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Tropical Storm Jimena Discussion Number 15
NWS National Hurricane Center Miami FL EP092021
500 AM HST Fri Aug 06 2021
A convective mass continues to persist over the center of Jimena,
although coldest cloud tops have warmed over the past few hours.
A fortuitous 1105 UTC AMSR-2 pass shows the center a bit west of
the earlier estimates, which places it beneath the coldest
remaining cloud tops. The intensity is held at 35 kt based on a
blend of Final-T and CI numbers from TAFB, SAB and ADT. This
intensity is also supported by overnight ASCAT data and a more
recent ship observation. Jimena is currently moving over SSTs near
24C. Going forward, westerly shear will increase along the
cyclone's path during the next 12-24 hr. These factors should cause
the tropical cyclone to weaken, and Jimena is expected to degenerate
into a remnant low by Saturday morning. The NHC intensity forecast
is in good agreement with the SHIPS and HCCA guidance.
The initial motion estimate is 300/8 kt. As Jimena weakens, the
increasingly shallow system is expected to be steered by the
low-level trade-wind flow, which should cause it to gradually turn
toward the west in about 48 hours. The ECMWF is a little faster and
lies on the southwest side of the guidance envelope, while the GFS
is slower and northeast of the consensus. The NHC forecast was
adjusted to the southwest of the previous forecast during the
first 12-24 hours based on the farther west initial position.
Thereafter, the track is close to the previous forecast, and in
best agreement with the HCCA and TVCN consensus models.
FORECAST POSITIONS AND MAX WINDS
INIT 06/1500Z 17.5N 139.3W 35 KT 40 MPH
12H 07/0000Z 18.0N 140.4W 30 KT 35 MPH
24H 07/1200Z 18.7N 141.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 08/0000Z 19.2N 143.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 08/1200Z 19.5N 144.9W 20 KT 25 MPH...POST-TROP/REMNT LOW
60H 09/0000Z 19.6N 146.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 09/1200Z...DISSIPATED
$$
Forecaster Hagen/Brown
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