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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.
FORECAST POSITIONS AND MAX WINDS
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
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