Small Craft Advisory 155, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
552 AM AKST SAT FEB 25 2012

.SHORT TERM...A RIDGE AT SURFACE AND ALOFT WILL MOVE EAST TODAY
WITH RIDGE AXIS MOVING ACROSS SOUTHERN SOUTHEAST ALASKA BY LATE
TONIGHT. THE INVERTED TROUGH THROUGH THE COASTAL WATERS WILL
WEAKEN TODAY AND CONTRACT TO THE SE THROUGH TONIGHT. A FRONTAL
BOUNDARY OVER THE WESTERN GULF PUSHES INTO THE RIDGE AND
DISSIPATES OVER THE EASTERN GULF TONIGHT.

 HAVE GENERALLY CLEAR SKIES ACROSS THE PANHANDLE THIS MORNING
WITH A MOSTLY SUNNY DAY EXPECTED FOR THE AREA. ISOLATED SHOWERS
OVER THE SOUTHERN COASTAL WATERS WILL DISSIPATE THROUGH THE
AFTERNOON AS THEY TRACK OFF TO THE SSE. OVERALL PRESSURE
GRADIENTS STILL SUPPORTING MAX SMCR TO MIN GALE THROUGH NORTHERN
INNER CHANNELS FORECAST TO WEAKEN TODAY AND BECOME LIGHT AS RIDGE
MOVES OVERHEAD TONIGHT. TEMPS SHOULD RECOVER NICELY TODAY WITH
SUNSHINE AND COULD REACH LOWER 30S MOST AREA TO LOWER 40S ALONG
OUTER COAST. TEMPS WILL FALL QUICKLY LATE AFTERNOON AND EVENING
WITH DRY BOUNDARY LAYER UNDER CLEAR SKIES THIS EVENING.

 EXPECT INCREASING HIGH AND MID CLOUDS OVERNIGHT AS FRONTAL
BOUNDARY MOVING INTO RIDGE DISSIPATES OVER EASTERN GULF. DO NOT
HAVE ANY PRECIP IN SHORT TERM FORECAST THROUGH TONIGHT. PAYA WILL
SEE SKIES BECOME OVERCAST BY LATE TONIGHT. TEMPS WILL DROP OFF
QUICKLY THIS EVENING WITH TEENS COMMON THROUGH INNER CHANNELS TO
SINGLE DIGITS NEAR INTERIOR PASSES. TEMPS SHOULD BOTTOM OUT BY
AROUND MIDNIGHT WITH A SLIGHT WARMING TREND BEGINNING LATE NIGHT
WITH INCREASING CLOUDS.

 GOOD MODEL AGREEMENT THROUGH THE SHORT TERM. USED THE NAM FOR
PRES AND WIND.

.LONG TERM...THE OVERALL WEATHER PATTERN IS BEING WELL DEPICTED
BY MOST FORECAST MODELS THROUGH NEXT WEEK. THERE IS SOME
DIFFERENCES IN THE DETAILS AND THE TRACK AND TIMING OF A STRONGER
SURFACE LOW MOVING INTO THE GULF AND OVER SE AK THURSDAY INTO
FRIDAY. SO WITH THAT SAID THERE IS AVERAGE FORECAST CONFIDENCE IN
THE LONG RANGE AND USED THE LATEST HPC GUIDANCE. IN MID RANGE
THERE IS FAIR MODEL AGREEMENT BUT P-TYPE IS THE TRICKIEST PART OF
THE FORECAST WITH THE FRONT MOVING OVER THE PANHANDLE SUN
AFTERNOON THROUGH MON AFTERNOON. USED A BLEND OF THE EC/NAM FOR
THIS TIME FRAME AS THEY SEEM TO HAVE A GOOD HANDLE ON THE PRESSURE
GRADIENT BUT THEY DO DIFFER SOME ON THE SPEED OF THE SURFACE TROF
MOVING INTO THE EASTERN GULF MON. OVERALL THERE IS ABOUT AVERAGE
FORECASTER CONFIDENCE IN THE MID RANGE BUT BELOW AVERAGE ON SNOW
AMOUNTS FOR THE INNER CHANNELS AS TEMPS AND WIND WILL PLAY A BIG
ROLL IN HOW MUCH PLACES GET.

AT THE START OF THE LONG TERM PERIOD A UPPER HIGH WILL BE LIFTING
OVER THE PANHANDLE INCREASING CLOUDS FROM NW TO SE. A WEATHER
FRONT WILL MOVE INTO THE NORTHERN GULF AND PRECIP WILL DEVELOP BY
THE EARLY AFTERNOON. THE PRECIP WILL START OUT AS SNOW NEAR PAYA
BUT AS THE WINDS BACK AROUND TO THE SSE TEMPS WILL WARM AND BEGIN
TO MIX WITH RAIN THROUGH THE EVENING HOURS. SNOW AMOUNTS WILL
RANGE FROM 1-3 INCHES THROUGH SUN AFTERNOON WITH POSSIBLE MORE
AMOUNTS SUN NIGHT BUT AS THE AIR TEMPS GO ABOVE FREEZING
SIGNIFICANT ACCUMULATIONS WILL BE MINIMAL. PERCIP WILL SPREAD INTO
THE INNER CHANNELS FROM NW TO SE LATE SUN AFTERNOON THROUGH LATE
SUN NIGHT. MOST PLACES WILL START OUT AS SNOW BUT FROM BERNERS BAY
SOUTHWARD THE SNOW WILL MIX WITH RAIN AND POSSIBLE BECOME ALL RAIN
THROUGH THE NIGHT AS GUSTY SE WINDS WILL INCREASE THROUGH THE
EVENING HOURS WITH THE SURFACE RIDGE BUILDING OVER THE AREA.
AMOUNTS WILL RANGE FROM 1-3 INCHES. FURTHER NORTH THE SNOW WILL
STICK AROUND A BIT LONGER BUT WITH THE SE WINDS INCREASING THROUGH
THE EVENING WITH STRONG WINDS DEVELOPING OVER PAGY THE SNOW WILL
MIX WITH RAIN AT SEA LEVEL BUT WILL REMAIN ALL SNOW ALONG THE
HIGHWAY. SNOW AMOUNTS WILL BE SIGNIFICANT THAT A WINTER WEATHER
PRODUCT WILL BE WARRANT. A MIX OF RAIN AND SNOW WILL PERSIST
OVER THE INNER CHANNELS THROUGH MON BUT AS THE COLD FRONT LIFTS
EAST MON NIGHT RAIN AND SNOW SHOWERS WILL MOVE OVER THE PANHANDLE.
THE SOUTHERN HALF OF THE AREA WILL SEE MAINLY RAIN BUT THERE MAY
BE SOME SNOW AS THE PRECIP GETS GOING LATE SUN NIGHT/EARLY MON MORNING.

THE SURFACE TROF WILL MOVE INTO THE EASTERN GULF BY MON MORNING
AND SMALL CRAFT WINDS SOME GALES WILL SPREAD ACROSS THE EASTERN
GULF. THE WINDS WILL SLOWLY DIMINISH BY MON AFTERNOON WITH WEST
WINDS TO 15 KT. OVER THE INNER CHANNELS AS THE SURFACE RIDGE
BUILDS THE SOUTHERN WINDS WILL INCREASE TO SMALL CRAFTS OVER THE
BY THE AFTERNOON OVER THE NORTHERN HALF. THE WINDS WILL CONTINUE
TO INCREASE THROUGH SUN NIGHT AS THE RIDGE SHARPENS WITH TROF
MOVING INTO THE EASTERN GULF. SO GALES WILL DEVELOP OVER NORTHERN
LYNN WITH 30KT OVER MOST OF THE REST OF THE INNER CHANNELS. OVER
LAND THERE WILL SOME GUSTY WINDS BUT FOR THE MOST WIND SPEEDS WILL
BE 10 TO 20 MPH WITH THE EXCEPTION TO THE FAR NORTHERN AREAS WHERE
GUSTS TO 45 MPH WILL DEVELOP NEAR PAGY THROUGH SUN EVENING AND
PERSIST INTO EARLY MON MORNING. THE WINDS OVER THE COASTAL AREAS
WILL INCREASE TO BE 15 TO 25 MPH MONDAY AS THE SURFACE TROF AND COLD
FRONT MOVES INTO THE EASTERN GULF. ALL WINDS WILL DIMINISH THROUGH
MON NIGHT AS THE PRESSURE GRADIENT WEAKENS AND TURNS TO THE NORTH.

A MIX OF RAIN AND SNOW WILL BE LIKELY FOR MOST OF THE REST OF THE
WEEK WITH A MEAN UPPER TROF REMAINING OVER THE GULF WITH COOLER
AIR ACROSS THE AREA.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ011>013-031>036-041>043.

&&

MM/ABJ