Aug 4 Friday 2017

Tropical Report

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Fri Aug 4 2017

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

1. A broad and elongated area of low pressure is producing disorganized
shower and thunderstorm activity several hundred miles south and
southwest of the Cabo Verde Islands. Environmental conditions
appear conducive for this system to consolidate and develop during
the next few days, and a tropical depression is likely to form by
the early or middle part of next week while moving
west-northwestward at 15 to 20 mph across the tropical Atlantic
Ocean.
* Formation chance through 48 hours…medium…50 percent.
* Formation chance through 5 days…high…80 percent.

2. A tropical wave is producing disorganized showers and thunderstorms
over the central and eastern Caribbean Sea. This disturbance is
expected to move west-northwestward at about 15 mph across the
western Caribbean Sea and Bay of Campeche through the middle of next
week, where environmental conditions appear conducive for
development.
* Formation chance through 48 hours…low…20 percent.
* Formation chance through 5 days…medium…60 percent.

Forecaster Berg

Tropical Depression Eleven-E Discussion Number 1
NWS National Hurricane Center Miami FL EP112017
900 AM MDT Fri Aug 04 2017

First-light 1-minute visible imagery from GOES-16 confirms that the
low pressure area located a few hundred miles west-southwest of
Manzanillo, Mexico, has a well-defined low-level center. Deep
convection has persisted since yesterday, mainly in the western
portion of the circulation, and Dvorak Final-T numbers from TAFB and
SAB are a consensus 1.5. Based on these factors, the system has
been classified as a 25-kt tropical depression.

The depression is strongly sheared from the northeast due to an
upper-level high centered over northern Mexico. The shear is not
expected to relax during the next few days, and this should keep the
system weak. In fact, I currently have no guidance that suggests
that the system will ever become a tropical storm. The intensity
forecast therefore shows no change in intensity until the system
becomes post-tropical in a couple of days due to the persistent
shear and a drier environment.

The depression is moving toward the west-northwest (300 degrees) at
13 kt, though the initial speed is somewhat uncertain since the
center has only recently become well defined. Since the cyclone is
forecast to remain weak, it should be steered primarily by the low-
to mid-level flow associated with the subtropical ridge. The GFS
and ECMWF are in fairly good agreement that this will keep the
depression moving in a near straight-line heading for the next day
or two. After that, the forward speed of the cyclone should slow
down substantially while it dissipates early next week. The track
forecast is very close to the model consensus, TVCN.

FORECAST POSITIONS AND MAX WINDS

INIT 04/1500Z 17.7N 109.2W 25 KT 30 MPH
12H 05/0000Z 18.3N 110.4W 25 KT 30 MPH
24H 05/1200Z 19.2N 112.1W 25 KT 30 MPH
36H 06/0000Z 19.8N 113.1W 25 KT 30 MPH
48H 06/1200Z 20.4N 114.0W 20 KT 25 MPH…POST-TROP/REMNT LOW
72H 07/1200Z 20.7N 114.6W 20 KT 25 MPH…POST-TROP/REMNT LOW
96H 08/1200Z…DISSIPATED

$$
Forecaster Zelinsky