553
WTNT45 KNHC 062058
TCDAT5
TROPICAL STORM HENRI DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102009
500 PM AST TUE OCT 06 2009
ALTHOUGH IT IS UNDER THE INFLUENCE OF STRONG SOUTHWESTERLY SHEAR...
THE AREA OF LOW PRESSURE LOCATED EAST OF THE LEEWARD ISLANDS HAS
CONTINUED TO PRODUCE DEEP CONVECTION...WHICH HAS NOW MIGRATED OVER
THE LOW-LEVEL CENTER. BASED ON THE SATELLITE PRESENTATION...AND A
1336 UTC ASCAT PASS WHICH INDICATED WINDS TO 35 KT NORTHEAST OF THE
CENTER...ADVISORIES ARE BEING INITIATED ON TROPICAL STORM HENRI.
HENRI WILL STILL BE IMPACTED BY 20-25 KT OF SHEAR OVER THE NEXT DAY
OR SO AND IS THEREFORE EXPECTED TO BE SHORT-LIVED. THE CYCLONE IS
EXPECTED TO WEAKEN TO A DEPRESSION OVER THE NEXT 24 HOURS...AND
MOST OF THE GLOBAL MODEL FIELDS SHOW HENRI DISSIPATING BY 48 HOURS.
THE INITIAL MOTION IS 300 DEGREES AT 17 KT. HENRI IS LOCATED ALONG
THE SOUTHWESTERN PERIPHERY OF A MID-LEVEL RIDGE EXTENDING WESTWARD
ACROSS THE ATLANTIC...AND IS EXPECTED TO CONTINUE MOVING TOWARD THE
WEST-NORTHWEST OR NORTHWEST UNTIL DISSIPATION. WATCHES ARE NOT
REQUIRED FOR THE LESSER ANTILLES AT THIS TIME SINCE THE FORECAST
TRACK KEEPS THE STRONG WINDS ASSOCIATED WITH HENRI WELL TO THE
NORTH OF THOSE ISLANDS.
THE FORMATION OF HENRI ILLUSTRATES HOW DIFFICULT IT IS TO ANTICIPATE
THE CHANGES IN CONVECTION THAT DISTINGUISH STRONG TROPICAL
DISTURBANCES FROM WEAK TROPICAL CYCLONES...PARTICULARLY WHEN
ENVIRONMENTAL CONDITIONS ARE MARGINAL FOR DEVELOPMENT.
HENRI IS A FRENCH NAME AND IS PRONOUNCED AS AHN-REE WITH THE ACCENT
ON THE SECOND SYLLABLE.
FORECAST POSITIONS AND MAX WINDS
INITIAL 06/2100Z 17.8N 54.0W 35 KT
12HR VT 07/0600Z 19.0N 56.0W 35 KT
24HR VT 07/1800Z 20.4N 58.6W 30 KT
36HR VT 08/0600Z 21.5N 61.0W 25 KT...REMNANT LOW
48HR VT 08/1800Z...DISSIPATED
FORECASTER BERG
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