Tropical Depression Four-E Discussion Number 2
NWS National Hurricane Center Miami FL EP042023
800 AM PDT Fri Jul 21 2023
Convection associated with Tropical Depression Four-E has persisted
overnight and into this morning. However, the convective pattern is
one of a strongly sheared system, with cold echo tops only over the
eastern side of the system. In the last few hours, Proxy-vis
satellite imagery shows that the low-level center has become exposed
near the western edge of the convection. Subjective Dvorak satellite
estimates from TAFB and SAB were T2.5 and T2.0, respectively. Given
the current structure with the low-level center becoming exposed,
and the subjective satellite estimates, the initial intensity for
this advisory remains at 30 kt.
The depression continues to be in an environment of strong
upper-level westerly wind shear of 25 to 30 knots, which has exposed
the low-level center, and displaced the convection to the east. The
system will be crossing the 25 degree C isotherm later today, with
cooler SSTs remaining along the forecast track. Given these marginal
conditions, it is likely the depression will be short-lived, with
the system becoming a remnant low later this weekend, and
dissipating by 60 hours. However, some models suggest it could
weaken and dissipate sooner.
The system is moving west-northwestward at 11 kt. A ridge centered
over the southwestern United States should continue to steer the
depression on this general heading and speed for the next day or
so. Afterward, the shallow remnant low is expected to turn more
westward in the low-level flow. The NHC track forecast lies near
the previous forecast, which is near the center of the consensus
aids.
FORECAST POSITIONS AND MAX WINDS
INIT 21/1500Z 15.2N 123.6W 30 KT 35 MPH
12H 22/0000Z 15.9N 125.4W 30 KT 35 MPH
24H 22/1200Z 16.5N 127.6W 30 KT 35 MPH
36H 23/0000Z 16.8N 129.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 23/1200Z 17.0N 131.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
60H 24/0000Z...DISSIPATED
$$
Forecaster Kelly/Brown
NWS National Hurricane Center Miami FL EP042023
800 AM PDT Fri Jul 21 2023
Convection associated with Tropical Depression Four-E has persisted
overnight and into this morning. However, the convective pattern is
one of a strongly sheared system, with cold echo tops only over the
eastern side of the system. In the last few hours, Proxy-vis
satellite imagery shows that the low-level center has become exposed
near the western edge of the convection. Subjective Dvorak satellite
estimates from TAFB and SAB were T2.5 and T2.0, respectively. Given
the current structure with the low-level center becoming exposed,
and the subjective satellite estimates, the initial intensity for
this advisory remains at 30 kt.
The depression continues to be in an environment of strong
upper-level westerly wind shear of 25 to 30 knots, which has exposed
the low-level center, and displaced the convection to the east. The
system will be crossing the 25 degree C isotherm later today, with
cooler SSTs remaining along the forecast track. Given these marginal
conditions, it is likely the depression will be short-lived, with
the system becoming a remnant low later this weekend, and
dissipating by 60 hours. However, some models suggest it could
weaken and dissipate sooner.
The system is moving west-northwestward at 11 kt. A ridge centered
over the southwestern United States should continue to steer the
depression on this general heading and speed for the next day or
so. Afterward, the shallow remnant low is expected to turn more
westward in the low-level flow. The NHC track forecast lies near
the previous forecast, which is near the center of the consensus
aids.
FORECAST POSITIONS AND MAX WINDS
INIT 21/1500Z 15.2N 123.6W 30 KT 35 MPH
12H 22/0000Z 15.9N 125.4W 30 KT 35 MPH
24H 22/1200Z 16.5N 127.6W 30 KT 35 MPH
36H 23/0000Z 16.8N 129.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 23/1200Z 17.0N 131.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
60H 24/0000Z...DISSIPATED
$$
Forecaster Kelly/Brown
