Gale Warning 3, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
325 PM AKST THU JAN 8 2009

.SHORT TERM...SNOW HAS STARTED FALLING OVER MUCH OF THE NORTHERN
PANHANDLE IN THE HOURS LEADING UP TO THE WINTER STORM THAT WILL
BLOW OVER THE AREA THIS EVENING AND INTO TOMORROW. ALREADY
VISIBILITIES AT GUSTAVUS HOONAH JUNEAU AND SITKA HAVE FALLEN TO
1 MILE OR LESS AT TIMES THIS AFTERNOON. THE CENTRAL PANHANDLE IS
EXPERIENCING SNOW SHOWERS AND THE SOUTHERN PANHANDLE HAS NOT SEEN
ANY PRECIP OUT OF THIS SYSTEM YET. SKAGWAY AND WHITE PASS REMAIN
VERY WINDY AND COLD TODAY. WINDS AT SKAGWAY ARE STILL BLOWING AT
25 MPH OUT OF THE NORTH WITH GUSTS TO 40 MPH AND TEMPS ARE MINUS
5 AT SKAGWAY AND MINUS 23 UP BY FRASER CAMP PRODUCING WIND CHILLS
OF UP TO MINUS 50 ALONG THE KLONDIKE HIGHWAY.

 UPPER ATMOSPHERE...A RIDGE REMAINS OFFSHORE ACCOMPANIED BY A
110 KT JET MAX. THIS RIDGE WILL MOVE ONSHORE AHEAD OF THE TROUGH
ASSOCIATED WITH THE NEXT SYSTEM.

 TONIGHT INTO FRIDAYS STORM WILL BE MAJOR SNOW MAKER ACROSS THE
CENTRAL AND NORTHERN PANHANDLE. THE PRECIP WILL START OUT AS SNOW
IN MOST AREAS BUT WILL TRANSITION TO MIX PRECIP OR ALL RAIN BY
FRIDAY MORNING FOR ZONES 23 27 AND 28 AS SOUTHERLY FLOW BEGINS TO
WARM THE AREA. CONSEQUENTLY...SNOWFALL AMOUNT FOR THOSE AREAS
WILL BE MUCH LESS THEN THE REST OF THE AREA AS THE SNOW WILL ONLY
BE FALLING FOR A SHORT TIME BEFORE THE CHANGE TAKES PLACE. AREAS
FARTHER NORTH WILL MOST LIKELY NOT SEE A CHANGE OVER UNTIL FRIDAY
EVENING FOR THE CENTRAL PANHANDLE. SNOW AMOUNTS WILL BE IN EXCESS
OF 1 TO 2 FEET IN THE HAINES ELFIN COVE TO WRANGELL AND HYDER
AREA DOWN TO A FEW INCHES IN THE SOUTHERN ZONES. LOCALLY HIGHER
AMOUNTS ARE POSSIBLE. MAIN FORCING FOR THE PRECIP IS THE
OVERRUNNING OF THE COLD ARCTIC AIR...HOWEVER MODERATE TO STRONG
UPPER FORCING FROM ISENTROPIC LIFTING...QVECTOR DIVERGENCE AND
SOME FRONTOGENSIS OVER THE CENTRAL AND NORTHERN PANHANDLE WILL
HELP TO PILE UP THE SNOW OVER THE AREA. HEAVIEST SNOW FALL IS
EXPECTED TO BE TONIGHT AS UPPER FORCING CENTERS ITSELF OVER THE
AREA.

 MODELS ARE FINALLY IN FAIRLY GOOD AGREEMENT ON THE TRACK AND
STRENGTH OF THE SYSTEM BRINGING THE MAIN LOW INTO THE NORTHERN
GULF EARLY TOMORROW AND SENDING A TRIPLE POINT FEATURE BETWEEN
CAPE SPENCER AND YAKUTAT. THIS TRACK WILL CAUSE LESSER SNOW FALL
AMOUNTS FOR THE YAKUTAT AREA AS THE MOISTURE RICH BANDS WILL BE
NARROWER AND WEAKER ON THE NORTHERN SIDE OF THE SYSTEM.

 GRIDS WERE UPDATED WITH A BLEND OF CURRENT GRIDS AND THE
GFS/GEM/NAM COMBINATION. THOUGHT THIS BLEND GAVE THE BEST RESULTS
FOR THE CANADIAN HIGH AND THE APPROACHING GULF LOW.

&&

.LONG TERM... PATTERN CHANGE PREDICTED IN THE LONG RANGE.
PERSISTENT COLD ZONAL FLOW THAT HAS AFFECTED SE AK PAST 10 DAYS IS
FORECAST BY ALL GLOBAL MODELS TO BUCKLE OVER N PACIFIC EARLY TO
MID NEXT WEEK. WARM UPR RIDGE NOW BUILDING OVER W CST CONUS IS
EXPECTED TO EXPAND AND AMPLIFY OVER MUCH OF WRN NORTH AMERICA AND
NOSE NWD INTO PANHANDLE. THIS IS IN RESPONSE TO DIGGING SPLIT FLOW OVER
CENTRAL PACIFIC AND COLD AIR DIGGING INTO HUDSON BAY/NE US.
FCSTR CONFIDENCE IS HIGH SINCE ENSEMBLES SUPPORT THIS SOLUTION IN
MED-LONG RANGE AS WELL.

FOR WEEKEND AND BEGINNING OF NEXT WEEK...SEVERAL SHORT WAVES WILL SWING
OUT OF DEVELOPING ANCHOR TROUGH OVER PAC. WAVE TRAIN IS
ORIGINATING OVER TROPICS NEAR 20N. AFTER FRIDAYS SNOW MAKER
ADDITIONAL WAVES WILL BRING PRECIP SUN AND MON. EACH ONE WILL DRAG
WARMER AIR FARTHER NORTH SO THAT BY MON RAIN IS LIKELY IN THE
LOWER ELEVATIONS UP TO ICY STR/JNU. THE BUILDING RIDGE FROM THE
SOUTH MAY AFFORD DRY WEATHER ABOUT MID WEEK.

AS THIS PATTERN EVOLVES WE WILL HAVE TO KEEP WATCH ON PRECIP
AMOUNTS AND BE WARY OF RAPID WARMING. A WET SNOW OR RAIN ON SNOW
COULD POSE PROBLEMS TO ROOFS...BOATS...ETC PARTICULARLY WHERE
MIXED RAIN/SNOW PCPN IS MOST LIKELY BETWEEN SUMNER STR AND ICY
STR/JNU SAT-MON.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER STORM WARNING UNTIL 6 PM AKST FRIDAY FOR AKZ019>022-
     024>026.
         WINTER WEATHER ADVISORY UNTIL 3 AM AKST FRIDAY FOR AKZ027.
         WINTER WEATHER ADVISORY UNTIL 3 AM AKST FRIDAY FOR AKZ023.
         WINTER WEATHER ADVISORY UNTIL 6 AM AKST FRIDAY FOR AKZ028.
         WINTER STORM WARNING UNTIL 6 PM AKST FRIDAY FOR AKZ029.
         WINTER WEATHER ADVISORY UNTIL MIDNIGHT AKST TONIGHT FOR AKZ018.
         WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM AKST FRIDAY
     FOR AKZ018.
         WINTER WEATHER ADVISORY UNTIL 6 PM AKST FRIDAY FOR AKZ017.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ012.
         STORM WARNING FOR PKZ012.
         GALE WARNING FOR PKZ011-013-021-022-033>036-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ031-032.

&&

EAL/TA