Small Craft Advisory 302, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
255 PM AKDT MON APR 4 2016

.SHORT TERM...PRECIPITATION SPREADING ACROSS THE PANHANDLE THIS
EVENING. RAIN WILL CONTINUE THROUGH TUESDAY AFTERNOON. GUSTY WINDS
EXPECTED ALONG THE COASTAL AREA OF BARANOF AND PRINCE OF WALES
ISLANDS LATE TONIGHT INTO EARLY MORNING ON TUESDAY. WIND GUSTS TO
40 MPH EXPECTED IN THE KETCHIKAN AREA.

THE SHORT TERM FORECAST PERIOD WILL START OFF WITH A FRONT
DISSIPATING OVER THE PANHANDLE LATE THIS AFTERNOON INTO THIS
EVENING. EARLY THIS AFTERNOON, PRECIPITATION WERE REPORTED ALL
ACROSS SOUTHEAST ALASKA, WITH THE EXCEPTION OF SKAGWAY AND YAKUTAT.
THE AREA OF PRECIPITATION WILL EXPAND INTO YAKUTAT AND SKAGWAY THIS
EVENING, AS A STRONGER AND MORE-ORGANIZED WEATHER FRONT MOVE
TOWARDS THE PANHANDLE FROM THE SOUTH. PRECIPITATION INTENSITY WILL
ALSO INCREASE OVERNIGHT. DO EXPECT 1 TO 2 INCHES OF RAINFALL
THROUGH TUESDAY AFTERNOON. HIGHEST RAINFALL AMOUNTS OVER THE
SOUTHER PANHANDLE INCLUDING PRINCE OF WALES ISLAND AND KETCHIKAN
AREA. THE WEATHER FRONT WILL PUSH INLAND INTO BRITISH COLUMBIA LATE
TUESDAY AFTERNOON.

BESIDES RAIN, WIND WILL BE THE BIG STORY FOR THE OUTER COAST AND
KETCHIKAN AREA. HIGH RESOLUTION MODELS ARE SHOWING STRONG SOUTHERLY
LOW LEVEL JET OF 40 TO 55 KT WILL BE PUSHING ACROSS THE SOUTHER
PANHANDLE. DO EXPECT SOUTHERLY WINDS TO 35 KT ALONG THE COASTAL
WATERS OF BARANOF AND PRINCE OF WALES ISLAND LATE TONIGHT. THE SAME
LOW LEVEL JET WILL BRING STRONG WIND GUSTS OF 40 MPH TO PRINCE OF
WALES ISLAND AND ALSO KETCHIKAN AREA. THE STRONGEST WINDS WILL BE
DURING THE OVERNIGHT HOURS INTO EARLY TUESDAY MORNING. AS THE
WEATHER FRONT PUSHES INLAND TOMORROW, THERE WILL BE PRESSURE RISE
IN THE SOUTHERN PANHANDLE. THE PRESSURE RISE WILL LEAD TO THE
DEVELOPMENT OF ISALLOBARIC WIND, WHICH MEANS THAT THERE IS LIKELY
TO BE A SOUTHERLY PUSH OF GUSTY WINDS IN THE AREA.

WITH CLOUDY SKIES AND RAIN, DIURNAL TEMPERATURE RANGE WILL BE
RATHER SMALL. OVERNIGHT LOW TEMPERATURES, GENERALLY IN THE LOW TO
MID 40S, WILL ONLY BE A FEW DEGREES COOLER THAN THE DAYTIME HIGH ON
MONDAY. DAYTIME HIGH TEMPERATURES FOR TUESDAY WILL BE IN THE MID TO
UPPER 40S.

UTILIZE ECMWF/NAM IN REFRESHING THE FORECAST PRODUCT. FORECAST
CONFIDENCE IS ABOUT AVERAGE. THERE IS SOME UNCERTAINTY IN HOW MUCH
MOMENTUM TRANSFER THERE WILL BE OVERNIGHT TO TRANSFER THE HIGHER
WIND SPEED ALOFT TO NEAR THE GROUND SURFACE.

.LONG TERM...LONG RANGE FORECAST CONTINUES TO LOOK WET THROUGH
LATE WEEK AS SW FLOW ALOFT CONTINUES TO DIRECT ACTIVE WAVES INTO
THE AREA. THE FORECAST FOR THE WEEKEND STILL LOOKS DRY MAINLY FOR
SAT, BUT LONG RANGE MODELS ARE BACKING OFF ON THE STRENGTH OF THE
UPPER RIDGE OVER THE EASTERN GULF AND PANHANDLE. CURRENT TREND IS
FOR A WEAKER, MORE PROGRESSIVE RIDGE THAT GETS PUSHED INTO BRITISH
COLUMBIA BY LATE SUN WITH ANOTHER TROUGH NOW PUSHING INTO THE
PANHANDLE AS EARLY AS SUN NIGHT.

LONG RANGE MODELS CONTINUE TO PLAY WITH THE LOW COMING INTO THE
GULF ON WED INTO THU. CURRENT MODEL TRENDS HAVE WEAKENED THE LOW A
LITTLE BUT STILL REMAIN DECENT ON TRACK. LIKELY THE BIGGEST CHANGE
FOR THIS SYSTEM IS THAT IT IS NOT AS WET AS PREVIOUS FORECASTS
HAVE INDICATED AS THE TROPICAL CONNECTION THAT THE MODELS WERE
DISPLAYING EARLIER NOW GETS CUT OFF (A RESULT OF THE SOUTHERN PART
OF THE TROUGH PINCHING OFF INTO A CUT OFF LOW EARLY THU). AS A
RESULT EVEN THROUGH THE INITIAL WAVE ON WED NIGHT WILL BE WET THE
TRAILING FRONT BEHIND IT WILL NOT HAVE AS MUCH MOISTURE TO TRAIN
INTO THE AREA. QPF AMOUNTS ARE NOW IN THE RANGE OF 1 TO 3 INCHES
RATHER THEN THE 2 TO 4 INCHES THAT WAS SUGGESTED A DAY OR TWO AGO.

SOME CHANGES CONTINUE INTO THE WEEKEND AS THE UPPER RIDGE THAT WAS
SUPPOSE TO BUILD OVER THE EASTERN GULF AND PANHANDLE NOW IS WEAKER
AND MORE PROGRESSIVE IN ITS EASTWARD MOVEMENT. AS A RESULT, THE
CHANCES OF RAIN ARE INCREASING FOR THE PANHANDLE THIS WEEKEND,
MAINLY FOR SUN INTO MON, AS MORE SYSTEMS ARE ALLOWED TO ENCROACH
INTO THE EASTERN GULF AND PANHANDLE. RIGHT NOW KEPT POPS AT CHANCE
TO SLIGHT CHANCE FOR THE LATE WEEKEND INTO EARLY NEXT WEEK AS A
RESULT.

LONG RANGE MODELS ARE STILL SHIFTING AROUND SO FORECAST
CONFIDENCE IS NOT THAT HIGH, ESPECIALLY FOR THE WEEKEND AND
BEYOND. THE OVERALL PATTERN IS WELL REPRESENTED IN THE MID RANGE
THROUGH SO DECIDED TO USE MAINLY ECMWF AND SOME GFS FOR MID RANGE
UPDATES. WPC WITH ITS USE OF ENSEMBLE GUIDANCE WAS MAINLY USED
FOR EXTENDED RANGE UPDATES.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM LATE MONDAY NIGHT THROUGH TUESDAY MORNING FOR
     AKZ027-028.
MARINE...GALE WARNING FOR PKZ036-041>043.
     SMALL CRAFT ADVISORY FOR PKZ021-022-031>035-051-052.
&&

RCL/EAL

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