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Tropical Storm Flossie Discussion Number  17
NWS National Hurricane Center Miami FL       EP072019
500 AM HST Thu Aug 01 2019

The structure of Flossie hasn't changed in any meaningful way since
last night. Recent SSMI microwave data indicate that the center of
the tropical storm is displaced to the northwest of all of its deep
convection, and its IR presentation hasn't changed since the last
advisory. Since Flossie's appearance and structure has been nearly
steady-state, the initial intensity remains 55 kt, based primarily
on earlier ASCAT data.

The NHC intensity forecast is very similar to the previous advisory,
and Flossie is still expected to remain a tropical storm for the
next 5 days. The intensity guidance is finally in good agreement on
the forecast, and all of the models indicate that that Flossie's
strength will not change substantially for the next day or two,
followed by gradual weakening through early next week. In fact, the
GFS now forecasts that Flossie will dissipate in about 5 days. The
new official intensity forecast is near the middle of the intensity
guidance envelope and is very close to IVCN at all forecast hours.

The initial motion of the cyclone is still 285/14 kt. There is high
confidence in the first 72 h the track forecast, and all of the
guidance continues to keep Flossie near its current heading and
speed through that period. The spread increases dramatically after
that, with the regional models (HWRF, HMON, COAMPS-TC) all taking a
weak Flossie farther south, possibly even south of Hawaii, while the
global models all show Flossie recurving east of the islands ahead
of a mid- to upper-level trough. For the moment, the NHC forecast
continues to favor the global model solution and does not show a
significant change to the track forecast, however it has been
tweaked slightly southward at days 4 and 5.

It is worth noting that the confidence in the 5-day forecast
position of Flossie is quite low, and the average error of track and
intensity forecasts at that range is about 200 miles and 20 mph,
respectively. In addition, hazards associated with tropical storms
extend well away from the center of circulation. Users should
therefore consult local forecasts from the National Weather Service
Forecast Office in Honolulu, Hawaii, at www.weather.gov/hfo for
information specific to the Hawaiian Islands.


FORECAST POSITIONS AND MAX WINDS

INIT  01/1500Z 15.1N 131.6W   55 KT  65 MPH
 12H  02/0000Z 15.6N 133.9W   55 KT  65 MPH
 24H  02/1200Z 16.3N 136.9W   55 KT  65 MPH
 36H  03/0000Z 16.9N 139.8W   55 KT  65 MPH
 48H  03/1200Z 17.5N 142.5W   50 KT  60 MPH
 72H  04/1200Z 18.4N 147.5W   45 KT  50 MPH
 96H  05/1200Z 19.5N 152.5W   45 KT  50 MPH
120H  06/1200Z 22.5N 155.5W   35 KT  40 MPH

$$
Forecaster Zelinsky

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