ZCZC HFOTCDCP2 ALL TTAA00 PHFO DDHHMM Post-Tropical Cyclone Flossie Discussion Number 35 NWS Central Pacific Hurricane Center Honolulu HI EP072019 500 PM HST Mon Aug 05 2019 Vigorous deep convection has been persistent through much of the day to the northeast of the cloud system center, which has become significantly elongated and poorly defined by several outflow boundaries. Recent analyses of satellite cloud drift winds suggest that the highly elongated cloud system center is lacking westerly winds that define a closed area of low pressure, and subjective Dvorak current intensity estimates were 25 kt from HFO and SAB, while JTWC deemed the system too weak to classify. Given these inputs and the presence of continued vertical wind shear of more than 30 kt, Flossie will be designated a post-tropical remnant low. The intensity will remain 30 kt, since an ASCAT-C pass earlier in the day detected winds this strong within the deep convection. While the cloud system center could arguably be a trough, a mean center location gives an initial motion of 300/10 kt. Under relentless vertical wind shear, the remnant low will continue to degenerate as it passes near the main Hawaiian Islands. The westerly vertical wind shear will be maintained by a deep upper-level trough parked northwest of the Hawaiian Islands. This upper trough is also eroding the low- to mid-level ridge that is steering Flossie. As a result, the remnant low will gradually turn toward the northwest tonight, then shift toward the north-northwest until dissipation on Wednesday. The track forecast was nudged to the right from the prior advisory and is near TVCN. All guidance shows weakening or little change in intensity until dissipation. This is the last advisory on Flossie. Additional information on this system can be found in the High Seas Forecasts issued by the National Weather Service in Honolulu under AWIPS header HFOHSFNP and WMO header FZPN40 PHFO. Interests in the main Hawaiian Islands should refer to products issued by the National Weather Service in Honolulu for information on flooding and surf impacts. FORECAST POSITIONS AND MAX WINDS INIT 06/0300Z 20.8N 154.6W 30 KT 35 MPH...POST-TROPICAL 12H 06/1200Z 22.1N 155.8W 30 KT 35 MPH...POST-TROP/REMNT LOW 24H 07/0000Z 24.0N 156.8W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 07/1200Z 26.0N 157.4W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 08/0000Z...DISSIPATED $$ Forecaster Wroe NNNN
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Page last modified: Tuesday, 31-Dec-2019 12:09:52 UTC