263  
WTNT44 KNHC 230252  
TCDAT4  
 
TROPICAL STORM LEE DISCUSSION NUMBER 19  
NWS NATIONAL HURRICANE CENTER MIAMI FL AL142017  
1100 PM AST FRI SEP 22 2017  
 
SEVERAL MICROWAVE OVERPASSES BETWEEN 2100 AND 2200 UTC INDICATED  
THAT LEE WAS BECOMING BETTER ORGANIZED, AT LEAST AT THE MID-LEVELS.  
IN PARTICULAR, A WINDSAT OVERPASS NEAR 21Z INDICATED THAT A  
MID-LEVEL EYE WAS ALREADY FORMING. SINCE THAT TIME, HOWEVER, CLOUD  
TOPS HAVE WARMED, THE CDO HAS SHRUNK, AND A GPM OVERPASS AROUND 0100  
UTC SHOWED THAT MOST OF THE CONVECTION IS CURRENTLY CONFINED TO THE  
SOUTHEAST SEMICIRCLE OF THE TROPICAL STORM. THE UW-CIMSS ADT  
SUPPORTS AN INTENSITY OF 35 KT, AND THE TAFB DVORAK ANALYST  
INDICATED THAT THE SUBJECTIVE CLASSIFICATION WOULD HAVE BEEN HIGHER,  
IF THE TECHNIQUE WASN'T CONSTRAINED BY THE FACT THAT CLASSIFICATIONS  
ON LEE ONLY RECENTLY RESTARTED. BASED ON THESE DATA, THE INITIAL  
INTENSITY HAS BEEN INCREASED TO 35 KT.  
 
THE INTENSITY FORECAST FOR LEE IS HIGHLY UNCERTAIN. THE TROPICAL  
STORM IS VERY SMALL, AND SMALL CYCLONES OFTEN QUICKLY STRENGTHEN OR  
WEAKEN. FURTHERMORE, LEE IS SMALL ENOUGH THAT SOME OF OUR MODELS  
(AND MANY OF OUR OBSERVING PLATFORMS) MAY HAVE TROUBLE RESOLVING THE  
INNER CORE OF THE STORM. GIVEN THE CURRENT CONVECTIVE STATE OF LEE,  
SIGNIFICANT STRENGTHENING IN THE SHORT TERM SEEMS UNLIKELY.  
HOWEVER, THE CYCLONE IS EXPECTED TO BE IN A FAIRLY UNSTABLE, LOW  
SHEAR ENVIRONMENT FOR AT LEAST THE NEXT 3 DAYS, SO IT IS POSSIBLE  
THAT RAPID INTENSIFICATION COULD OCCUR AT SOME TIME DURING THAT  
PERIOD. ON THE OTHER HAND, I CAN'T RULE OUT THAT THE CYCLONE COULD  
DISSIPATE ENTIRELY, AS DEPICTED BY THE GFS, WITHIN A COUPLE DAYS.  
FOR NOW, MY FORECAST IS CLOSEST TO THE HWRF FOR THE FIRST 72 H,  
SINCE THAT MODEL TENDS TO DO WELL IN LOW-SHEAR ENVIRONMENTS AND  
SHOULD HAVE SUFFICIENT RESOLUTION TO MODEL LEE'S CORE. AFTER THAT  
TIME, THE FORECAST IS CLOSE TO THE HCCA AND IVCN INTENSITY CONSENSUS  
MODELS.  
 
LEE HAS CONTINUED TO MOVE NORTH AROUND 6 KT. LITTLE CHANGE HAS BEEN  
MADE TO THE TRACK FORECAST, AND LEE IS STILL FORECAST TO MOVE AROUND  
A SUBTROPICAL RIDGE FOR THE NEXT 72 H. AT DAYS 4 AND 5, A RIDGE  
BUILDING BETWEEN LEE AND MARIA TO THE WEST SHOULD CAUSE A TURN MORE  
TOWARD THE SOUTH, AS LONG AS LEE IS SUFFICIENTLY DEEP TO BE STEERED  
BY THAT FEATURE. THE FORECAST CONTINUES TO BE CLOSE TO THE ECMWF,  
SINCE IT IS STILL THE GLOBAL MODEL WITH THE STRONGEST REPRESENTATION  
OF LEE, IN LINE WITH THE NHC FORECAST.  
 
FORECAST POSITIONS AND MAX WINDS  
 
INIT 23/0300Z 31.5N 49.0W 35 KT 40 MPH  
12H 23/1200Z 32.2N 48.5W 40 KT 45 MPH  
24H 24/0000Z 32.5N 47.8W 45 KT 50 MPH  
36H 24/1200Z 32.4N 46.6W 50 KT 60 MPH  
48H 25/0000Z 32.1N 45.2W 60 KT 70 MPH  
72H 26/0000Z 31.3N 43.1W 75 KT 85 MPH  
96H 27/0000Z 30.0N 42.5W 75 KT 85 MPH  
120H 28/0000Z 29.5N 43.5W 65 KT 75 MPH  
 

 
FORECASTER ZELINSKY  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab TPC Page Main Text Page