Gale Warning 25, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST THU JAN 10 2008

.SYNOPSIS...
.SHORT RANGE...THE LATEST SATELLITE IMAGERY SHOWS A LOW PRESSURE
SYSTEM ROTATING JUST WEST OF DIXON ENTRANCE WITH MOSTLY CLOUDY
SKIES OVER THE SOUTHERN HALF OF THE PANHANDLE. THE NORTH CENTRAL
PANHANDLE IS UNDER PARTLY CLOUDY TO MOSTLY CLEAR SKIES WITH
SOME HIGH THIN CLOUDS OVER THE FAR NORTHERN AREAS AND OVER THE
NORTHERN GULF. THE LOW WILL CONTINUE TO WEAKEN THROUGH TODAY AND
SLOWLY LIFT INTO BC BY FRIDAY MORNING. THE LOW IS SPREADING
PRECIP OVER THE SOUTHERN HALF OF THE PANHANDLE THIS MORNING AND
WILL CONTINUE TO DO SO INTO TONIGHT AS THE LOW LIFTS INLAND. MOST
OF THE STATIONS ARE REPORTING RAIN BUT OVER THE
PETERSBURG/WRANGELL AREA SNOW IS THE MAINLY P-TYPE. THINK THAT
THEY WILL REMAIN ALL SNOW BUT THERE MAY BE SOME RAIN MIXED IN BY
THE AFTERNOON. AMOUNTS WILL VARY FROM 1 TO 2 INCHES THROUGH THIS
AFTERNOON WITH A POSSIBLE ANOTHER 1 TO 2 INCHES TONIGHT. THE
NORTHERN AREAS WILL REMAIN ON THE DRY SIDE THROUGH LATE TONIGHT
WITH HIGH CLOUDS BEING ADVECTED OVER THE AREA THROUGH THIS
EVENING.

WINDS WILL REMAIN ON THE LIGHT SIDE THROUGH THE FRIDAY AFTERNOON.

THERE ARE SOME STRONGER WINDS OVER THE SOUTHERN AREAS THIS
MORNING ASSOCIATED WITH THE SURFACE LOW. THESE WINDS WILL SLOWLY
DIMINISH THROUGH TONIGHT AS THE LOW MOVES AWAY. A NORTHERLY
PRESSURE GRADIENT OVER THE NORTHERN AREAS IS PRODUCING WINDS 15
TO 20 KT WITH SOME STRONGER GUSTS NEAR PAGY...THESE CONDITIONS
WILL SLOWLY DIMINISH THROUGH TONIGHT.

A UPPER LEVEL LOW OVER THE INTERIOR OF AK WITH A COLD TROF
EXTENDING SW INTO THE NW GULF ATTM WILL DRIFT EAST AND INTERACT
WITH A SHORTWAVE MOVING OUT OF THE NORTH PACIFIC. THIS WILL THE
INCREASE THE ONSHORE SW FLOW ALOFT LATE TONIGHT THROUGH FRI ALONG
WITH MOVING A WEAK SURFACE TROF OVER THE NORTH AREAS. AS THE
ONSHORE FLOW INCREASES...THE THREAT OF PRECIP WILL ALSO INCREASE
ALONG THE NORTHERN GULF LATE TONIGHT AND THEN THROUGH THE REST OF
THE NORTHERN PANHANDLE. THE PRECIP WILL BE ALL SNOW WITH AMOUNTS
OF 1 TO 2 INCHES THROUGH FRI AFTERNOON. THERE IS POTENTIAL THAT
THIS ONSHORE FLOW AT ALL LEVELS MAY PRODUCE MORE SNOW FOR FRI
THAN THE CURRENT THINKING AS THERE WILL BE A CONSTANT FLOW OF
MOISTURE ALONG WITH THE SOUTHERN BRANCH SHORTWAVE MOVING OVER THE
AREA THROUGH THE DAY. THE SOUTHERN AREAS WILL ALSO SEE SNOW BUT
THINK THE FAR SOUTHERN AREAS WILL MIX WITH SOME RAIN THROUGH THE
DAY. THE PRECIP WILL TAPER OF OVER PRINCE OF WALES AND MISTY
FJORDS AS A WEAK SURFACE RIDGE WILL BUILD OVER THE AREA AHEAD OF
AN ADVANCING LOW IN THE NORTH PACIFIC.

.LONG RANGE...CURRENT MODEL GUIDANCE LEANING MORE TOWARDS A MORE
NORTHERLY TRACK FOR A VERY LARGE AND DEEP SYSTEM FORECAST TO
DEVELOP SOUTH OF THE ALEUTIANS AND TRACK NORTH INTO THE BERING
SEA. A BLEND OF GFS AND ECMWF WILL BE USED THROUGH SUNDAY
AFTERNOON. THIS DUE TO THE GOOD AGREEMENT BETWEEN THESE MODELS
INSOFAR AS THEY IMPACT SEAK WEATHER. NO CHANGES PLANNED FOR
SUNDAY NIGHT ONWARD EXCEPT POSSIBLY TO REFINE TEMPERATURES AND
SNOWFALL.

THE LONG RANGE FORECAST BEGINS WITH A POTENT SHORT WAVE HAVING
ALREADY ROUNDED THE BASE OF AN UPPER LEVEL TROUGH THAT EXTENDS
SOUTH FROM THE INTERIOR INTO THE WESTERN GULF. THE ASSOCIATED
SURFACE LOW WILL TRACK NORTHEAST INTO THE EASTERN GULF AND
INTERACT WITH A LINGERING SURFACE LOW OVER THE NORTH CENTRAL GULF
AND SPREAD PRECIPITATION FROM SOUTH TO NORTH FRIDAY NIGHT THROUGH
SATURDAY. QPF VALUES ARE SUBSTANTIAL AND A RAIN-SNOW MIX OVER A
MAJORITY OF THE PANHANDLE ON SATURDAY SHOULD GIVE WAY TO ALL SNOW
SATURDAY NIGHT. NO CONFIDENCE AT THIS POINT IN CALLING IT A HEAVY
SNOW EVENT BUT THE POTENTIAL IS THERE.

ON SUNDAY AND SUNDAY NIGHT ANOTHER LOW WILL TRACK NORTHEAST OVER
THE SOUTHERN PORTIONS OF THE PANHANDLE AS THE UPPER LEVEL TROUGH
BEGINS TO MOVE EAST. THE UPPER TROUGH AND CORRESPONDING JET WILL
PROVIDE A GREAT DEAL OF SUPPORT TO THE SURFACE LOW AND SO BELIEVE
THIS WILL RESULT IN SEVERAL MORE INCHES OF SNOW FOR CENTRAL AND
SOUTHERN PANHANDLE LOCATIONS.

COLD AIR AND A LITTLE LESS PRECIPITATION IS EXPECTED EARLY NEXT
WEEK AS A SURFACE AND UPPER RIDGE BRIEFLY BUILD OVER THE EASTERN
GULF AND PANHANDLE BUT ANOTHER FRONT WILL PUSH THROUGH THE
PANHANDLE BY MID WEEK AND BRING WITH IT A LOW OF MOISTURE AND
WARMER AIR FROM THE SOUTH SO THE SECOND HALF OF THE WEEK WILL SEE
MORE RAIN AND LESS SNOW THROUGHOUT THE FORECAST AREA.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...NONE
MARINE...SCA...ENTIRE COASTAL WATERS PKZ35 36 12