299 
WTPZ45 KNHC 131434
TCDEP5
 
Hurricane Darby Discussion Number  17
NWS National Hurricane Center Miami FL       EP052022
500 AM HST Wed Jul 13 2022
 
Surprise! The eye of Darby reappeared this morning in IR imagery 
after a hiatus overnight. Recent TAFB and SAB Dvorak estimates, and 
the U-W CIMSS ADT all support an intensity of 90 kt, so Darby's 
intensity was adjusted to that value. It should be stressed that 
this appears to be a short-term fluctuation and has not changed the 
overall thinking behind the intensity forecast, which calls for 
Darby to generally weaken over the next few days.
 
Darby could maintain its intensity with small fluctuations today, 
but all available intensity guidance indicates it will resume 
weakening by tonight or tomorrow (if not sooner). This is likely 
because it is moving through a marginal environment that includes 
SSTs dropping below 26 deg C and 700-500 mb relative humidities 
between 55-60 percent based on GFS and ECMWF-based SHIPS 
diagnostics. After 24 h, an increase in wind shear should cause 
Darby to weaken at a faster rate, particularly given the small size 
of the hurricane. Simulated satellite output from the GFS, ECMWF and 
HWRF models indicate Darby will lose all deep convection and become 
post-tropical in about 60 h. The cyclone should subsequently 
dissipate about a day after that. The NHC intensity forecast is 
similar to the previous forecast and is near or just below the 
intensity consensus (IVCN) at all forecast hours.
 
Virtually no change was made to the NHC track forecast. Darby 
appears to have started an expected brief west-northwestward jog, 
with an initial motion just north of due west at 14 kt. Darby should 
complete that turn and move west-northwestward today, and then turn 
westward tomorrow as it weakens through the end of the week. The 
official track forecast is based heavily on the multi-model 
consensus aids HCCA and TVCE.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/1500Z 15.0N 135.4W   90 KT 105 MPH
 12H  14/0000Z 15.4N 137.4W   85 KT 100 MPH
 24H  14/1200Z 16.0N 140.0W   75 KT  85 MPH
 36H  15/0000Z 16.4N 142.5W   60 KT  70 MPH
 48H  15/1200Z 16.6N 145.2W   50 KT  60 MPH
 60H  16/0000Z 16.6N 148.0W   40 KT  45 MPH...POST-TROPICAL
 72H  16/1200Z 16.3N 151.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  17/1200Z...DISSIPATED
 
$$
Forecaster D. Zelinsky