Gale Warning 379, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
350 PM AKST SUN DEC 21 2014

.SHORT TERM.../ SUNDAY NIGHT AND MONDAY / NO LARGE SCALE FEATURES
ACROSS SOUTHEAST ALASKA THIS EVENING ON SATELLITE IMAGERY. CAN SPOT
THE JET STREAM FLOWING ACROSS THE PACIFIC TO THE WASHINGTON AND
OREGON COAST AND THE START OF THE BAROCLINIC LEAF THAT WILL BECOME
A WEATHER MAKER FOR THE AREA LATE MONDAY.

IN THE MEAN TIME THERE IS ROUGHLY ONE TROUGH OF SHOWERS LIFTING
SLOWLY NORTHWARD INTO THE NORTHERN PANHANDLE THROUGH LATE
AFTERNOON AND EVENING. CONDITIONS ACROSS THE SOUTHERN PANHANDLE
STARTED TO BREAK OUT ON WEB CAMS AND OBSERVATIONS THROUGH THE
EVENING HOWEVER WEAK ONSHORE FLOW WILL CONTINUE TO PUSH SCATTERED
SHOWER ACTIVITY INTO THE NORTHERN PANHANDLE. EXPECT A BREAK AGAIN
ON MONDAY IN ADVANCE OF THE NEXT SYSTEM.

ACROSS THE CENTRAL AND NORTHERN PANHANDLE SHOWERS EXITING ARE LEADING
TO A BREAK IN THE DEVELOPMENT AS THE SHOWERS TRY TO MOVE NORTHWARD
TODAY. CHANCE TO LIKELY POPS FOR MUCH OF THIS AREA...BUT AMOUNTS
SHOULD BE GENERALLY LIGHT. NORTHERN PANHANDLE WILL PERSIST WITH
PRECIPITATION TYPE ISSUES. SNOW AGGRESSIVELY HANGING ON FROM
HAINES AND SKAGWAY NORTHWARD. ALSO STILL SOME ISOLATED SNOW OVER
THE DEEP INLAND VALLEYS AROUND JUNEAU. OTHERWISE PRECIPITATION
SHOULD BE RAIN. BEST SNOW AMOUNTS OVER NORTHERN LYNN CANAL ZONES
BUT AMOUNTS UNDER 2 INCHES SHOULD BE EXPECTED.

NO BIG WARNINGS OR ADVISORIES OTHER THAN SOME SMALL CRAFT IN THE
MARINE FORECASTS. WITH WINTER SOLSTICE THIS AFTERNOON DAYS WILL
SLOWLY INCREASE NOW. CONFIDENCE THROUGH THE SHORT TERM IS
SLIGHTLY ABOVE AVERAGE THROUGH MONDAY.

.LONG TERM...LATEST MODEL RUNS HAVE STAYED CONSISTENT IN TRACKING
THE LOW PRESSURE SYSTEM MONDAY NIGHT AND TUESDAY ACROSS THE FAR
SOUTHERN PANHANDLE. LOOKING AT LATEST GUIDANCE AND PREVIOUS
FORECAST DECIDED TO LEAVE MOST OF IT AS IS FOR THIS STORM SYSTEM.
STILL EXPECTING GALE FORCE SOUTHEASTERLY WINDS IN THE SOUTHEAST
GULF AND SOUTHERN INNER CHANNELS. STRONG NORTHERLY PRESSURE
GRADIENT OVER THE NORTHERN PANHANDLE WILL DEVELOP MONDAY NIGHT AS
THIS LOW TRACKS INTO THE AREA WITH GALE FORCE WINDS DEVELOPING
THERE. STRONG WIND HEADLINES WILL LIKELY BE NEEDED FOR THE
SOUTHERN PANHANDLE WITH GUSTS OF 40 TO 50 MPH ON TUESDAY. WITH THE
FARTHER SOUTHERN TRACK EXPECT THE STRONGEST WINDS WILL STAY SOUTH
AND MAINLY IMPACT THE HAIDA GWAII AREA. STRONG OFFSHORE FLOW WILL
KEEP PRECIPITATION MAINLY CONFINED TO SOUTH OF FREDERICK SOUND.
THE NORTHERLY WINDS WILL ALSO HELP TO USHER IN A BIT COOLER AIR
TO THE NORTHERN PANHANDLE.

THE LOW WEAKENS AND PULLS INTO BRITISH COLUMBIA ON TUESDAY NIGHT.
WEAK SURFACE RIDGING DEVELOPS OVER THE GULF WITH MULTIPLE WEAK
SHORTWAVES MOVING OVER TOP OF IT INTO SOUTHEAST ALASKA WEDNESDAY
THROUGH FRIDAY. THINK THERE WILL BE A WEAK OVERRUNNING EVENT
WEDNESDAY INTO THURSDAY. AS FOR PRECIPITATION TYPE, 850 MB
TEMPERATURES FALL TO -6 TO -8 C BY THIS TIME AS A COOLER AIRMASS
MOVES INTO THE AREA FROM THE WEST. 1000-850 MB THICKNESS FALL TO
AROUND 1285 M AND LIGHT SURFACE WINDS SUGGEST PRECIPITATION OVER
THE NORTHERN PANHANDLE WOULD LIKELY BE IN THE FORM OF SNOW. AT
THIS TIME PRECIPITATION AMOUNTS ARE EXPECTED TO BE LIGHT. MODELS
ARE SUGGESTING A MORE ORGANIZED AREA OF PRECIPITATION WILL IMPACT
THE AREA LATE THURSDAY INTO FRIDAY.

AS MENTIONED BY THE PREVIOUS SHIFT, MODELS HAVE BACKED OFF THE
IDEA OF A BLOCKING RIDGE NEXT WEEKEND AND HAVE GONE TOWARDS A MORE
PROGRESSIVE PATTERN OVER THE AREA. HOWEVER, MODEL AGREEMENT ON
INDIVIDUAL FEATURES STILL REMAINS POOR IN THIS TIME FRAME.

OPTED TO MAKE ONLY MINOR CHANGES AS PREVIOUS FORECAST MATCHED UP
WELL WITH LATEST MODEL GUIDANCE. USED 12Z ECMWF FOR UPDATES
THROUGH DAY 4 THEN LATEST WPC GUIDANCE FOR THE REMAINDER OF THE
LONG TERM. FORECASTER CONFIDENCE IS INCREASING ON A MORE SOUTHERLY
TRACK OF THE LOW EARLY THIS WEEK INTO THE FAR SOUTHERN PANHANDLE.
CONFIDENCE DECREASES LATER IN THE WEEK WITH MODEL DISAGREEMENT
CONTINUING.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-036-041.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ022-042-043-051-052.

&&

BEZENEK/TPS

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