[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 192042
TCDAT2

Tropical Storm Bret Discussion Number   5
NWS National Hurricane Center Miami FL       AL022017
500 PM AST Mon Jun 19 2017

An Air Force WC-130 invest mission this afternoon into the
disturbance was able - after much effort - to find a well-defined
closed circulation.  The location of the center was substantially
farther west than anticipated, as the system is now moving toward
the west-northwest at a very quick 26 kt.  Because the system
has developed a well-defined center, it is now considered a tropical
storm and has been named Bret.

Convection continues to display robust bands on the northwestern
and southeastern quadrants of the disturbance, as seen in the
geostationary satellite and Trinidad radar imagery.  The Hurricane
Hunter mission also found maximum surface winds of about 35 kt,
which agrees with the Dvorak 2.5 CI number from TAFB.  These winds
are only occurring in the northern semicircle due to the very quick
translational velocity of the system.

While the convective structure has been impressive today, it
appears that the window of opportunity for the system to
further develop is closing.  Between interaction with the landmass
of Venezuela and increasing vertical shear beginning in about a day,
the intensity model guidance does not show any significant
intensification.  The official intensity forecast is steady state
for about a day, followed by gradual weakening until dissipation in
about three days. An alternative scenario - given that the
disturbance has tracked left, or equatorward, of the guidance thus
far - is that it could remain south of the forecast track and
dissipate over Venezuela and never reach the Caribbean Sea.

The system is anticipated to slow somewhat, but still move at a
rapid rate toward the west-northwest until dissipation, steered by
strong trade winds south of the Bermuda high.  The official track
forecast is based upon the HCCA corrected consensus technique and is
faster compared with the previous advisory, due to the farther west
initial position.


FORECAST POSITIONS AND MAX WINDS

INIT  19/2100Z  9.4N  59.8W   35 KT  40 MPH
 12H  20/0600Z 10.1N  62.1W   35 KT  40 MPH
 24H  20/1800Z 11.3N  65.3W   35 KT  40 MPH
 36H  21/0600Z 12.2N  68.5W   30 KT  35 MPH
 48H  21/1800Z 13.0N  73.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  22/1800Z...DISSIPATED

$$
Forecaster Landsea
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