Small Craft Advisory 52, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
336 PM AKST SUN JAN 16 2011

.SHORT TERM...THE BIG NEWS IS THAT THE STRONG NORTHERLY OUTFLOW
WILL DISSIPATE THIS EVENING. A 989 MB LOW IN DIXON ENTRANCES
MOVES EAST INTO CENTRAL B.C. WHILE THE HIGH OVER THE YUKON
WEAKENS. STILL HAVE GALE AND HVY FREEZING SPRAY FOR NRN LYNN
CANAL BUT THIS WILL DIMINISH BELOW SMCR BY MORNING.

 FRONTAL PRECIP ASSOCIATED WITH THE DIXON ENTRANCE LOW CONTINUES
ACROSS SOUTHERN ZONE AND SOME OF THIS MOISTURE HAS BEEN PICKED UP
BY A AN UPPER LEVEL TROUGH THAT IS MOVING ACROSS THE AREA FROM
THE WEST AND IS PRODUCING SNOW ACROSS NORTHERN AREAS NOW.
HEAVIEST PRECIP WILL WILL ALONG SOUTHERN COAST MT'S WHERE IT WILL
FALL AS SNOW AND STILL HAVE WSW IN EFFECT FOR 26 AND 29 TIL
MIDNIGHT. ALONG THE SOUTHERN COASTAL ZONES TEMPS ARE ABOVE
FREEZING WITH RAIN. SHOULD SEE AN ADDITIONAL 2 INCHES OF SNOW
OVER NORTHERN AREAS TONIGHT AND 4 TO 8 INCHES IN 26 AND 29 BY
MIDNIGHT. HAVE ENDED FZ RA ADVISORY WITH COLD ARE SOUTH OF ARCTIC
FRONT NOW MIXED OUT.

 THERE IS A LOW MOVING ACROSS THE NORTHERN GULF THAT DISSIPATES
AS IT MOVES ACROSS NORTHERN PANHANDLE MONDAY. THE ASSOCIATED COLD
FRONT WILL PUSH ACROSS THE AREA TONIGHT. WILL SEE A BIT OF CCA
LATER TONIGHT BUT SHORT LIVED. BEHIND THIS THROUGH NW WINDS
INCREASE AND REACH GALE FORCE IN COASTAL WATERS. A SECOND TROUGH
PUSHES TO NE GULF MON AFTERNOON AND WILL LIKELY SPREAD SNOW TO
THE COAST BY MORNING AND INTO INNER CHANNELS BY LATE AFTERNOON.

.LONG TERM...THE PERIOD OF WINDY ARCTIC COLD OVER THE NORTHERN
2/3 OF THE PANHANDLE IS ENDING. WARMER AIR ALREADY OVER THE
SOUTHERN PANHANDLE WILL SPREAD NORTHWARD AND INLAND ACROSS THE
PANHANDLE DURING THE WEEK AHEAD. THERE WILL BE INCREASING EPISODES
OF PRECIPITATION THIS WEEK AND BY ABOUT THUR PRECIP SHOULD BE IN
THE FORM OF RAIN AT SEA LEVEL EVERYWHERE EXCEPT PERHAPS SKAGWAY.

 CONSENSUS OPINION IS THE LAST TWO GFS AND ECMWF MODEL RUNS ARE
SIMILAR AND ACCEPTED FOR HANDLING THE PATTERN EVOLUTION THIS
WEEK. GFS ENSEMBLE MEMBERS PRETTY CONSISTENT TOO. MOS TEMPERATURE
GUIDANCE SHOWS WARMING ALL AREAS BUT ENSEMBLE TEMPS WED COVER
BROAD RANGE. THIS IS THE PERIOD OF MOST UNCERTAINTY IN THE
DETAILS OF TEMPS AND PRECIP TYPE /RAIN VS SNOW/ ACROSS THE
NORTHERN HALF OF PANHANDLE BECAUSE THE IMPACTS OF CHANGING TO
FROZEN TO LIQUID PRECIP MAY BE SIGNIFICANT.

 VERY DEEP STORM SFC/ALF WEST OF THE DATELINE AT 45N TODAY WILL
MOVE SLOWLY EAST THIS WEEK. AHEAD OF THIS STORM SEVERAL SMALL
FEATURES MOVE EAST ACROSS THE NORTHERN GULF AND MAINTAIN A COOL
NW FLOW ALOFT AND KEEP THE RAIN/SNOW LINE NEAR FREDERICK SOUND
THROUGH TUE NIGHT. BY WED THE DEEPER STORM APPRCHG FROM THE
DATELINE WILL BE CLOSE ENOUGH TO BEGIN STEERING A WARMER SW
JETSTREAM AND SFC WARM FRONT INTO THE ERN GULF. BASED ON GFS
MODEL PREDICTED UPPER AIR SOUNDINGS THE RAIN/SNOW LINE WILL BEGIN
LIFTING N ACROSS ENTIRE PANHANDLE LATER TUES BUT THE WARM LAYER
MAY BE SHALLOW. THE UNCERTAINTY COMES FROM WHETHER THE WARM FRONT
STALLS FOR A WHILE OVER THE CENTRAL PANHANDLE. THIS WOULD ALLOW
FOR A LONGER PERIOD OF SNOW TUE NIGHT AND WED ALONG AND NORTH OF
A JNU-CAPE SPENCER LINE...OR WORSE...LOCALIZED FRZG RAIN. STILL
BELIEVE THE ONSHORE FLOW ALFT WILL BE STRONG ENOUGH THUR-FRI TO
WARM SFC TEMPS ABOVE FREEZING CLEAR INTO NORTHERN LYNN CANAL.
SNOW LEVELS PREDICTED TO RISE BY FRI TO ABOVE 4000 FT FAR SRN
PANHANDLE TO AROUND 1500 FT JNU AND 1000 FEET FAR NORTHERN ZONES.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER STORM WARNING UNTIL MIDNIGHT AKST TONIGHT FOR
	AKZ026-029.
	FREEZING RAIN ADVISORY UNTIL 4 PM AKST THIS AFTERNOON
	FOR AKZ027- 028.
	WIND ADVISORY UNTIL 6 PM AKST THIS EVENING FOR
 	AKZ017-019-020-022-025.
 	WINTER STORM WARNING UNTIL 6 PM AKST THIS EVENING FOR AKZ018.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ011-013-031.
 	HEAVY FREEZING SPRAY WARNING FOR PKZ012.
 	GALE WARNING FOR PKZ011>013-021-022-031>035-041.
 	SMALL CRAFT ADVISORY FOR PKZ036-042-043-051-052.

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