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TROPICAL DEPRESSION CHRIS DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT SAT AUG 19 2000
 
CHRIS REMAINS A POORLY ORGANIZED SYSTEM WITH A DIFFICULT TO LOCATE
CENTER.  SATELLITE FIXES FROM SAB AND TAFB WERE ABOUT 60 NM APART...
AND MULTISPECTRAL INFRARED IMAGERY HINTS THAT THE CENTER MAY BE
FARTHER WEST THAN EITHER FIX.  THE UNCERTAINTY MEANS THAT A GREAT
DEAL OF CONTINUITY AND EXTRAPOLATION WILL BE USED IN THIS PACKAGE.

THE BEST ESTIMATE OF THE INITIAL MOTION IS 300/10.  A LARGE LOW/MID
LEVEL RIDGE REMAINS IN PLACE NORTH OF CHRIS...WHILE THE CYCLONE IS
MOVING INTO A BROAD UPPER LEVEL TROUGH.  LARGE-SCALE MODELS INDICATE
THE RIDGE TO THE NORTH WILL WEAKEN SOMEWHAT WITH TIME...WHICH MAY
ALLOW CHRIS TO TURN MORE NORTHWARD.  MOST NHC TRACK GUIDANCE
REFLECTS THIS.  HOWEVER...IF THE CENTER IS FURTHER WEST...THE SYSTEM
WOULD BE WEST OF THE PREVIOUS FORECAST TRACK.  THE OFFICIAL FORECAST
COMPROMISES BETWEEN THE TWO POSSIBILITIES AND IS ALONG THE LEFT EDGE
OF THE GUIDANCE.

SOME CONVECTION IS PRESENT NORTH OR NORTHEAST OF THE CENTER...AND
THE INITIAL INTENSITY REMAINS 30 KT.  WATER VAPOR IMAGERY INDICATES
THE UPPER LEVEL TROUGH IS CONTINUING TO CAUSE SOUTHWESTERLY VERTICAL
SHEAR.  LARGE-SCALE GUIDANCE SUGGESTS THE SHEAR COULD CONTINUE FOR
24-48 HR.  THIS SHOULD AT LEAST SLOW INTENSIFICATION...AND THERE IS
SOME CHANCE CHRIS COULD DISSIPATE DURING THE FORECAST PERIOD.  TO
KEEP SOME CONTINUITY...THE INTENSITY FORECAST WILL SLOW THE
PREVIOUSLY FORECAST INTENSIFICATION BY 12 HR.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     19/0900Z 17.9N  57.7W    30 KTS
12HR VT     19/1800Z 18.6N  59.1W    30 KTS
24HR VT     20/0600Z 19.7N  61.0W    35 KTS
36HR VT     20/1800Z 20.8N  62.9W    40 KTS
48HR VT     21/0600Z 22.0N  65.0W    45 KTS
72HR VT     22/0600Z 24.5N  70.0W    55 KTS
 
 
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