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Tropical Storm Flossie Discussion Number  23
NWS Central Pacific Hurricane Center Honolulu HI   EP072019
500 PM HST Fri Aug 02 2019
 
Tropical Storm Flossie has crossed into the Central North Pacific
basin as a messy system. Satellite images indicated limited deep
convection displaced northeast of the partially exposed low level
circulation center. Dvorak intensity estimates came in at 3.0/45 kt
from PFHO, JTWC, and SAB, and the CIMSS ADT value at 3/0000 UTC was
3.3/51 kt. Based on a blend of these estimates, and the poor
appearance in satellite imagery, the initial intensity for this
advisory has been lowered to 50 kt.

There is no change to the forecast track plan. Flossie continues to
move west-northwestward under the influence of a subtropical ridge
to the north of the cyclone. This direction of motion is expected to
continue over the next 48 hours but with a slightly slower forward
speed. Large-scale models indicate that the ridge will weaken as an
upper level trough approaches from the northwest. This should turn
Flossie toward a northwestward, and then northward track beyond the
48 hour time frame. All of the models are in general agreement with
this scenario, though HWRF and HMON indicate less of a turn and are
thus on the southern side of the guidance envelope. The forecast for
this advisory is right on the previous forecast through 24 hours,
then nudged slightly south of the previous track from 36 hours and
beyond to line up more closely with the TVCN and HCCA consensus.

Flossie is expected to traverse over marginal sea surface
temperatures through the forecast period. Furthermore, vertical
shear is expected to increase to above 30 knots after 48 hours in
the ECMWF SHIPS guidance. Given these factors, the model intensity
guidance shows continued weakening through the forecast period. The
current forecast is close to the IVCN and HCCA guidance, and makes
Flossie a tropical depression after 48 hours to the east of the main
Hawaiian Islands. 

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  03/0300Z 17.9N 141.0W   50 KT  60 MPH
 12H  03/1200Z 18.4N 143.0W   45 KT  50 MPH
 24H  04/0000Z 19.0N 145.5W   45 KT  50 MPH
 36H  04/1200Z 19.4N 147.8W   40 KT  45 MPH
 48H  05/0000Z 19.9N 150.0W   35 KT  40 MPH
 72H  06/0000Z 22.4N 154.2W   30 KT  35 MPH
 96H  07/0000Z 26.0N 156.0W   25 KT  30 MPH
120H  08/0000Z 31.0N 155.0W   25 KT  30 MPH
 
$$
Forecaster Kodama
 
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