[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 221449
TCDAT2

TROPICAL DEPRESSION KARL DISCUSSION NUMBER  33
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122016
ISSUED BY THE NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1100 AM AST THU SEP 22 2016

Even with visible satellite imagery this morning, Karl's center has
still been difficult to locate, and it's unclear exactly how well
defined it is.  Deep convection has increased markedly since
yesterday, but the overall cloud pattern is rather elongated from
the east-southeast to the west-northwest.  In the absence of any in
situ data, the initial intensity remains 30 kt based on Dvorak
estimates from TAFB and SAB.

Karl is moving northwestward and appears to have sped up
temporarily with an initial motion of 305/15 kt.  The cyclone is
moving between a mid-level high centered to its northeast and a
mid-level low located north of Puerto Rico.  Karl is expected to
move around the western periphery of the high during the next few
days, turning northward by 36 hours and then accelerating
northeastward into the mid-latitude westerlies by 48 hours.  Based
on the adjustment of the initial position, the track guidance has
shifted a bit left of the positions indicated in the previous
advisory.  As a result, the updated official forecast has been
adjusted westward during the first 48 hours, lying close to the
ECMWF solution as well as the TVCN multi-model consensus.  Even
with this shift, the official forecast lies close to the eastern
edge of the guidance envelope.

Karl lies right along the edge of a zone of higher shear to its
west, and the various analyses are showing about 15 kt of
southeasterly shear over the system.  The global models continue to
show the shear decreasing at least some during the next couple of
days, but there are differences.  For example, GFS fields show the
shear decreasing below 10 kt for a day or two, while the ECMWF only
shows the shear decreasing below 10 kt for about 12 hours.  This
continues to make the intensity forecast difficult.  For now, the
official intensity forecast remains close to the ICON intensity
consensus, and no significant changes were made to the previous
forecast.

Based on the latest forecast, the western edge of the
tropical-storm-force wind field could begin to affect Bermuda
during the next 36 to 48 hours.  The Bermuda Weather Service has
therefore issued a Tropical Storm Watch for the island.

FORECAST POSITIONS AND MAX WINDS

INIT  22/1500Z 25.0N  62.3W   30 KT  35 MPH
 12H  23/0000Z 26.3N  63.7W   35 KT  40 MPH
 24H  23/1200Z 28.3N  64.8W   40 KT  45 MPH
 36H  24/0000Z 30.2N  64.7W   45 KT  50 MPH
 48H  24/1200Z 32.3N  62.5W   55 KT  65 MPH
 72H  25/1200Z 38.0N  50.8W   70 KT  80 MPH
 96H  26/1200Z 48.0N  32.0W   60 KT  70 MPH...POST-TROP/EXTRATROP
120H  27/1200Z...DISSIPATED

$$
Forecaster Berg/Campbell/Rubin-Oster

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