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Tropical Storm Rina Discussion Number   7
NWS National Hurricane Center Miami FL       AL182023
1100 PM AST Fri Sep 29 2023
 
Rina continues to produce persistent but poorly organized shower and
thunderstorm activity well to the east of its exposed surface
center. Despite the apparent lack of organization, a pair of ASCAT 
passes near 00Z revealed that Rina's wind field was both slightly 
larger and stronger than previously estimated. Both ASCAT passes 
showed a large swath of winds of 40-45 kt east and northeast of 
Rina's center. Based on this new information, the intensity of Rina 
has been increased to 45 kt. Both ASCAT passes had slightly higher 
winds in the deep convection that were flagged as marginal for 
rain contamination, so they weren't considered as representative. 
That said, its possible 45 kt could be slightly conservative.
 
With SHIPS-analyzed 850-200 mb shear higher than 40 kt for the next 
24 h, its very unlikely Rina will become any better organized than 
it is now. Nearly all of the dynamical models forecast that Rina 
will dissipate in the next 24 to 48 h. Based on the structure 
information provided by ASCAT, it appears unlikely that the tropical 
storm will dissipate that quickly. Therefore the the NHC official 
forecast is a little more conservative, but still shows Rina slowly 
weakening, close to the intensity consensus. It is worth noting that 
the vortex tracker associated with a few models flipped to Philippe 
beyond 72 h and the tracks are therefore not representative of the 
actual model forecast.
 
Rina is heading northwestward near 10 kt. The combination of
Tropical Storm Philippe to its west-southwest and a subtropical
ridge to the northeast should keep Rina on this general heading for
a couple of days. The NHC track forecast is near the center of the
guidance envelope, between the simple and corrected consensus aids.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  30/0300Z 20.4N  48.8W   45 KT  50 MPH
 12H  30/1200Z 21.1N  50.2W   45 KT  50 MPH
 24H  01/0000Z 22.2N  51.9W   40 KT  45 MPH
 36H  01/1200Z 23.3N  53.7W   35 KT  40 MPH
 48H  02/0000Z 24.8N  55.6W   30 KT  35 MPH...POST-TROP/REMNT LOW
 60H  02/1200Z 26.7N  56.8W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  03/0000Z...DISSIPATED
 
$$
Forecaster D. Zelinsky
 
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