Hurricane DENNIS

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HURRICANE DENNIS DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT THU JUL 07 2005
 
AN AIR FORCE RESERVE HURRICANE HUNTER MEASURED 700-MB FLIGHT-LEVEL
WINDS OF 134 KT IN THE NORTHEAST EYEWALL AT 07/2314Z...AND ALSO
REPORTED THAT THE CENTRAL PRESSURE OF DENNIS HAD DROPPED TO 951 MB. 
SINCE THAT TIME...THE SATELLITE SIGNATURE OF DENNIS HAS NOT CHANGED
SIGNIFICANTLY.  BASED ON THIS AND ON 115 KT SATELLITE INTENSITY
ESTIMATES FROM SAB AND TAFB...DENNIS IS UPGRADED TO A CATEGORY FOUR
HURRICANE ON THE SAFFIR-SIMPSON HURRICANE SCALE.  DENNIS MAY HAVE
UNDERGONE AN EYEWALL REPLACEMENT CYCLE DURING THE AFTERNOON...AS
THE 9 N MI WIDE EYE SEEN EARLIER IS NOW 16 TO 20 N MI WIDE.  IT
SHOULD BE NOTED THAT THE 950 MB CENTRAL PRESSURE IS AN ESTIMATE AND
COULD WELL BE TOO HIGH.

THE INITIAL MOTION IS 310-315 AT ABOUT 13 KT.  DATA FROM A
TWO-AIRCRAFT SYNOPTIC SURVEILLANCE MISSION SHOWS THAT A
MID/UPPER-LEVEL RIDGE REMAINS WELL ESTABLISHED ALONG 26N OVER
FLOIDA AND THE ADJACENT GULF OF MEXICO.  A LOW-LEVEL RIDGE IS ALSO
PRESENT...BUT IS SOMEWHAT WEAKER.  GUIDANCE MODELS ARE IN GOOD
AGREEMENT THAT DENNIS SHOULD CONTINUE GENERALLY NORTHWESTWARD FOR
ABOUT 24 HR.  AFTER THAT TIME...THERE IS SOME DIVERGENCE...WITH THE
UKMET TAKING DENNIS NORTHWESTWARD TOWARD LOUISIANA...THE CANADIAN
TAKING DENNIS NORTHWARD ALONG THE FLORIDA WEST COAST...AND THE
OTHER GUIDANCE IN BETWEEN.  THE GFDL HAS SHIFTED SOMEWHAT LEFT FROM
ITS PREVIOUS FORECAST...WHILE THE GFS HAS SHIFTED A LITTLE TO THE
RIGHT IN THE FIRST 36 HR AND A LITTLE TO THE LEFT THEREAFTER.  AS
DENNIS HAS NOT YET DEVIATED FROM THE PREVIOUS FORECAST TRACK...THE
NEW FORECAST IS BASICALLY AN UPDATE OF THAT TRACK THROUGH THE FIRST
36 HR.  AFTER THAT...THE FORECAST TRACK IS SHIFTED SLIGHTLY TO THE
LEFT...WEST...AND LIES ALONG THE RIGHT EDGE OF THE MAIN CLUSTER OF
GUIDANCE.
 
THE INTENSITY FORECAST IS PROBLEMATIC.  IN THE SHORT TERM...DENNIS
COULD CONTINUE TO STRENGTHEN UNTIL THE CORE ENCOUNTERS CENTRAL
CUBA...AND THIS IS REFLECTED IN THE INTENSITY FORECAST.  AFTER
THAT...SEVERAL FACTORS COME INTO PLAY.  THESE INCLUDE...WILL THE
CURRENTLY TIGHTLY WOUND CORE OF DENNIS SURVIVE PASSAGE ACROSS
LAND...WHAT CONCENTRIC EYEWALL CYCLES MAY OCCUR...AND HOW MUCH
ENERGY IS AVAILABLE IN THE WARM...BUT THIN...SURFACE LAYER OF THE
GULF OF MEXICO.  THE SHIPS MODEL SUGGEST THAT THE OCEANIC HEAT
CONTENT WILL DECREASE AS DENNIS MOVES NORTHWARD...CAUSING THE STORM
TO WEAKEN.  ON THE OTHER HAND...THE GFDL AND GFDN BOTH CALL FOR
SIGNIFICANT INTENSIFICATION OVER THE GULF.  THE INTENSITY FORECAST
WILL COMPROMISE BETWEEN THESE EXTREMES.
 
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      08/0300Z 19.9N  77.6W   115 KT
 12HR VT     08/1200Z 21.2N  79.2W   120 KT
 24HR VT     09/0000Z 23.0N  81.2W   100 KT...INLAND
 36HR VT     09/1200Z 24.8N  83.1W   100 KT
 48HR VT     10/0000Z 26.8N  84.6W   110 KT
 72HR VT     11/0000Z 30.5N  87.0W   100 KT...INLAND
 96HR VT     12/0000Z 35.5N  88.0W    30 KT...INLAND
120HR VT     13/0000Z 38.5N  86.0W    20 KT...INLAND
 
 
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