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Tropical Storm COSME


Tropical Storm Cosme Discussion Number   5
NWS National Hurricane Center Miami FL       EP032019
800 AM PDT Sun Jul 07 2019

After a brief convective hiatus overnight, a small burst of
thunderstorms has redeveloped near and to the northeast of the
low-level center this morning, making positioning of the tropical
cyclone a little difficult. However, convection has been on the wane
during the past couple of hours despite relatively low vertical
wind shear conditions. The initial intensity has been maintained at
35 kt due to the increase in central convection.

The initial position and motion estimate of 305/08 kt are based
primarily on passive microwave satellite data. Cosme is forecast to
maintain a northwestward to west-northwestward motion over the next
few days due to the influence of a deep-layer ridge located to the
north of the cyclone. A 72-hr post-tropical position was added due
to the global models now hanging on to a closed surface low a
little bit longer. Otherwise, the new NHC forecast track is similar
to but north of the previous advisory track, mainly due to the more
northward initial position, and lies close to a blend of the HCCA
and the simple consensus models.

Cosme is moving over over marginal 26-deg-C SSTs, and the water
beneath the cyclone is forecast to cool to near 25C in about 24
hours. The unfavorable oceanic conditions, combined with the
entrainment of drier and more stable low- and mid-level air,
should result in complete loss of deep convection near the center by
Monday. As a result, Cosme is forecast to become a depression
later today, degenerate into post-tropical remnant low on Monday,
and dissipate in the 72-96 hour time period. The new official
intensity forecast is similar to the previous advisory, and closely
follows the HCCA and IVCN intensity consensus models.


INIT  07/1500Z 17.7N 118.4W   35 KT  40 MPH
 12H  08/0000Z 18.4N 119.5W   30 KT  35 MPH
 24H  08/1200Z 19.1N 120.4W   30 KT  35 MPH
 36H  09/0000Z 19.7N 121.2W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  09/1200Z 20.2N 122.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  10/1200Z 21.2N 124.2W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  11/1200Z...DISSIPATED

Forecaster Stewart