[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 300836
TCDAT3

Tropical Storm Rina Discussion Number   8
NWS National Hurricane Center Miami FL       AL182023
500 AM AST Sat Sep 30 2023

Rina remains a sheared tropical cyclone.  Deep bursts of convection
have been flaring to the southeast of an exposed low-level
circulation.  However, recent trends in geostationary satellite
imagery have shown the convection shrinking in areal coverage and
becoming shallower.  The latest subjective Dvorak intensity
estimates were T3.0 (45 kt) and T2.5 (35 kt) from TAFB and SAB,
respectively.  The initial intensity is held at a possibly
generous 45 kt in deference to the earlier scatterometer pass and
the latest TAFB estimate.

It is unlikely Rina will regain significant convective organization.
Global model guidance indicates that the deep-layer vertical wind
shear is likely to remain strong for the entirety of the forecast
period.  Simulated satellite imagery shows convection attempting
to re-form near the center for the next couple of days, but it is
quickly stripped away by the strong upper-level winds.  The NHC
intensity forecast shows Rina gradually weakening and becoming a
remnant low in 48 h.

Rina is moving to the west-northwest at 9 kt.  Tropical Storm
Philippe, to its west-southwest, and a subtropical mid-level ridge
to the northeast are likely to steer Rina generally
west-northwestward to northwestward through 48 h.  Only minor
adjustments have been made to the latest track forecast.


FORECAST POSITIONS AND MAX WINDS

INIT  30/0900Z 20.9N  49.5W   45 KT  50 MPH
 12H  30/1800Z 21.7N  50.9W   40 KT  45 MPH
 24H  01/0600Z 22.9N  52.8W   40 KT  45 MPH
 36H  01/1800Z 24.2N  54.6W   35 KT  40 MPH
 48H  02/0600Z 26.0N  56.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 60H  02/1800Z 27.6N  56.9W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  03/0600Z...DISSIPATED

$$
Forecaster Bucci
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