Small Craft Advisory 31, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
620 AM AKST WED JAN 11 2012

.SHORT TERM...RADAR DATA AND PANHANDLE PRESSURE TRENDS
INDICATING THAT THE CURRENT WEATHER FRONT IS VERY NEAR THE OUTER
COAST AS OF EARLY THIS MORNING. LOW LEVEL WARM SECTOR AIR REACHED
YAKUTAT EARLIER IN THE NIGHT AND SNOW THERE CHANGED TO RAIN AFTER
STORM TOTALS OF UP TO 17 INCHES. WINTER STORM WARNING FOR ZONE
19 CONTINUES WITH TEMPERATURES IN HAINES SLIGHTLY ABOVE FREEZING
THROUGH THE NIGHT AND TEMPS OUT THE HIGHWAY SLIGHTLY BELOW
FREEZING. LET THE WINTER WEATHER ADVISORIES FOR ZONES 20, 21, AND
22 EXPIRE ON TIME AT 5 AM THIS MORNING. AS THE WARM SECTOR MOVES
OVER THE PANHANDLE, TEMPS EVERYWHERE EXPECTED TO RISE ABOVE
FREEZING WITH THE POSSIBLE EXCEPTION OF NEAR THE BORDER ALONG THE
HAINES HIGHWAY AND THE KLONDIKE HIGHWAY. ACCORDINGLY, HAVE EITHER
RAIN, OR SNOW CHANGING TO RAIN FOR ALL LOCATIONS EXCEPT HAINES
ZONE AND NEAR WHITE PASS FOR TODAY. PRECIP RATES FORECAST TO
DIMINISH THROUGH THE DAY ALONG THE OUTER COAST AS THE FRONT COMES
ASHORE. LOCATIONS BETWEEN BERNERS BAY AND TRACY ARM WILL SEE AN
INCREASE IN PRECIP RATES AS THE FRONT PASSES TO THE EAST INTO
CANADA.

 A DEVELOPING WAVE WELL TO THE SOUTH AND WEST ALONG THE FRONTAL
BOUNDARY IS FORECAST TO DEVELOP INTO A CLOSED LOW LATER TODAY AND
TRACK TO THE NORTHEAST. THIS FEATURE SHOULD BE OVER THE EASTERN
GULF BY THE END OF THE SHORT RANGE FORECAST PERIOD EARLY THURSDAY
MORNING. MOISTURE PLUME ASSOCIATED WITH THIS WAVE IS FORECAST TO
PRODUCE ANOTHER ROUND OF MODERATE TO HEAVY PRECIPITATION LATE
TONIGHT FOR THE NORTHERN TWO THIRDS OF THE PANHANDLE. HEAVIEST
AMOUNTS EXPECTED BETWEEN CAPE SPENCER SOUTH TO SITKA AND EAST
FROM GUSTAVUS SOUTH TO KAKE. WARMER LOW LEVEL AIR ASSOCIATED WITH
THIS DEVELOPING WAVE SHOULD KEEP TEMPS WARM ENOUGH LONG ENOUGH TO
KEEP SNOW ACCUMULATIONS BELOW ADVISORY LEVELS. IT WILL BE CLOSE,
THOUGH, IN AND AROUND JUNEAU, WHERE THERE ARE 2 TO 5 INCHES IN
THE OVERNIGHT FORECAST. ALSO HAVE ANOTHER 2 TO 4 INCHES FOR
HAINES AND THE HAINES HIGHWAY OVERNIGHT.

 WINDS ASSOCIATED WITH THE CURRENT FRONT NOW WINDING DOWN AND
REMAINING GALES LIMITED TO COASTAL MARINE ZONES SOUTH OF CAPE
EDGECUMBE AS WELL AS CLARENCE STRAIT. INNER CHANNEL WINDS
DIMINISHING TO SMALL CRAFT OR BELOW BY THIS AFTERNOON. COASTAL
WATERS SOUTH OF CAPE SPENCER, ICY STRAIT, CROSS SOUND, AND
SOUTHERN INNER CHANNELS BEGIN TO RAMP UP AGAIN OVERNIGHT IN
ADVANCE OF THE DEVELOPING WAVE AND ASSOCIATED SURFACE TROUGH.

 USED ECMWF FOR SHORT TERM FORECAST BASED ON SUPERIOR
INITIALIZATION OF MID LEVEL MOISTURE, JET STRENGTH/LOCATION, AND
TREATMENT OF THE DEVELOPING WAVE AS IT APPROACHES SOUTHEAST
ALASKA. FORECAST CONFIDENCE IS ABOVE AVERAGE.

.LONG TERM...THE FORECAST MODELS CONTINUE TO BE IN GOOD AGREEMENT
WITH THE PATTERN CHANGE STARTING FRIDAY NIGHT. A UPPER LOW OVER
THE GULF WILL DRIFT SE THROUGH FRIDAY NIGHT AS A STRONG UPPER HIGH
MOVES OVER WESTERN AK. AS THIS UPPER HIGH BUILDS A SURFACE HIGH
WILL BUILD OVER THE YUKON AND INCREASE THE NORTHERLY PRESSURE
GRADIENT OVER THE PANHANDLE THIS WEEKEND. THE INCREASE OFFSHORE
FLOW WILL PRODUCE COLD, LOCALLY WINDY CONDITIONS AND CLEAR SKIES
FOR THE THIS WEEKEND. SOME CLOUDS WILL LINGER OVER THE FAR
SOUTHERN AND NORTHERN AREAS EARLY IN THE WEEKEND BUT SHOULD CLEAR
OUT ONCE A UPPER LEVEL TROF DRIFTS SOUTH FROM THE YUKON SUN NIGHT.
THE WINDS WILL INCREASE TO GALES FROM THE NORTH OVER THE INNER
CHANNELS FRIDAY NIGHT WITH VERY STRONG GUSTS FROM INTERIOR PASSES
OVER THE NORTHERN GULF AND INNER CHANNELS. LAND AREAS WILL SEE
LOCALLY WINDY CONDITIONS WITH STRONG WIND GUSTS NEAR PAGY AND
DOWNTOWN JUNEAU OVER THE WEEKEND. VERY COLD AIR WILL ADVECT OVER
SE AK THIS WEEKEND WITH TEMPS RANGING FROM THE 20 OVER THE SOUTH TO
SINGLE DIGITS OVER THE NORTHERN AREAS. THE COLD TEMPS AND STRONG
WINDS WILL PRODUCE FREEZING SPRAY THIS WEEKEND AND MAY PERSIST
INTO EARLY NEXT WEEK.

BEFORE ALL THIS...A DEVELOPING WAVE WILL ROLL UP THE COAST OF THE
PANHANDLE THURSDAY. THIS WAVE WILL PRODUCE A MIX OF RAIN AND SNOW
OVER THE NORTHERN HALF IN THE MORNING AND THEN RAIN AS MORE WARM
AIR LIFTS NORTH. SNOW AMOUNTS WILL RANGE FROM 2 TO 4 INCHES WITH
THE HIGHEST AMOUNTS ALONG THE HAINES AND KLONDIKE HIGHWAYS. THE
SOUTHERN AREAS WILL SEE ALL RAIN WITH SOME WINDY CONDITIONS
THURSDAY MORNING. THE COLD FRONT WILL DRIFT EAST OF THE AREA
THROUGH THURSDAY NIGHT WITH THE START OF THE CAA. SO THE RAIN
SHOWERS WILL CHANGE BACK TO ALL SNOW SHOWERS THROUGH THE THURSDAY
NIGHT WITH SNOW SHOWERS ACROSS THE FORECAST AREA BY FRIDAY. THE
UPPER LEVEL WILL CONTINUE TO SEND SNOW SHOWERS OVER THE AREA
FRIDAY BUT A THE COLD DRIER AIR BEGINS TO DROP SOUTH FROM THE
INTERIOR THE SHOWERS WILL SLOWLY DISSIPATE AND THE SKIES WILL
BEGIN TO CLEAR OUT LATE FRIDAY NIGHT INTO SAT MORNING.

THERE IS ABOVE AVERAGE FORECAST CONFIDENCE AND USED MAINLY THE
UKMET/EC THROUGH FRIDAY MORNING THEN EC/GFS THROUGH DAY 5. DID NOT
CHANGE THE FORECAST MUCH IN THE EXTENDED PERIODS AS THE TREND FOR
DRY AND COLD CONDITIONS STILL LOOKS GOOD.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER STORM WARNING UNTIL 4 PM AKST THIS AFTERNOON FOR AKZ019.
MARINE...GALE WARNING FOR PKZ036-041-042.
         SMALL CRAFT ADVISORY FOR PKZ011>013-021-022-031>035-043-051-052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ053.

&&

FRITSCH/ABJ