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Tropical Storm Kristy Discussion Number  10
NWS National Hurricane Center Miami FL       EP132018
200 AM PDT Thu Aug 09 2018

Deep convection has continued to increase near and to the north and
east of Kristy's center, and cirrus outflow has expanded some in all
quadrants. Satellite intensity estimates supported an intensity of
40 kt at 0600 UTC, but the recent increase in convection, along with
a Dvorak estimate of T3.0/45 kt from TAFB and and a UW-CIMSS ADT
estimate of T2.9/43 kt, justify increasing the advisory intensity to
45 kt.

Kristy has turned to north-northwest and is now moving 345/05 kt.
The cyclone is expected to turn toward the north later today,
followed by a motion toward the north-northeast or northeast in the
24-48 h time period as Kristy and much larger Tropical Storm John
undergo some weak binary interaction. However, the two cyclones
separate by 72 h as John weakens over cold waters and its influence
on Kristy diminishes, resulting in a turn to the north. By 96 h and
beyond, Kristy will also be located over much colder water and is
expected to have degenerated into a shallow remnant low pressure,
becoming steered more westward by the deep-layer easterly trade
wind flow. There remains considerable divergence among the global
and regional hurricane models, with the GFS, HWRF, and HMON models
keeping Kristy moving northward after 72 h, and the ECMWF and UKMET
models moving Kristy westward. The guidance envelope has shifted
markedly to the right of the previous forecast track, and the new
official forecast track has also been shifted in that direction.
However, the new track forecast was not shifted as far east as the
consensus models HCCA and FSSE, out of respect for the reliable
ECMWF model.

There is a narrow window of opportunity of about 24 h for Kristy to
strengthen a little more while the cyclone remains over SSTs of
26-26.5 deg C and in a low-shear environment. After that time,
however, cooler waters and the entrainment of much drier mid-level
air is expected to induce steady weakening through the remainder of
the forecast period, with the cyclone becoming post-tropical by 72
h, if not sooner. The official intensity forecast is similar to the
intensity consensus model IVCN through 24 h, and then is a little
lower than IVCN after that due to Kristy moving over sub-25 deg C
SSTs.

FORECAST POSITIONS AND MAX WINDS

INIT  09/0900Z 15.8N 130.1W   45 KT  50 MPH
 12H  09/1800Z 16.5N 130.2W   45 KT  50 MPH
 24H  10/0600Z 17.6N 129.9W   50 KT  60 MPH
 36H  10/1800Z 18.7N 129.3W   45 KT  50 MPH
 48H  11/0600Z 19.8N 128.9W   45 KT  50 MPH
 72H  12/0600Z 21.4N 129.0W   35 KT  40 MPH...POST-TROPICAL
 96H  13/0600Z 22.8N 129.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  14/0600Z 23.5N 132.0W   20 KT  25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Stewart

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