Tropical Storm GREG (Text)


Tropical Storm Greg Discussion Number  23
NWS National Hurricane Center Miami FL       EP072017
800 PM PDT Sat Jul 22 2017

Greg's cloud pattern remains unimpressive, with a rather
disorganized area of convection found to the west and northwest of
the low-level center. The latest Dvorak estimates are about the same
as before, so the initial intensity estimate remains 45 kt.

Little change in strength is expected during the first 24 hours, as
the near-storm environment is not expected to change much during
that time. Afterward, however, the usually lethal combination of
cooling SSTs and a drying low- to mid-level atmosphere, along with
increasing shear at days 4-5, should bring about the gradual demise
of Greg. Remnant low status is now forecast by 96 hours, and the new
NHC intensity forecast is in line with the bulk of the latest

A timely SSMIS pass from 23/0005Z was helpful in establishing the
initial position of Greg, which is a little south and west of
previous estimates. Based on this, the initial motion estimate is
265/11, as Greg continues moving to the south of an expansive low-
to mid-level ridge over the eastern Pacific. This ridge will begin
to weaken in 48-72 hours, which should result in Greg turning a
little more poleward during that time with a slight decrease in
forward speed. By the end of the period, the shallow remnants of
Greg should turn westward in the low-level trade wind flow over the
central Pacific. Based on the initial position and the trend in the
latest guidance, the new NHC track forecast is faster and has been
adjusted to the left of the previous forecast, especially at days 3
through 5. The NHC prediction is close to the latest consensus aids
through day 3, but lies a bit to the right of those aids at days 4
and 5 out of respect to continuity.


INIT  23/0300Z 14.9N 126.5W   45 KT  50 MPH
 12H  23/1200Z 14.9N 128.3W   45 KT  50 MPH
 24H  24/0000Z 14.8N 130.8W   45 KT  50 MPH
 36H  24/1200Z 14.9N 132.9W   40 KT  45 MPH
 48H  25/0000Z 15.2N 134.6W   35 KT  40 MPH
 72H  26/0000Z 16.3N 137.2W   30 KT  35 MPH
 96H  27/0000Z 17.5N 140.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  28/0000Z 17.5N 143.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

Forecaster Brennan


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Page last modified: Monday, 23-Oct-2017 12:10:04 UTC