Tropical Report

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Sun Jul 16 2017

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

1. A low pressure trough over the central tropical Atlantic Ocean is
producing disorganized showers and thunderstorms. Although this
system is close to dry air, some slow development is possible over
the next few days while the system moves westward at 15 to 20 mph.
An Air Force Reserve reconnaissance aircraft is scheduled to
investigate the disturbance Monday afternoon, if necessary.
* Formation chance through 48 hours…low…20 percent.
* Formation chance through 5 days…medium…40 percent.

Forecaster Stewart

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Sun Jul 16 2017

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

The National Hurricane Center is issuing advisories on Hurricane
Fernanda, located well to the west-southwest of the southern tip of
the Baja California peninsula.

1. A broad low pressure area located a couple of hundred miles
southwest of Acapulco, Mexico, continues to produce disorganized
showers and thunderstorms. Environmental conditions are forecast
to be somewhat conducive for gradual development during the next
few days, and a tropical depression could form by early next week
while the system moves slowly toward the west-northwest at 5 to
10 mph.
* Formation chance through 48 hours…medium…50 percent.
* Formation chance through 5 days…high…70 percent.

2. Disorganized cloudiness and showers located about 800 miles
south-southwest of the southern tip of the Baja peninsula are
associated with another broad area of low pressure. Upper-level
winds are only marginally conducive and any development should be
slow to occur as the system moves slowly west-northwestward.
* Formation chance through 48 hours…low…20 percent.
* Formation chance through 5 days…low…30 percent.

Forecaster Brown

Hurricane Fernanda Discussion Number 14
Hurricane Fernanda Discussion Number 18
NWS National Hurricane Center Miami FL EP062017
200 AM PDT Sun Jul 16 2017

A 0235Z SSMI/S microwave overpass indicated that Fernanda was still
undergoing an eyewall replacement cycle (ERC), with concentric
eyewalls remaining at about 20 and 45 n mi diameters. Although the
eye has once again cleared out and become warmer, the convective
cloud tops surrounding the eye have not cooled much. However, the
overall convective cloud pattern has improved and become more
symmetric, and outer banding features have developed in the
southeastern semicircle. Satellite intensity estimates are a
consensus T6.0/115 kt from TAFB and SAB, and T6.2/122 kt from
UW-CIMSS ADT. Therefore, the intensity has been increased slightly
to 115 kt, making Fernanda once again a category 4 hurricane.

The initial motion estimate is 285/10 kt. There is no significant
change to the previous track forecast reasonings. Fernanda is
forecast to be steered generally west-northwestward for the next 72
h by a large low-/mid-level ridge that spans the central and eastern
Pacific Ocean, extending from north of the Hawaiian Islands eastward
to the U.S. west coast. After that time, a broad upper-level trough
currently located north of Hawaii is expected to weaken and lift
out to the northeast, causing the ridge to build slightly southward
and forcing Fernanda on a more westward track. The new NHC track
forecast is similar to the previous advisory track, and lies close
to the consensus model TVCN.

Although Fernanda has about 24 hours or so remaining over warm-water
and within a low vertical wind shear environment, there are already
indications in SST data from Remote Sensing Systems that upwelling
beneath the hurricane has begun. This cooler water, coupled with the
ongoing ERC, makes the intensity forecast difficult in the near
term. As a result, little change from the current intensity is
forecast for the next 24 hours, although some intensity fluctuations
could easily occur during that time. By 36 hours and beyond, steady
weakening is forecast as Fernanda moves over sub-26C SSTs, and
enters a hostile westerly wind shear regime by 96-120 hours. The
official intensity forecast is similar to the previous one, and
closely follows the consensus models ICON and IVCN.

FORECAST POSITIONS AND MAX WINDS

INIT 16/0900Z 12.1N 126.2W 115 KT 130 MPH
12H 16/1800Z 12.6N 127.9W 115 KT 130 MPH
24H 17/0600Z 13.4N 130.1W 115 KT 130 MPH
36H 17/1800Z 14.2N 132.0W 105 KT 120 MPH
48H 18/0600Z 15.1N 133.5W 95 KT 110 MPH
72H 19/0600Z 16.6N 136.2W 70 KT 80 MPH
96H 20/0600Z 17.3N 139.4W 50 KT 60 MPH
120H 21/0600Z 17.6N 142.7W 35 KT 40 MPH

$$
Forecaster Stewart

Weather In Cayman

Synopsis

Isolated showers and thunder are expected across the Cayman area for the next 24 hours as an upper level low lingers over the northwest Caribbean. Further east, a tropical wave east of Jamaica is expected to move into our area in the next 24 hours and interact with the upper level low and continue to support similar weather conditions. Radar images show isolated showers in and around the Cayman area which continue to drift towards the west.