Small Craft Advisory 370, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
226 PM AKDT FRI JUN 15 2012

.SHORT TERM...UNSEASONABLY STRONG SYSTEM INCLUDES STRONG FRONTAL
BOUNDARIES, ALONG WITH A COMPLEX TRIPLE PT THAT ON THE GOES IR
THAT IS IN THE VICINITY OF 200 NM S OF PAKT AT THIS TIME. NOTE
THE GALE AND SCA LISTINGS IN MARINE TABLE BELOW. GALE FORCE WINDS
ARE UNUSUAL IN JUNE. ALSO NOTE THE PUBLIC ZONE 27 HAS A  WIND
ADVISORY FOR THIS EVENING, AND THE GUSTS OF 40 MPH THAT SHOULD
SHOW UP IN THE OBS AT PAHY ARE ALSO UNUSUAL FOR JUNE.

 THE OLD PARENT LOW IS A 982 MB 300 NM S OF PACD. THE COMPLEX
TRIPLE IS IN AN AREA CENTERED ON A POINT ABOUT 200 NM SW OF PAKT
WITH A SEQUENCE OF TWO FAST MOVING JET STREAKS MOVING TOWARD IT
FROM THE SW. ALSO: GOES IR FOR REGION WITHIN 300 NM S OF THE AK
PEN IS CONSISTENT WITH VORT LOBES SUPPORTING A LOW DVLPG NE
TOWARD THE GULF THAT IS SYNOPTICALLY DISTINCT FROM THE FRONTAL
WAVES TO THE S THAT ARE TRACKING TOWARD THE TRIPLE PT.

 DETAILED COORDINATION WITH AFC OCCURRED AS NEEDED FOR LOW TRACKS
MOVING ACROSS THE BNDRY OF OUR AORS.

 MODELS: CONSENSUS HAS OVERALL IMPROVED WITH THE SUCCESSION OF
MODEL RUNS. FOR EXAMPLE THE GFS IS EASIER TO RECONCILE WITH SIM
FOR THE JET EXIT REGION THAT THIS MORNING WAS ABOUT 600 NM S OF
PAMD. THICKNESS GRADIENT AND BAROCLINITY VALUES RETRIEVED FROM
BIORKA RADAR: THE CLOUD SHIELD DOES NOT HIDE ADDITIONAL AVAILABLE
POTENTIAL THAT CAN BE CONVERTED TO KINETIC ENERGY, OR IN OTHER
WORDS, THE MODELS ARE DO NOT HAVE WHAT CAN BECOME THE LARGE
SYNOPTIC SCALE ERRORS THAT OCCUR A COUPLE OF TIMES A YEAR.

.LONG TERM...LIMITED CHANGES TO LONG TERM THRU 12Z MON TO FOCUS
ON THE WINDING DOWN SIDE OF THE WEEKEND STORM. THE MODELS WERE
HAVING ISSUES WITH HOW LOW SFC PRESSURES WERE THIS MORNING OVER
THE SRN GULF AND NE PAC AREAS...WITH NONE OF THE MODELS QUITE LOW
ENOUGH. THE ECMWF HAD BEST FIT TO WHERE FEATURES WERE LOCATED SO
ENDED UP USING THAT MODEL AS PRIMARY GUIDANCE...BUT ENDED UP
DEEPENING THE CENTRAL PRESSURE OF THE LOW OVER THE GULF A COUPLE
OF MB TO TAKE INTO ACCOUNT THE LOWER PRESSURES NOW OUT THERE.

 MAIN IMPACT OF THIS ADJUSTMENT WAS TO BOOST WINDS A BIT
ESPECIALLY ON THE NRN AND ERN SIDE OF THE LOW. THE STRONGEST
WINDS WILL BE OVER THE NRN GULF BY TIME LONG RANGE PERIOD BEGINS
SAT EVENING...WITH AROUND 30 KT E-SE WINDS EXPECTED THERE.
ELSEWHERE WINDS WILL ALREADY BE ON THE DECREASE FROM THEIR SHORT
TERM PEAKS...WITH GENERALLY LESS THAN SCA LEVEL WINDS EXPECTED BY
EARLY SAT EVENING. MAY STILL HAVE SCA LEVEL S WINDS OVER NRN LYNN
CANAL EARLY SAT EVENING BEFORE DROPPING OFF LATER SAT NIGHT.

 AS FAR AS PRECIP FROM THIS SYSTEM...MAIN AREAS WILL BE OVER SRN
PANHANDLE NEAR A SHORTWAVE MOVING ENE JUST TO THEIR S...AND NEAR
THE PAYA AREA ON E SIDE OF SFC LOW. IN BETWEEN LIFTING MECHANISMS
WILL BE ON THE WEAK SIDE BUT PROBABLY ENOUGH TO SPIT OUT A FEW
HUNDREDTHS OF AN INCH OF RAIN SO KEPT POPS IN MOST PLACES AT
LIKELY OR HIGHER LEVELS SAT NIGHT INTO SUN. THE POPS GRADUALLY
DECREASE LATER SUN INTO SUN NIGHT AS MAIN LOW WEAKENS QUICKLY AND
BEGINS TO SHIFT SEWD.

 FURTHER OUT...AREA WILL BE IN FAIRLY WEAK FLOW ALOFT MUCH OF
NEXT WEEK SO SYSTEM MOVEMENTS WILL BE TRICKY AT THIS POINT. LOOKS
LIKE WEAK RIDGING DEVELOPS OVER NW CANADA WHILE WEAK UPPER
LOW/TROF GOES BY THE AREA TO THE S BY LATE NEXT WEEK. CURRENT
FORECAST STILL LOOKS REASONABLE AT THIS POINT FROM MON ON OUT SO
LEFT IT PRETTY MUCH AS IS. OVERALL NEXT WEEK LOOKS DRIER AND
WARMER THAN RECENT WEEKS HAVE BEEN...BUT TEMPS WILL PROBABLY ONLY
WARM TO NEAR NORMAL LEVELS.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY UNTIL MIDNIGHT AKDT TONIGHT FOR AKZ027.
MARINE...GALE WARNING FOR PKZ036-041>043.
         SMALL CRAFT ADVISORY FOR PKZ021-022-031>035-051-052.

&&

JBT/RWT