[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 052042
TCDAT4

POST-TROPICAL CYCLONE HERMINE DISCUSSION NUMBER  34
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL092016
500 PM AST MON SEP 05 2016

The satellite presentation of Hermine remains non-tropical, with
a rather linear band of deep convection situated north and northwest
of the estimated center.  There continues to be multiple low-level
swirls over the inner part of the circulation.  Overall, the
appearance of the system is gradually losing organization.  The
advisory intensity remains at 60 kt based on earlier reconnaissance
data and a ship report from this afternoon.  The system is forecast
to move over SSTs of 23 to 24 deg C on Tuesday and these cooler
waters should cause weakening.  The official intensity forecast is
close to the model consensus and, although this guidance may not be
very valid for a post-tropical cyclone, the NHC forecast is also
consistent with the trends shown by the global models.  Some of
these models, such as the ECMWF suggest that the cyclone could
dissipate within 72 hours.

Earlier aircraft center fixes and a more recent satellite-derived
fix result in a motion estimate of 300/6 kt.  A weak mid-level
ridge to the north of Hermine should maintain the
west-northwestward motion overnight.  After that, the ridge breaks
down and the cyclone is expected to become trapped in a region of
weak steering currents.  This should result in a slow and erratic
motion through 48 hours.  By the end of the forecast period, if the
cyclone survives, a faster east-northeastward motion could occur
due to the influence of the mid-latitude westerlies.  The official
track forecast is a little to the west of the previous one but
generally to the right of the latest dynamical model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  05/2100Z 39.3N  69.5W   60 KT  70 MPH...POST-TROPICAL
 12H  06/0600Z 39.7N  70.6W   55 KT  65 MPH...POST-TROPICAL
 24H  06/1800Z 39.9N  71.3W   50 KT  60 MPH...POST-TROPICAL
 36H  07/0600Z 40.0N  71.5W   45 KT  50 MPH...POST-TROPICAL
 48H  07/1800Z 40.3N  71.3W   35 KT  40 MPH...POST-TROPICAL
 72H  08/1800Z 42.0N  69.0W   25 KT  30 MPH...POST-TROPICAL
 96H  09/1800Z...DISSIPATED

$$
Forecaster Pasch
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