Storm Warning 4, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
314 PM AKST SUN FEB 24 2013

.SHORT TERM...SATELLITE IMAGES THIS MORNING ARE SHOWING THAT
MOST OF THE SNOW AND RAIN SHOWERS THAT WERE IN THE PANHANDLE THIS
MORNING HAVE MOVED INTO CANADA. OVERNIGHT ACCUMULATIONS AT SEA
LEVEL WERE MOSTLY LIGHT. THE FEW EXCEPTIONS WERE PELICAN WITH
3.5 INCHES, AND HYDER WITH 3.8. WE ARE LEFT WITH SOME WIDELY
SCATTERED SHOWERS THAT HAVE DROPPED VISIBILITIES AT TIMES TO 2 OR
3 MILES BUT THEY HAVE USUALLY HAVE NOT LASTED MORE THAN THAN
1 HOUR. OTHERWISE THE CLOUD COVER HAS BROKEN UP TO REVEAL SOME
PEAKS OF THE SUN TODAY COURTESY OF A BUILDING RIDGE OVER THE AREA.

FOR TONIGHT INTO TOMORROW, ANOTHER ROUND OF WELL ORGANIZED SNOW
AND RAIN SHOWERS WILL BE MOVING THROUGH THE PANHANDLE LATE TONIGHT
AND EARLY TOMORROW ASSOCIATED WITH ANOTHER TROUGH OF LOW PRESSURE.
THIS ONE IS ABOUT THE SAME STRENGTH AS THIS MORNING'S TROUGH SO
NOT MUCH WARM AIR ADVECTION NOR WIND WILL BE PRODUCED BY IT.
CONSEQUENTLY SNOW LEVELS WILL REMAIN ROUGHLY WHERE THEY ARE FOR
THE NEXT 24 HOURS WITH SURFACE TEMPERATURES RANGING FROM THE UPPER
20S TO LOW 30S FOR LOWS TONIGHT TO THE MID TO UPPER 30S FOR HIGHS
TOMORROW. SOME SNOW ACCUMULATION IS EXPECTED FOR THE NORTHERN HALF
OF THE AREA THROUGH TOMORROW AFTERNOON WITH 1 TO 2 INCHES
POSSIBLE.

AS FOR WINDS, THE RIDGE POKING NORTH TODAY HAS CAUSED THE WINDS
IN LYNN CANAL AND SKAGWAY TO JUMP UP TO 25 KT. THESE WINDS WILL
DECREASE THIS EVENING AS THE RIDGE IS PUSHED OFF TO THE EAST BY
THE APPROACHING TROUGH. CAPE SPENCER ALSO HAS BEEN SEEING WIND
GUSTS AS HIGH AS 37 KT TODAY AS THE WESTERLY WINDS ARE FUNNELED
INTO CROSS SOUND. WINDS THERE WILL DIMINISH THIS AFTERNOON AND
EVENING BEFORE SWITCHING AROUND TO THE EAST AS THE TROUGH
APPROACHES. THOSE WINDS WILL REMAIN EAST THROUGH THE REST OF THE
SHORT RANGE PERIOD AS LOW PRESSURE CONTINUES TO RESIDE OUT IN THE
GULF. OTHERWISE THE ONLY OTHER HAZARDS ARE OUT IN THE GULF WHERE
SOME ADDITIONAL SMALL CRAFT WINDS WILL BE PRODUCED AS THE TROUGH
MOVES THROUGH TONIGHT. FOLLOWING THAT SE WINDS PICK UP AGAIN IN
THE EXTREME SW PART OF THE OFFSHORE ZONE AS THE BEGINNING EFFECTS
OF THE NEXT STRONG SYSTEM START TO MAKE THEMSELVES KNOWN.

SHORT RANGE MODELS WERE IN DECENT AGREEMENT TODAY THOUGH SOME
DETAILS STILL NEEDED TO BE WORKED OUT. ECMWF SEEMED TO HAVE THE
BEST INITIALIZATION OF THE TROUGH CURRENTLY OUT IN THE GULF. IT
WAS ALSO ABOUT RIGHT WITH WHERE THE PRECIP WAS. NAM WAS NOT TOO
FAR BEHIND, BUT THE REST OF THE MODELS WERE TOO SLOW WITH BRINGING
THE PRECIP ACROSS THE GULF. GENERALLY WENT TOWARD THE ECMWF WITH A
BIT OF THE NAM FOR SHORT RANGE UPDATES TODAY. FORECAST CONFIDENCE
IS ABOUT A LITTLE ABOVE AVERAGE.

&&

.LONG TERM...A STACKED LOW PRESSURE SYSTEM MOVES INTO THE CENTRAL GULF
OVERNIGHT MONDAY INTO TUESDAY. THIS LOW WILL BRING GALE FORCE
WINDS TO THE OUTSIDE WATERS AND OCEAN ENTRANCES OF 35-40KT LATE
MONDAY NIGHT THROUGH TUESDAY MORNING. SIMILAR GUSTS CAN BE
EXPECTED ALONG COASTAL LAND AREAS. THE EDGE OF THE PRECIP WITH
THE OCCLUDED FRONT WRAPPING AROUND THE MAIN LOW WILL REACH THE
COAST WITH THE WINDS. MAJORITY OF THE ENERGY WILL BE ALONG THE
SOUTHERN OUTER COAST AND MODELS HAVE BEEN DELAYING THE PRECIP OVER
THE NORTHERN INNER CHANNELS. THE FRONT WILL MODERATE TEMPERATURES
AT THE MID LEVELS AND KEEP THOSE SOUTHERN COASTAL AREAS IN LIQUID
PRECIP.

THE UPPER LEVEL LOW WEAKENS TO A TROUGH AS IT LIFTS NORTH OVER
THE PANHANDLE. THE SURFACE PATTERN CLOSELY FOLLOWS THE UPPER LEVEL
ONE WITH THE TROUGH/FRONT LIFTING NORTH OVER THE AREA TUESDAY
NIGHT. GUSTY WINDS WILL MOVE IN WITH THE FRONT. THE ORIENTATION OF
THE TROUGH AXIS WILL CAUSE NORTH WINDS AHEAD OF IT THROUGH LYNN
CANAL AND OTHER NORTHERN INSIDE WATERS. THIS WILL HELP TO DELAY
THE ONSET OF PRECIP AND ALSO KEEP TEMPERATURES COLD ENOUGH FOR
MOST OF IT TO FALL AS SNOW OVER THE NORTH. EXPECTING ABOUT 2-5IN
OVER THE NORTHERN THIRD OF THE PANHANDLE TUESDAY NIGHT THROUGH
WEDNESDAY.

SWLY ONSHORE FLOW CONTINUES WEDNESDAY THROUGH FRIDAY WITH A BROAD
UPPER LEVEL TROUGH OVER THE WESTERN GULF/AK PENINSULA. ANOTHER
WAVE WILL PASS OVER THE AREA WED NIGHT INTO THURS WITH A BURST OF
WIND...MORE RAIN OVER THE SOUTH AND SNOW OVER THE NORTH. MODELS
HAVE COME INTO BETTER AGREEMENT FOR THE MONDAY NIGHT/TUESDAY
SYSTEM...ALTHOUGH WITH SOME DIFFERENCES IN THE DETAILS STILL.
THEY ARE ALSO IN AGREEMENT IN THE OVERALL FLOW UNTIL FRIDAY NIGHT
THEN THE SOLUTIONS DIVERGE.

PREFERRED THE ECMWF SOLUTION FOR SIMILAR REASONS AS STATED
IN THE SHORT TERM SECTION...THEN TRANSITIONED TO MORE HPC GUIDANCE FOR
THE SECOND HALF OF THE PERIOD. WARMED TEMPS UP SOME TO REFLECT THE
RECENT TRENDS USING MAINLY THE SREF BC AND HPC BC. FORECAST
CONFIDENCE IS AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ022-041>043-051-052.

&&

EAL/HANNON