Potential Tropical Cyclone Six Discussion Number 3
NWS National Hurricane Center Miami FL AL062024
400 AM CDT Mon Sep 09 2024
Satellite imagery shows that the disturbance is producing
considerable deep convection with cloud tops colder than -70 deg C.
However, the cloud pattern is still in the organizing stage with not
much evidence of banding features at this time. Upper-level outflow
is becoming established over the area. Observations from an Air
Force reconnaissance aircraft, data buoy 42055, and a partial ASCAT
overpass suggest that the system has not yet developed a well-
defined center of circulation. The intensity is held at 45 kt for
this advisory with the assumption of some undersampling of the winds
over the western part of the circulation. However, this could be
generous.
Since the center is still not well defined, the initial motion is a
rather uncertain, but slow, 340/4 kt. During the next day or so,
the system is expected to move along the western side of a mid-level
ridge over the Gulf of Mexico. This motion should keep the core of
the system off the coast of northeastern Mexico and southern Texas
for the next 24-36 hours. Then, a shortwave trough over Texas is
expected to induce a turn toward the northeast with an increase in
forward speed, which would take the center of the system near and
across the northwestern or northern Gulf coast late Wednesday. The
official track forecast has again been nudged eastward in the 48-72
hour period, but not quite as far east as the ECMWF and corrected
consensus model predictions. It should be noted that confidence in
the track forecast is lower than normal since the system lacks a
well-defined center.
Since the system is still not very well-organized and lacks an inner
core structure, only slow strengthening is expected through this
morning. However, the disturbance is expected to soon become better
organized while remaining over very warm waters, with high low- to
mid-tropospheric humidity, and low vertical shear for the next 48
hours. Therefore steady strengthening is likely to begin by later
today. This is also shown by most of the numerical guidance. When
the system nears landfall, the global models show increasing
upper-level westerlies near the northwestern Gulf coast, and this
could lead to stronger vertical wind shear over the cyclone.
Therefore the rate of strengthening could at least level off as the
center nears the coast. The official intensity forecast is similar
to the previous NHC prediction, close to the Decay-SHIPS guidance,
and continues to show the system as a hurricane at landfall.
KEY MESSAGES:
1. The system is forecast to become a tropical storm today as it
moves near the western Gulf of Mexico coast. Tropical Storm Watches
are in effect for northeastern Mexico and extreme southern Texas.
2. The system is forecast to become a hurricane before it reaches
the northwestern Gulf Coast by the middle of the week. While it is
too soon to pinpoint the exact location and magnitude of impacts,
the potential for life-threatening storm surge and damaging winds
are increasing for portions of the Louisiana and Upper Texas
coastlines beginning Tuesday night. Hurricane and Storm Surge
Watches will likely be issued for a portion of that area later
today, and residents should ensure they have their hurricane plan in
place.
3. Potential Tropical Cyclone Six is expected to bring heavy
rainfall and the risk of considerable flash flooding along the coast
of far northeast Mexico, portions of southernmost Texas, southern
Louisiana, and southern Mississippi into Thursday morning. A risk
of flash and urban flooding exists across portions of the Mid-South
from Wednesday into Friday morning.
FORECAST POSITIONS AND MAX WINDS
INIT 09/0900Z 22.2N 94.8W 45 KT 50 MPH...POTENTIAL TROP CYCLONE
12H 09/1800Z 23.0N 95.3W 45 KT 50 MPH...TROPICAL CYCLONE
24H 10/0600Z 24.1N 95.9W 55 KT 65 MPH
36H 10/1800Z 25.2N 95.7W 60 KT 70 MPH
48H 11/0600Z 26.8N 94.8W 65 KT 75 MPH
60H 11/1800Z 28.5N 93.3W 70 KT 80 MPH
72H 12/0600Z 30.7N 91.8W 50 KT 60 MPH...INLAND
96H 13/0600Z 34.9N 90.2W 30 KT 35 MPH...POST-TROPICAL
120H 14/0600Z 37.5N 89.0W 20 KT 25 MPH...POST-TROPICAL
$$
Forecaster Pasch
