Small Craft Advisory 59, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
110 PM AKST WED JAN 19 2011

.SHORT TERM...A MODERATLY STRONG OCCLUDED FRONT WILL PUSH
THROUGH THE EASTERN GULF THIS AFTERNOON THEN ROTATE NORTHWARD
THROUGH SOUTHEAST ALASKA TONIGHT AND EXIT THE FAR NORTHERN
PORTION EARLY THURSDAY. AN ARCTIC FRONT EXTENDING FROM JUST NORTH
OF SITKA THROUGH FREDERICK SOUND TO JUST NORTH OF WRANGELL WILL
CONTINUE TO RETREAT NORTH TODAY AND EXPECTED TO BE NORTH OF
JUNEAU BY LATE EVENING AND CLEAR HAINES AND SKAGWAY EARLY
THURSDAY. A 1028 MB HIGH OVER THE YUKON AND ITS ASSOCIATED VERY
COLD AIR MASS WILL SLIDE OFF THROUGH THE DAY AND RELAX NORTHERLY
GRADIENTS OVER NORTHERN PANHANDLE.

 ESE GALES NOW IN COASTAL WATERS WILL PEAK BY LATE AFTERNOON AND
DIMINISH WITH A WIND SHIFT TO THE SOUTHWEST THIS EVENING. MAIN
EXCEPTION WILL BE ALONG THE NORTH GULF COAST WHERE EASTERLY
BARRIER JET WILL KEEP GALES INTO EARLY EVENING. SE WIND WILL
INCREASE ACROSS SOUTHERN ZONES THIS AFTERNOON BUT THINK WILL STAY
BELOW ADVISORY LEVELS AND WILL JUST KEEP G35 MPH IN PUBLIC ZONES.
 NEAR ADVISORY LEVEL NORTHEAST WINDS IN SKAGWAY WILL DIMINISH
THROUGH THE DAY AND EXPECTED TO TURN SOUTHERLY BY LATE TONIGHT.

 OVERRUNNING PRECIP OCCURRING OVER ALMOST ALL PANHANDLE AT THIS
TIME WILL INCREASE TO MODERATE RATES AS A SW 850H WIND MAX MOVES
INLAND. RAIN SNOW LINE WILL MOVE NORTH WITH ARCTIC BOUNDARY TODAY
AND THIS IS EXPECTED TO LIMIT SNOWFALL AMOUNTS FOR ALL BUT
PAJN-PAHN TO LESS THAN ADVISORY LEVELS. PAJN UNDER A WINTER
WEATHER ADVISORY AS A BURST OF HEAVY SNOW IS EXPECTED DURING THE
AFTERNOON/EARLY EVENING COMMUTE BEFORE TURNING TO RAIN LATE
EVENING AND A HEAVY SNOW WARNING IS OUT FOR HAINES WHERE PRECIP
STAYS SNOW ALL NIGHT ALBEIT IT BECOMES WET SNOW LATE TONIGHT.
LATEST NAM HAS TEMPS IN PAYA WARMING BETWEEN MIDNIGHT AND 3 AM
WHILE GFS SHOW THIS HAPPENING AROUND 9 PM. WILL NEED TO MONITOR
FOR ADVISORY LEVEL SNOW IF THEY HOLD ONTO COLD AIR LONGER.
SOUTHERN AND COASTAL AREAS COULD SEE 1-2 INCHES OF RAIN BY THIS
EVENING WITH QPF CLOSER TO ONE HALF INCH THROUGH CENTRAL AND
NORTHERN INNER CHANNELS.

 TEMPERATURES WILL STEADILY WARM THROUGH THE NIGHT AND WILL BE
ABOVE FREEZING ALL BUT FAR NORTH AND CLOSE TO 40 ALONG THE COAST.

 MODELS WHERE INITIALIZED WELL WITH NO MAJOR DISCREPANCIES.
CURRENT GRID PACKAGE LOOKS GOOD AND WILL NOT MAKE ANY WHOLESALE
CHANGES BUT JUST MAKE MINOR TWEAKS.

&&

.LONG TERM...MODELS ARE IN FAIR AGREEMENT WITH UPPER LEVEL
GENERAL RIDGING ACROSS THE FORECAST DOMAIN AND A SERIES OF
EMBEDDED UPPER LEVEL SHORTWAVE PULSES AND SURFACE FRONTAL PASSAGES
PASSING ACROSS THE AREA. UNDER THE GENERAL RIDGING
PATTERN...ACTIVE MOISTURE CHANNEL CONNECTED SOUTHWESTWARD
CONTINUES INVITING SEVERAL STORMS INTO THE EASTERN GULF AND
SOUTHEAST ALASKA. OPTED TO USE THE BEST CONSISTENT GFS SOLUTIONS
THROUGH SATURDAY TIME FRAME THEN SWITCHED TO THE ENSEMBLE MEANS
FORECAST OF HPC THROUGH THE END OF THE PERIOD.

 CONTINUED ONSHORE FLOW WILL GRADUALLY BRING THE WARMING TREND TO
ITS FULL STAGE BY THURSDAY NIGHT INTO FRIDAY. EXCEPT THE NORTHERN
MOST ZONES AND NEAR HYDER...PRECIPITATION SHOULD BE ALL RAIN. ONE
AFTER ONE...A SERIES OF FRONTAL PASSAGES WILL SWEEP ACROSS THE
FORECAST DOMAIN THROUGH THE LONG TERM PERIODS. A BRIEF BREAK IS
EXPECTED IN BETWEEN THE SERIES OF FRONTAL BOUNDARIES...BUT THE
LONG TERM FORECAST IS STAYING ON ALL WET SIDE UNDER LIKELY TO
CATEGORICAL POPS WITH OCCASIONAL HEAVY PRECIPITATION. SMALL CRAFT
WINDS/SEAS WILL PREVAIL ACROSS THE OUTSIDE WATERS AND GENERALLY 20
TO 25 KNOTS WINDS ARE EXPECTED ACROSS THE INNER CHANNELS.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY UNTIL 9 PM AKST THIS EVENING FOR AKZ025.
         WINTER STORM WARNING UNTIL 5 AM AKST THURSDAY FOR AKZ019.
MARINE...GALE WARNING FOR PKZ041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011>013-021-022-031>036.

&&

MM/AHN