Hurricane Oscar Discussion Number 10
NWS National Hurricane Center Miami FL AL162018
500 AM AST Mon Oct 29 2018

The cloud pattern of Oscar has continued to become better
organized, with a growing CDO and convective banding features
are better defined, especially over the southern semicircle of
the hurricane. Upper-level outflow is gradually becoming better
established to the south. Although the most recent Dvorak Current
Intensity estimates from TAFB and SAB are at 65 kt, given that the
eye is becoming better defined, the advisory intensity is set at 70
kt. Oscar is currently under some northerly to north-northwesterly
shear, but the shear is expected to diminish somewhat later today.
Also, the tropical cyclone is expected to move through a modestly
moist air mass for the next day or two. Therefore, additional
strengthening is forecast through 36 hours in agreement with the
latest intensity model consensus. Around 48 hours into the forecast
period, the shear begins to increase significantly, with notably
cooler SSTs. This should lead to the onset of a steady weakening
trend. By about 72 hours, the global models indicate that Oscar
will become embedded in a frontal zone, so the official forecast
shows the system becoming an extratropical cyclone at that time.

Oscar has slowed its forward motion and is now moving at about
270/11 kt. A mid-level high to the north of the cyclone is
expected to quickly shift eastward, while a mid-latitude trough
approaches Oscar from the west in a day or so. This evolution of
the steering flow should cause Oscar to turn northward to
north-northeastward in 24-48 hours. Later in the forecast period,
Oscar is likely to move quickly northeastward on the eastern side
of the trough. There has been some inconsistencies in the track
model guidance around 5 days over the last few forecast cycles,
with the model consensus, TVCN, shifting significantly southward and
then northward. The official forecast track is somewhat to the
left of the previous one near the end of the period, to reflect the
latest consensus prediction.

FORECAST POSITIONS AND MAX WINDS

INIT 29/0900Z 25.7N 57.8W 70 KT 80 MPH
12H 29/1800Z 26.1N 58.7W 75 KT 85 MPH
24H 30/0600Z 27.7N 58.7W 80 KT 90 MPH
36H 30/1800Z 30.0N 57.5W 85 KT 100 MPH
48H 31/0600Z 33.0N 54.7W 85 KT 100 MPH
72H 01/0600Z 41.5N 46.5W 70 KT 80 MPH…POST-TROP/EXTRATROP
96H 02/0600Z 46.0N 35.5W 60 KT 70 MPH…POST-TROP/EXTRATROP
120H 03/0600Z 48.0N 26.0W 55 KT 65 MPH…POST-TROP/EXTRATROP

$$
Forecaster Pasch

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Mon Oct 29 2018

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

1. An elongated area of low pressure is located several hundred miles
south of Manzanillo, Mexico. Although upper-level winds are only
marginally conducive, and a tropical depression could still form
during the next couple of days while the system moves westward at
about 10 mph.
* Formation chance through 48 hours…medium…40 percent.
* Formation chance through 5 days…medium…50 percent.

2. A well-defined low pressure system located about 1100 miles
south-southwest of the southern tip of the Baja California peninsula
continues to produce disorganized shower and thunderstorm activity.
However, some slow development of this system will be possible over
the next several days while the low moves toward the west or
west-northwest at about 10 mph.
* Formation chance through 48 hours…low…20 percent.
* Formation chance through 5 days…medium…40 percent.

Forecaster Stewart

Global Tropics & Benefits Outlook

Weather in Cayman

SYNOPSIS