Heavy Freezing Spray Warning 2, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
348 PM AKST FRI JAN 13 2012

.SHORT TERM...LOW PRESSURE IN THE GULF IS CAUSING SCATTERED SNOW
SHOWERS ACROSS THE PANHANDLE TODAY. GREATEST SNOWFALL AMOUNTS
HAVE BEEN OVER THE FAR SOUTHERN ZONES IN HEAVIER BURSTS WHERE
12 INCHES FELL IN A PERIOD OF 3 HOURS NEAR KETCHIKAN. THESE
SHOWERS ARE WIDELY SCATTERED WITH SOME AREAS SEEING MUCH LESS AND
WITH CLEARING SKIES IN BETWEEN BURSTS. HAVE ISSUED A WINTER STORM
WARNING FOR THE KLAWOCK AND KETCHIKAN AREAS TO ACCOUNT FOR THESE
SHOWERS THROUGH 9PM WHERE AN ADDITIONAL 2 TO 4 INCHES IS
EXPECTED. THE HYDER AREA WILL LIKELY SEE SNOW SHOWERS INCREASE
INTO THE EVENING AS WELL WITH 2 TO 4 INCHES EXPECTED.

 AS THE LOW IN THE GULF MOVES TO THE SOUTHEAST OVERNIGHT WINDS
WILL SHIFT TO THE NORTH AND INCREASE THROUGH INTERIOR PASSES.
HAVE GONE WITH A HIGH WIND WARNING FOR SKAGWAY STARTING MIDNIGHT
TONIGHT THROUGH NOON SATURDAY WHERE GUSTS UP TO 60MPH ARE
POSSIBLE. A STORM WARNING AND HEAVY FREEZING SPRAY WARNINGS ARE
IN EFFECT FOR NORTHERN LYNN CANAL STARTING LATE TONIGHT. THE
REMAINING NORTHERN LAND AREAS HAVE A STRONG WIND HEADLINE AS
GUSTS OF 40 TO 50 MPH ARE POSSIBLE OUT OF INTERIOR PASSES AS WELL
AS DOWNTOWN JUNEAU.

 CLOUD COVER WILL DECREASE FROM NORTH TO SOUTH AS THE LOW MOVES
AWAY. THE RESULTING RADIATIONAL COOLING OVERNIGHT ALONG WITH THE
STRONG COLD AIR ADVECTION OUT OF THE NORTH WILL CAUSE
TEMPERATURES TO FALL THROUGH THE NIGHT AND CONTINUE FALLING
THROUGH THE DAY SATURDAY. THESES COLD TEMPERATURES AND STRONG
WINDS WILL BRING WIND CHILLS DOWN TO NEGATIVE 30 NEAR THE
NORTHERN CANADIAN BOARDERS.

 MODELS HAVE BEEN IN GOOD AGREEMENT FOR THE COLD AIR OUTBREAK.
FORECASTER CONFIDENCE IS ABOUT AVERAGE FOR THE WINDS AND COLD
TEMPERATURES EXPECTED...BUT BELOW AVERAGE FOR SNOWFALL AMOUNTS IN
THE WIDELY SCATTERED SNOW SHOWERS ACROSS THE SOUTH. UPDATED THE
GOING FORECAST WITH MAINLY THE NAM.

 &&

 .LONG TERM...WHILE SNOW AND CLOUDY SKIES MAKE WAY FOR CLEAR AND
DRY CONDITIONS FOR THE UP COMING WEEK, LIGHT WINDS AND MODERATE
TEMPERATURES WILL BE REPLACED BY ARCTIC TEMPERA TUES AND STRONG
WINDS WITH HIGH GUSTS OUT OF INTERIOR PASSES AND CHANNELED
TERRAIN. WITH BARE GROUND OVER AREAS OF THE CENTRAL PANHANDLE
CONCERN WILL BE FOR PIPES FREEZING. LOCATIONS WITH SNOW COVER
FROM FRIDAY STORMS WILL BE LUCKY ENOUGH TO HAVE THE ADDED GROUND
INSULATION.

 STRONG 500MB BLOCKING HIGH PRESSURE RIDGE WILL BUILD OVER THE
NORTH PACIFIC, BERING SEA AND WESTERN GULF WITH 500 MB LOW OVER
KAMCHATKA TO THE WEST AND 500 MB LOW OVER NEWFOUNDLAND TO THE
EAST. THIS BLACKING PATTERN WILL LAST THOUGH NEXT WEEK WITH LOWS
BEGINNING TO UNDER CUT THE HIGH AS IT MOVES NORTH. SOME QUESTION
ON THE TIMING OF THE BREAK DOWN OF THE BLOCKING RIDGE. NEXT
CHANGE FOR PRECIPITATION WILL BE AT THE END OF THE WEEK OVER THE
SOUTHERN PANHANDLE AS THE UNDER CUTTING LOW CENTERS MOVES TOWARD
HAIDA GWAII. GAP FLOW WINDS WHILE HIGH WILL ONLY EFFECT LOCALIZED
AREAS...SOME LOCATIONS WILL SEE GUSTS UP TO 60 MPH WHILE OTHERS
WILL BE CALM. TAKU EVENT FOR DOWN TOWN JUNEAU SETTING UP FOR SAT
EVENING BUT CRITICAL LEVEL NOT AS IDEAL MOVING INTO SUNDAY.
EITHER WAY LOOKING AT SOME STRONG GAP FLOW WINDS. TEMPERATURES AS
PREVIOUS INDICATED WILL BE COLD, VERY COLD WITH LOWS BELOW 0 AND
HIGHS IN THE TEENS TO SINGLE DIGITS. AS ARCTIC AIR FLOWS DOWN
FORM THE EAST SIDE OF THE BLOCKING RIDGE.

 MODELS ARE IN GOOD AGREEMENT FOR MOST OF THE LONG TERM BUT BEGIN
TO SHOW INCREASED SPREAD BY THE END OF THE WEEK. AS MODELS
USUALLY HAVE ISSUE WITH THE TIMING OF BLOCKING RIDGE BREAKS DOWN
THIS IS NOT SURPRISING. PREVIOUS EVENTS HAVE SHOWN MOST MODELS
ARE A BIT TOO QUICK KNOCKING DOWN THE RIDGE DECIDED TO TONE DOWN
THE LOW PRESSURE SYSTEMS IN THE SOUTHERN AK GULF FOR NEXT
THURSDAY AND FRIDAY A BIT. OTHERWISE CHANGES WERE MINOR. DID
INCREASE WINDS FOR DOWNTOWN JUNEAU GAP FLOW SLIGHTLY BUT MAY NOT
BE HIGH ENOUGH SO WILL NEED TO WATCH FOR HIGH WIND WARNING GUSTS
FOR SAT NIGHT AND SUNDAY. USED A BLEND OF 00Z EC/GFS TO UPDATE
CURRENT GRIDS TO DAY 4 THEN USED NEW HPC THROUGH DAY 7, WHICH WAS
A SUPER BLEND WITH A BIT MORE EMPHASIS ON THE 00Z GFS. FORECAST
CONFIDENCE IS ABOVE AVERAGE WITH RESPECT TO SYNOPTIC SCALE
FEATURES WITH SOME QUESTION ON STRENGTH OF GAP FLOW WINDS.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER STORM WARNING UNTIL 9 PM AKST THIS EVENING FOR AKZ027-028.
         STRONG WIND FROM 3 AM AKST SATURDAY THROUGH LATE SUNDAY NIGHT
     FOR AKZ025.
         STRONG WIND SATURDAY MORNING FOR AKZ022.
         STRONG WIND FROM MIDNIGHT AKST TONIGHT THROUGH LATE SUNDAY NIGHT
     FOR AKZ020.
         STRONG WIND FROM 9 PM AKST THIS EVENING THROUGH LATE SUNDAY
     NIGHT FOR AKZ019.
         HIGH WIND WARNING FROM MIDNIGHT TONIGHT TO NOON AKST SATURDAY
     FOR AKZ018.
         STRONG WIND UNTIL MIDNIGHT AKST TONIGHT FOR AKZ018.
         STRONG WIND FROM SATURDAY AFTERNOON THROUGH LATE SUNDAY NIGHT
     FOR AKZ018.
         STRONG WIND THROUGH SATURDAY AFTERNOON FOR AKZ017.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ012.
         STORM WARNING FOR PKZ012.
         GALE WARNING FOR PKZ011-013-021-022-031-043-051-053.
         SMALL CRAFT ADVISORY FOR PKZ032>036-041-042-052.

&&

HANNON/PRB