Small Craft Advisory 635, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
324 PM AKDT TUE OCT 30 2012

.SHORT TERM...AFTERNOON SATELLITE LOOP REVEALS ABOUT 996 MB LOW
ROTATING ACROSS THE NORTHERN GULF WITH AN OCCLUDED FRONTAL
PASSAGE SWEEPING ACROSS THE NORTHERN PANHANDLE AND A COLD FRONT
BEHIND THE OCCLUSION OVER THE CENTRAL GULF. IN BETWEEN THESE TWO
FRONTAL BOUNDARIES...TRAPPED WARM AIR MASS APPROACHES THE
NORTHEASTERN GULF COAST. SOUTHERLY LOW LEVEL WINDS HAVE BEEN
INCREASING SLIGHTLY ACROSS THE OUTER COASTAL WATERS...NORTHERN
AND CENTRAL INNER CHANNELS. SNOW CONTINUES OVER THE NORTHERN MOST
PANHANDLE AND SNOWFALL RATE QUITE HEAVY AT TIMES IN HAINES AREA
AND ACROSS HIGHER ELEVATION ALONG THE KLONDIKE HIGHWAY. WINTER
STORM WARNING REMAINS IN EFFECT FOR LOCATION ABOVE 1500 FEET
ALONG THE KLONDIKE HIGHWAY THROUGH EARLY WEDNESDAY
MORNING...ALONG WITH WINTER WEATHER ADVISORY FOR HAINES

MODELS REMAIN FAIRLY CONSISTENT WITH THE 996 MB LOW OVER THE
NORTHERN GULF TONIGHT SLOWLY DRIFTS SOUTHWESTWARD AND WEAKENS TO
ABOUT 1002 MB NEAR KODIAK BY WEDNESDAY EVENING THEN DISSIPATES
THROUGH LATE WEDNESDAY NIGHT. REFRESHED THE INHERITED FORECAST
PACKAGE WITH THE NAM AND ECMWF FOR THEIR GOOD INITIALIZATION AND
CONSENSUS. SKIES WILL REMAIN MOSTLY CLEAR TO PARTLY CLOUDY OVER
THE SOUTHERN PANHANDLE THROUGH WEDNESDAY. THE WARM AIR MASS HAS
ALREADY ARRIVED OVER YAKUTAT AREA BUT THE OVERRUNNING SCENARIO
OVER THE NORTHERN MOST PANHANDLE WILL CONTINUE THROUGH TONIGHT
BEFORE MIXING WITH RAIN BY EARLY WEDNESDAY MORNING. CATEGORICAL
POPS WILL PREVAIL TONIGHT OVER THE NORTHERN HALF OF THE PANHANDLE
WITH SNOW CHANGING TO RAIN LATE TONIGHT ACROSS THE CENTRAL
PANHANDLE.

.LONG TERM...FRIDAY NIGHT THROUGH SATURDAY WILL BE A TRANSITION PERIOD:
MOST OF THE AREA OF RESPONSIBILITY WILL CHANGE FROM WINDS FROM THE
INTERIOR TO ONSHORE FLOW. AN EXPLOSIVE CYCLOGNESIS WILL OCCUR FOR A
LOW TRACKING N INTO THE WESTERN GULF THURSDAY AND THURSDAY NIGHT,
AND WILL SEND A FAST MOVING OCCLUDED FRONT NE THROUGH THE PANHANDLE
EARLY SAT. CONFIDENCE IS AVERAGE, ALBEIT THE TIMING OF THE FRONTAL
PASSAGE EARLY SATURDAY IS GIVEN WITH LESS CONFIDENCE AS THIS WILL
BE A RELATIVELY SUDDEN SPEED UP OF THE FRONT OVER TWO DAYS IN THE
FUTURE. CHANGES TO THE LONG RANGE FORECAST PACKAGE ARE SMALL.

500 NM S OF ADAK A 992 MB IS TRACKING E. LOW REACHING 500 NM S OF
SEWARD 12Z THU AND REACHING 974 MB DURING EXPLOSIVE CYCLOGENESIS.
500 NM S OF SEWARD AT 12Z FRI THE LOW WILL BE AT IT'S GREATEST
DEPTH OF 952 MB WITH A STRONG OCCLUDED FRONT EXTENDING FROM NEAR
THE LOW IN AND ARC 300 NM S OF PADQ 300 NM S OF CORDOVA AND 300 NM
SW OF KETCHIKAN. THE SOUTH AND EAST QUADRANTS OF THIS LOW WILL
HAVE STRONG CONTOUR GRADIENTS THAT ARE SUPPORTING A FRONT THAT IS
BOTH STRONG AND FAST MOVING.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY UNTIL 7 AM AKDT WEDNESDAY FOR AKZ019.
         WINTER STORM WARNING UNTIL 7 AM AKDT WEDNESDAY FOR AKZ018.
MARINE...SMALL CRAFT ADVISORY FOR PKZ011-012-021-022-031>035-041>043-051-
     052.

&&

AHN/JBT