831 
 WTPZ45 KNHC 250843
 TCDEP5
 
 Tropical Depression Twenty-E Discussion Number   1
 NWS National Hurricane Center Miami FL       EP202018
 300 AM MDT Tue Sep 25 2018
 
 The low pressure system that NHC has been monitoring off the coast
 of southwestern Mexico has now become a tropical depression, the
 twentieth of the eastern North Pacific 2018 season.  ASCAT data from
 around 0400 UTC indicated that the system had a well-defined center
 and maximum winds in the 25-30 kt range.  In addition, satellite
 images show deep convection increasing in coverage and intensity
 near the center.  The initial wind speed is set at 30 kt, based on
 the ASCAT data, but this is a little below the latest Dvorak
 estimate from TAFB.
 
 Since the depression has only recently formed, the initial motion
 is an uncertain 280/7 kt.  Mid-level ridging to the north of the
 system should keep the depression on a westward to west-
 northwestward path at about the same forward speed for the
 next few days.  Thereafter, the models show the ridge breaking down
 due to a large cut off deep-layer low moving toward the west coast
 of the United States.  In response, the cyclone is expected to turn
 to the northwest this weekend.  The models agree on this overall
 scenario, but there is a fair amount of spread by the end of the
 forecast period.  The NHC track forecast lies near the middle of
 the guidance envelope and close to the best performing models, the
 consensus aids.
 
 The environmental conditions appear favorable for the depression to
 strengthen.  SSTs are expected to remain quite warm beneath the
 cyclone for the next several days while vertical wind shear values
 are around 10 kt or less.  These conditions combined with a
 moist airmass should allow for at least steady strengthening during
 the next 3 to 4 days.  Some weakening is possible by the end of the
 forecast period due to slightly cooler SSTs and an increase in
 shear.  The NHC intensity forecast shows a slower rate of
 strengthening than the guidance, since the system is still
 in the developing stage, but predicts peak winds near the IVCN
 consensus model.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  25/0900Z 14.5N 107.2W   30 KT  35 MPH
  12H  25/1800Z 14.9N 108.2W   35 KT  40 MPH
  24H  26/0600Z 15.5N 109.8W   40 KT  45 MPH
  36H  26/1800Z 15.8N 111.2W   55 KT  65 MPH
  48H  27/0600Z 16.1N 112.6W   70 KT  80 MPH
  72H  28/0600Z 16.9N 115.6W   90 KT 105 MPH
  96H  29/0600Z 18.3N 118.1W   90 KT 105 MPH
 120H  30/0600Z 20.7N 119.5W   85 KT 100 MPH
 
 $$
 Forecaster Cangialosi
 
 

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