Small Craft Advisory 10, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
616 AM AKST TUE JAN 3 2012

.SHORT TERM...A COMPLEX 965 MB LOW CENTERED NEAR 50/150 WILL
SEND A STRONG OCCLUDED FRONT NE AND ACROSS SOUTHERN SOUTHEAST
ALASKA TODAY AND THEN WEAKENING ACROSS NORTHERN PANHANDLE
TONIGHT. A SMALL 980 MB LOW IS DEVELOPING ALONG THE FRONT OVER
THE SOUTHEAST GULF THIS MORNING THAT DUMBBELLS NNW INTO THE
CENTRAL GULF TONIGHT. BEHIND THE FRONT THERE WILL BE A SMALL E TO
W RIDGE LIFTING NORTH ACROSS SOUTHEAST ALASKA. THERE IS A SECOND
WAVE JUST BEGINNING TO DEVELOP ALONG THE TRAILING FRONT NEAR
38N/144W THAT HAS POTENTIAL TO 1)BOMB INTO A TIGHTLY WOUND 968 MB
STORM AS IT MOVES TO JUST WEST OF DIXON ENTRANCE 12Z WED 2)DEEPEN
TO A 982 OPEN WAVE WITH SMCR WINDS JUST WEST OF DIXON ENTRANCE OR
3) DEEPEN TO A MODERATE 980 MB LOW THAT MOVES TO NEAR CWRO.

CURRENTLY THE OCCLUDED FRONT IS PUSHING ACROSS HAIDA GAWII
ISLANDS AND WILL MOVE THROUGH THE SOUTHERN ZONES THIS MORNING. THE
E-W ORIENTATION OF THIS FRONT IS KEEPING SUBSTANTIAL EASTERLY
GRADIENT OF THE AREA. THIS TENDS TO LIMIT WIND GUSTS TO INTERIOR
PASSES AND LESS SO FOR PAKT AND CLARENCE SO JUST WENT WITH STRONG
WINDS FOR AKZ027 THIS MORNING. PRECIP ACROSS SOUTHERN WILL BE RAIN
OR QUICKLY CHANGING TO RAIN EXCEPT FOR NEAR HYDER WHICH COULD STAY
SNOW MOST OF THE DAY WITH 4 INCHES ACCUM POSSIBLE BEFORE MIXING
WITH RAIN LATE AFTERNOON. AS THE SE GULF LOW MOVES NORTH AND
BEHIND THE FRONT AND AHEAD OF THE APPROACHING RIDGE...GRADIENT
ACROSS SOUTHERN SOUTHEAST ALASKA GAINS MORE SLY COMPONENT WHICH
WILL HELP BRING GALES TO CLARENCE STRAIT LATE MORNING INTO
AFTERNOON.

CENTRAL PANHANDLE WILL START OUT AS SNOW WITH ABOVE FREEZING
TEMPERATURES DUE TO WET BULB EFFECTS BUT WILL GO TO RAIN BY THIS
AFTERNOON WITH STRONG WAA AT 85H MB. RAIN CONTINUES TONIGHT BUT
TAPERS OFF AS WEAK RIDGE MOVES THROUGH LATE. E-NE WIND WILL REACH
GALE FORCE IN MARINE AREAS BUT THINK GUSTS STAY BELOW 4O MPH IN
PUBLIC AREAS. WIND DIMINISH OVERNIGHT WHICH COULD LEAD TO LOWER
CIGS AND VSBYS.

FARTHER NORTH GRADIENT GAINS NE COMPONENT TODAY WHICH WILL LIMIT
PRECIP AND KEEP LOWER DEW POINTS DURING THE DAY AND ADVECT SOME
COLDER AIR NEAR INTERIOR PASSES. A CRITICAL LEVEL (CYCLONIC CASE)
BRIEFLY SETS UP OVER JUNEAU THIS AFTERNOON BEFORE COLLAPSING WITH
THE ONSET OF PRECIP AND STRONGER SSE WINDS ALOFT. PRECIP WILL
BEGIN AS LIGHT SNOW THIS AFTERNOON AND INCREASE IN INTENSITY THIS
EVENING JUST AHEAD OF FRONT AND COULD SEE A QUICK 2-4 INCHES. ONCE
FRONT PUSHES THROUGH EXPECT PRECIP TO MIX WITH OR TURN TO RAIN
DEPENDING ON DEW POINT TEMPERATURES. ATMO FAIRLY STABLE SO DO NOT
SEE VERY STRONG WINDS UNTIL FRONT MOVES THROUGH THEN
SOUTHEASTERLIES COULD G35 MPH. STEPHEN PASSAGE AND CLARENCE WILL
PICK UP A N-NE GALE JUST AHEAD OF THE FRONT THAT DIMINISHES AND
TRIES TO BRIEFLY GO SE.

IN THE NORTH SHOULD BE A MAINLY DRY HIGH CLOUD AND COOL DAY.
ISOLATED SHOWERS ARE NOTED ON SATELLITE WEST OF PAYA AND COULD SEE
SOME FLURRIES BY LATE AFTERNOON. WIND WILL BE INCREASING FROM THE
NORTH THAT REACH GALE FORCE BY LATE AFTERNOON AND CONTINUE MOST OF
TONIGHT. SNOW WILL SPREAD INTO PAYA-PAHN-PAGY THIS EVENING AS
FRONT MOVES ALOFT AND KEPT AMOUNTS IN 2-4 INCH RANGE DUE TO FAIRLY
DRY LOWER ATMO.

THE BIG QUESTION IS WHAT WILL HAPPEN TO WAVE CURRENTLY DEVELOPING
IN CENTRAL PACIFIC THAT RACES NE TO DIXON ENTRANCE AREA BY 12Z WED
UNDER 130KT 500 MB JET. THE 00Z GFS/UKMET AND LESSOR EXTENT GEM
GLOBAL WANT TO BOMB THIS WAVE DEEPENING IT 30 MBS INTO A TIGHTLY
WOUND 968-973 MB LOW IN 24 HRS. THIS RESULTS IN A SOLID STORM
FORCE WINDS TO POSSIBLE HURRICANE FORCE WIND IN DIXON ENTRANCE. EC
DOES NOT GET TOO EXCITED AND THEREFORE SHOWS ONLY SMCR WINDS FOR
SE GULF. A QUICK LOOK AT THE 12Z NAM DEEPENS THE WAVE CONSIDERABLY
TO 980 MB BUT TAKES IT ACROSS HAIDA GAWII. NEEDLESS TO SAY
CONFIDENCE IS LOW WITH THIS FEATURE ESPECIALLY SINCE IT IS SOUTH
OF SOME OUR OPERATION DOMAINS AND IS LOCATED IN DATA VOID
AREA...BUT NEEDS TO BE MONITORED EXTREMELY CLOSELY DUE TO
POTENTIAL IMPACTS TO SE AK RIGHT AT THE END OF THE SHORT TERM
PERIOD. OUR COLLABORATED SOLUTION WAS TO TAKE A 975 MB LOW INTO SE
GULF ON WED MORNING WITH MAX GALES OD SE GULF AND MAX WIND
ADVISORY FOR AKZ027-028 AFTER MIDNIGHT TONIGHT.

&&

.LONG TERM.../WEDNESDAY THROUGH MONDAY/...ACTIVE WEATHER PATTERN CONTINUES
THROUGH THE EXTENDED FORECAST PERIOD. WEDNESDAY STARTS OUT WITH A
COMPLEX LOW PRESSURE SYSTEM IN THE GULF. MODELS HAVE STARTED
TRENDING TOWARD A SOLUTION OF A NEW LOW DEVELOPING AND MOVING NORTH
OVER THE SOUTHERN PANHANDLE BY EARLY WEDNESDAY MORNING. THE
GFS...GEM AND UKMET ARE THE STRONGEST WITH THE NAM AND ECMWF WEAKER
WITH JUST A TROUGH IN THE SAME AREA...HOWEVER STRONGER AND CLOSER TO
THE OTHERS IN LATEST RUNS. THIS NEW LOW DEVELOPMENT WOULD BRING
STRONG WINDS TO THE FAR SOUTHERN AREAS OF HYDABURG AND KETCHIKAN.
STRONGEST SOLUTIONS SHOW GUST OF UP TO 60 MPH POSSIBLE...HOWEVER DUE
TO CONTINUED UNCERTAINTY HAVE GONE WITH GUSTS OF 40 TO 45 MPH FOR
WEDNESDAY MORNING AND MAX GALES FOR CLARENCE STRAIT...BUT WILL NEED
TO BE MONITORED FOR A POSSIBLE HIGH WIND AND STORM WARNINGS.
OTHERWISE THIS LOW WILL BRING RAIN TO THE REGION...AND CONTINUE THE
COOLER NORTHERLIES THROUGH LYNN CANAL WITH HAINES AND SKAGWAY SEEING
SNOW. RAIN WILL BECOME HEAVY AT TIMES AS THE LOW LIFTS NORTH AND
DISSIPATES TO A TROUGH WEDNESDAY NIGHT. 2 TO 4 INCHES OF ADDITIONAL
SNOW FOR THE HAINES AREA IS EXPECTED THROUGH THE DAYTIME PERIOD.

BY WEDNESDAY NIGHT THE PARENT LOW WILL MOVE NORTH INTO THE ANCHORAGE
AREA WITH ANOTHER ASSOC FRONTAL TROUGH MOVING INTO THE PANHANDLE.
THIS FRONT LOOKS TO CHANGE RAIN BACK TO SNOW FOR A SHORT TIME BEFORE
A RIDGE BUILDS AND SCATTERS PRECIP WITH SOME BREAKS IN CLOUD COVER.
AS A RESULT THURSDAY EVENING WILL COOL OFF QUICKLY DUE TO
RADIATIONAL COOLING THEN WARMING THROUGH FRIDAY MORNING AS THE NEXT
SYSTEM MOVES INTO THE REGION. HAVING THE DIURNAL TEMPERATURE TRENDS
OFF LIKE THIS HAS BEEN A FORECAST CHALLENGE. THIS MAKES FOR
RAIN/SNOW TIMES NOT MATCHING UP WITH TYPICAL MAX/MIN TEMPERATURE
TIMES...LEADING TO RAIN AND SNOW BEING MENTIONED IN MOST PERIODS.

THE SYSTEM FOR LATE THURSDAY INTO FRIDAY MORNING WILL BRING ANOTHER
BATCH OF STRONG WINDS TO THE OUTSIDE WATERS AND COASTAL AREAS. AGAIN
THE GFS IS STRONGER WITH THIS FRONT AND HAS STORM FORCE WINDS FOR
THE OUTSIDE WATERS AND THE ECMWF IS WEAKER...HAVE GONE WITH MAX
GALES AS A COMPOMISE. THE NEXT LOW PRESSURE SYSTEM MOVES INTO THE
GULF SATURDAY BRINGING PRECIP TO THE AREA THROUGH SUNDAY. AGAIN THIS
SYSTEM LOOKS TO BRING STRONG WINDS TO THE COASTAL AREAS AND HAVE
USED WINDY WORDING IN SOME OF THE ZONES.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL NOON AKST TODAY FOR AKZ027.
         STRONG WIND FROM LATE TONIGHT THROUGH WEDNESDAY MORNING FOR
     AKZ027-028.
MARINE...GALE WARNING FOR PKZ012-013-022-031>036-042.
         SMALL CRAFT ADVISORY FOR PKZ011-021-041-043-051>053.

&&

MM/HANNON