ZCZC HFOTCDCP2 ALL
TTAA00 PHFO DDHHMM
 
Tropical Storm Flossie Discussion Number  29
NWS Central Pacific Hurricane Center Honolulu HI   EP072019
500 AM HST Sun Aug 04 2019
 
Strong thunderstorms in Flossie's eastern semicircle persisted for 
the first half of the night, prevented from moving over the low-
level circulation center (LLCC) by persistent westerly vertical
wind shear near 25 kt. Those thunderstorms began diminishing
shortly after midnight, and while the LLCC remains obscured by mid-
and high-level cloudiness, it appears poised to make an appearance. 
Subjective and objective Dvorak intensity estimates indicate that 
Flossie is barely hanging on as a tropical storm, and with the LLCC 
becoming increasingly exposed, the initial intensity estimate for 
this advisory is lowered to 35 kt. 

Without any overnight microwave passes to assist with center-
finding, the initial motion estimate is primarily based on tracking 
what can be seen of the LLCC, yielding 280/11 kt. A low- to mid-
level ridge north of the cyclone is expected to support a general 
motion toward the west over the next 24-36 hours, especially as 
Flossie weakens further and is steered by the low-level trade wind 
flow. After that, Flossie will round the western portion of the 
ridge, interact with a persistent deep-layer trough northwest of 
Hawaii, and dissipate. The updated track forecast was changed
little from the previous, which represented a significant westward
shift, and lies close to the EMXI and HCCA. Given average forecast
error, a Tropical Storm Watch may be required for portions of the
Hawaiian Islands later today. 

The gradual spin-down of Flossie is expected to continue as it
draws closer to the Hawaiian Islands, despite SSTs gradually warming
to near 27C. The forecast track takes Flossie into an area of even
greater vertical wind shear, leading to steady weakening, soon
followed by dissipation. The intensity forecast has changed little,
and mimics trends indicated by both the statistical and dynamical
guidance.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  04/1500Z 19.3N 147.8W   35 KT  40 MPH
 12H  05/0000Z 19.4N 149.7W   35 KT  40 MPH
 24H  05/1200Z 19.7N 152.2W   35 KT  40 MPH
 36H  06/0000Z 20.4N 154.8W   30 KT  35 MPH
 48H  06/1200Z 21.6N 156.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  07/1200Z...DISSIPATED
 
$$
Forecaster Birchard
 
NNNN