Gale Warning 439, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
4 PM AKST SUN DEC 29 2013

.SHORT TERM...SATELLITE IMAGERY SHOWS A PLUME OF MOISTURE
EXTENDING FROM THE TROPICS TO SE ALASKA. THIS FRONT IS ONLY
CAUSING CLOUDS OVER THE REGION THIS AFTERNOON BUT PRECIPITATION
CAN BE SEEN APPROACHING FROM THE SOUTH AT THE FAR REACHES OF THE
RADAR. AN UPPER LEVEL WAVE WILL MOVE ACROSS THE NORTH PACIFIC AND
CAUSE A TRIPLE POINT LOW TO FORM A THE SURFACE. THIS LOW WILL
TRACK NORTHWARD ALONG THE FRONT AND DEEPEN OFF BARANOF ISLAND LATE
TONIGHT. WITH THE LOW DEVELOPING ON OUR DOOR STEP EXPECT WINDS TO
COME UP QUICKLY. HAVE EAST WINDS TO GALE FORCE SOUTH OF DOUGLAS
ISLAND AND THROUGH CROSS SOUND. ALSO HAVE GALE FORCE WINDS IN
CLARENCE STRAIT NEAR LINCOLN ROCK. WITH THE DEEPENING LOW TO THE
SOUTH HAVE CONTINUED THE STRONG NORTH WINDS THROUGH SKAGWAY
THROUGH MONDAY AND INCREASE WINDS THROUGH LYNN CANAL TO 45
KT...STRONGEST NORTH OF ELDRED ROCK.

THE RAIN SNOW LINE WILL AGAIN BE ALONG ICY STRAIT AND JUNEAU.
EXPECT ANOTHER ROUND OF WET SNOW FOR THOSE AREAS AND ALL SNOW FOR
AREAS NORTH. HAVE ISSUED WINTER WEATHER ADVISORIES FOR SNOW IN
GUSTAVUS AND JUNEAU WHERE 3-8 INCHES IS EXPECTED THROUGH MONDAY
AFTERNOON. THE WET SNOW WILL COMPACT QUICKLY AND BE SLUSHY.
LIMITED SNOWFALL AMOUNTS FOR THIS REASON TO 3-5:1 RATIO...SIMILAR
TO WHAT WAS SEEN YESTERDAY. AN ADVISORY WAS ALSO ISSUED FOR
HAINES...WHICH WILL BE COLD ENOUGH FOR THE SNOW TO HAVE TYPICAL
RATIOS AND EXPECT 4-9 INCHES THROUGH MONDAY AFTERNOON. SOUTH OF
ICY STRAIT RAIN WILL BE THE PREDOMINANT TYPE AND BECOME HEAVY AT
TIMES LATE TONIGHT.

MODELS HAVE DIFFERED ON HOW FAR NORTH/HOW DEEP TO MAKE THE LOW
OVER THE PAST COUPLE DAYS SO THERE IS SOME UNCERTAINTY WITH
TIMING. HAVE GONE WITH A CONSENSUS SOLUTION OF ECMWF/GFS/GEM WITH
AN EMPHASIS ON THE 12Z ECMWF. THE NAM HAS BEEN AN OUTLIER AND IS
SLOWER MOVING THE LOW NORTH WHICH WOULD DELAY THE ONSET
PRECIPITATION AND LIMIT SNOW AMOUNTS OVER THE NORTHERN AREAS.
FORECAST CONFIDENCE IS AVERAGE.

.LONG TERM...HAD A GREAT PLAN YESTERDAY WHICH FELL TO PIECES WITH
29/12Z MODEL RUNS NOW SENDING A SERIES OF STRONGER SHORT WAVES
THROUGH THE OVERALL ONSHORE FLOW ALOFT. THIS MEANS SIGNIFICANT
ADJUSTMENTS FOR TUE THROUGH FRI IN TODAYS FORECASTS. FIRST THE
UPPER LEVEL FLOW ALOFT REMAINS ONSHORE MONDAY NITE FOR A MOISTURE
SOURCE WHICH GETS SHUT OFF TUE DUE TO A RAPIDLY MOVING UPR RIDGE
FROM THE WEST. NEXT ANOTHER WEATHER SYSTEM WITH LOTS OF MOISTURE
HITS TUE NITE AND WED. THE NEXT UPR RIDGE ARRIVES THU EVENING. SO
THE BIG PICTURE IS TRANSIENT SYSTEMS AND ONE HAS TO REMAIN HOPEFUL
THAT WE HAVE DOWN THE TIMING AS PER THE FORECASTS BEING ISSUED.
CONFIDENCE ON TIMING IN SUCH A PATTERN CAN NEVER BE HIGH BUT
METHINKS MODERATE IN DESCRIBING SOME BREAKS. USED A BLEND OF 12/29
AK-GFS-40 AND 12/29 ECMWF. WPC PRES PROGS AND UPR LEVEL FLOW WERE
USED DAYS 4 THOUGH 7.

NOTES ON SOME DETAILS: 1) KEEPING THE SNOW GOING NORTHERN SECTIONS
MONDAY NITE. 2) HAD TO INCLUDE SOME GALE FORCE WINDS TUE NITE DUE
TO THE FRONT COMING UP TO THE COAST LOOKING STRONG IN THE MODELS.
3) THE BREAKS INDICATED LOOK LIKE REAL BREAKS SO IF OCCURRING AT
NIGHT TEMPS MAY BE COLDER IN WIND SHELTERED AREAS. 4) MOST OF THE
SNOW WILL BE WET WET GLOP. THIS MEANS ACCUMULATION WILL COMPACT
RAPIDLY AT LOW ELEVATIONS LIKE THE PREVIOUS SYSTEMS.
&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY 11 PM THIS EVENING TO 6 PM MON
         AKZ020-025.
         WINTER WEATHER ADVISORY 3 AM TO 6 PM MON AKZ019.
         STRONG WIND THROUGH MON AFTERNOON FOR AKZ018.
MARINE...GALE WARNING FOR PKZ012-013-022-031-036.
         SMALL CRAFT ADVISORY PKZ011-021-032>035-041>043-051>053.

FERRIN/JC

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>