING OF NEXT WEEK. DESPITE BRINGING HIGH END
GALES AND WET WEATHER TO THE NORTHERN GULF...THIS LOW SHOULD HAVE
LITTLE ADVERSE IMPACT ON INLAND AREAS OF SOUTHCENTRAL. LIGHT
NORTHERLY WINDS ON BACKSIDE OF THE LOW SHOULD KEEP SKIES MOSTLY CLEAR
ACROSS THE REGION AND HELP ADVECT COLDER AIR SOUTHWARD. AS A
RESULT...FROST IS CERTAINLY A POSSIBILITY ACROSS MUCH OF THE MAT-SU
VALLEY AND ANCHORAGE BOWL STARTING TONIGHT.

.SOUTHWEST ALASKA...A RELATIVELY BENIGN WEATHER PATTERN IS IN STORE
FOR SOUTHWEST ALASKA THROUGH THE WEEKEND. SHOWERS ARE POSSIBLE TODAY
AND TOMORROW ALONG THE COAST AS AN OLD FRONTAL BOUNDARY WEAKENS AND
DISSIPATES. OTHERWISE LOOK FOR PARTLY CLOUDY CONDITIONS INLAND WITH
TEMPERATURES GRADUALLY FALLING AS COLDER AIR FILTERS SOUTHWARD...WITH
DAYTIME HIGHS FALLING FROM THE MID 50S TO THE MID 40S BY THE END OF
THE WEEKEND.

.ALEUTIANS AND BERING SEA...THE WESTERN ALEUTIANS ARE SEEING A BRIEF
REPRIEVE FROM THE CURRENT WET WEATHER PATTERN AS THE AREA FALLS UNDER
THE DRY SLOT ASSOCIATED WITH A LOW NEAR SHEMYA. CLOUDS AND RAIN WILL
WRAP AROUND THE BACKSIDE OF THE SYSTEM AS IT TRACKS ACROSS THE
ALEUTIANS LATER TODAY AND PERSIST THROUGH TOMORROW MORNING. RAIN
SHOWERS WILL END FROM WEST TO EAST DURING THE DAY TOMORROW AS THE LOW
TRACKS INTO THE WESTERN GULF. GALE FORCE WINDS WILL IMPACT THE
COASTAL MARINE ZONES SURROUNDING THE ALEUTIANS TODAY...BUT THESE
WINDS SHOULD REMAIN JUST SOUTH OF THE ISLAND CHAIN. THE EASTERN
ALEUTIANS AND THE AKPEN COULD SEE WINDS OVER GALE FORCE TOMORROW AS
THE LOW INTENSIFIES AND TRACKS SOUTH OF THE REGION.

.LONG TERM FORECAST...
A PROGRESSIVE AND ACTIVE WEATHER PATTERN LOOKS TO SHAPING UP FOR NEXT
WEEK. THE REMNANTS OF TROPICAL STORM (OR POSSIBLY TYPHOON) MALAKAS
ARE EXPECTED TO IMPACT THE WESTERN BERING BY LATE THIS WEEKEND AND
THEN SPREAD ACROSS THE BERING THROUGH EARLY NEXT WEEK. THE LOW THAT
ENTERS THE GULF THIS WEEKEND GRADUALLY FILLS AND DISSIPATES ON
TUESDAY...BUT THE POST-TROPICAL LOW THAT WAS MALAKAS QUICKLY FOLLOWS
ON ITS HEELS AND ENTERS THE GULF MIDWEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING...120 130 132 138 150 155 165 170 172.
FIRE WEATHER...NONE.

KS SEP 10