Tropical Storm BONNIE

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TROPICAL STORM BONNIE DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032010
1100 PM EDT THU JUL 22 2010

AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT EARLIER FOUND
1500 FT FLIGHT-LEVEL WINDS OF 43 KT IN THE NORTHEASTERN
QUADRANT...AND BELIEVABLE SFMR WINDS OF 35-39 KT.  BASED ON THIS
TROPICAL DEPRESSION THREE WAS UPGRADED TO TROPICAL STORM BONNIE. 
SATELLITE IMAGERY SINCE THAT TIME SUGGESTS LITTLE CHANGE IN
STRENGTH...WITH SOUTHERLY VERTICAL WIND SHEAR DISPLACING THE
CONVECTION TO THE NORTH OF THE LOW-LEVEL CENTER.  THE NEXT AIRCRAFT
IS SCHEDULED TO REACH BOONIE AROUND 06Z.

THE CENTER HAS BEEN WOBBLING NORTHWESTWARD DURING THE PAST SEVERAL
HOURS...WITH THE INITIAL MOTION A SOMEWHAT UNCERTAIN 305/12. 
BONNIE IS ON THE EAST SIDE OF A LARGE MID/UPPER-LEVEL LOW OVER THE
EASTERN GULF OF MEXICO AND SOUTH OF A DEEP-LAYER RIDGE OVER THE
SOUTHEASTERN UNITED STATES.  AS THE UPPER LOW MOVES WESTWARD...
BONNIE SHOULD TURN WEST-NORTHWESTWARD IN RESPONSE TO THE FLOW
AROUND THE RIDGE...WITH THE TRACK GUIDANCE MODELS IN GOOD AGREEMENT
ON THIS SCENARIO THROUGH 72 HR.  THIS MOTION SHOULD BRING THE
CENTER ACROSS THE FLORIDA PENINSULA OR KEYS ON FRIDAY...AND NEAR OR
OVER THE NORTHERN GULF COAST IN 60-72 HR.  AFTER THAT...THE CYCLONE
IS EXPECTED TO MOVE NORTHWARD AROUND THE WESTERN END OF THE RIDGE. 
THE NEW FORECAST TRACK HAS BEEN SHIFTED NORTHWARD DURING THE FIRST
72 HR BASED ON THE CURRENT POSITION AND MOTION.  HOWEVER...IT LIES
SOUTH OF THE MODEL CONSENSUS THROUGH THE FIRST 48 HR AND SOME
ADDITIONAL NORTHWARD ADJUSTMENT MAY BE NECESSARY LATER.

IN ADDITION TO THE SOUTHERLY SHEAR...BONNIE IS CURRENTLY IN AN AREA
OF UPPER-LEVEL CONFLUENCE ON THE EASTERN SIDE OF THE GULF UPPER
LOW.  THIS IS A LESS THAN IDEAL ENVIRONMENT FOR STRENGTHENING...AND
THE INTENSITY GUIDANCE FORECASTS ONLY MODEST INTENSIFICATION BEFORE
BONNIE REACHES FLORIDA.  THE FORECAST HAS BECOME MORE PROBLEMATIC
OVER THE GULF OF MEXICO.  THE SHIPS AND LGEM MODELS...PERHAPS
RESPONDING TO SOME DECREASE IN THE SHEAR...NOW FORECAST BONNIE TO
PEAK NEAR 60 KT OVER THE GULF.  ON THE OTHER HAND...THE
GFDL...GFDN...AND HWRF DO NOT FORECAST SIGNIFICANT STRENGTHENING...
AND NEITHER DO THE GLOBAL MODELS.  SINCE THE LARGE UPPER LOW IS
FORECAST TO DOMINATE THE NORTHERN GULF THROUGH 48 HR...THE
INTENSITY FORECAST WILL LEAN IN FAVOR OF THE DYNAMICAL MODELS.  THE
NEW INTENSITY FORECAST IS THE SAME AS THE PREVIOUS FORECAST.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/0300Z 23.4N  76.5W    35 KT
 12HR VT     23/1200Z 24.4N  78.7W    40 KT
 24HR VT     24/0000Z 25.4N  81.9W    45 KT
 36HR VT     24/1200Z 26.5N  84.9W    45 KT
 48HR VT     25/0000Z 27.6N  87.5W    45 KT
 72HR VT     26/0000Z 30.0N  91.0W    40 KT...INLAND
 96HR VT     27/0000Z 33.0N  93.0W    25 KT...INLAND
120HR VT     28/0000Z 35.5N  92.5W    20 KT...POST-TROP/REMNT LOW
 
$$
FORECASTER BEVEN
 
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