Small Craft Advisory 724, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
609 AM AKST MON NOV 14 2011

.SHORT TERM...AN EXTENDED TROUGH OF LOW PRESSURE FROM NORTHERN
BRITISH COLUMBIA ACROSS THE NORTHERN PANHANDLE AND WEST TO COOK
INLET. THERE IS SMALL LOWS ON THIS THROUGH THAT ARE RUNNING EAST
ACROSS THE NORTHERN PANHANDLE. ONE OF THEM MOVED ACROSS THE
JUNEAU AREA AND PROLONGED PERIOD OF HEAVY SNOW FROM ABOUT 9 PM TO
4 AM RESULTED IN ABOUT 10 TO 12 INCHES OF SNOWFALL OVER NIGHT.
ANOTHER FEW INCHES ARE POSSIBLE YET IN THE MORNING SO THE HEAVY
SNOW WARNING WAS EXTENDED TO 9 AM.

THE SHORT WAVES/IMPULSES ARE LOCALIZING THE SNOW BANDS OVER THE
NORTHERN PANHANDLE MAKING THE FORECASTING OF AMOUNTS A LITTLE
DIFFICULT.

SOUTH OF THE LOW PRESSURE TROUGH THE WESTERLY WINDS CONTINUE
HOWEVER ARE SLOWLY SUBSIDING WITH WINDS NOW ONLY 35 KT THE
WIDESPREAD SHOWERS VISIBLE IN SATELLITE IMAGERY OVER THE EASTERN
GULF OF ALASKA. EXPECT THE TROUGH TO DRIFT SOUTH WITH THE
NORTHERLY WINDS INCREASING TONIGHT AS HIGH PRESSURE BEGINS TO
BUILD INTO THE ALASKAN INTERIOR AND NORTHWEST CANADA.

SHOWERS WILL BE TAPERING OFF OR ENDING OVER THE NORTHERN AND
CENTRAL PANHANDLE. ACROSS THE SOUTHERN PANHANDLE EXPECT THE
SHOWERS TO CONTINUE THROUGH TODAY AND TONIGHT BUT BEGINNING TO
TAPER OFF LATE.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...TUESDAY STARTS OFF WITH A
WEAKENING LOW IN THE NORTHERN GULF WITH A TROUGH EXTENDING INTO
THE PANHANDLE. THIS LOW WILL BE REPLACED BY ANOTHER STRONGER LOW
MOVING INTO THE NORTHERN GULF FROM THE WEST TUESDAY EVENING. BOTH
SYSTEMS WILL CONTINUE THE WESTERLY ONSHORE FLOW AND PRECIP CHANCES...HOWEVER
THE SECOND LOW WILL BRING WITH IT MORE MOISTURE AND A FRONTAL
SYSTEM. AN ARCTIC BOUNDARY WILL SET UP TO THE NORTH ALONG THE
CANADIAN BOARDER AND YAKUTAT AND REMAIN STATIONARY. BY LATE
TUESDAY AFTERNOON AND EVENING THE WARM FRONT ASSOCIATED WITH THE
SECOND LOW WILL MOVE INTO THE REGION. MOST OF THE PANHANDLE WILL
INITIALLY SEE SNOW THEN AS THE WARMER AIR ALOFT MOVES IN WITH
THE FRONT SNOW WILL MIX WITH RAIN OVERNIGHT. AREAS THAT WILL MIX
WITH RAIN INCLUDE FROM ELFIN COVE SOUTH AND MAINLY ALONG THE COAST
WHILE THE FAR NORTHERN AREAS WILL REMAIN ALL SNOW. JUNEAU AREA
WILL BE TRICKY...850MB TEMPERATURES GRADUALLY WARM FROM -10C TUES
AFTERNOON TO -5C WED MORNING BEFORE COOLING AGAIN. THEREFORE HAVE
INCLUDED SNOW FOR TUES NIGHT AND ADDED IN MIXING WITH RAIN FOR
WED. GREATEST SNOWFALL AMOUNTS WILL BE TUESDAY NIGHT...WITH SOME
AREAS BECOMING HEAVY AT TIMES...RANGING FROM 3-7IN ACROSS THE
NORTH FOLLOWED BY AN ADDITIONAL 2-4IN THROUGH WED AFTERNOON AND
1-3IN ACCUM OVER THE SOUTH. THESE AMOUNTS WILL VARY GREATLY DEPENDING ON
TIMING OF PRECIP CHANGING TO RAIN. SNOW AND RAIN WILL DIMINISH
FROM NORTH TO SOUTH THROUGH WED EVENING INTO THURS AS THE LOW
MOVES SEWRD. THIS WILL CAUSE MID-LEVEL FLOW TO TURN OFFSHORE
DECREASING PRECIP FURTHER. AS THE LOW MOVES SOUTH THE
STRENGTHENING ARCTIC COLD FRONT MENTIONED ABOVE WILL SHIFT
SOUTHWARD AND SURFACE WINDS WILL TURN OUT OF THE NORTH. THE
COMBINATION OF THE LOW TO THE SOUTH AND HIGH PRESSURE BUILDING TO
THE NORTH WILL RESULT IN A STRONG NORTHERLY PRESSURE GRADIENT WITH
STORM FORCE WINDS THROUGH LYNN CANAL AND GALES THROUGH OTHER
INSIDE CHANNELS FOR WED AND THURS. HIGHEST WINDS WILL BE THROUGH
PASSES AND GAPS IN THE MOUNTAINS OPEN TO THE NORTH...INCLUDING BUT
NOT LIMITED TO DISENCHANTMENT BAY IN YAKUTAT BAY AND CHILKAT AND
TAIYA VALLEYS.

EXPECT BELOW NORMAL TEMPERATURES THURS THROUGH SATURDAY AS CAA OUT
OF THE NORTH CONTINUES UNDER PARTLY CLOUDY SKIES. SUNDAY WILL SEE A
SYSTEM APPROACHING THE COASTAL AREAS WITH THE CHANCE OF SNOW.

THERE IS A LOT OF DISAGREEMENT IN MODEL SOLUTIONS FOR
TIMING/LOCATION OF THE TUES/WED LOW AND WHEN/HOW IT MOVES SOUTH. THE
GENERAL IDEA OF THE ARCTIC BOUNDARY TO THE NORTH AND LIKELY PRECIP
ARE SIMILAR. DIFFERENCES IN LOW PLACEMENT WILL RESULT IN SLIGHTLY
DIFFERENT WIND SPEEDS AND DIRECTIONS...AS WELL AS TIMING OF WINDS
SHIFTING FROM SOUTH TO NORTH. HAVE GONE WITH A CONSENSUS SOLUTION
FOR PRESSURE WITH FORECASTER CONFIDENCE AT ABOUT AVERAGE. TRENDED
TOWARD THE GFS FOR PRECIP HOWEVER AS IT INITIALIZED TODAYS SNOW THE
BEST.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER STORM WARNING UNTIL 9 AM AKST THIS MORNING FOR AKZ025.
MARINE...SMALL CRAFT ADVISORY FOR PKZ022-033-036-041>043-051-052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ053.

&&

BEZENEK/HANNON