Small Craft Advisory 34, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
613 AM AKST THU JAN 12 2012

.SHORT TERM...A LOW IN THE SOUTHEASTERN GULF IS FORECAST TO COME
ASHORE VICINITY CAPE SPENCER LATER TODAY AND TRACK NORTHEAST INTO
THE YUKON TONIGHT. ASSOCIATED SURFACE TROUGH HAS BEEN BRINGING
LIGHT TO MODERATE PRECIPITATION OVER MOST OF THE PANHANDLE
THROUGH THE NIGHT. PRECIPITATION TYPE PREDOMINANTLY RAIN OR A
RAIN-SNOW MIX EXCEPT FOR SKAGWAY AND ALONG THE HIGHWAYS, WHICH
HAVE SEEN SNOW MOST OF THE NIGHT.

 PRESSURE GRADIENT RESULTING FROM THE TROUGH OFFSHORE AND A RIDGE
OF HIGH PRESSURE OVER BRITISH COLUMBIA HAS BEEN PRODUCING STRONG
WINDS OVER THE SOUTHERN OUTER COAST AND LOCATIONS NEAR CLARENCE
STRAIT AND VERY GUSTY CONDITIONS OVER MANY OTHER LOCATIONS. HAVE
SOUTHEASTERLY GALES IN SUMNER STRAIT, CLARENCE STRAIT, AND
COASTAL MARINE ZONE 41. SMALL CRAFT WINDS ELSEWHERE. AS THE LOW
MOVES OVER LAND AND THE PRESSURE GRADIENT RE-ORIENTS, GALES WILL
SHIFT NORTH TO NORTHERN LYNN CANAL AND SMALL CRAFT
SOUTHWESTERLIES WILL PREVAIL ALONG THE OUTER COAST.

 TODAY WILL BE THE LAST DAY FOR REASONABLY MILD TEMPS ACROSS THE
PANHANDLE TODAY, COURTESY OF WARM AIR ASSOCIATED WITH THE TROUGH
OFFSHORE. MANY LOCATIONS WILL START OUT THE DAY AT OR NEAR THEIR
FORECAST HIGHS FOR THE DAY AND REMAIN STEADY OR NEARLY SO FOR
MOST OF THE DAY. TEMPS WILL BEGIN TO FALL TONIGHT...AND KEEP
FALLING FOR QUITE A WHILE.

 USED A BLEND OF NAM AND ECMWF FOR THE SHORT TERM FORECAST.
FORECAST CONFIDENCE IS ABOVE AVERAGE.

.LONG TERM...NOT MUCH CHANGE IN THE OVERALL WEATHER PATTERN FOR
THIS WEEKEND INTO NEXT WEEK. VERY STRONG HIGH PRESSURE WILL BUILD
OVER THE YUKON FRIDAY AND THEN OVER THE NORTHERN HALF OF THE SE
AK FRIDAY NIGHT. THE HIGH WILL EXTEND INTO BC THROUGH SAT AND
PERSIST. THIS SURFACE FEATURE ALONG WITH THE HIGH AMPLITUDE UPPER
RIDGE BUILDING OVER WESTERN AK WILL SEND VERY COLD AIR ALONG WITH
PRODUCING VERY STRONG WINDS FROM THE NORTH. FORECAST MODELS ALONG
WITH ENSEMBLES ALL SHOW THAT THE UPPER LEVEL OFFSHORE FLOW AND THE
SURFACE HIGH PRESSURE WILL PERSIST INTO AT LEAST MID NEXT WEEK.
THERE IS ABOVE AVERAGE FORECASTER CONFIDENCE.

THE SURFACE LOW OVER THE GULF AT THE START OF THE LONG RANGE
PERIOD WILL SLIDE SE TO BE JUST WEST OF DIXON ENTRANCE BY FRIDAY
NIGHT AS THE HIGH PRESSURE BUILDS IN THE YUKON. THE SNOW SHOWERS
ACROSS THE PANHANDLE WILL SLOWLY DIMINISH AS THE OFFSHORE FLOW
INCREASES THROUGH FRIDAY NIGHT. SNOW AMOUNTS WILL RANGE FROM 1 TO
3 INCHES THROUGH FRIDAY NIGHT. THE NORTH WINDS WILL BEGIN TO
INCREASE THROUGH FRIDAY NIGHT AS TEMPS TUMBLE INTO THE TEENS OVER
THE NORTHERN AREAS TO THE MID 20S OVER THE SOUTHERN AREAS. GALE
FORCE WINDS WILL DEVELOP OVER THE NORTHERN INNER CHANNELS LATE
FRIDAY AND CONTINUE TO INCREASE THROUGH SAT. THERE WILL ALSO BE
VERY STRONG WINDS FROM INTERIOR PASSES DEVELOPING THROUGH FRIDAY
NIGHT WITH GUSTS FROM 60 TO 70 KT BY SAT MORNING. THESES STRONG
WINDS WILL PERSIST THROUGH THE WEEKEND ALONG WITH THE STRONG GUSTS
FROM INTERIOR PASSES. FREEZING SPRAY WILL ALSO DEVELOP AS THE
TEMPS FALL AND WINDS INCREASE.

LAND AREAS WILL SEE LOCALLY VERY WINDY CONDITIONS FROM SAT
THROUGH NEXT WEEK. TAKU WINDS NEAR JUNEAU WILL DEVELOP LATE FRIDAY
NIGHT AND PERSIST THROUGH MON. IN WINDY AREAS THERE WILL COLD WIND
CHILLS AS TEMPS CONTINUE TO FALL THROUGH THE WEEKEND WITH HIGHS IN
THE SINGLE DIGITS OVER THE NORTHERN AREAS AND TEENS OVER THE
SOUTHERN AREAS. LOW WILL RANGE FROM BELOW ZERO OVER THE NORTHERN
AREAS TO SINGLE DIGITS OVER THE SOUTHERN AREAS. THE KLONDIKE
HIGHWAY MAY SEE WIND CHILL OF 45 BELOW AS TEMPS WILL BE ABOUT 20
BELOW AND WINDS OF 20 MPH. 850MB TEMPS WILL RANGE FROM 20 BELOW TO
30 BELOW FOR MOST OF THE WEEKEND INTO THE EARLY NEXT WEEK. THIS IS
ABOUT 3 STANDARD DEVIATIONS BELOW NORMAL. THE MODELS HAVE BEEN
SHOWING THIS SOLUTION FOR A WHILE SO THERE IS HIGH FORECAST
CONFIDENCE THAT THESE CONDITIONS WILL CONTINUE INTO NEXT WEEK AN
POSSIBLE LONGER.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 9 AM AKST THIS MORNING FOR AKZ027-028.
MARINE...GALE WARNING FOR PKZ012-035-036-041.
         SMALL CRAFT ADVISORY FOR PKZ011-013-021-022-031>034-042-043-051-
     052.

&&

FRITSCH/ABJ