Gale Warning 503, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
342 PM AKST THU DEC 27 2012

.SHORT TERM...SNOWY OR WET DAY ACROSS THE AREA AS A DECENT
STRENGTH FRONT COMES ASHORE THIS AFTERNOON AND EVENING. PRECIP
HAS STARTED UP IN MOST PLACES. TEMPERATURES HAVE BEEN COLD ENOUGH
THAT THE PRECIP IS PREDOMINATELY SNOW FOR THE INNER CHANNELS.
VISIBILITIES HAVE DROPPED TO AS LOW AS 1/2 MILE IN SOME PLACES
DUE TO THE SNOW. THE CENTRAL AND SOUTHERN OUTER COAST, THE
SOUTHERN PANHANDLE, AND YAKUTAT HAVE ACTUALLY SEEN ENOUGH WARM
AIR ADVECTION FOR A MIX WITH RAIN OR A COMPLETE CHANGE OVER TO
RAIN TO ALREADY OCCUR. AS FOR WINDS, THEY HAVE MOSTLY BEEN
CONFIDED TO THE OUTER COAST (GUSTS AS HIGH AS 30 KT IN SITKA) AND
THE GULF (GALE FORCE WINDS FOR MOST OF THE MORNING).

 INTO TONIGHT PRECIP WILL CONTINUE BUT THERE WILL BE A FEW HOURS
BREAK AS THE DRY SLOT BEHIND THE FRONT MOVES OVER THE PANHANDLE
BEFORE THE WEAK TROUGH BEHIND IT MOVES IN FOR FRI MORNING. THE
EXCEPTION IS HYDER WHICH WILL SEE SNOW THROUGH TONIGHT AS THE
MOISTURE PLUME ASSOCIATED WITH THE FRONT JUST CATCHES THAT AREA.
PRECIP TYPE WILL BE DIFFICULT TO PIN DOWN AS IT ALL DEPENDS ON
HOW FAST DIFFERENT AREAS WARM UP TODAY. THERE IS STILL SOME
DECENT COLD AIR STUCK IN THE INNER CHANNELS AND THE SOUTHERLY
FLOW IS NOT THAT STRONG. JUNEAU AIRPORT IS STILL AT 22 DEGREES AS
OF NOON AND HAINES AND SKAGWAY ARE STILL IN THE TEENS. OTHER
AREAS FARTHER SOUTH AND WEST ARE IN THE MID 20S TO LOW 30S.
TEMPERATURES TONIGHT ARE EXPECTED TO REMAIN MOSTLY STEADY OR RISE
SLIGHTLY WITH CONTINUED WARMING EXPECTED TOMORROW. THE AREAS THAT
ARE STILL SNOW AT THE MOMENT SHOULD START TO MIX WITH RAIN THIS
AFTERNOON FOR THE SOUTHERN INNER CHANNELS, THE WESTERN PART OF
ZONE 26, AND ALONG THE OUTER COAST. OTHER AREAS FROM JUNEAU AND
GUSTAVUS SOUTHWARD MAY NOT SEE A MIX UNTIL TONIGHT OR FRI. HAINES
AND SKAGWAY WILL MOST LIKELY BE SNOW THROUGH TOMORROW. AS FOR
AMOUNTS, STILL EXPECTING ADVISORY SNOW FALLS FOR MOST INNER
CHANNEL AREAS FROM GUSTAVUS AND JUNEAU SOUTHWARD TO PETERSBURG
AND WRANGELL WITH THIS INITIAL FRONTAL BAND. AFTER THE DRY SLOT
TONIGHT, MORE SNOW MAY FALL WITH THE NEXT TROUGH FRI MORNING BUT
BY THIS POINT THERE SHOULD BE ENOUGH WARM AIR IN THE INNER
CHANNELS THAT MOST PLACES WILL SEE RAIN MIXING IN WITH THE SNOW
AND ACCUMULATIONS SHOULD BE ON THE LOW SIDE.

 WINDS WILL NOT BE MUCH OF A PROBLEM. ONCE THE INITIAL FRONT
MOVES THROUGH THIS EVENING WINDS ALONG THE OUTER COAST AND IN THE
SOUTHERN PANHANDLE WILL DIMINISH. WINDS IN THE NORTH/SOUTH INNER
CHANNELS WILL BE SWITCHING TO THE S TONIGHT AND TOMORROW AS WELL
BUT WITH THE PARALLEL GRADIENT WIND SPEEDS ARE EXPECTED TO BE
LIGHT.

 SHORT RANGE MODELS WERE IN DECENT AGREEMENT TODAY. DECIDED TO GO
WITH THE GFS FOR UPDATES TODAY AS IT HAD THE BEST INITIALIZATION
COMPARED TO SATELLITE IMAGES TODAY. ECMWF WAS A CLOSE SECOND AND
NAM WAS NOT TOO FAR BEHIND THAT. FORECAST CONFIDENCE IS ABOUT
AVERAGE WITH BELOW AVERAGE CONFIDENCE ON SNOWFALL AMOUNTS DUE TO
UNCERTAINTY ON THE STRENGTH OF THE WARM AIR ADVECTION.

.LONG TERM...AN ACTIVE WEATHER PATTERN WILL CONTINUE FOR
SOUTHEAST ALASKA THROUGH AT LEAST THE MIDDLE OF NEXT WEEK. A
SERIES OF LOW PRESSURE SYSTEMS WILL TRACK FROM THE NORTHERN
PACIFIC INTO THE WESTERN GULF SENDING MULTIPLE FRONTS AND ROUNDS
OF PRECIPITATION INTO THE PANHANDLE. THIS WILL RESULT IN LIKELY TO
CATEGORICAL PRECIPITATION CHANCES FOR MUCH OF THE PANHANDLE
THROUGH THE PERIOD.

AT THE BEGINNING OF THE PERIOD ON FRIDAY NIGHT...AN UPPER LEVEL
RIDGE WILL QUICKLY PUSH EAST ACROSS THE PANHANDLE. THIS WILL
RESULT IN PRECIPITATION BECOMING MORE PERIODIC AND MAINLY CONFINED
TO THE NORTHERN HALF OF THE PANHANDLE THROUGH THE FIRST HALF OF
SATURDAY. A FEW BREAKS IN THE CLOUDS ARE POSSIBLE AS THIS
OCCURS...HOWEVER DEEP LAYER ONSHORE FLOW WILL KEEP MUCH OF THE
PANHANDLE UNDER MOSTLY CLOUDY TO CLOUDY SKY CONDITIONS. AT THE
SURFACE...A LOW NEAR THE ALEUTIANS WILL PUSH A WEAK OCCLUDED FRONT
ACROSS THE GULF ON SATURDAY. THIS FRONT WILL BECOME VERY
DISORGANIZED WHEN IT MOVES ACROSS THE GULF AS ITS PARENT LOW
PUSHES NORTH INTO THE BERING SEA. PERIODS OF LIGHT PRECIPITATION
CAN BE ANTICIPATED AS THIS FRONT MOVES ACROSS THE PANHANDLE
SATURDAY. A MORE SIGNIFICANT SURFACE LOW AND ASSOCIATED FRONTAL
BOUNDARY WILL MOVE FROM THE NORTHERN PACIFIC INTO THE GULF LATE
SUNDAY. STEADY PRECIPITATION WILL ACCOMPANY THIS FRONT BEGINNING
SUNDAY AND LASTING INTO EARLY MONDAY. THE NEXT SYSTEM ENTERS THE
GULF LATE MONDAY WITH ANOTHER ROUND OF STEADY PRECIPITATION DURING
THE TUESDAY TO WEDNESDAY TIME FRAME.

GALE FORCE WINDS WILL ACCOMPANY EACH FRONT AS THEY MOVE ACROSS THE
GULF. AM EXPECTING WINDS ALONG THE INSIDE CHANNELS TO GRADUALLY
INCREASE OVER THE WEEKEND WITH SMALL CRAFT CONDITIONS FOR MANY
AREAS INTO NEXT WEEK. AS EACH FRONT GETS CLOSER TO THE SOUTHEAST
ALASKA COAST...OCEAN ENTRANCES IN CROSS SOUND...SOUTHERN
CHATHAM...SUMNER...AND CLARENCE STRAIT WILL LIKELY EXPERIENCE GALE
CONDITIONS. THE FRONTS IMPACTING THE REGION SUNDAY AND EARLY NEXT
WEEK DO APPEAR TO HAVE MORE FAVORABLE DYNAMICS WITH A STRONGER LOW
LEVEL JET. THIS WILL HAVE TO WATCHED AS STRONG WIND HEADLINES MAY
BE NEEDED FOR COASTAL LAND ZONES IF THE THE STRENGTH OF THE LOW
LEVEL WINDS PERSIST IN FUTURE MODEL RUNS.

AS FOR PRECIPITATION TYPE...SOUTHERLY WINDS AND THE EXPECTED STORM
TRACK FROM THE NORTHERN PACIFIC INTO THE GULF WILL CAUSE SLOWLY
WARMING TEMPERATURES THIS WEEKEND. THIS WILL RESULT IN MAINLY RAIN
WITH SOME SNOW POTENTIALLY MIXED IN AT TIMES AS TEMPERATURES COOL.
THE ONE EXCEPTION WILL BE ACROSS THE FAR NORTHERN PANHANDLE IN THE
SKAGWAY AND HAINES AREAS...ESPECIALLY ALONG THE HIGHWAYS.
THICKNESSES BEGIN TO FALL A BIT BY THE MIDDLE PART OF NEXT WEEK SO
A BIT OF A COOLING TREND COULD OCCUR.

USED THE GFS THROUGH THE FIRST HALF OF SUNDAY BEFORE TRANSITIONING
TO A BLEND OF THE GFS/EC THROUGH TUESDAY. THEREAFTER...ENSEMBLE
APPROACH CONTINUED TO WORK WITH A LOT OF HPC INFLUENCE. CONFIDENCE
IS AVERAGE THROUGH THE WEEKEND BEFORE DROPPING NEXT WEEK DUE TO
UNCERTAINTY IN THE TIMING AND STRENGTH OF EACH WAVE MOVING INTO
THE GULF.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY UNTIL 3 AM AKST FRIDAY FOR AKZ026.
         WINTER WEATHER ADVISORY UNTIL 9 PM AKST THIS EVENING FOR AKZ025.
MARINE...GALE WARNING FOR PKZ043.
         SMALL CRAFT ADVISORY FOR PKZ022-034>036-041-042-051-052.

&&

EAL/TPS