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Tropical Storm DOLLY (Text)

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TROPICAL STORM DOLLY DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052014
400 AM CDT TUE SEP 02 2014

An Air Force Reserve reconnaissance aircraft investigating the
cyclone early this morning found 925 mb flight-level winds of 50-53
kt in the northeast quadrant and adjusted SFMR winds of at least 40
kt.  In addition, two ASCAT overpasses at 0313 UTC and 0406 UTC
indicated surface winds of 40-41 kt in the eastern quadrant. Based
on these wind data, the intensity has been increased to 40 kt,
making the cyclone the fourth tropical storm of the 2014 Atlantic
hurricane season. These wind data also required the initial
position to be relocated about 60 nmi north of the previous track.

The initial motion estimate is northwestward or 305/12 kt, which is
based on a blend of passive microwave, scatterometer, and
conventional satellite fix data. Other than the northward relocation
of the center position, the forecast track reasoning remains
unchanged from the previous advisories. The tropical storm is
expected to gradually turn more toward the west-northwest as Dolly
skirts along the southern periphery of a strong mid-level ridge that
is located across most of the Gulf of Mexico and the southeastern
United States. Landfall along the northeastern coast of Mexico is
expected in about 24 hours, followed by dissipation in 48 hours
over the rugged terrain of the Sierra Madre Oriental mountains. The
NHC forecast track is similar to the consensus model TVCA, and lies
roughly in the middle of the guidance envelope.

About 20 kt of north-northwesterly vertical shear is affecting
Dolly, which has resulted in most of the convection being displaced
well to the south and east of the exposed low-level circulation.
However, new convection has recently developed near and just to the
southeast of the center, and with the shear forecast to decrease to
about 15 kt during the next 12 hours, some additional slight
strengthening is possible before Dolly makes landfall.

The surface wind data from the reconnaissance aircraft and the
two scatterometer passes indicate that the tropical-storm-force wind
field has expanded significantly in the eastern semicircle. Since
the pressure gradient between Dolly and the large high over the
Gulf of Mexico is expected to remain quite strong for the next 36
hours or so, the Government of Mexico has extended the tropical
storm warning area northward to Barra El Mezquital. However, no
additional northward extension of the warning area appears likely
at this time.

The primary threat from this system is expected to be heavy
rainfall, which is likely to cause flash flooding and mud slides
over portions of eastern Mexico.

FORECAST POSITIONS AND MAX WINDS

INIT  02/0900Z 22.6N  94.8W   40 KT  45 MPH
 12H  02/1800Z 23.1N  95.9W   45 KT  50 MPH
 24H  03/0600Z 23.7N  97.5W   45 KT  50 MPH
 36H  03/1800Z 24.1N  98.9W   35 KT  40 MPH...INLAND
 48H  04/0600Z...DISSIPATED INLAND

$$
Forecaster Stewart

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