NHC issues Tropical Cyclone Discussion (TCD) at Oct 9, 7:00 AM AST149
WTNT43 KNHC 090240
TCDAT3
Hurricane Leslie Discussion Number 27
NWS National Hurricane Center Miami FL AL132024
1100 PM AST Tue Oct 08 2024
This evening, Leslie's structure has improved further as deep
convection can be seen wrapping around the center on GOES-16
infrared imagery. An earlier ISS-COWVR microwave pass at 2021 UTC
also showed a small inner-core eyewall feature. Subjective Dvorak
fixes from TAFB and SAB were both T4.0/65-kt, but objective
estimates from ADT and SATCON have jumped up to 79 and 74 kt
respectively, and thus the initial intensity is raised to 70 kt, in
between the subjective and objective estimates.
One thing that hasn't changed is Leslie's current motion, still off
to the northwest at 310/10 kt. Over the next couple of days, Leslie
will be approaching the westward extent of the subtropical ridge
that has been its primary steering mechanism, resulting in a gradual
slow down and turn northward by the end of this week. Leslie is then
expected to be captured by an approaching long-wave trough, leading
to a northeastward motion by the end of the forecast period. The NHC
track continues to be in good agreement with the track guidance, and
is just a touch west compared to the prior forecast.
Leslie's intensity prospects in the short-term have undergone a
reversal from yesterday. The shear that had been affecting the
hurricane has subsided, and SHIPS guidance now shows deep-layer
shear reaming under 10 kt for at least the next 24 hours. Even
though Leslie has been traveling over a cooler ocean left behind
from Kirk last week, the sea-surface temperatures still appear to be
warm enough (27-28 C) to promote intensification, as evidence of its
continued deep convective bursts which have helped reform its inner
core. The intensity guidance has responded to these changes by now
showing more intensification. In fact, the raw 18 UTC HAFS-A/B runs
now show intensification up to 80-85 kt in 36 hours. In addition,
the latest ECMWF run, not usually known for being at the upper-end
of the intensity guidance, shows significant deepening in the
short-term, with a forecast pressure down to 969 mb by early
Thursday morning. Based on these signals, the intensity guidance was
raised upward significantly in the short term, and now shows Leslie
peaking as an 80 kt hurricane in 24-36 hours. After that time, a
large upper-level anticyclone approaching from the northwest
(partially related to outflow from both AL93 and Milton) should lead
to an abrupt increase in northerly shear. Thus, rapid weakening is
still anticipated beyond that time, and Leslie still appears likely
to become a post-tropical cyclone in about 3 days, as its convection
is stripped away by the shear. The intensity forecast is on the
upper-end of the guidance over the first 36 h, but falls back to the
guidance mean by the end of the forecast period.
FORECAST POSITIONS AND MAX WINDS
INIT 09/0300Z 20.7N 47.0W 70 KT 80 MPH
12H 09/1200Z 21.7N 48.0W 75 KT 85 MPH
24H 10/0000Z 22.7N 49.0W 80 KT 90 MPH
36H 10/1200Z 23.6N 49.7W 80 KT 90 MPH
48H 11/0000Z 24.8N 49.9W 60 KT 70 MPH
60H 11/1200Z 26.6N 49.1W 45 KT 50 MPH
72H 12/0000Z 29.0N 47.0W 40 KT 45 MPH...POST-TROPICAL
96H 13/0000Z 33.0N 39.5W 35 KT 40 MPH...POST-TROPICAL
120H 14/0000Z 35.1N 32.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
$$
Forecaster Papin
Source:
NHC issues Tropical Cyclone Discussion (TCD) at Oct 9, 7:00 AM AST---------------
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