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Tropical Storm Ivo Discussion Number   3
NWS National Hurricane Center Miami FL       EP102019
900 PM MDT Wed Aug 21 2019

An earlier GMI microwave overpass that arrived after the release of
the previous advisory revealed a tightly coiled band of convection
that wrapped around the southern and southeastern portion of the
circulation.  More recent microwave imagery, however, shows that
the system is being impacted by northeasterly shear with the center
now located near the northeast portion of the primary convective
mass.  Objective and subjective Dvorak intensity estimates
unanimously supported an intensity of 45 kt, and the initial
intensity has been increased accordingly.

Ivo is expected to remain over warm SSTs and in a moist environment
during the next 36 h or so.  These conditions favor strengthening
however the aforementioned moderate northeasterly shear is likely
to temper the rate of intensification during that time.  The NHC
forecast calls for steady strengthening and again brings Ivo to
hurricane status within 36 h. After that time, cooler waters and a
drier and more stable air mass should cause weakening, and Ivo is
forecast to become post-tropical by day 4.  The official intensity
forecast shows a peak a little higher than most of the guidance but
otherwise is close to the model consensus.

Ivo is moving west-northwestward or 285/16 kt. The storm should
slow down later tonight or Thursday as it begins to move around the
southwestern portion of a subtropical ridge.  In about 24 hours, a
weakness is expected to develop in the ridge which is expected to
cause Ivo to turn northwestward.  A general northwestward motion
should then continue through the remainder of the forecast period.
An additional reduction in forward speed is likely late in the
forecast period as the system weakens and becomes vertically
shallow.  The track guidance as trended toward a slower motion
after 72 hours, and the updated NHC track has been adjusted a little
southward.


FORECAST POSITIONS AND MAX WINDS

INIT  22/0300Z 16.1N 111.3W   45 KT  50 MPH
 12H  22/1200Z 16.5N 113.2W   55 KT  65 MPH
 24H  23/0000Z 17.6N 114.9W   60 KT  70 MPH
 36H  23/1200Z 18.8N 116.0W   70 KT  80 MPH
 48H  24/0000Z 20.0N 116.9W   65 KT  75 MPH
 72H  25/0000Z 23.2N 118.5W   50 KT  60 MPH
 96H  26/0000Z 26.4N 120.4W   35 KT  40 MPH...POST-TROPICAL
120H  27/0000Z 28.8N 121.8W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Brown

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