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Tropical Storm John Discussion Number   4...Corrected
NWS National Hurricane Center Miami FL       EP122018
900 AM MDT Mon Aug 06 2018

Corrected to remove the percent symbols in the text

Early morning visible satellite images and recent microwave data
show that John continues to quickly become better organized.
Banding features now wrap nearly completely around the center, with
the development of a fairly symmetric CDO.  One-minute GOES-16
imagery also show several overshooting convective cloud tops near
and to the east of the center.  A TAFB Dvorak estimate of T3.5 was
the basis of the 1200 UTC intensity of 55 kt, but with the increase
in organization since that time, and raw objective T-numbers above
4.0 for the past few hours, the advisory intensity has been
increased to 60 kt.

John is within a very favorable environment for intensification.
The hurricane will be moving over SSTs around 30C, and in a low
shear and moist environment.  These conditions are expected to
allow for rapid strengthening during the next day or so.  The SHIPS
Rapid Intensification Index shows a nearly 80 percent chance of RI
over the the next 24 h, and DTOPS gives an 80 percent chance of a
40 kt increase in intensity during the next 24 h.  Based on these
data and the very aggressive guidance, the NHC forecast calls for a
40 kt increase in strength from 1200 this morning through 1200 UTC
Tuesday. The NHC forecast calls for a peak intensity that is close
to the FSSE and HCCA models in 36 to 48 hours.  After that time,
John will be moving over cooler waters and into a more stable
environment which is expected to cause rapid weakening.

John is moving west-northwestward at about 7 kt.  The tropical
storm should turn northwestward and accelerate over the next day or
so as it is steered around the western portion of a mid-level ridge
that is centered over northern Mexico.  As noted in the previous
discussion, some interaction with Ileana is likely, which could
cause some slow down of the forward speed of John.  However since
John is the larger system, it should remain the dominant tropical
cyclone.  The latest dynamical model guidance was similar to the
previous cycle and no significant change to the NHC forecast was
required. The NHC forecast is in best agreement with the ECMWF and
is close to the HFIP corrected consensus.


FORECAST POSITIONS AND MAX WINDS

INIT  06/1500Z 15.5N 107.9W   60 KT  70 MPH
 12H  07/0000Z 16.0N 108.6W   75 KT  85 MPH
 24H  07/1200Z 17.0N 109.6W   95 KT 110 MPH
 36H  08/0000Z 18.3N 111.0W  110 KT 125 MPH
 48H  08/1200Z 19.8N 112.7W  110 KT 125 MPH
 72H  09/1200Z 22.9N 116.6W   85 KT 100 MPH
 96H  10/1200Z 25.5N 120.7W   55 KT  65 MPH
120H  11/1200Z 26.8N 125.0W   35 KT  40 MPH...POST-TROPICAL

$$
Forecaster Brown

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