Small Craft Advisory 313, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
330 PM AKDT THU APR 7 2016

.SHORT TERM...EARLY AFTERNOON SATELLITE IMAGERY SHOWS A LOW
PRESSURE SYSTEM OVER NORTHEAST GULF COAST CONTINUES TO HEAD NORTH.
GUSTY WINDS OF 40 TO 45 MPH WERE OBSERVED IN YAKUTAT AREA AS A
60-KT LOW-LEVEL JET MOVES INTO THE NORTHEAST GULF COAST. IN
ADDITION, THERE IS EXTENSIVE CLOUD COVER NORTH AND EAST OF THE
SYSTEM. THE CLOUD SHIELD COVERS NORTHEAST GULF OF ALASKA INTO THE
NORTHERN AND CENTRAL PANHANDLE. THE SPORT PASSIVE MICROWAVE
SATELLITE IS SHOWING RAIN RATE OF ONE TENTH TO TWO TENTH OF AN
INCH PER HOUR IN A NARROW NORTH-SOUTH BAND STRETCHING FROM YAKUTAT
INTO THE EASTERN GULF. THERE ARE SOME CLEAR BREAKS IN THE CLOUD
COVER OVER THE SOUTHERN PANHANDLE. THE 850-MB LEVEL TEMPERATURES
AS HIGH AS 6 TO 8 C ARE FORECASTED BY NUMERICAL MODELS. SO FAR,
TEMPERATURES ROSE TO THE LOW TO MID 60S IN PART OF PRINCE OF WALES
ISLAND AND KETCHIKAN AREA. SAXMAN, JUST SOUTH OF KETCHIKAN, SAW
TEMPERATURES RISE UP TO 65 F. WITH PERSISTENT SKY COVER AND RAIN,
AFTERNOON TEMPERATURES IN THE NORTHERN PANHANDLE ONLY GOT UP TO
THE UPPER 40S. MID TO UPPER 50S ARE COMMON ACROSS CENTRAL
PANHANDLE.

HEAVY RAIN WILL CONTINUE TONIGHT FOR THE YAKUTAT AREA, AS THE AXIS
OF MOISTURE FLUX CONTINUES TO AIM TOWARDS YAKUTAT, EVEN AS IT IS
CHANGING ITS TILT FROM SOUTHERLY TO SOUTHEASTERLY OVERNIGHT.
EXPECT 1 TO 2 INCHES OF RAIN IN THE YAKUTAT AREA. THE NORTHERN
AREAS INCLUDING SKAGWAY AND HAINES WILL ALSO SEE PERSISTENT CLOUD
AND PRECIPITATION OVERNIGHT, WHILE THE REST OF THE PANHANDLE
REMAINS DRY. BY EARLY FRIDAY MORNING, THE RAIN BAND WILL SHIFT
EAST AND MAKE LANDFALL OVER THE OUTER COAST, THIS WILL LEAD TO
GENERAL RISING MOTION ACROSS THE PANHANDLE. IN ADDITION, THERE
WILL BE COLD AIR ALOFT PASSING THROUGH THE PANHANDLE ON FRIDAY.
THUS, EXPECT RAIN SHOWERS ACROSS THE PANHANDLE ON FRIDAY. SHOWERS
WILL INTENSIFY DURING THE DAY WITH SURFACE HEATING, THEN
DIMINISH IN THE EARLY EVENING.

IN ADDITION, A GENERAL RIDGE OF HIGH PRESSURE WILL BUILD INTO THE
PANHANDLE FROM THE SOUTH DURING THE DAY ON FRIDAY AS THE FRONT
MOVES INLAND INTO BRITISH COLUMBIA. THE RAPID PRESSURE RISE WILL
LEAD TO A PUSH OF STRONG SOUTHERLY WIND ACROSS THE NORTHERN
PANHANDLE. DO EXPECT WIND GUSTS OF 40 TO 45 MPH IN SKAGWAY AREA,
AND GALE FORCE WINDS IN NORTHERN LYNN CANAL FOR FRIDAY AFTERNOON.

FORECAST CONFIDENCE IS ABOUT AVERAGE. UTILIZED ECMWF TO REFRESH
THE INHERITED FORECAST PACKAGE.

.LONG TERM...DEEP LAYER RIDGE WILL BUILD ACROSS THE AREA FRI NIGHT
THEN SHIFT E SAT. AN OCCLUDED FRONT WILL PUSH INTO THE CENTRAL
GULF BY SAT EVENING...THEN DRIFT SLOWLY NE AND WEAKEN AS IT
CROSSES THE AREA SUN AND SUN NIGHT. LOOKS LIKE ANOTHER SYSTEM WILL
TRY TO MOVE INTO THE AREA AROUND TUE...BUT MODELS DIFFER SOMEWHAT
ON THIS. UPPER PATTERN WILL BE SOMEWHAT PROGRESSIVE FOR MUCH OF
NEXT WEEK SO EXPECT PERIODS OF PRECIP WITH SOME DRY INTERVALS AS
WELL...BUT MODEL TIMING ON THE SYSTEMS DIFFERS SO KEPT IN MIDDLE
GROUND PRECIP POTENTIAL FORECAST AFTER TUE. OVERALL...FORECAST
CHANGES WERE GENERALLY SMALL AT MOST.

WITH RIDGE MOVING IN FRI NIGHT...SHOULD SEE SHOWERS DIMINISH
DURING THE NIGHT. SAT AND SAT NIGHT LOOKS MOSTLY DRY EXCEPT WILL
SEE INCREASING PRECIP CHANCES FOR THE CENTRAL GULF AND NE GULF
COAST AS OCCLUDED FRONT MOVES IN. SOME OF THIS PRECIP MAY MOVE
INTO THE REMAINING AREA SUN INTO SUN NIGHT...WITH BETTER CHANCES
AS YOU GO NWD...BUT WITH FRONT WEAKENING...MAY NOT BE MUCH IN THE
WAY OF RAINFALL WITH IT. USED THE 12Z ECMWF TO HANDLE THE SUN/SUN
NIGHT SYSTEM TO SHOW BETTER DEFINITION OF THE FRONTAL TROF. USED
LATEST WPC FOR LATE SUN NIGHT ONWARD AFTER COORD WITH WFO PAFC
ALTHOUGH MADE MINIMAL CHANGES TO POPS.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FRIDAY AFTERNOON FOR AKZ018.
     STRONG WIND UNTIL 10 PM AKDT THIS EVENING FOR AKZ017.
MARINE...GALE WARNING FOR PKZ012-043-051>053.
     SMALL CRAFT ADVISORY FOR PKZ013-022-031-035-041-042.
&&

RCL/RWT

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