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Tropical Storm LESLIE


Tropical Storm Leslie Discussion Number  15
NWS National Hurricane Center Miami FL       AL132018
1100 PM AST Sat Sep 29 2018

The structure of Leslie consists of a large, broken outer band
wrapped around the eastern semicircle of the cyclone, with little
convection west of the center.  ASCAT data recently showed 40-45 kt
within that band, so the maximum winds will stay at 45 kt.  The
storm should gradually move over somewhat warmer waters within a
lighter shear environment during the next few days.  Thus gradual
intensification is shown, similar to the model consensus.  The only
notable change to the previous forecast is to move up the peak
intensity close to Leslie's southernmost position before it stalls.
It would seem that after that time, the relatively large system
would be moving close to its previous track over its self-generated
cooler upwelled waters, and weaken somewhat at long range.

Leslie continues to move southwestward, and its initial motion is
235/5 kt.  This storm should move slowly to the southwest through
Sunday, then creep southward by late Monday due to steering
partially by northerly flow from a distant ridge over the western
Atlantic and a nearby large mid- to upper-level trough. Eventually,
a new ridge rebuilds over the east-central Atlantic east of Leslie,
which causes the cyclone to move to the north at a faster pace by
day 5. As you could imagine in such a complex pattern, the models
aren't in good agreement on how quickly the storm ejects, and this
is a pretty uncertain forecast at long range.  Until some forecast
scenarios become clear, the forecast will stay close to the
corrected-consensus aids, resulting in mostly cosmetic changes to
the last forecast.

Large swells generated by Leslie when it was a strong extratropical
low will affect Bermuda, the east coast of the United States, and
most of the Greater and Lesser Antilles through at least the
weekend. These swells could cause life-threatening surf and rip


INIT  30/0300Z 33.9N  52.0W   45 KT  50 MPH
 12H  30/1200Z 33.4N  52.8W   45 KT  50 MPH
 24H  01/0000Z 33.0N  53.4W   50 KT  60 MPH
 36H  01/1200Z 32.6N  53.9W   50 KT  60 MPH
 48H  02/0000Z 32.2N  54.2W   55 KT  65 MPH
 72H  03/0000Z 31.0N  54.5W   65 KT  75 MPH
 96H  04/0000Z 31.7N  54.2W   60 KT  70 MPH
120H  05/0000Z 34.5N  53.5W   60 KT  70 MPH

Forecaster Blake