Small Craft Advisory 889, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
352 PM AKST WED DEC 28 2011

.SHORT TERM...THE LATEST SATELLITE IMAGERY SHOWS A LOW PRESSURE
SYSTEM WEAKENING AS IT LIFTS OVER THE PASI AREA. THIS LOW WILL
CONTINUE TO TRACK TO THE NE THROUGH THIS EVENING TO BE IN CANADA
LATE TONIGHT AS A SURFACE RIDGE BUILDS OVER THE PANHANDLE LATE
TONIGHT AND PERSIST THROUGH THURSDAY. MOST STATIONS OVER THE
NORTHERN HALF IS REPORTING LIGHT SNOW WITH MAINLY RAIN SOUTH OF
FREDRICK SOUND. MOST AREA HAVE RECEIVED ABOUT 2 INCHES SO FAR
TODAY AS WARM AIR ALOFT RIDES ABOVE THE COLD AIR AT THE SURFACE.
THE COLD AIR WILL REMAIN IN PLACE AS THE LOW LEVEL WINDS AREA
LIGHT OR FROM THE NE. A STRONG COLD FRONT WILL PUSH EAST TO KEEP
THE COLD AIR AND PRODUCE ANOTHER 3 TO 5 INCHES OVER THE NORTH CENTRAL
AREAS AND 5 TO 10 INCHES NEAR THE HAINES AREAS WILL FALL THROUGH LATE
TONIGHT INTO EARLY THURSDAY MORNING. THE ONLY CHANGE TO THE
WINTER WEATHER PRODUCE WAS TO ADD ZONE 22 AS THEY SEE ADVY LEVEL
SNOW AMOUNTS. SO WITH THAT SAID THE WINTER WEATHER ADVY IS STILL
IN AFFECT THROUGH MIDNIGHT BUT WITH THE TIMING OF THE EASTWARD
MOVEMENT OF THE UPPER TROF THE ADVY MAY NEED TO BE EXTENDED. FROM
FREDRICK SOUND SOUTHWARD THE RAIN WILL MIX WITH SNOW LATE THIS
EVENING AS THE COLDER AIR BEGINS TO FILTER INTO THE AREA. BY LATE
TONIGHT MOST OF THE SOUTHERN HALF WILL SEE SNOW SHOWERS WITH
AMOUNTS GENERALLY LESS THAN 2 INCHES BUT THE CENTRAL ARES MAY SEE
UP TO 3 INCHES.

THE SNOW SHOWERS ACROSS THE FORECAST AREA THURSDAY MORNING WILL
TAPPER OFF TO SCATTERED THROUGH THE MORNING HOURS AS THE UPPER
LEVEL DYNAMICS MOVES INTO CANADA. SNOW AMOUNTS RANGING FROM 1 TO 4
INCHES THROUGH THURSDAY FROM THE SNOW SHOWERS.

THE WINDS WILL INCREASE TO GALES THROUGH THE LATE AFTERNOON AND
EARLY EVENING ACROSS THE GULF FROM THE WEST AS THE LOW LIFTS
INLAND. THESE WINDS WILL SLOWLY DIMINISH THROUGH LATE TONIGHT AND
THEN BE LESS THAN 20KT BY THURSDAY AFTERNOON. THE COASTAL AREAS
WILL SEE STRONG WINDS EARLY THIS EVENING FROM THE WEST AS THE LOW
LIFTS INLAND THE COLD FRONT PASSES. THESE STRONG WINDS WILL NOT
LAST LONG AND THE GRADIENT RELAXES LATE TONIGHT. OVER THE INNER
CHANNELS...THE SOUTHERN HALF WILL SEE THE GALES FROM THE SOUTH
RELAX THROUGH TONIGHT. THE CENTRAL AREAS WILL SEE THE NORTHERLY
WINDS TO 20 KT BECOME A STRONG SE 30 KT THIS EVENING AS THE RIDGE
BUILDS OVER THE PANHANDLE FROM S TO N. THE FAR NORTHERN AREAS WILL
SEE THE SMALL CRAFT WINDS FROM THE SOUTH BECOME LIGHT THIS EVENING
AS THE LOW MOVES OVER THE AREA AND THEN SEE A SOUTHERLY PUSH OF
GALES LATE TONIGHT. THESE STRONG SOUTHERLY WINDS WILL SLOWLY
DIMINISH THROUGH THURSDAY AS THE RIDGE TAKES HOLD OVER THE AREA
AND THE PRESSURE GRADIENT RELAXES. LAND AREAS WILL SEE THE STRONG
SOUTHERLY PUSH TONIGHT WITH SOUTHEAST WINDS INCREASING WITH SOME
HIGHER GUSTS. THE STRONG WINDS WILL BE OVER THE FAR NORTHERN
AREAS...SO PAHN AND PAGY WILL SEE THE NORTHERLY WINDS BACK AROUND
TO THE SOUTH TONIGHT AND GUST TO 40 MPH. THESE STRONG GUSTS WILL
DECREASE THROUGH THE MORNING HOURS ON THURSDAY.

USED THE 00Z EC FOR THE SHORT TERM PERIOD AND THERE IS ABOUT
AVERAGE FORECASTER CONFIDENCE.

.LONG TERM...WE WILL HAVE A SEVERAL DAYS OF A SIMILAR SEQUENCE:
A LANDFALLING LOW IS FOLLOWED BY A COOLER AIRMASS WITH THE NET
RESULT OF FALLING TEMPERATURES AND THE SNOW LEVEL FALLING TO
SEA LEVEL IN A N TO S SEQUENCE. THE OVERALL THE FORECAST CONFIDENCE
IS AVERAGE. THE STRONGEST SYSTEM IS FOR SUN AND SUN NIGHT WITH
GALES FOR THE INSIDE WATERS AND STORM FORCE FOR THE OUTSIDE.

THE NEXT LANDFALLING LOW, AFTER THE ONE DESCRIBED ABOVE IN THE
SHORT RANGE SECTION ABOVE, WILL TRACK ENE OVER CWZV 12Z FRI WITH
A 982 MB CENTER. THIS LOW WILL BE FOLLOWED BY A MARITIME POLAR
AIRMASS. THE NEXT POLAR FRONT ZONE WAVE WILL TRACK NE INTO THE
GULF WHILE DEEPENING TO ABOUT 970 MB WITH A CENTER REACHING
A POINT ABOUT 240 NM S OF PADQ. THIS SECOND SYSTEM WILL SEND
A LARGE AND STRONG OCFNT ONSHORE SUN NIGHT, AND ALONG WITH
THE STORMS AND GALES MENTIONED ABOVE, WILL ALSO BE A SNOW
EVENT FOR THE PANHANDLE N OF FREDERICK SOUND.

THE OVERALL THE FORECAST CONFIDENCE IS AVERAGE. WE TYPICALLY
HAVE A LOWERING OF CONFIDENCE THE FARTHER IN THE FUTURE WE ARE
FORECASTING FOR, AND THIS FORECAST PACKAGE IS NO EXCEPTION. THE
MARINE FORECAST PACKAGE HAS THE NORTHERN INNER CHANNEL WIND
DIRECTIONS SWINGING BACK AND FORTH BY 180 DEGREES SEVERAL TIMES
FROM THU NIGHT THROUGH MON. THE TIMING OF THESE CHANGES IS
PREDICTED WITH DECREASING CONFIDENCE PER INCREASING FORECAST TIME.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 9 PM AKST THIS EVENING FOR AKZ027-028.
         WINTER WEATHER ADVISORY UNTIL MIDNIGHT AKST TONIGHT FOR AKZ020-
     021-025.
         WINTER WEATHER ADVISORY UNTIL MIDNIGHT AKST TONIGHT FOR AKZ022.
         STRONG WIND FROM MIDNIGHT AKST TONIGHT THROUGH THURSDAY MORNING
     FOR AKZ019.
         WINTER STORM WARNING UNTIL 9 AM AKST THURSDAY FOR AKZ019.
         STRONG WIND FROM MIDNIGHT AKST TONIGHT THROUGH THURSDAY MORNING
     FOR AKZ018.
MARINE...GALE WARNING FOR PKZ012-013-022-033-036-041>043.
         SMALL CRAFT ADVISORY FOR PKZ011-021-031-032-034-035-051-052.

&&

ABJ/JBT