Aug 9 Wednesday 2017

Tropical Report

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Wed Aug 9 2017

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

The National Hurricane Center is issuing advisories on Tropical
Storm Franklin, located off the west coast of the Yucatan peninsula.

1. A trough of low pressure located about 550 miles east of the
Leeward Islands continues to produce disorganized showers and
thunderstorms. Environmental conditions are expected to remain
hostile for significant development during the next couple of
days. However, environmental conditions are forecast to become
somewhat conducive for development late this week while the
system moves generally west-northwestward at about 15 mph over the
western Atlantic.
* Formation chance through 48 hours…low…near 0 percent.
* Formation chance through 5 days…medium…40 percent.

Forecaster Landsea

FRANKLIN STRENGTHENS A LITTLE MORE

Tropical Storm Franklin Discussion Number 11
NWS National Hurricane Center Miami FL AL072017
400 AM CDT Wed Aug 09 2017

Reports from an Air Force Reserve Hurricane Hunter aircraft near
0500 UTC showed 700-mb flight-level winds of 65 kt about 40 n mi
northeast of the center, and surface wind estimates from the SFMR
of 50-55 kt in the same area. Satellite imagery has shown increased
organization, with a well-defined convective band that yields
satellite intensity estimates of 55 kt from TAFB and SAB. Based on
these data, the initial intensity is increased to 55 kt.

The initial motion is now 280/11, a little faster than before.
A mid- to upper-level ridge to the north and northwest of Franklin
should keep the cyclone moving generally westward for the next
24 hours or so, followed by a south of west motion as Franklin’s
circulation interacts with the mountainous terrain of Mexico. The
new forecast track, which is nudged a little north of the previous
track, has the center making landfall in the Mexican state of
Veracruz just past the 24 hour point, followed by a motion into the
mountains of eastern Mexico. The new track is in good agreement
with the various consensus models.

Franklin is crossing the very warm waters of the Bay of Campeche
and continued strengthening appears likely. Indeed, the SHIPS
Rapid Intensification Index shows a 40-50 percent chance of 25 kt of
strengthening during the next 24 hours. However, the large-scale
models forecast moderate northeasterly shear to develop during that
time, which may slow intensification below rapid levels. The new
intensity forecast calls for Franklin to become a hurricane in 12 h
and reach a peak intensity of 70 kt near the time of landfall. This
forecast again lies close to the upper edge of the intensity
guidance. After landfall, rapid weakening is forecast as Franklin
moves into the mountains of eastern Mexico, and the low-level center
is likely to dissipate completely by 48 h. It should be noted that
some large-scale models re-form the low-level center over the
Pacific as the remnants of Franklin reach that basin in about 72 h.

The initial 34-kt wind radii were revised based on a combination of
aircraft, surface, and scatterometer data. However, Franklin is
expected to increase in size, and this requires a northward
extension of the Tropical Storm Warning on the eastern coast of
Mexico.

FORECAST POSITIONS AND MAX WINDS

INIT 09/0900Z 20.4N 92.7W 55 KT 65 MPH
12H 09/1800Z 20.5N 94.4W 65 KT 75 MPH
24H 10/0600Z 20.3N 96.5W 70 KT 80 MPH
36H 10/1800Z 19.9N 98.8W 35 KT 40 MPH…INLAND
48H 11/0600Z…DISSIPATED

$$
Forecaster Beven

 

 Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Wed Aug 9 2017

For the eastern North Pacific…east of 140 degrees west longitude:

1. An area of low pressure is expected to form just off the
west-central coast of Mexico late this week in association with the
remnants of Atlantic Tropical Storm Franklin after it moves across
southern Mexico. Some development of this system is possible this
weekend before it moves west-northwestward into less conducive
environmental conditions.
* Formation chance through 48 hours…low…near 0 percent.
* Formation chance through 5 days…low…30 percent.

2. Another area of low pressure is forecast to form well south of the
coast of southern Mexico late this week. Environmental conditions
are expected to be conducive for some gradual development of this
system over the weekend and early next week.
* Formation chance through 48 hours…low…near 0 percent.
* Formation chance through 5 days…low…30 percent.

Forecaster Cangialosi