[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 202044
TCDAT2

TROPICAL STORM KARL DISCUSSION NUMBER  26
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122016
ISSUED BY THE NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
500 PM AST TUE SEP 20 2016

Karl's center had lost some definition throughout the day, but deep
convection has redeveloped near the center late in the afternoon.
Dvorak Current Intensity estimates were lowered to 2.5 from TAFB and
2.0 from SAB, and the latest UW-CIMSS ADT estimate is T3.2. A NOAA
P-3 flight currently conducting a research mission into Karl has
not yet found tropical-storm-force winds, but it has not sampled
the entire circulation yet. The initial intensity is therefore held
at 35 kt pending additional data from the P-3. The minimum pressure
is lowered to 1005 mb based on dropsonde data from the NOAA G-IV
jet, which is also flying near Karl.

Little to no change is expected in the strength of Karl over the
next 24 hours as the influence of an upper low continues to shear
out the western side of the storm. The global models indicate that
the shear should relax in the next 24 to 36 hours allowing a slight
strengthening in that period. As Karl rounds the mid-level ridge
it will find itself in a more favorable environment with warm
SSTs and lower shear. An increased rate of intensification should
take place in the 48 to 72 hour time frame, and Karl is expected to
reach hurricane strength by the end of that period. The official
intensity forecast has been nudged slightly downward based on the
latest guidance, however it is still on the upper end of the
guidance spread.

The center of Karl continues pushing west near the 20th parallel
with an initial motion of 275 at 12 kt.  Karl is expected to make a
turn toward the west-northwest shortly and should reach the western
edge of the subtropical high during the next 48 hours, turning to
the northwest by day 2 and to the north by day 4. Karl will then
accelerate to the northeast as it gets picked up by the westerlies
ahead of an upper level trough. Global model guidance continues to
show considerable spread into the day 5 period. The ECMWF is
significantly slower than the other models because the upper level
trough does not pick up Karl. The official track forecast follows
close to the previous forecast and remains near a consensus of the
GFS and ECMWF.

FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 20.1N  55.2W   35 KT  40 MPH
 12H  21/0600Z 20.8N  57.0W   35 KT  40 MPH
 24H  21/1800Z 22.3N  59.2W   40 KT  45 MPH
 36H  22/0600Z 24.1N  61.4W   45 KT  50 MPH
 48H  22/1800Z 25.6N  63.5W   55 KT  65 MPH
 72H  23/1800Z 28.5N  65.5W   70 KT  80 MPH
 96H  24/1800Z 32.5N  61.5W   85 KT 100 MPH
120H  25/1800Z 38.5N  51.0W   80 KT  90 MPH

$$
Forecaster Krekeler/Berg
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