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Tropical Storm Irwin Discussion Number   9
NWS National Hurricane Center Miami FL       EP102023
500 PM HST Mon Aug 28 2023
 
Irwin has surprisingly recovered some of its convective organization
over the past few hours. Convection is primarily north of Irwin's
center of circulation, which may have contributed to the tropical
storm moving well to the right of NHC's forecasts for the last 18
hours or so. Earlier ASCAT data and the latest Dvorak analysis from
TAFB support the 35-kt intensity analysis.
 
Despite its recent poleward jog, Irwin is forecast to finally turn
westward tonight. The track models are in very good agreement now
on the forecast for Irwin, so only a small northward adjustment was
made to the NHC track forecast to account for Irwin's recent
right-of-track motion. A low- to mid-level ridge to the north of
Irwin should keep the cyclone moving westward for the majority of
the forecast period, whether it retains its tropical cyclone status
or not. The NHC track forecast is based on the variable track
consensus aid TVCN.
 
Despite cool waters beneath Irwin and dry air surrounding the
tropical cyclone, simulated satellite imagery from most dynamical
models continues to indicate that Irwin will sustain some deep
convection for at least a couple more days. Small fluctuations in
intensity are possible during that period. Sooner or later, the
environment should cause Irwin to weaken and become post-tropical.
No changes of note were made to the NHC intensity forecast.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/0300Z 19.3N 125.7W   35 KT  40 MPH
 12H  29/1200Z 19.5N 127.8W   35 KT  40 MPH
 24H  30/0000Z 19.2N 130.7W   35 KT  40 MPH
 36H  30/1200Z 19.1N 133.2W   30 KT  35 MPH
 48H  31/0000Z 19.1N 135.4W   30 KT  35 MPH
 60H  31/1200Z 19.3N 137.2W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  01/0000Z 19.4N 138.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  02/0000Z 19.6N 140.8W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  03/0000Z 19.6N 143.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster D. Zelinsky
 
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