Wind Advisory 3, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
148 PM AKST WED JAN 6 2010

.SHORT TERM...THE LATEST SATELLITE IMAGERY SHOW A LOW PRESSURE
SYSTEM LIFTING OVER THE DIXON ENTRANCE WITH ANOTHER LOW LIFTING
NORTH OUT OF THE PACIFIC THAT WILL MOVE INTO THE EASTERN GULF BY
THURSDAY AFTERNOON. ATTM MOST STATIONS ALONG COASTAL LOCATION AND
OVER THE SOUTHERN AREAS ARE REPORTING RAIN WHILE STATIONS OVER
THE CENTRAL INNER CHANNELS ARE SEEING A WINTER MIX OF
RAIN,SNOW,SLEET AND AREAS OF FREEZING RAIN. THE FAR NORTHERN
AREAS ARE REPORTING PERIODS OF LIGHT SNOW. THERE IS SO WIND OVER
THE GULF WITH SOME BREEZY CONDITIONS OVER THE COASTAL AND
SOUTHERN AREAS. THESE CONDITIONS WILL PERSIST THROUGH MOST OF
TODAY.

 A UPPER LEVEL TROF WILL MOVE OVER THE FORECAST AREA THROUGH THIS
EVENING. A WEAK AND TRANSIENT UPPER RIDGE WILL MOVE OVER THE AREA
TONIGHT THE RIDGE WILL SLOWLY DRIFT TO THE EAST THROUGH THURSDAY
AS ANOTHER UPPER TROF LIFTS INTO THE EASTERN GULF THAT AFTERNOON.
THE SURFACE HIGH OVER CANADA WILL SLOWLY WEAKEN THROUGH THE SHORT
TERM PERIOD SO THE STRONG PRESSURE GRADIENT WILL SLOWLY RELAX
THROUGH TIME FRAME. THERE IS A LOT OF WARM AIR THAT IS MOVING
OVER THE AREA AND THIS WARM AIR WILL SLOWLY PUSH THE COLD AIR AT
THE SURFACE OUT OF THE AREA. SO THE WINTERY MIX OVER THE CENTRAL
AREAS WILL CHANGE TO ALL RAIN FROM SOUTHERN LYNN CANAL THROUGH
TONIGHT AS THE WARM AIR MIXES TO THE SURFACE. THERE WILL BE SNOW
ACCUMULATION OF LESS THAN 2 INCHES BUT FURTHER NORTH IT WILL
REMAIN ALL SNOW THROUGH THE TIME FRAME WILL ACCUMULATIONS OF 3 TO
6 INCHES THROUGH TONIGHT. WILL CONTINUE THE WINTER WEATHER ADVY
TO MIDNIGHT TONIGHT AS THE PRECIP WILL BECOME LIGHT AS THE FRONT
LIFTS OVER THE AREA AND THE UPPER LEVEL DYNAMICS MOVE INTO
CANADA.

 FOR THURSDAY THE PRECIP WILL BE MAINLY IN THE LIQUID FORM OVER
MOST OF THE FORECAST AREA BUT SNOW OVER THE FAR NORTHERN AREAS
WITH A POSSIBILITY OF SOME FREEZING RAIN NEAR PAHN. THE RAIN WILL
SLOWLY INCREASE OVER THE SOUTHERN AREAS THROUGH THE DAY ON
THURSDAY AS THE FRONT LIFTS INTO THE EASTERN GULF. ASSOCIATED
WITH THIS FRONT WILL BE SOME STRONG WINDS FROM THE SOUTHEAST.
WITH THAT SAID GALE FORCE WINDS WILL INCREASE OVER THE GULF AND
COASTAL AREAS ALONG WITH CLARENCE STRAIT. A STRONG 70KT 850MB LLJ
WILL MOVE OVER THE SOUTHERN AREAS THROUGH THURSDAY WITH GUSTS TO
40 MPH NEAR ZONE 27. THE REST OF THE SOUTHERN AREAS WILL SEE
BREEZY TO WINDY CONDITIONS.

&&

.LONG TERM...STRONG UPPER LEVEL RIDGE ALONG THE WEST COAST WILL
CONTINUE TO SLOWLY MOVE EAST. A SERIES OF MID PACIFIC OCCLUSIONS
WILL RIDE NORTH ALONG THE WESTERN SIDE OF THIS RIDGE AND ACROSS
SOUTHEAST ALASKA THROUGH THE WEEKEND. THIS WILL BRING MILD AND
WETTER CONDITIONS TO THE PANHANDLE ALONG WITH PERIODS OF MODERATE
TO POSSIBLE STRONG WINDS.

MODELS IN DECENT AGREEMENT IN THROUGH AROUND 120 HOURS BUT THEN
DIVERGE SUBSTANTIALLY WITH LARGE SENSIBLE WEATHER DIFFERENCES FOR
DAYS 6 AND 7. NCEP HAS DISCARDED THE EC AT THIS TIME FRAME TO ITS
ODD BEHAVIOR AND OPTED TO USE THE NORTH AMERICAN ENSEMBLE
PRODUCTS. THIS SEEMS TO BE A REASONABLE SOLUTION AND DOES NOT
DRASTICALLY DIFFER FROM THE GFS. I USED NAM/GFS BLEND THROUGH 84 HRS
AND TRANSITIONED TO HPC SOLUTION FOR GRIDS BEYOND.

A DEVELOPING 985 MB LOW IN NORTH CENTRAL PACIFIC WILL LIFT NORTH
TO SOUTHEAST GULF THURSDAY EVENING THEN CURVE BACK TO NW THROUGH
THURSDAY NIGHT AND FRIDAY. THE ASSOCIATED OCCLUSION...WITH A 60
KT 85H LOW LEVEL SE JET...PUSHES NORTH THROUGH THE PANHANDLE AND
WEAKENS ACROSS NORTHERN AREAS LATE FRIDAY. EXPECT THIS TO SPREAD SE
GALES AND WIND ADVISORIES INTO SOUTHERN PANHANDLE THURSDAY NIGHT
AND SMCR AND BREEZY CONDITIONS TO CENTRAL. PLENTY OF WARM AIR
WITH FRONT SO EXPECT PRECIP TO BE RAIN EXCEPT FOR IN THE FAR NORTH
WHERE LOCAL DRAINAGE WILL KEEP TEMPS COLD ENOUGH FOR SNOW IN PAHN.
PRECIP AMOUNTS EXPECTED TO BE AROUND ONE HALF INCH WITH FRONT.

A SECOND STRONGER LOW DEVELOPING IN THE NORTH PACIFIC FOLLOWS A
SIMILAR TRACK THROUGH THE EASTERN GULF...THIS SYSTEM POWERED BY A
120 KT SW JET MAX...WILL BRING A SECOND ROUND OF GALES TO STORM
FORCE WINDS TO SOUTHERN SATURDAY AND GALES TO NORTHERN BY SUNDAY.
WIND ADVISORIES WILL BE NEED AGAIN FOR SOUTHERN. PRECIP RATES WILL
BE LARGER AND COULD SEE 2 INCHES OF RAIN IN SOUTHERN AND COASTAL
ZONES. AGAIN FREEZING LEVELS CLIMB ABOVE MTN TOP S AND WILL BE ALL
RAIN OR RAIN TO SNOW FOR PAHN. WILL NEED TO MONITOR AVALANCHE AND
FLOOD POTENTIAL WITH THIS ONE AS HEIGHT CLIM WELL INTO THE
540S....BUT ALSO LOWER SLOPES ARE HOLDING WELL BELOW NORMAL SNOW PACK.

MILD PATTERN APPEARS TO CONTINUE INTO NEXT WEEK ALTHOUGH THERE IS
A BRIEF SHOT OF COLD AIR BETWEEN SYSTEMS FOR NOW STAYING WITH RAIN
AND MAX SMCR TO MIN GALES.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY UNTIL MIDNIGHT AKST TONIGHT FOR AKZ019-
     020-025-026.
         WIND ADVISORY FROM 9 AM THURSDAY TO 9 AM AKST FRIDAY FOR AKZ027.
         WIND ADVISORY FROM 9 PM THURSDAY TO 9 AM AKST FRIDAY FOR AKZ028.
MARINE...GALE WARNING FOR PKZ022-036-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011>013-021-031>035.

&&

ABJ/MM