724  
WTNT42 KNHC 072044  
TCDAT2  
 
TROPICAL DEPRESSION NINE DISCUSSION NUMBER 1  
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092018  
500 PM AST FRI SEP 07 2018  
 
SATELLITE IMAGES INDICATE THAT THE LOW PRESSURE SYSTEM OVER THE  
EASTERN TROPICAL ATLANTIC HAS DEVELOPED A WELL-DEFINED CENTER AND  
SUFFICIENT DEEP CONVECTION TO BE CLASSIFIED A TROPICAL DEPRESSION,  
THE NINTH ONE OF THE 2018 ATLANTIC HURRICANE SEASON AND SECOND ONE  
OF THE DAY. THE INITIAL INTENSITY IS SET TO 30 KT BASED ON A 2.0  
DVORAK CLASSIFICATION FROM TAFB AND EARLIER ASCAT DATA.  
 
THE DEPRESSION HAS NOT MOVED MUCH TODAY, AND IT HAS EVEN WOBBLED A  
BIT TO THE EAST RECENTLY. THIS SLOW MOTION IS A RESULT OF VERY  
WEAK STEERING WITH BROAD TROUGHING TO THE NORTH AND TROPICAL  
DEPRESSION EIGHT TO ITS EAST. LITTLE MOTION IS EXPECTED THROUGH  
TONIGHT, BUT A WESTWARD MOTION WITH A GRADUAL INCREASE IN FORWARD  
SPEED IS FORECAST THEREAFTER AS A SUBTROPICAL RIDGE BUILDS TO THE  
NORTH OF THE CYCLONE. THE NHC TRACK FORECAST LIES CLOSEST TO THE  
HCCA GUIDANCE AND TAKES THE SYSTEM TOWARD THE LESSER ANTILLES BY THE  
END OF THE FORECAST PERIOD.  
 
THE DEPRESSION IS EXPERIENCING SOME INFLUENCES OF EASTERLY SHEAR,  
WHICH IS WHY THE CENTER IS CURRENTLY ON THE EASTERN EDGE OF THE  
CONVECTION. LITTLE CHANGE IN INTENSITY IS EXPECTED DURING THE NEXT  
12 TO 24 HOURS SINCE THE CYCLONE IS STILL IN THE DEVELOPING STAGE  
AND BECAUSE MODERATE SHEAR IS EXPECTED TO CONTINUE. HOWEVER, THE  
SHEAR IS EXPECTED TO DECREASE TO LESS THAN 10 KT IN ABOUT 24 HOURS.  
THESE MORE FAVORABLE WINDS ALOFT COMBINED WITH RELATIVELY WARM  
WATERS AND A FAIRLY MOIST AIRMASS SHOULD ALLOW FOR STEADY  
STRENGTHENING BEGINNING LATER IN THE WEEKEND. THERE IS A LARGE  
SPREAD IN THE INTENSITY GUIDANCE, WITH THE HWRF SHOWING THE SYSTEM  
BECOMING A MAJOR HURRICANE AND HMON SHOWING ALMOST NO STRENGTHENING.  
THE NHC INTENSITY FORECAST LIES A LITTLE BELOW CONSENSUS MODELS  
SINCE IT APPEARS THAT IT WILL TAKE SOME TIME FOR THE SYSTEM TO  
STRENGTHEN.  
 
FORECAST POSITIONS AND MAX WINDS  
 
INIT 07/2100Z 13.6N 34.9W 30 KT 35 MPH  
12H 08/0600Z 13.9N 35.2W 30 KT 35 MPH  
24H 08/1800Z 14.0N 36.2W 30 KT 35 MPH  
36H 09/0600Z 14.0N 37.6W 40 KT 45 MPH  
48H 09/1800Z 14.0N 39.3W 50 KT 60 MPH  
72H 10/1800Z 14.0N 44.0W 60 KT 70 MPH  
96H 11/1800Z 14.1N 48.9W 70 KT 80 MPH  
120H 12/1800Z 14.5N 54.5W 75 KT 85 MPH  
 

 
FORECASTER CANGIALOSI  
 
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