Tropical Storm Flossie Winds: 55 kt
Pressure: 994 mbar
Advisory 17 / 2:00 PM PDT Thursday, August 1, 2019

There has been little change to the appearance of Flossie today, with the low-level circulation partially exposed to the west of deep convection. A WindSAT pass received just after the previous advisory indicates that things are not completely solemn for Flossie, as the storm has a well-defined mid-level eye feature underneath that convection; there may be hints of this feature on visible imagery. An 18z ASCAT pass showed a wide swath of 45-50kt winds; accounting for the instrument's low bias and Flossie's concentrated wind field, the initial intensity remains 55kt.

Flossie is experiencing about 20kt of vertical wind shear, and SHIPS analyses indicate these upper-level winds may only fall to between 10-15kt for 18 hours or so. During that time, ocean temperatures are expected to hover between 26-27C, indicative of a marginal thermodynamic environment, especially coupled with mid-level relative humidity values in the low 50s percent. The HWRF and ECMWF continue to indicate the potential for some slight re-intensification in the short term, and this may be backed up by the presence of the mid-level eye. Thus, the new forecast continues to show an upward trend for the next 24 hours, although it would not be surprising if Flossie just continued to succumb to strong wind shear instead. By 36 hours and beyond, upper-level winds are expected to become downright hostile. This should cause quick weakening. The primary change to this forecast is to show degeneration at day 5, though this feasibly could occur sooner. Both the GFS and ECMWF show intensification of the cyclone on day 5, but this does not appear to be through tropical processes.

Flossie is moving rapidly west-northwest, positioned south of a stout mid-level ridge to the storm's north. This trajectory should continue for the next 72 hours. Thereafter, a mid-level trough to the west of Hawaii should erode the ridge and force Flossie toward the west-northwest and eventually north. This curve has become much more pronounced in modeling today, decreasing but not wholly eliminating the odds that Flossie strikes Hawaii.


INIT 01/2100Z 55 KT 65 MPH

12H 02/0600Z 60 KT 70 MPH

24H 02/1800Z 65 KT 75 MPH

36H 03/0600Z 60 KT 70 MPH

48H 03/1800Z 55 KT 65 MPH

72H 04/1800Z 45 KT 50 MPH

96H 05/1800Z 35 KT 40 MPH

120H 06/1800Z 30 KT 35 MPH...POST-TROP/REMNT LOW

Forecaster TAWX14
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