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WTNT45 KNHC 201443

TCDAT5

 

Hurricane Nigel Discussion Number  21

NWS National Hurricane Center Miami FL       AL152023

1100 AM AST Wed Sep 20 2023



Nigel is maintaining a ragged-appearing eye on visible and 

infrared satellite imagery.  Bands of deep convection with tops to 

around -70C continue to rotate around the center, and the system's 

cloud pattern remains fairly symmetrical.  Although microwave 

imagery from around 0900 UTC showed a closed eyewall, recent 

geostationary images suggest breaks in the eyewall over the 

eastern portion of the circulation.  Dvorak CI numbers from TAFB and 

SAB are 4.5, corresponding to a 77-kt intensity, and an objective 

ADT estimate from UW-CIMSS was 79 kt.  Based on these values, the 

advisory intensity estimate was reduced only slightly, to 80 kt.  

NOAA Hurricane Hunter aircraft are scheduled to investigate Nigel 

soon.



The hurricane is moving northward, or perhaps slightly east of 

north, with an initial motion of 010/16 kt.  The system has been 

moving around the western periphery of a mid-level high pressure 

area.  A mid-latitude trough to the northwest of Nigel should cause 

the cyclone to turn toward the northeast and the cyclone 

should continue to move northeastward at a faster forward speed over 

the next couple of days.  In 48 to 72 hours, Nigel is expected to 

rotate counter-clockwise around the eastern side of a large 

extratropical cyclone over the north Atlantic.  Although the 

official forecast shows track points at 4 and 5 days, there is a 

good chance that Nigel will merge with,  or become absorbed by, the 

other cyclone around that time.  The official forecast is very 

similar to the previous NHC track prediction.



Nigel has only about 12 hours remaining before moving over cooler 

waters, and southwesterly vertical shear is forecast to increase 

tonight.  Gradual weakening is expected over the next 2-3 days, in 

general agreement with the consensus intensity forecast guidance.  

The intensity forecast in the latter part of the forecast period is 

uncertain, given the distinct possibility that Nigel could merge 

with the other extratropical cyclone.



 

FORECAST POSITIONS AND MAX WINDS

 

INIT  20/1500Z 36.1N  54.4W   80 KT  90 MPH

 12H  21/0000Z 38.4N  51.8W   80 KT  90 MPH

 24H  21/1200Z 41.6N  46.4W   75 KT  85 MPH

 36H  22/0000Z 44.6N  39.0W   65 KT  75 MPH

 48H  22/1200Z 47.6N  31.0W   55 KT  65 MPH...POST-TROP/EXTRATROP

 60H  23/0000Z 51.3N  24.8W   50 KT  60 MPH...POST-TROP/EXTRATROP

 72H  23/1200Z 55.0N  23.0W   50 KT  60 MPH...POST-TROP/EXTRATROP

 96H  24/1200Z 57.0N  24.0W   40 KT  45 MPH...POST-TROP/EXTRATROP

120H  25/1200Z 58.0N  23.0W   40 KT  45 MPH...POST-TROP/EXTRATROP

 

$$

Forecaster Pasch