Mike Doran: your right - mysterious weakening
Posted by JAC on 7/12/2009, 10:06 pm
TROPICAL STORM CARLOS DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  EP042009
200 PM PDT SUN JUL 12 2009

CARLOS HAS CONTINUED IN THE LAST SEVERAL HOURS TO SHOW A
DETERIORATION OF ITS CONVECTIVE STRUCTURE.  WHILE TAFB/SAB DVORAK
AND ADT CURRENT INTENSITY VALUES SUGGEST AROUND 65-75 KT...THE DATA
T NUMBERS AND MOST RECENT IMAGERY INDICATE THAT THE CYCLONE HAS
DROPPED BELOW HURRICANE FORCE.  MOREOVER...THE EXTENT OF THE DEEP
CONVECTION HAS CONTRACTED WITH A CENTRAL DENSE OVERCAST EXTENDING
ONLY ABOUT 200 NM IN DIAMETER.  THUS THE WIND RADII ARE CONTRACTED
FROM THAT INDICATED EARLIER.

INITIAL MOTION IS ESTIMATED TO BE 270/9.  THE POSITION HAS MORE
CERTAINTY THAN EARLIER TODAY DUE TO A FORTUITOUS SSMIS PASS AT
1535Z.  CARLOS IS EXPECTED TO CONTINUE MOVING WESTWARD DURING THE
NEXT FEW DAYS UNDER THE PRIMARY INFLUENCE OF A DEEP LAYER RIDGE TO
ITS NORTHEAST.  THE RELIABLE GLOBAL AND HURRICANE MODELS ARE
TIGHTLY CLUSTERED...EXCEPT FOR THE NOGAPS AND GFDN MODELS WHICH
TAKE THE CYCLONE SUBSTANTIALLY FARTHER NORTHWARD.  THIS BEHAVIOR
MAY BE DUE TO THE OVERLY LARGE-SIZED VORTEX IN THE NOGAPS MODEL.
THE TRACK FORECAST IS A BLEND OF THE REMAINING TRACK MODELS ALONG
WITH THE PREVIOUS PREDICTION...WHICH WAS SLIGHTLY TO THE NORTH OF
THE CURRENT FORECAST.

IT STILL IS A BIT OF MYSTERY WHY THE CYCLONE WEAKENED AS MUCH AS IT
HAS TODAY. THE GFDL AND HWRF DYNAMICAL MODELS INSIST ON A
SUBSTANTIAL RE-INTENSIFICATION...WHILE THE SHIPS AND LGEM
STATISTICAL TECHNIQUES ONLY BRING CARLOS BACK UP A FEW KNOTS. THERE
DOES EXIST A TWO TO THREE DAY WINDOW FOR CARLOS TO RESTRENGTHEN AS
IT TRAVERSES OVER WARM WATERS AND THROUGH AN ENVIRONMENT OF LOW
VERTICAL SHEAR AND MOIST UNSTABLE AIR. AT DAYS FOUR AND FIVE...THE
CYCLONE WILL ENCOUNTER SLIGHTLY COOLER SSTS AND MORE VERTICAL
SHEAR...WHICH SHOULD WEAKEN THE SYSTEM. THE INTENSITY FORECAST IS A
BLEND BETWEEN THE MORE AGGRESSIVE PREVIOUS PREDICTION AND THE MORE
CONSERVATIVE CONSENSUS TECHNIQUE...ICON. 

FORECAST POSITIONS AND MAX WINDS

INITIAL      12/2100Z 10.3N 121.9W    60 KT
12HR VT    13/0600Z 10.4N 123.6W    65 KT
24HR VT    13/1800Z 10.5N 126.1W    70 KT
36HR VT    14/0600Z 10.7N 128.5W    75 KT
48HR VT    14/1800Z 10.9N 130.7W    75 KT
72HR VT    15/1800Z 11.5N 135.0W    70 KT
96HR VT    16/1800Z 12.5N 139.0W    65 KT
120HR VT    17/1800Z 13.0N 144.0W    55 KT

$$
FORECASTER LANDSEA/FRANKLIN
12
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Could Carlos be first US cane of season? - UMRSMASOrtt, 7/10/2009, 11:01 pm
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