High Wind Watch 2, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
557 AM AKST FRI FEB 6 2009

.SHORT TERM...A COMPLICATED WEATHER SCENARIO THROUGH TONIGHT
ACROSS THE PANHANDLE. A WEAK FRONTAL BOUNDARY IS CURRENTLY
ADVECTING THROUGH THE PANHANDLE THIS MORNING SUPPORTING A STRONG
OVERRUNNING EVENT. RADAR RETURNS FROM THE RADAR NEAR BIORKA
ISLAND CONTINUE TO BLOSSOM AT THIS HOUR AS THE OVERRUNNING EVENT
STRENGTHENS WITH UPPER LEVEL JET SUPPORT ADVECTING INTO THE
EASTERN GULF. 30 TO 35 KNOT SOUTH TO SOUTHWEST WINDS ALONG THE
FRONTAL BOUNDARY ARE OVERRUNNING THE COLD AIR IN PLACE AT THE
SURFACE FROM FREDERICK SOUND NORTHWARD ALLOWING FOR CONTINUED
SNOWFALL. THIS FRONTAL BOUNDARY LATER ON THIS AFTERNOON WILL ALSO
ACT TO THE DEMISE OF THE SNOW EVENT ACROSS THE CENTRAL PANHANDLE
AS IT WILL ADVECT NORTHWARD BRINGING WARMER AIR INTO THE CENTRAL
PANHANDLE AND THIS WILL CHANGE THE SNOW TO RAIN. WENT WITH THE
06Z NAM12 AND THE 00Z GFS FOR TODAYS PACKAGE AS THE 06Z NAM12 HAD
THE BEST PRESSURE FIELD AND SURFACE WINDS, BUT PREFERRED THE 00Z
GFS FOR ITS MID LEVEL VORTICITY STRUCTURE AND FRONTOGENESIS
FIELDS WITHIN THE CURRENT FRONTAL BAND AND DEVELOPING SURFACE LOW
IN THE NORTHERN PACIFIC.

 FOR TODAY UPGRADED THE WINTER STORM WATCHES TO WARNINGS FOR
AKZ018,19,21 AND 25 FOR DIFFERENT TIMES AS THERE WILL BE TWO
DIFFERENT SNOW EVENTS THROUGH TONIGHT. THE FIRST SNOW EVENT IS ON
GOING FOR AKZ021 AND AKZ025 AND THE OVERRUNNING CONTINUES IN
AKZ025 ALONG THE FRONTAL BOUNDARY AND FAVORABLE EASTERLY UPSLOPE
WINDS REMAIN IN AKZ021. NEAR PAGS AND PAEL SNOWFALL WILL CONTINUE
INTO THE AFTERNOON BUT WITH WARMER SOUTHWESTERLY SURFACE AIR
ADVECTING INTO CROSS SOUND AND SOUTHEASTERLY PARCEL TRAJECTORIES
INTO PAGS EXPECT SNOWFALL AMOUNTS TO BE LESS. THIS FIRST FRONTAL
BAND WILL PUSH NORTHWARD THROUGH THE PANHANDLE INTO THE AFTERNOON
ALLOWING FOR SOUTHERLY FLOW AND WARMER AIR TO PUSH NORTHWARD ALL
THE WAY INTO NORTHERN LYNN CANAL. EXPECT A RAIN/SNOW MIX INTO THE
AFTERNOON NEAR THE ICY STRAIT CORRIDOR AND REMAINING ALL SNOW
FROM PAYA TO PAHN TO PAGY. WINDS WILL REMAIN LOCALLY BREEZY ALONG
THE OUTER COAST WITH THIS FIRST FRONTAL BAND TODAY AND RAINFALL
AMOUNTS WILL BE BELOW A HALF AN INCH ACROSS THE SOUTHERN
PANHANDLE. EXPECT PAPG AND PAWG TO SEE SNOW THIS MORNING AS COLD
EASTERLY FLOW CONTINUES BUT BY LATE MORNING THE SOUTHERLY FLOW
COMPONENT WILL HAVE INCREASED ENOUGH TO MIX OUT THE COLD AIR.

 FOR TONIGHT A STRENGTHENING SURFACE LOW IN THE NORTHERN PACIFIC
WILL ADVECT INTO THE NORTHERN GULF ALLOWING FOR THE SURFACE WIND
COMPONENT TO BRIEFLY TURN AROUND TO THE NORTHEAST IN THE EVENING
BRINGING THE COLDER AIR BACK DOWN LYNN CANAL. HOWEVER...THE
SECONDARY 850 MB FRONTAL BAND ASSOCIATED WITH THE SURFACE LOW IN
THE GULF WILL QUICKLY ADVECT ACROSS THE CENTRAL PANHANDLE
ALLOWING SNOW LEVELS TO RISE ABOVE 1500 FEET FROM THE ICY STRAIT
CORRIDOR SOUTHWARD. WITH THE LEFT EXIT REGION OF AN UPPER LEVEL
JET STREAK OVER THE PANHANDLE TONIGHT AND STRONG ONSHORE FLOW
EXPECT LOCALLY HEAVY RAINFALL TONIGHT. THE HEAVY SNOWFALL WILL
REMAIN NEAR PAHN AND PAGY TONIGHT AS THE COLD AIR WILL REMAIN
THERE THE LONGEST BEFORE THE SECONDARY 850 MB FRONTAL BAND
ADVECTS INTO THE YUKON LATE TONIGHT. CONCERNED THAT PAYA COULD
SEE HEAVY SNOWFALL TONIGHT SO ISSUED ADVY, HOWEVER, STRONG
EASTERLY FLOW SHOULD KEEP SNOWFALL AMOUNTS NEAR ADVY CRITERIA.
SNOWFALL AMOUNTS ALSO OF CONCERN IN THE HYDER AREA TONIGHT WITH
THE LOCALLY HIGH PRECIP RATES, BUT BELIEVE SNOW WILL CHANGE TO
RAIN TONIGHT AS SOUTHWESTERLY FLOW ADVECTS NORTHWARD THROUGH
PORTLAND CANAL. EXPECT THE 12Z MODELS WILL HAVE A BETTER HANDLE
ON THE COLD AIR NEAR HYDER. SO THIS SITUATION BEARS WATCHING.
ALSO WITH THE SECONDARY FRONTAL BAND MOVING ACROSS THE PANHANDLE
AND 850 MB WINDS NEAR 55 KNOTS TONIGHT EXPECT LOCALLY WINDY
CONDITIONS ACROSS THE SOUTHERN PANHANDLE AND GALES IN ASSOCIATED
COASTAL WATERS. FORECAST CONFIDENCE IS BELOW AVERAGE IN THE SHORT
TERM WITH THIS TWO PRONGED FRONTAL EVENT.

.LONG TERM...LONG TERM FORECAST THIS TIME AROUND IS MAINLY DEALING
WITH THE REMAINS OF FRIDAYS STORM. THE MOISTURE FROM IT WILL LINGER
AROUND THE PANHANDLE THROUGH SUNDAY MORNING MAINLY IN THE SOUTHERN
ZONES. AT HAND OFF FROM THE SHORT TERM MOST OF THE AREA WILL BE WARM
ENOUGH FOR THE PRECIPITATION TO FALL AS RAIN. ONLY THE HIGHER
ELEVATIONS NORTH OF SKAGWAY AND YAKUTAT WILL STILL BE SEEING SNOW
SATURDAY MORNING. THE WINDS AND RAIN WILL GRADUALLY DIMINISH FROM
NORTH TO SOUTH SATURDAY AFTERNOON INTO SUNDAY AS THE SYSTEM PULLS
AWAY TO THE SOUTHEAST. WE WILL BE LEFT WITH ONSHORE FLOW AND SHOWERS
THROUGH MID WEEK NEXT WEEK.

THE NEXT SYSTEM MAKES AN APPEARANCE IN THE FORECAST BY LATE MONDAY
NIGHT AS A LOW MOVES INTO THE SOUTH CENTRAL GULF AND BRUSHES THE
SOUTHERN PANHANDLE TUESDAY. AT PRESENT A CHANCE OF PRECIPITATION IS
EXPECTED FOR THE EXTREME SOUTHERN ZONES AND LESSER POPS FARTHER
NORTH AS THE LOW SLIDES BY TO THE SOUTH.

MODELS ARE IN FAIRLY GOOD AGREEMENT THROUGH LATE SUNDAY. BY MONDAY
THEY HAVE SOME DIVERGENCE ON WHAT THE TUESDAY SYSTEM WILL DO.
THOUGHT THE EC HANDLED THE SYSTEM A LITTLE BETTER THEN THE GFS.
FORECAST WAS UPDATED WITH THE 00Z NAM THROUGH 00Z MONDAY AND THEN
SWITCHED TO THE EC FOR THE REST OF THE PERIOD. THE NAM WAS CHOSEN
BECAUSE IT HAD FAIRLY GOOD RUN TO RUN CONSISTENCY.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM AKST SATURDAY FOR
     AKZ027.
         WINTER STORM WARNING UNTIL 6 PM AKST THIS AFTERNOON FOR AKZ021-
     025.
         WINTER STORM WARNING FROM NOON TODAY TO MIDNIGHT AKST TONIGHT
     FOR AKZ019.
         WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 3 AM AKST
     SATURDAY FOR AKZ017.
         WINTER STORM WARNING FROM 6 PM THIS EVENING TO MIDNIGHT AKST
     TONIGHT FOR AKZ018.
MARINE...GALE WARNING FOR PKZ033-036-041-042.
         SMALL CRAFT ADVISORY FOR PKZ012-013-021-022-031-032-034-035-043-
     051-052.

PSS/EAL