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Tropical Storm MICHAEL


Tropical Storm Michael Discussion Number   5
NWS National Hurricane Center Miami FL       AL142018
400 PM CDT Sun Oct 07 2018

Deep convection has continued to develop over the eastern
semicircle of the cyclone, and data from the reconnaissance
aircraft indicate that the center has re-formed farther east,
closer to the convection.  The Air Force aircraft has measured peak
925-mb flight-level winds of 56 kt, and believable SFMR winds of
40-45 kt.  Based on these data, the initial wind speed has been
increased to 45 kt.

Due to the center reformation, the initial motion estimate is a
highly uncertain 020/3 kt.  The overall forecast reasoning has not
changed much since the previous advisory.  Although there could be
some additional eastward re-formation of the center, the tropical
storm is forecast to begin moving northward between a ridge over the
western Atlantic and a deep-layer trough over the west-central
United States.  A general northward motion at around 10 kt is then
expected to continue during the next 2 to 3 days. After that time,
Michael should turn northeastward ahead of an approaching trough.
The track guidance remains in overall agreement on this scenario,
however, significant along-track (forward speed and timing)
differences remain.  The HWRF brings Michael onshore the northern
Gulf coast within 72 hours, while the ECMWF is much slower and has
Michael still offshore at day 4. The new NHC track has been shifted
eastward primarily in the short term due to the more eastward
initial position.  The latter portion of the track forecast is again
close to the consensus aids due to the large along- and cross-track
guidance spread.

Michael has strengthened today despite moderate westerly shear.  The
shear is forecast to gradually decrease over the next couple of days
while the system moves over warm waters.  This should allow for
steady strengthening and most of the intensity models bring Michael
to hurricane strength within the next couple of days.  It should
also be noted that the global models also significantly deepen the
storm over the next 72 hours to pressures below 970 mb.  The new NHC
intensity forecast calls for Michael to become a hurricane in about
36 hours when the storm reaches the southeastern Gulf of Mexico.
Additional strengthening is indicated through 72 hours when the
storm is forecast to be near the northern Gulf coast, and the NHC
forecast is near the higher SHIPS and HWRF models.

Key Messages:

1.  Michael is expected to produce heavy rainfall and flash flooding
over portions of western Cuba and the northeastern Yucatan Peninsula
of Mexico during the next couple of days.

2.  Tropical storm conditions are expected tonight over portions of
western Cuba and the northeastern Yucatan Peninsula, where tropical
storm warnings are in effect.

3.  Michael is forecast to be a hurricane when it reaches the
northeastern Gulf Coast by mid-week, and the risk of dangerous storm
surge, rainfall, and wind impacts continues to increase. In
addition, Michael is expected to affect portions of the Florida Gulf
Coast that are especially vulnerable to storm surge, regardless of
the storm's exact track or intensity. Residents in these areas
should monitor the progress of this system and follow any advice
given by local officials.


INIT  07/2100Z 19.2N  85.5W   45 KT  50 MPH
 12H  08/0600Z 20.1N  85.6W   50 KT  60 MPH
 24H  08/1800Z 21.5N  85.8W   60 KT  70 MPH
 36H  09/0600Z 23.2N  86.2W   70 KT  80 MPH
 48H  09/1800Z 25.0N  86.7W   80 KT  90 MPH
 72H  10/1800Z 29.2N  85.7W   85 KT 100 MPH
 96H  11/1800Z 33.7N  80.4W   50 KT  60 MPH...INLAND
120H  12/1800Z 39.0N  68.5W   55 KT  65 MPH...POST-TROP/EXTRATROP

Forecaster Brown