Small Craft Advisory 296, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
202 PM AKDT SAT MAY 5 2012

.SHORT TERM...UPPER TROF WILL CONTINUE TO AMPLIFY OVER THE
E-CENTRAL PAC NWD INTO SW AK. A DEVELOPING LOW WILL MOVE NNE TO
THE S-CENTRAL GULF BY LATE TONIGHT...THEN CURVE NWWD TO JUST S OF
THE KENAI PEN BY LATE SUN. STRONG OCCLUDED FRONT WILL MOVE NE
INTO THE ERN GULF BY LATE TONIGHT...THEN PUSH ONSHORE OVER THE
NRN AND CENTRAL PANHANDLE AREA SUN AFTERNOON. USED BLEND OF THE
12Z GFS AND NAM FOR PRESSURE GRIDS...AND USED THAT BLEND ALONG
WITH SOME LOCAL WRF MODEL FOR WINDS.

 MAIN FORECAST CONCERNS ARE WINDS AND PRECIP AMOUNTS/INTENSITY.
WINDS WILL INCREASE TO GALES OVER MUCH OF THE ERN GULF AND FAR
SRN INNER CHANNELS BY LATE THIS EVENING...THEN SPREAD TO THE
CENTRAL INNER CHANNELS LATE TONIGHT AND SUN MORNING. WILL BE
HEADLINING FOR STRONG WINDS IN MOST ZONES...STARTING ALONG THE
SRN COAST AROUND 06Z THIS EVENING...THEN SPREADING N AND E TO
COVER MOST OF THE AREA BY 15Z SUN. ONCE THE FRONT PUSHES ONSHORE
OVER THE NRN AND CENTRAL AREAS...WINDS SHOULD DROP OFF
SOMEWHAT...WITH POSSIBLE EXCEPTION OF FAR NRN INNER CHANNELS
WHERE WINDS WILL PICK UP. WILL  NOT HEADLINE ZONES 18 AND 19 FOR
STRONG WINDS YET FOR LATE SUN BUT THEY MAY NEED IT. WINDS MAY
PEAK NEAR MIN STORM FORCE ALONG THE FAIRWEATHER GROUNDS AS WELL
AS NEAR CAPE SUCKLING AREA SUN...BUT FOR NOW WILL KEEP PEAK WINDS
AT MAX GALES AFTER COORD WITH WFO PAFC ON THIS.

 AS FOR PRECIP...THIS SYSTEM HAS A LOW LATITUDE SOURCE REGION
JUST WEST OF HAWAII...AND THIS WILL MEAN LOCALLY HEAVY RAINFALL
ESPECIALLY OVER THE SRN HALF OF THE AREA WHERE FRONT WILL BE
SLOWER TO PUSH THRU. RAINFALL MAY EXCEED 4 INCHES OVER THE SRN
AREA THRU LATE SUN AFTERNOON...WITH UP TO 2 INCHES FOR THE NRN
AREA. ATTM WILL NOT BE ISSUING ANY HYDRO STATEMENTS AS RIVERS AND
STREAMS ARE FAIRLY LOW RIGHT NOW...BUT GIVEN THE AMOUNT OF
SNOWPACK STILL REMAINING IN THE 1000-2500 FT LEVEL OF THE
MOUNTAINS...WILL NEED TO KEEP AN EYE ON STREAMS SUN. COORD WITH
RFC ABOUT THIS AND THEY SAID THEY DO NOT EXPECT ANY FLOODING IN
THE GAGED STREAMS AND RIVERS. WILL LIKELY ISSUE HYDRO STATEMENT
ABOUT SIGNIFICANT RIVER/STREAM RISES HOWEVER.

 &&

 .LONG TERM...THE BEGINNING OF THE LONG RANGE SEES THE HEAVY RAIN
AND WIND EVENT FROM SUNDAY BEGINNING TO WIND DOWN THROUGH SUN
NIGHT AS THE FRONT MOVES THROUGH THE PANHANDLE AND THE MOISTURE
PLUME HEADS SOUTH OF THE AREA. THERE STILL WILL BE THE
POSSIBILITY OF A QUARTER TO A HALF INCH OF RAINFALL SUN NIGHT
BEFORE DIMINISHING LATE SUN NIGHT. HIGHEST AMOUNTS WILL BE IN THE
SOUTHERN PANHANDLE WHERE THE MOISTURE PLUME IS AIMED AT. THE WIND
WILL FOR THE MOST PART BE OVER AS THE HIGHER WINDS WERE PRE-
FRONTAL AND THE MAIN LOW IS WELL WEST OVER COOK INLET AT THE START
OF THE EXTENDED RANGE. THERE STILL MAY BE SOME BREEZY CONDITIONS
IN THE SOUTHERN PANHANDLE SUN EVENING AS THE FRONT MAY NOT HAVE
COMPLETELY PASSED THROUGH THAT AREA YET.

 HEAVIER RAIN RETURNS FOR THE SOUTH MON AFTERNOON AS THE MOISTURE
PLUME THAT WAS FEEDING THE FRONT AGAIN MAKES ITS WAY NORTH. A
WEAK TROUGH APPROACHING FROM THE SW IS RESPONSIBLE FOR THE
NORTHWARD DRIFT AS THE MORE SOUTHERLY FLOW AHEAD OF IT PUSHES THE
TERMINUS OF THE PLUME FROM BRITISH COLUMBIA INTO THE SOUTHERN
PANHANDLE. ANOTHER HALF INCH TO AN INCH OF RAINFALL IS EXPECTED
IN THE SOUTHERN PANHANDLE THROUGH EARLY TUES MORNING AS THIS
TROUGH MOVES THROUGH. RIVERS AND STREAM THAT MAY ALREADY BE HIGH
FROM SUNDAY'S RAIN MAY RISE A BIT HIGHER DUE TO MORE RUNOFF AS
THE GROUND WILL BE SATURATED FROM THE FIRST EPISODE OF RAIN.
MUDSLIDES MAY ALSO BE A POSSIBILITY IN STEEPER TERRAIN. SOME OF
THIS PRECIP MAY GET DRAWN NORTHWARD MON NIGHT AS THE TROUGH HEADS
NORTH SO I HAVE SOME CATEGORICAL POPS IN FOR THE NORTHERN
PANHANDLE MON NIGHT BUT QPF AMOUNTS WILL NOT BE AS HIGH. RAIN
WILL AGAIN DIMINISH FOR TUES AS THE PLUME RETREATS BACK TO THE
SOUTH AND THE TROUGH HEADS INTO THE YUKON.

 IN ADDITION TO THE RAIN THE TROUGH WILL ALSO BRING A BIT OF WIND
TO THE SOUTHERN PANHANDLE MON NIGHT THROUGH NOT AS STRONG AS
SUNDAY. I AM ONLY EXPECTING BREEZY CONDITIONS IN THE LAND AREAS
AND SMALL CRAFT WINDS FOR CLARENCE STRAIT AND SOUTHERN OUTSIDE
WATERS AT MOST.

 FOR MID WEEK AND BEYOND IS FOR THE MOST PART QUIETER WITH SOME
WEAK TROUGHS MOVING THROUGH FROM THE SW ON THE LEE SIDE OF A
PERSISTENT LONG WAVE UPPER TROUGH THAT IS OVER MUCH OF THE
NORTHERN PACIFIC AND BERING SEA. NEXT SIGNIFICANT STORM IS
SUGGESTED FOR FRI AS ANOTHER LOW AND FRONT ARRIVES FROM THE SW
BRINGING MORE RAIN AND WIND.

 EXTENDED RANGE MODELS ARE IN GOOD AGREEMENT THROUGH THE PERIOD.
MAIN DIFFERENCES START SHOWING UP MID WEEK WITH THE NAM TAKING A
SLIGHTLY DIFFERENT ROUTE FROM THE EC AND GFS WITH THE WEAK
FEATURES IN THE GULF. DIFFERENT TRACKS ARE TAKEN FOR THE LATE
WEEK SYSTEM BUT THEY FOR THE MOST PART AGREE ON THE GENERAL AREA
WHERE IT WILL OCCUR. USED A BLEND OF THE NAM AND GFS FOR SUN
NIGHT INTO MON NIGHT THEN TRANSITIONED TO EC/GFS AND HPC FOR
LATER PERIODS. SOME GEM AND SREF WERE ALSO USED IN THE POP FIELD
AS WELL. FORECAST CONFIDENCE IS ABOUT AVERAGE.

.AJK WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...GALE
WARNING FOR PKZ036-041>043-051-052.          SMALL CRAFT ADVISORY
FOR PKZ021-022-033>035-053.

 &&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM 1 AM AKDT SUNDAY THROUGH SUNDAY AFTERNOON FOR
     AKZ023-026.
         STRONG WIND FROM 10 PM AKDT THIS EVENING THROUGH SUNDAY
     AFTERNOON FOR AKZ027.
         STRONG WIND FROM LATE TONIGHT THROUGH SUNDAY AFTERNOON FOR
     AKZ020-021-024.
         STRONG WIND FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR
     AKZ025.
         STRONG WIND FROM LATE TONIGHT THROUGH SUNDAY AFTERNOON FOR
     AKZ022.
         STRONG WIND FROM 1 AM AKDT SUNDAY THROUGH SUNDAY EVENING FOR
     AKZ028.
         STRONG WIND FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR
     AKZ017.
MARINE...GALE WARNING FOR PKZ012-013-021-022-031>036-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011-053.

&&

RWT/EAL