Gale Warning 76, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
354 PM AKST SUN JAN 18 2015

.SHORT TERM...VERY WELL DEVELOPED LOW SPIRALING THROUGH THE
EASTERN GULF AT THE MOMENT. SATELLITE IMAGES SHOW A VERY CLEAR
COMMA SHAPE TO THE MAIN CLOUD SHIELD WITH A VERY WELL DEFINED DRY
SLOT WRAPPING IN BEHIND THE MAIN FRONT. DESPITE THE STRONG
APPEARANCE OF THE LOW WINDS ASSOCIATED WITH IT HAVE NOT BEEN THAT
STRONG. OFFSHORE BUOYS HAVE ONLY SEEN MAYBE 20 KT AS THE MAIN
FRONT CAME THROUGH AND BUOY 46184 ON THE SOUTH SIDE OF THE STORM
IS ONLY RECORDING 30 TO 35 KT. THERE WAS A SHIP ON THE WEST SIDE
OF THE STORM THAT WAS REPORTING AROUND 35 KT FROM THE N THOUGH
AROUND 11 AM. AS FOR PRECIP THE MAIN RAIN BAND HAS MADE IT AS FAR
NORTH AS ANGOON AND HOONAH AND AS FAR EAST AS PETERSBURG AND
KETCHIKAN. NO HEAVY RAIN OUT OF THIS SYSTEM SO FAR AS HIGHEST
AMOUNTS SO FAR WERE AROUND 12 HUNDREDTHS OF AN INCH IN ONE HOUR AT
ANNETTE AROUND NOON. THE BACK EDGE OF THE RAIN IS ALREADY VISIBLE
ON RADAR AND IS APPROACHING SITKA AS OF NOON.

FOR TONIGHT INTO TOMORROW THE CURRENTLY STALLED LOW WILL START TO
DRIFT TO THE NE AND GRADUALLY WEAKEN. IT WILL PASS NEAR SITKA
EARLY TOMORROW AS A 1000 MB LOW BEFORE COLLAPSING INTO AN OPEN
TROUGH OVER THE NORTHERN PANHANDLE ON MON. AS FOR THE FRONT IT
WILL CONTINUE NORTHWARD THROUGH THE EVENING SPREADING ITS PRECIP
FARTHER NORTH. THE AREA TO WATCH WILL BE THE HAINES AND KLONDIKE
HIGHWAYS TONIGHT AS N TO NW WINDS ARE STILL BLOWING DOWN THOSE
RESPECTIVE VALLEYS. AS A RESULT TEMPS WILL BE GETTING CLOSE TO OR
BELOW FREEZING OVERNIGHT RESULTING IN THE POSSIBILITY OF SNOW FOR
THESE AREAS. HOWEVER BY THIS POINT THE RAIN BAND WILL HAVE
WEAKENED IN THE DIFFLUENT FLOW ALOFT SO THERE WILL NOT BE MUCH
PRECIP TO SQUEEZE OUT OF THE REMAINING CLOUDS. EXPECTED SNOW
ACCUMULATIONS ON EITHER HIGHWAY WILL ONLY AMOUNT TO AROUND 1 TO 3
INCHES TONIGHT AND LIGHTER AMOUNTS TOMORROW WITH HIGHEST AMOUNTS AT
HIGHER ELEVATIONS. BEHIND THE MAIN FRONT THE SW FLOW WILL BRING IN
MORE SHOWERY TYPE PRECIP. HOWEVER AS THE WEAKENING LOW COMES ON
SHORE THE OCCLUDED FRONT THAT HAS WRAPPED AROUND THE LOW CENTER
WILL CAUSE LIKELY MAKE DIFFERENTIATING BETWEEN STRATIFORM AND
CONVECTIVE PRECIP TRICKY. SO WENT WITH A MORE STRATIFORM RAIN
WITH EMBEDDED CONVECTION FOR LATE TONIGHT INTO TOMORROW.

THE WIND IS ANOTHER MATTER. THE NEAR GALE FORCE WINDS MEASURED ON
THE S AND W SIDE OF THE LOW WILL HIT THE SOUTHERN OUTER COAST
LATER THIS EVENING IN A SLIGHTLY WEAKENED FORM. I EXPECT THAT THE
WINDS WILL NOT REACH STRONG WIND CRITERIA IN ZONE 27 BUT SOME
GUSTS TO 35 MPH ARE NOT OUT OF THE QUESTION OVERNIGHT. WINDS TO 25
OR 30 KT WILL ALSO INVADE THE SE GULF, SOUTHERN CHATHAM, SUMNER,
AND CLARENCE STRAIT BEFORE DIMINISHING TOMORROW AS THE LOW MOVES
NORTHWARD. FARTHER NORTH, THE NORTHERLY 25 KT WINDS CURRENTLY
BLOWING THROUGH LYNN CANAL WILL STICK AROUND THROUGH TONIGHT AS
THE LOW APPROACHES THE COAST. THESE WINDS WILL GRADUALLY DIMINISH
TOMORROW AS THE LOW WEAKENS AND EVENTUALLY PASSES OVER THE AREA
LATE TOMORROW AFTERNOON.

SHORT RANGE MODELS WERE IN DECENT AGREEMENT OVERALL BUT THERE ARE
STILL SOME SLIGHT DIFFERENCES ON HOW FAST THE LOW MOVES ONSHORE
AND THEN OVER THE NORTHERN PANHANDLE. THE NAM IS NOTICEABLY SLOWER
IN THAT REGARD BUT NOT TO THE EXTENT THAT IT WAS YESTERDAY. THE
GFS, GEM, AND ECMWF WERE IN BETTER ALIGNMENT TODAY SO DECIDED TO
HEAD IN THAT DIRECTION FOR SHORT RANGE UPDATES.

.LONG TERM...LITTLE CHANGE IN THE OVERALL SYNOPTIC PATTERN
THROUGH THE EXTENDED WITH AN UPPER LOW OVER THE ALEUTIANS AND
RIDGING OVER THE ERN GULF/SE AK. SEVERAL IMPULSES WILL EJECT OUT
THE BASE OF THE PARENT LOW AND MOVE ACROSS THE GULF BRINGING
PERIODS OF GUSTY WINDS AND MODERATE-OCCASIONALLY HEAVY PRECIP TO
THE REGION. MAIN FORECAST CHALLENGE IS THE TIMING/TRACK OF THESE
STORMS. THE FIRST WAVE WILL MOVE ACROSS THE GULF MON NIGHT INTO
TUE...BUT MODEL SOLUTIONS CONTINUE TO SHOW FAIRLY LARGE SPREAD
WITH REGARDS TO THE PLACEMENT OF THE LOW. EC WAS FURTHEST W WITH
THIS FEATURE WHILE NAM CONTINUES TO BE AN EASTERN OUTLIER. GFS AND
GEM WERE FAIRLY SIMILAR AND WERE BLENDED WITH THE INHERITED
FORECAST. SHORT WAVE RIDGE WILL FOLLOW THIS FIRST LOW RESULTING IN
SLIGHTLY DRIER WX ALONG THE N GULF COAST TUE NIGHT INTO
WED...BUT MODELS CONTINUE TO SHOW ENOUGH SPREAD TO WARRANT LOW
END CHC POPS. ACROSS THE PANHANDLE...PRECIP CHANCES WILL PERSIST
WITH HEAVIEST PRECIP ACROSS THE CENTRAL-SOUTHERN PANHANDLE. MODEL
SOLUTIONS CONTINUE TO SHOW LARGE SPREAD BEYOND WED...SO TRENDED
FORECAST TOWARDS MORE ENSEMBLE WEIGHTED WPC GUIDANCE. PRECIP
THROUGH THE MAJORITY OF THE EXTENDED WILL CONTINUE TO FALL AS
RAIN...HOWEVER...THE FAR NORTHERN INNER CHANNELS AND LOCATIONS
CLOSEST TO THE COAST MOUNTAINS WILL LIKELY BECOME MIXED WITH SNOW.
OVERALL...CONFIDENCE REMAINS ABOVE AVERAGE IN THE SYNOPTIC
PATTERN...BUT DETERIORATES WHEN TRYING TO DEPICT THE TIMING/TRACK
OF THE INDIVIDUAL STORMS.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ041.
         SMALL CRAFT ADVISORY FOR PKZ012-013-033>036-042.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ043-051-052.

&&

EAL/BC

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