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Tropical Depression NINE-E Forecast Discussion


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000
WTPZ44 KNHC 221454
TCDEP4

Tropical Depression Nine-E Discussion Number   5
NWS National Hurricane Center Miami FL       EP092017
1000 AM CDT Sat Jul 22 2017

The depression has failed to strengthen as previously indicated, and
both the circulation and the convection are not currently as
organized as it seemed to be 24 hours ago when advisories were
initiated. Microwave data reveal that the center appears to be
located on the south side of the main convection, and the low and
mid-level centers are not aligned. Based on Dvorak numbers, the
maximum winds are estimated at 30 kt. Having said that, the
depression is expected to move through a very favorable moist
environment of low shear during the next several days, and the ocean
is plenty warm.  With these conditions present, the NHC forecast
insists on strengthening and still anticipates that the depression
will become a hurricane in about 48 hours. Guidance is a little bit
less aggressive than earlier but still forecasts intensification.

With the low-level center difficult to locate, the initial motion
has become uncertain. The best estimate is toward the west-northwest
or 290 degrees at 10 kt. A persistent subtropical ridge extending
from Mexico westward across the Pacific will keep steering the
cyclone on the same general track for the next five days. This is
the solution provided by track guidance which, in fact, is tightly
clustered. The NHC forecast is in the middle of the tight envelope,
and is not very different from the previous official forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  22/1500Z 10.0N  98.2W   30 KT  35 MPH
 12H  23/0000Z 10.5N  99.4W   35 KT  40 MPH
 24H  23/1200Z 11.6N 101.3W   40 KT  45 MPH
 36H  24/0000Z 12.5N 103.0W   50 KT  60 MPH
 48H  24/1200Z 13.5N 104.5W   65 KT  75 MPH
 72H  25/1200Z 15.0N 108.0W   85 KT 100 MPH
 96H  26/1200Z 16.5N 111.5W   90 KT 105 MPH
120H  27/1200Z 18.0N 115.0W   95 KT 110 MPH

$$
Forecaster Avila