Tropical Report

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Sun Oct 7 2018

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical
Storm Leslie, located over the central Atlantic Ocean, and on
Tropical Depression Fourteen, located over the northwest Caribbean
Sea.

1. A broad non-tropical low pressure system located a few hundred miles
south of the Azores is producing a large area of disorganized
showers and thunderstorms, mainly to the north and east of its
center. This system could gradually acquire subtropical or tropical
characteristics over the next couple of days while it moves slowly
eastward. By Tuesday, environmental conditions are expected to
become unfavorable for further development to occur. Additional
information on this system can be found in high seas forecasts
issued by Meteo France.
* Formation chance through 48 hours…low…30 percent.
* Formation chance through 5 days…low…30 percent.

Public Advisories on Tropical Depression Fourteen are issued under
WMO header WTNT34 KNHC and under AWIPS header MIATCPAT4.
Forecast/Advisories on Tropical Depression Fourteen are issued under
WMO header WTNT24 KNHC and under AWIPS header MIATCMAT4.

Additional information on the eastern Atlantic low pressure system
can be found in high seas forecasts issued by Meteo France…under
WMO header FQNT50 LFPW.

Forecaster Zelinsky

DEPRESSION EXPECTED TO STRENGTHEN… …HEAVY RAINS WILL SPREAD OVER WESTERN CUBA LATER TODAY

Tropical Depression Fourteen Discussion Number 3
NWS National Hurricane Center Miami FL AL142018
400 AM CDT Sun Oct 07 2018

Radar data from Belize and infrared satellite imagery indicate that
the low pressure system centered just off the coast of the Yucatan
Peninsula has continued to become better organized, with deep
convection consolidating just to the northeast of the low-level
center. Dvorak estimates have increased to T2.0 from TAFB and T1.5
from SAB, indicating that the convective pattern has become
sufficiently organized for the low to now be declared a tropical
depression. The maximum winds are estimated to be 30 kt based on
earlier ASCAT data.

The Belize radar data was extremely helpful in locating the
depression’s center, and the system’s 12-hour average motion is
north-northwestward, or 340 degrees, at a very slow 3 kt. The
depression is expected to move generally northward during the next
3 days, gradually gaining speed as it enters the southerly flow
between high pressure over the western Atlantic and an advancing
deep-layer trough over the western half of the United States. After
day 3, the trough is expected to cause the cyclone to turn
northeastward and accelerate further across the southeastern United
States. While the track models agree on the general scenario,
there are some speed differences, most notably with the ECMWF model
being slower than the other guidance. Also, the ECMWF and GFS
models are located along the western edge of the guidance envelope.
In light of these facts, the new NHC prediction is just a little
slower than the previous one, and it lies to the west of the TVCN
multi-model consensus and the HCCA model during the first 3 days of
the forecast.

The depression is still being hampered by 20-30 kt of westerly
shear, however it is also located in an environment of upper-level
diffluence to the southeast of a stationary trough over the Gulf of
Mexico. The shear in the immediate vicinity of the cyclone is
forecast to gradually abate during the next 2-3 days while the
diffluent upper-air pattern continues, and along with sufficiently
warm waters of 28-30 degrees Celsius, all indications are that the
depression will gradually strengthen while it moves northward over
the Gulf of Mexico. In fact, nearly every piece of intensity
guidance brings the cyclone to hurricane strength before it reaches
land, including the GFS, ECMWF, and UKMET global models, which all
show significant deepening of the central pressure. The updated NHC
intensity forecast generally lies between the ICON intensity
consensus and the HCCA model for the entire forecast period, and it
now explicitly shows the cyclone reaching hurricane strength by 72
hours.

Key Messages for Tropical Depression Fourteen:

1. The depression is producing heavy rainfall and flash flooding
over portions of Central America, and these rains will spread over
western Cuba and the northeastern Yucatan Peninsula of Mexico during
the next couple of days.

2. The depression is forecast to become a tropical storm later
today, and tropical storm conditions are expected by tonight over
portions of western Cuba and the northeastern Yucatan Peninsula,
where tropical storm warnings are in effect.

3. Storm surge, rainfall, and wind impacts are possible over
portions of the northern Gulf Coast by mid-week, although it is
too soon to specify the exact location and magnitude of these
impacts. Residents in these areas should monitor the progress of
this system.

FORECAST POSITIONS AND MAX WINDS

INIT 07/0900Z 18.6N 86.9W 30 KT 35 MPH
12H 07/1800Z 19.4N 86.7W 35 KT 40 MPH
24H 08/0600Z 20.8N 86.4W 45 KT 50 MPH
36H 08/1800Z 22.3N 86.6W 50 KT 60 MPH
48H 09/0600Z 23.9N 87.1W 55 KT 65 MPH
72H 10/0600Z 27.6N 87.3W 65 KT 75 MPH
96H 11/0600Z 32.0N 84.0W 45 KT 50 MPH…INLAND
120H 12/0600Z 37.0N 76.0W 45 KT 50 MPH…NEAR THE VA COAST

$$
Forecaster Berg