Tropical Storm CHRIS

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TROPICAL STORM CHRIS DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032006
500 PM EDT TUE AUG 01 2006
 
ON THE FIRST AIRCRAFT MISSION INTO CHRIS...THE AIR FORCE RESERVE
UNIT HURRICANE HUNTERS FOUND A VERY SMALL CORE OF STRONG WINDS WITH
A CENTRAL PRESSURE OF 1007 MB.  THIS IS ACTUALLY A RATHER LOW
PRESSURE CONSIDERING THE HIGH ENVIRONMENTAL BAROMETER READINGS. 
MAXIMUM FLIGHT LEVEL WINDS WERE 53 KT JUST TO THE SOUTHEAST OF THE
CENTER.  BASED ON THE STANDARD 80 PERCENT REDUCTION FROM THE 1000
FT FLIGHT LEVEL THE CURRENT INTENSITY IS SET AT 40 KT.  THE
ENVIRONMENT IS RELATIVELY STABLE...SOME NORTH-NORTHWESTERLY
VERTICAL SHEAR IS IMPACTING THE SYSTEM...AND THE GLOBAL MODELS
CONTINUE TO FORECAST WEAKENING.  HOWEVER...THERE IS A WELL-MARKED
UPPER-TROPOSPHERIC OUTFLOW CHANNEL EMANATING WEST-SOUTHWESTWARD
FROM CHRIS...AND A FAIR AMOUNT OF OUTFLOW IS ALSO EVIDENT OVER THE
EASTERN QUADRANT.  THIS DIVERGENCE ALOFT COULD ALLOW ADDITIONAL
INTENSIFICATION.  ADDITIONALLY THE GFDL MODEL FORECASTS
STRENGTHENING UNTIL THE MODELED CIRCULATION INTERACTS WITH
HISPANIOLA.  THE OFFICIAL FORECAST CLOSELY FOLLOWS THE SHIPS
GUIDANCE...WHICH DOES SHOW A SLIGHT DECREASE IN VERTICAL SHEAR
AFTER A COUPLE OF DAYS.

A MID-TROPOSPHERIC RIDGE EXISTS TO THE NORTH OF CHRIS WITH A MID- TO
UPPER-LEVEL WEAKNESS IN THE VICINITY OF 70W LONGITUDE.  THE TROUGH
NEAR 70W IS FORECAST TO SHIFT WESTWARD WITH TIME SO THAT THE RIDGE
TO THE NORTH OF THE TROPICAL CYCLONE IS MAINTAINED...OR EVEN
STRENGTHENED.  DYNAMICAL GUIDANCE MODEL TRACKS HAVE BEEN GRADUALLY
SHIFTING TO THE LEFT OVER THE LAST COUPLE OF RUNS...MOST LIKELY IN
RESPONSE TO A BUILDING RIDGE.  THE OFFICIAL FORECAST IS THEREFORE
ADJUSTED A LITTLE TO THE LEFT OF THAT FROM THE PREVIOUS PACKAGE. 
THIS IS NORTH OF THE LATEST DYNAMICAL CONSENSUS AND THE FSU
SUPERENSEMBLE TRACK.

A TROPICAL STORM WARNING HAS BEEN ISSUED FOR PUERTO RICO AND THE
U.S. AND BRITISH VIRGIN ISLANDS.  THE TROPICAL STORM WARNING FOR
THE NORTHERN LEEWARDS IS MAINTAINED AT THIS TIME.  IT SHOULD BE
NOTED THAT...EVEN IF THE CENTER OF CHRIS PASSES JUST TO THE NORTH
OF SOME OF THESE ISLANDS...RATHER STRONG WINDS COULD BE EXPERIENCED
IN THE ISLANDS DUE TO RAIN BANDS OVER THE SOUTHERN SEMICIRCLE OF
THE STORM.  IN FACT AT THIS TIME IT APPEARS THAT THE HEAVIEST
WEATHER IS OCCURRING OVER THE SOUTHERN PORTION OF THE CIRCULATION.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      01/2100Z 17.7N  61.2W    40 KT
 12HR VT     02/0600Z 18.3N  62.6W    45 KT
 24HR VT     02/1800Z 19.1N  64.5W    45 KT
 36HR VT     03/0600Z 19.9N  66.6W    50 KT
 48HR VT     03/1800Z 20.5N  68.7W    50 KT
 72HR VT     04/1800Z 21.5N  73.0W    50 KT
 96HR VT     05/1800Z 22.5N  77.0W    55 KT
120HR VT     06/1800Z 23.5N  80.5W    55 KT
 
$$
FORECASTER PASCH
 
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