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TROPICAL STORM DANIELLE DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL042016
1000 AM CDT MON JUN 20 2016

An Air Force Reserve reconnaissance aircraft this morning measured
an 850-mb maximum flight-level wind of 52 kt north of the center
along with an SFMR surface wind of 40 kt. Based on these data and
the overall improvement in the satellite presentation, the
depression was upgraded to a tropical storm. Danielle becomes the
earliest fourth-named storm in the Atlantic basin, surpassing
Tropical Storm Debbie of 2012.

The initial motion estimate is 280/06 kt. Recon wind data indicate
that Danielle made a jog to the northwest, probably due to
reformation of the low-level center closer to an earlier burst of
strong convection. However, the general east-to-west deep layer
steering flow supports a slow but steady motion toward the west or
west-northwest for the next 24 hours, resulting in Danielle moving
inland along the east coast of Mexico later today or tonight. The
official forecast track lies close to the HWRF model.

Some modest strengthening before landfall cannot be ruled out, but
no rapid or significant strengthening is expected due to Danielle's
imminent interaction with land. Rapid weakening of the wind field is
forecast after landfall occurs, with dissipation expected by 36 h.

Heavy rainfall continues to be the primary threat associated with
Danielle.  These rains could cause life-threatening flash floods
and mudslides over portions of eastern Mexico during the next couple
of days.

FORECAST POSITIONS AND MAX WINDS

INIT  20/1500Z 20.7N  96.3W   40 KT  45 MPH
 12H  21/0000Z 20.8N  97.2W   40 KT  45 MPH...NEAR THE COAST
 24H  21/1200Z 20.8N  98.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  22/0000Z...DISSIPATED INLAND

$$
Forecaster Stewart

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