[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 230251
TCDAT2

TROPICAL STORM KARL DISCUSSION NUMBER  35
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122016
1100 PM AST THU SEP 22 2016

Reports from Air Force Reserve and NOAA Hurricane Hunter aircraft
indicate that Karl has become significantly better organized during
the past 24 hours, with dropsonde data showing that a well-defined
circulation now exists from the surface to 400 mb.  The maximum
flight-level winds were 56 kt at 8000 ft, and there were numerous
SFMR surface wind estimates of 35-40 kt.  The minimum central
pressure estimated from the aircraft data is 1001 mb based on a 1003
mb dropsonde with surface winds of 24 kt. Based on these data and
observations from NOAA buoy 41049, the initial intensity is now 40
kt.  Additional aircraft data should be available starting at about
0600 UTC.

The initial motion is now 315/14 as Karl continues moving
northwestward between the subtropical ridge and a mid- to
upper-level trough north of Hispaniola and east of the Bahamas.
During the next 24-36 hours, Karl should turn northward and then
northeastward as it moves through a break in the ridge into the
westerlies.  Subsequently, the cyclone should accelerate
northeastward.  The model guidance is in excellent agreement with
this scenario, although there remains some spread in the forecast
forward speed late in the forecast period between the slower ECMWF
and the other faster models.  The new forecast track remains down
the center of the guidance and overall is similar to the previous
track.  The new forecast track is shifted a little closer to
Bermuda, with the closest approach now forecast between
24 and 36 hours.

While there remain some differences in the model details, Karl is
expected to move into an area of decreasing vertical shear during
the next 48 hours, which should allow continued development.  After
that, the cyclone should begin extratropical transition, which is
likely to be complete by 72 hours according the the latest dynamical
model guidance.  The new intensity forecast is similar to the
previous forecast and calls for Karl to steadily intensify to
hurricane strength in about 48 hours, followed by rapid weakening
after extratropical transition.  The forecast also follows the
dynamical models in calling for Karl to be absorbed by another
extratropical low by 120 hours.


FORECAST POSITIONS AND MAX WINDS

INIT  23/0300Z 27.0N  64.0W   40 KT  45 MPH
 12H  23/1200Z 28.4N  65.0W   45 KT  50 MPH
 24H  24/0000Z 30.5N  64.8W   50 KT  60 MPH
 36H  24/1200Z 32.4N  62.6W   60 KT  70 MPH
 48H  25/0000Z 35.2N  57.4W   70 KT  80 MPH
 72H  26/0000Z 43.5N  41.0W   70 KT  80 MPH...POST-TROP/EXTRATROP
 96H  27/0000Z 53.0N  26.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  28/0000Z...ABSORBED BY EXTRATROPICAL LOW

$$
Forecaster Beven
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