524 
 WTNT43 KNHC 210833
 TCDAT3
 
 TROPICAL STORM LISA DISCUSSION NUMBER   7
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132016
 500 AM AST WED SEP 21 2016
 
 Lisa's cloud pattern has gradually become better organized into a
 comma-like shape, although the system still appears to be somewhat
 elongated from southwest to northeast.  Upper-level outflow
 remains weak over the southeastern quadrant of the circulation.
 Dvorak classifications from both TAFB and SAB yield an intensity
 estimate of 45 kt, and that value is used for the advisory.  The
 storm has less than 24 hours before west-southwesterly shear
 associated with an upper-level trough near 40W-50W longitude becomes
 prohibitively large for strengthening.  Therefore, some slight
 additional intensification could occur today, but beyond 24 hours
 Lisa is forecast to steadily weaken.  By days 4-5, although the
 shear is predicted to weaken when Lisa moves under the trough axis,
 the cyclone should have been disrupted too much by the earlier
 hostile environment to make a recovery.  The official forecast is
 close to the LGEM guidance through 48 hours and a little below that
 model thereafter.
 
 The center is not easy to locate and the initial motion is a rather
 uncertain 315/8 kt, which is partially based on continuity from
 earlier estimates.  A weak mid-tropospheric ridge to the north and
 northeast of Lisa should maintain a generally northwestward motion
 through 72 hours or so.  Later in the forecast period, an
 approaching trough in the westerlies, which is also expected to
 accelerate Karl to the northeast, should cause Lisa to turn
 northward over the eastern Atlantic.  The official track forecast
 is similar to the previous one and is close to a consensus of the
 ECMWF, GFS, and UKMET global models.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  21/0900Z 17.5N  32.2W   45 KT  50 MPH
  12H  21/1800Z 18.2N  33.2W   50 KT  60 MPH
  24H  22/0600Z 19.1N  34.5W   50 KT  60 MPH
  36H  22/1800Z 20.1N  35.9W   45 KT  50 MPH
  48H  23/0600Z 21.3N  37.4W   40 KT  45 MPH
  72H  24/0600Z 24.1N  40.4W   30 KT  35 MPH
  96H  25/0600Z 27.5N  43.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 120H  26/0600Z 32.5N  43.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
 $$
 Forecaster Pasch