Gale Warning 171, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
552 AM AKST TUE MAR 1 2011

.SHORT TERM...LOW PRESSURE WILL REMAIN NEAR THE SOUTHERN
CHARLOTTES AND SEND A TROF NWD INTO SRN SE AK TODAY...THEN THE
TROF WILL MOVE OFFSHORE TONIGHT. THE LOW ITSELF WILL WEAKEN AS A
MORE POWERFUL STORM MOVES NE TO JUST OFFSHORE THE PAC NW STATES
BY LATE TONIGHT. HIGH PRESSURE WILL PERSIST OVER THE YUKON
THROUGH TONIGHT.

 MAIN FORECAST ISSUE WILL BE WINDS. ATTM...STRONGEST WINDS ARE
OCCURRING OUT OF INTERIOR PASSES OF THE ERN INNER CHANNELS AND NE
GULF COAST WITH A FAIRLY STG NE PRESSURE GRADIENT IN PLACE. THE
GRADIENT WILL TIGHTEN A BIT MORE AS TROF MOVES INTO SRN AREA
TODAY. ALSO...A WEAK MID-LEVEL TROF ACROSS CENTRAL SE AK WILL
DRIFT TO THE NRN AREA TODAY...AND THIS WILL INCREASE THREAT FOR
MTN WAVE DEVELOPMENT IN THE PAJN AREA AS CRITICAL LEVEL FORMS
AROUND THE 500-700 MB LAYER. WHILE CROSS BARRIER FLOW MAY BE
5-10 KT LESS LATER TODAY THAN IT IS NOW...THE PRESENCE OF THE
CRITICAL LEVEL WILL OFFSET THIS AND KEEP FAIRLY STG NE WINDS
LOCALLY TODAY. DURING TONIGHT THE CRITICAL LEVEL IS FORECAST TO
DISAPPEAR AS THE MID-LEVEL FLOW BACKS TO A MORE ELY
DIRECTION...SO LOOKS LIKE WINDS WILL DROP OFF SOMEWHAT...BUT THIS
DROP WILL NOT LAST LONG AS ANOTHER INCREASE IN WINDS IS EXPECTED
JUST AFTER TONIGHT. WILL KEEP THE PLACEMENT OF ADVYS/WARNINGS AS
IS THROUGH THE SHORT TERM PERIOD.

 OTHER ISSUE IS POTENTIAL FOR PRECIP OVER THE SRN AREA. WITH TROF
MOVING IN...FLOW WILL BECOME MORE SELY JUST ABOVE SFC AND THIS
WILL ALLOW SOME OF THE SNOW SHOWERS NOW GOING ON OVER HECATE
STRAIT TO REACH SRN AREA TODAY. THEY WILL BE LESS CONCENTRATED
THAN THEY ARE NOW TO THE S OF THE AREA BUT ENOUGH SHOULD MAKE IT
IN TO WARRANT LIKELY POPS FOR ZONES 27 AND 28 THIS AFTERNOON AND
EVENING. THINK SNOWFALL WILL BE AN INCH OR LESS THERE. WILL SEE
MAINLY CLOUDS AND A LOW POP FOR SNOW SHOWERS IN AREAS JUST N AND
E OF THE LIKELY POP AREA. EXPECT THE SNOW SHOWERS TO RAPIDLY
DIMINISH LATER THIS EVENING AND OVERNIGHT AS DEEPER LAYER
OFFSHORE FLOW IS REESTABLISHED AHEAD OF THE NEXT STORM.

 OTHERWISE...IT WILL REMAIN VERY COLD THROUGH TONIGHT WITH ONLY A
SMALL MODERATION IN TEMPS EXPECTED OVER THE SRN AREA. SNOW COVER
WILL LIMIT THE DAYTIME HEATING TO SOME DEGREE...BUT WINDS WILL
LIMIT NIGHTTIME TEMP DROP IN MOST AREAS.

&&

.LONG TERM...MAIN FORECAST CONCERN FOR THE EXTENDED RANGE PERIOD
CONTINUES TO BE VERY STRONG OUTFLOW WINDS THROUGH THURSDAY MORNING
AND CONTINUED VERY COLD TEMPERATURES. PEAK WIND CONDITIONS LOOK
LIKE THEY WILL BE DURING THE DAY WEDNESDAY WITH A GRADUAL
RELAXATION THEREAFTER. DRIVING FACTORS ARE CONTINUING STRONG HIGH
PRESSURE OVER WESTERN CANADA AND ANOTHER LOW THAT WILL ENTER THE
EXTREME SOUTHEASTERN GULF WEDNESDAY NIGHT. RESULTING PRESSURE
GRADIENT WILL MAX OUT WELL BEFORE THE LOW ARRIVES AS AN INVERTED
TROUGH SETS UP ALONG THE OUTER COAST. AFTER A BRIEF BREAK FROM THE
WIND...IT LOOKS LIKE WE WILL SEE ANOTHER ROUND OF STRONG OUTFLOW
WINDS AGAIN LATE FRIDAY AND FOR A GOOD PART OF THE WEEKEND AS
ANOTHER LOW TRACKS INTO THE GULF FROM THE SOUTH. MODEL SPREAD IS
STILL FAIRLY LARGE ON THE STRENGTH AND POSITION OF THIS LOW...SO
DO NOT HAVE A VERY GOOD FEEL FOR THE STRENGTH OF THE ASSOCIATED
WINDS.

TEMPS CONTINUE TO RUN WELL BELOW NORMAL BUT LOW LEVEL WARM AIR
ADVECTION FROM THE WEDNESDAY NIGHT LOW AND WEEKEND LOW WILL OFFER
A LITTLE RELIEF. AM EXPECTING TO SEE DAYTIME HIGHS ANYWHERE FROM 5
TO 10 DEGREES WARMER BY SATURDAY. OVERNIGHT LOWS WILL STILL BE
GETTING DOWN TO THE SINGLE DIGITS OR EVEN BELOW ZERO UNDER MOSTLY
CLEAR SKIES AND COLD...DRY CANADIAN OUTFLOW.

AS WITH THE PUBLIC ZONES...MARINE WINDS WILL REMAIN STRONG FOR THE
ENTIRE EXTENDED RANGE FORECAST PERIOD WITH WIDESPREAD GALE FORCE
WINDS OVER ALL THE INNER CHANNELS THROUGH SATURDAY AND STORM FORCE
WINDS OVER GLACIER BAY AND NORTHERN LYNN CANAL WEDNESDAY AND
WEDNESDAY NIGHT.

USED NAM FOR UPDATES TO THE LONG RANGE FORECAST THROUGH THURSDAY
NIGHT. FORECAST CONFIDENCE IS ABOVE AVERAGE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY UNTIL NOON AKST THURSDAY FOR AKZ019>022-026-029.
         HIGH WIND WARNING UNTIL NOON AKST THURSDAY FOR AKZ025.
         WINTER WEATHER ADVISORY UNTIL NOON AKST THURSDAY FOR AKZ018.
         HIGH WIND WARNING UNTIL 11 AM AKST THURSDAY FOR AKZ017.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ021.
         HEAVY FREEZING SPRAY WARNING FOR PKZ011>013-022-031.
         HEAVY FREEZING SPRAY WARNING FOR PKZ034-035.
         GALE WARNING FOR PKZ011>013-021-022-031-032-034>036-043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ033-041-042-053.

&&

RWT/FRITSCH