Official Discussion issued by the National Hurricane Center

Kirk (AL122018) DATA RELEASED: 9/26/2018 11:00:00 PM UTC

Copy of official data

Tropical Storm Kirk Discussion Number  13
NWS National Hurricane Center Miami FL       AL122018
1100 PM AST Wed Sep 26 2018

Strengthening vertical shear is beginning to take its toll on Kirk,
with the low-level center displaced to the west of the deep
convection.  An Air Force Reserve Hurricane Hunter aircraft found
that the central pressure has risen to 1002 mb, with maximum 850 mb
flight-level winds of 56 kt and believable SFMR winds as high as 44
kt.  Based on these wind data, Kirk's initial intensity is lowered
to 45 kt.  Vertical shear is forecast to increase further, reaching
over 30 kt in about 24 hours, which should cause Kirk to continue
weakening over the next day or two.  And, based on the latest global
model guidance, the cyclone could open up into a trough any time
after passing by the Lesser Antilles.  The new NHC intensity
forecast is mainly an update of the previous one to account for the
lower initial intensity, and it continues to closely follow the
intensity consensus, IVCN, and the HCCA guidance.  Dissipation is
now shown by day 4, but as mentioned above, this could occur a lot

Kirk appears to have slowed down just a little, with an initial
motion toward the west-northwest, or 285/14 kt.  Ridging to the
north should maintain Kirk on this general trajectory, with perhaps
just a slight deceleration as it moves into the eastern Caribbean
Sea.  There are some speed differences among the models, with the
ECMWF showing a weaker and faster system, while the GFS shows a
slightly stronger and slower system.  The NHC track forecast is
between these two solutions and is closest to the HCCA model.


INIT  27/0300Z 13.0N  57.0W   45 KT  50 MPH
12H  27/1200Z 13.6N  58.6W   45 KT  50 MPH
24H  28/0000Z 14.4N  60.9W   40 KT  45 MPH
36H  28/1200Z 15.1N  63.3W   35 KT  40 MPH
48H  29/0000Z 15.6N  65.6W   30 KT  35 MPH
72H  30/0000Z 16.0N  69.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
96H  01/0000Z...DISSIPATED

Forecaster Berg