Gale Warning 53, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
414 PM AKST TUE JAN 6 2015

.SHORT TERM...A FRONT IS MOVING NORTH OVER THE EASTERN GULF AND
SOUTHEAST ALASKA, PUSHING WARM, MOIST AIR UP AND OVER A VERY COLD
SURFACE LAYER. LIGHT FREEZING RAIN STILL A CONCERN, BUT THE MAJOR
WEATHER IMPACT WILL BE ACCUMULATING SNOWFALL OVER THE CENTRAL AND
NORTHERN PORTIONS OF THE PANHANDLE. STRONG NORTHEASTERLY OUTFLOW
WINDS WILL ACT TO KEEP THE AIR COLUMN DRY AND INHIBIT
PRECIPITATION FROM REACHING THE GROUND. OUTFLOW WINDS WILL ALSO
KEEP STRONG WINDS GOING ALONG THE KLONDIKE HIGHWAY AND STORM FORCE
WINDS OVER LYNN CANAL. ALSO HAVE A WIND CHILL ADVISORY OUT FOR THE
KLONDIKE DUE TO A COMBINATION OF THE COLD AIR TEMPS AND STRONG
WINDS. OCCASIONAL GUSTS TO 40 MPH POSSIBLE IN JUNEAU, BUT HAVE NOT
HEADLINED THE FORECAST FOR STRONG WINDS.

TOOK A VERY CLOSE LOOK AT TEMPERATURES AS WELL AS DEW POINTS, QPF
AND POP TODAY IN ORDER TO EVALUATE THE WINTER STORM WATCH. THE
FRONT LOOKS LIKE IT IS MAKING FASTER PROGRESS THAN ORIGINALLY
EXPECTED, THUS HAVE BEGUN THIS EVENT 6-9 HOURS EARLIER THAT
ORIGINALLY FORECAST. TOTAL SNOW ACCUMULATIONS LESS THAN ORIGINALLY
EXPECTED, PROBABLY A RESULT OF THE MID LEVEL DRYING FROM COLD, DRY
CONTINENTAL OUTFLOW. END RESULT HERE IS A WINTER WEATHER ADVISORY
FOR HAINES, GUSTAVUS (4 TO 6 INCHES), AND JUNEAU (5 TO 8 INCHES)
OVER THE 24 HOUR TIME FRAME FROM THIS EVENING TO TOMORROW EVENING
WEATHER ADVISORY FOR PEAK SNOWFALL RATES RUNS FROM MIDNIGHT TONIGHT
TO NOON TOMORROW.

USED PRIMARILY NAM FOR UPDATES TO PRESSURE AND WIND FOR THE SHORT
TERM EXCEPT FOR THE VERY END. PREFERRED GEM HERE DUE TO NAM
HOLDING ON TO A WEAKENING LOW OVER THE EASTERN GULF A LITTLE TOO
LONG. POP AND QPF ALSO FROM NAM TODAY. TWEAKS TO EXISTING
TEMPERATURE AND DEWPOINT GRIDS VERY MINOR. OVERALL FORECAST
CONFIDENCE IS AVERAGE.

.LONG TERM...AS THE MAIN PRECIPITATION ACTION ARRIVES TONIGHT,
RIDGING WILL BEGIN TO DRY SOUTHEAST ALASKA BEGINNING LATE
WEDNESDAY. TWO THINGS, FIRST, UPWARD MOTION WILL LARGELY BE NIXED
WEDNESDAY NIGHT THUS MITIGATING PRECIPITATION CHANCES, SNOW FOR
THE NORTH AND RAIN FOR THE SOUTH. IN ADDITION, BUILDING NORTHWEST
FLOW ON THE FRONT SIDE OF THE RIDGE BEHIND THE COAST MOUNTAINS
WILL HELP REINFORCE COLD AIR ON THE OTHER SIDE OF THE RANGE. THIS
WILL STRENGTHEN HIGH PRESSURE AND FLEX, IF YOU WILL, THE PRESSURE
GRADIENTS ACROSS THE MOUNTAINS. OUTFLOW WINDS WILL ALSO HELP
CURTAIL PRECIPITATION CHANCES, BUT ALSO KEEP RESIDUAL PRECIP
LARGELY SNOW. IT REMAINS TO BE SEEN HOW STRONG WINDS WILL BE OVER
SALISBURY RIDGE, BUT THE POTENTIAL IS CERTAINLY THERE FOR STRONG
WIND. AND CANNOT RULE OUT THE POSSIBILITY OF HIGH WIND GUSTS.
HOWEVER, AT THIS TIME, NOT SEEING A TRIGGER MECHANISM TO BRING THE
WINDS TO THE SURFACE NEAR DOWNTOWN JUNEAU. WITH SOME STABILIZING
CONDITIONS, RESIDUAL MOISTURE MAY YIELD A BIT OF DRIZZLE, WHICH
DURING SUB-FREEZING TEMPERATURES WILL LIKELY BE FREEZING AT THE
TIME. THIS HAPPENS RARELY IN SOUTHEAST, SO GOING WITH ONLY THE
POSSIBILITY. STORM FORCE WINDS FOR LYNN CANAL POSSIBLY MAY BE A
SLIGHTLY OVERDONE THROUGH THURSDAY, AS THE GRADIENT IS STRONGEST
FROM NORTHEAST TO SOUTHWEST DURING THIS TIME FRAME, BUT RESISTED
URGE TO CHANGE IT AS CONFIDENCE LOW WITH SO MUCH COLD AIR
INVOLVED.

AS THE RIDGE AMPLIFIES, TO THE SOUTH A LOW WILL PUSH NORTHWARD AND
IRONICALLY HELP KEEP THINGS DRY FOR SOUTHEAST FROM THURSDAY INTO
FRIDAY, AS THIS INDUCES A LITTLE MORE OFFSHORE GRADIENT IN THE
MID-LEVELS. AS THIS SYSTEM GRACES OUR PRESENCE FOR THE WEEKEND, IT
WILL HELP RE-WELCOME STORMINESS FROM THE SOUTH. THIS WILL WARM
THINGS ENOUGH TO CHANGE PRECIPITATION TO RAIN BY NEXT WEEK.

KEPT CHANGES TO A MINIMUM. USED A LITTLE 12Z GFS AND 18Z NAM FOR
ANY CHANGES MADE WEDNESDAY NIGHT/THURSDAY. USED WPC TO INCREASE
WINDS SUNDAY THROUGH NEXT WEEK. FORECAST CONFIDENCE AVERAGE FOR
PERIOD.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON AKST
     WEDNESDAY FOR AKZ019-020-025.
         WINTER STORM WARNING UNTIL 6 PM AKST WEDNESDAY FOR AKZ029.
         STRONG WIND THROUGH WEDNESDAY AFTERNOON FOR AKZ018.
         WIND CHILL ADVISORY UNTIL 6 PM AKST WEDNESDAY FOR AKZ018.
MARINE...STORM WARNING FOR PKZ012.
         GALE WARNING FOR PKZ013-021-022-031-034>036-041>043.
         SMALL CRAFT ADVISORY FOR PKZ011-032-033-051>053.

&&

FRITSCH/ADKINS

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