Gale Warning 415, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
352 PM AKST WED DEC 18 2013

.SHORT TERM...CLEAR COLD DAY TRANSITIONS SNOW WITH WARMING
TEMPERATURES OVERNIGHT AS WEATHER FRONT MOVES INTO THE REGION.

COLD ARCTIC AIR MOVED OVER THE PANHANDLE FROM THE YUKON WITH
TEMPERATURES IN THE LOW TEENS TO SINGLE DIGITS FOR THE CENTRAL AND
NORTHERN PANHANDLE. SOME LINGERING CLOUDS OVER THE SOUTHERN
PANHANDLE KEPT TEMPERATURES A BIT WARMER IN THE LOW TO UPPER 20S.
CLEARING SKIES AND CALM WINDS FOR MOST OF THE REGION WITH THE
EXCEPTION OF THE NORTHERN PANHANDLE WHERE PRESSURE GRADIENT
BETWEEN THE YUKON HIGH AND AN INVERTED TROUGH OVER THE PANHANDLE
PRODUCED STRONG NORTHERLY WINDS THIS MORNING. AS THE YUKON HIGH
PUSHED TO THE EAST INTO BRITISH COLUMBIA THE GRADIENT AND WINDS
HAVE SHIFTED AND DIMINISHED THROUGH THE AFTERNOON.

A 972 MB LOW CURRENTLY OVER THE WESTERN TIP OF THE ALEUTIANS WILL
REMAIN NEARLY STATIONARY AS ASSOCIATED FRONT CROSSES THE AK GULF
MOVING TOWARD THE PANHANDLE THROUGH THURSDAY. CIRRUS SHIED IS
ALREADY REACHING THE PANHANDLE COAST THIS AFTERNOON. A TRIPLE
POINT LOW WILL DEVELOP ALONG THE FRONT LATE WEDNESDAY NIGHT INTO
THURSDAY MORNING IN THE NORTHERN GULF AND THEN BEGIN TO MOVE OVER
THE PANHANDLE LATE THURSDAY AFTERNOON. SNOW WILL DEVELOP FROM THE
NORTHWEST TO SOUTHEAST THROUGH THE LATE EVENING AND INTO EARLY
THURSDAY MORNING. WITH DEEP ARCTIC AIR MASS IN PLACE AND WARM
MOIST AIR MASS MOVING IN AN OVER RUNNING SNOW EVENT IS SHAPING UP.
EXPECTING HEAVIEST SNOW TO FALL THURSDAY MORNING ALONG THE FRONTAL
THERMAL GRADIENT AS SEEN AT 700 MB AND 850 MB WHICH WILL ENHANCE
LIFT. HIGHEST QPF AMOUNTS WITH THE COLDEST TEMPERATURES AND
HIGHEST SNOW ACCUMULATIONS STILL IN THE CENTRAL PANHANDLE WHILE
THE SOUTHERN REGIONS SNOW TOTALS SHOULD BE LESS AS TEMPERATURES
RISE AND SNOW CHANGES TO RAIN. COLDEST TEMPERATURES MEASURED THIS
EVENING AND WILL THEN BEGIN TO RISE OVERNIGHT AS WARM AIR MASS
BEHIND THE FRONT MOVES IN. SNOW FALL AMOUNTS IN THE 3 TO 5 INCH
RANGE FOR THE CENTRAL AND NORTHERN PANHANDLE TONIGHT WITH 1 TO 3
FOR THE SOUTHERN PANHANDLE. ADDITIONAL SNOW ACCUMULATION OF 4 TO 8
INCHES TOMORROW WITH 1 TO 2 FOR THE SOUTHERN PANHANDLE BEFORE
CHANGING TO RAIN.

WINDS WILL INCREASE TO GALE FORCE OVER THE COASTAL WATERS WITH
THE ADVANCING FRONT WITH STRONG WINDS DEVELOPING ALONG THE COASTAL
PANHANDLE. EAST-WEST ORIENTED CHANNELS WILL INCREASE TO GALES
WHILE THE PARALLEL GRADIENT WILL CAUSES WEAKER WINDS OVER THE
NORTHERN INNER CHANNELS. AS THE FRONT PASSES OVERLAND WINDS WILL
PICK UP TO THE 15 TO 25 MPH RANGE. WILL ALSO SEE A SHIFT FROM
NORTHERLY TO SOUTHERLY FLOW WAS THE FRONT PASSES OVER THE REGION
TONIGHT INTO THURSDAY.

MODELS WERE IN GOOD AGREEMENT FOR THE FIRST PART OF THE SHORT
TERM AND INITIALIZED WELL. MODEL ARE THEN IN DISAGREEMENT WITH A
POSSIBLE SECOND WAVE DEVELOPING IN THE GULF LATE THURSDAY
AFTERNOON. NAM/ECMWF WERE ALIGNED NOT DEVELOPING THE WAVE WHILE
GFS/UKMET HAD A FEATURE FORMING. KEPT WITH A NAM/ECMWF BLEND FOR
MESO SCALE FEATURES AND RUN TO RUN CONSISTENCY. MAIN FORECAST
ISSUES WILL BE ELFIN COVE-PELICAN REGION WHERE HIGHER SNOW TOTALS
ARE POSSIBLE IF COLD AIR POOLS REMAINS IN PLACE. FORECAST
CONFIDENCE IS ABOVE AVERAGE.

&&

.LONG TERM...SOME DIFFERENCES IN THE MODEL SOLUTIONS HOWEVER
STAYED WITH PICKS OF PREVIOUS FORECAST AND THE SHORT TERM-ER OF A
BLEND OF THE NAM AND ECWMF THROUGH ABOUT SUNDAY. FIRST LOW IS
MOVED QUICKLY ACROSS THE SOUTHERN PANHANDLE AREA WITH A BRIEF
BREAK AS THE NEXT SYSTEM GATHERS ITSELF OVER THE NORTH CENTRAL
PACIFIC THE WILL THEN MOVE PAST KODIAK ISLAND SATURDAY EVENING
SPREADING MORE PRECIPITATION INTO THE PANHANDLE SATURDAY NIGHT AND
SUNDAY. FOR THE PRESENT THINK MOST OF THAT WILL BE SNOW ACROSS THE
NORTHERN INNER CHANNELS.

BOTH THE FIRST SYSTEM MENTIONED ABOVE AND THE ONE FOR SATURDAY
NIGHT LOOK LIKE THAT THEY HAVE A GOOD TROPICAL MOISTURE SOURCE SO
WILL BE EXPECTING A GOOD LIQUID WATER EQUIVALENTS FROM THE SNOW
AND AND RAINS

DID LITTLE IN THE WAY OF ALTERATIONS IN THE EXTENDED TIME FRAMES
AND DID BLEND A LITTLE TO THE THE NEW WPC SOLUTIONS FOR THE
EXTENDED.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER STORM WARNING FROM 6 AM THURSDAY TO MIDNIGHT AKST
     THURSDAY NIGHT FOR AKZ026.
         STRONG WIND THURSDAY MORNING FOR AKZ023-027.
         WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM AKST

     THURSDAY FOR AKZ022-024.
         WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM AKST
THURSDAY
     FOR AKZ019>021-025.
         WINTER WEATHER ADVISORY FROM 6 AM TO 6 PM AKST THURSDAY
FOR
     AKZ018.
         WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO NOON AKST
THURSDAY
     FOR AKZ017.
MARINE...GALE WARNING FOR PKZ021-022-034-036-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ012-031>033-035-053.

&&

PRB/BEZENEK