Tropical Storm Flossie Winds: 60 kt
Pressure: 992 mbar
Advisory 13 / 2:00 PM PDT Wednesday, July 31, 2019

Flossie has weakened significantly today. The low-level circulation has become exposed to the west of the associated deep thunderstorm activity, a sign that strong upper-level winds continue to affect the cyclone. Satellite intensity estimates from this morning supported a healthy Category 1 hurricane; however, closer inspection of microwave imagery from the same time indicates that these values were likely too high considering Flossie's inner core had dissipated and the center had become displaced from the convection. An 1820z ASCAT pass showed peak winds of 50-55kt in the northeast quadrant; therefore, the initial intensity is sharply decreased to 60kt. This may be generous.

Clearly, the usually-reliable HWRF model will not score a coup in this case. Upper-level winds according to the SHIPS have increased to over 20kt, and similar values are depicted through 24 hours. Shear is then expected to decrease for a short period thereafter, which may allow for some re-intensification amid marginal ocean temperatures and mid-level relative humidity values. After 72 hours, the environment is expected to become hostile as wind shear increases again. The updated forecast reflects this philosophy.

Flossie is still moving toward the west, and a trajectory between west and west-northwest is expected to continue for the remainder of the period as mid-level ridging remains stout north of the cyclone. On this path, Flossie will likely approach the Hawaiian Islands about 5 days from now, though this approach will be as a weakening storm.


INIT 31/2100Z 60 KT 70 MPH

12H 01/0600Z 55 KT 65 MPH

24H 01/1800Z 60 KT 70 MPH

36H 02/0600Z 65 KT 75 MPH

48H 02/1800Z 70 KT 80 MPH

72H 03/1800Z 65 KT 75 MPH

96H 04/1800Z 60 KT 70 MPH

120H 05/1800Z 50 KT 60 MPH

Forecaster TAWX14
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