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 669 
 WTPZ42 KNHC 061522 CCB
 TCDEP2
 
 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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It was last modified on: , 17 2014 - 1841 UTC
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