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Tropical Storm Barbara Discussion Number 1
NWS National Hurricane Center Miami FL EP022019
900 AM MDT Sun Jun 30 2019
Satellite imagery indicates that the area of low pressure and
associated convection located several hundred miles southwest of
southern Mexico has become better organized, with the center
embedded in the northern side of a large area of deep convection.
In addition, earlier scatterometer data revealed that 35-kt winds
existed in the eastern semicircle of the developing cyclone.
This intensity is in agreement with the latest subjective satellite
estimate from TAFB and thus advisories are started on Tropical
Storm Barbara, the second named storm of the Eastern Pacific
Barbara's initial motion is 285/14 kt. A mid-level ridge to the
north of the cyclone will steer it to the west-northwest for the
next several days. Later on in the forecast period, Barbara will
approach the southwestern periphery of the ridge which should induce
some slowing of the forward motion. The NHC track forecast lies in
the middle of a suite of guidance that is tightly clustered through
96 hours and begins to diverge slightly beyond that time frame.
The overall satellite presentation of Barbara suggests that there is
some shear affecting the convection over the northern part of the
cyclone. Statistical guidance concurs with this and indicates
10-15 kt of northwesterly shear currently over the circulation.
This shear is forecast by the guidance to begin to abate in about 24
hours. Otherwise, Barbara is expected to be in a favorable
environment for intensification and over warm waters for the next 4
to 5 days. The official forecast takes into account this initial
shear during the early inner-core development stages of Barbara, and
calls for a slow and steady strengthening through 24 hours.
Thereafter, the lower-shear environment and likely consolidating
inner-core should allow for a faster rate of intensification. The
official forecast intensity is close to the dynamical guidance
through 72 hours, and is near the upper edge of the guidance beyond
72 hours, bringing Barbara to category 2 intensity by 72 hours.
After 96 hours, Barbara will be approaching a tight gradient in SSTs
to its north. Also, both dynamical and statistical guidance indicate
that the cyclone will be approaching a region with increasing
southwesterly shear. Both of these factors should contribute to a
gradual weakening after 96 hours.
FORECAST POSITIONS AND MAX WINDS
INIT 30/1500Z 10.6N 110.4W 35 KT 40 MPH
12H 01/0000Z 11.1N 112.7W 40 KT 45 MPH
24H 01/1200Z 11.6N 115.9W 45 KT 50 MPH
36H 02/0000Z 12.0N 118.7W 55 KT 65 MPH
48H 02/1200Z 12.4N 121.0W 65 KT 75 MPH
72H 03/1200Z 13.5N 125.2W 85 KT 100 MPH
96H 04/1200Z 15.0N 128.5W 90 KT 105 MPH
120H 05/1200Z 16.0N 131.5W 85 KT 100 MPH