264 
 WTNT43 KNHC 090857
 TCDAT3
 
 Tropical Storm Leslie Discussion Number  52
 NWS National Hurricane Center Miami FL       AL132018
 500 AM AST Tue Oct 09 2018
 
 Leslie has been steady state overnight.  The low-level center is
 estimated to be on the southern side of a persistent area of deep
 convection.  The satellite intensity estimates are largely
 unchanged, so the initial intensity is held at 55 kt for this
 advisory.
 
 The tropical storm is moving southeastward at 11 kt steered by the
 flow on the southwest side of a broad mid- to upper-level trough.
 This motion, but a slower pace, is expected during the next 24 to 36
 hours as the trough pulls away.  After that time, another trough is
 expected to dig southward over the north Atlantic, which should
 cause Leslie to accelerate east-northeastward.  Although the models
 are in fair agreement for the next few days, they remain in in poor
 agreement on whether or not the trough will continue to carry Leslie
 eastward or leave the storm behind around day 5.  The GFS and ECMWF
 have flip flopped, with the GFS now showing Leslie meandering over
 the east Atlantic by day 5 and the ECMWF moving the system eastward
 toward Morocco.  The ensemble spread remains large in those two
 global models and there has not been much run-to-run consistency
 either.  The NHC track forecast remains near the various consensus
 aids, which is usually a good place to be when there is considerable
 uncertainty like this.
 
 Leslie should slowly strengthen during the next few days while
 it moves over slightly warmer waters and into a more moist
 environment.  These favorable conditions should allow Leslie to
 become a hurricane once again, likely within a day or two.
 Weakening is expected to commence this weekend when Leslie is
 forecast to move over cooler waters and into an atmosphere of
 stronger shear and drier air, and the system is forecast to become
 post-tropical by day 5.  However, the long range intensity forecast
 is strongly linked to where Leslie will be, so since the track
 forecast is uncertain, the intensity prediction is likewise.
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  09/0900Z 32.2N  43.9W   55 KT  65 MPH
  12H  09/1800Z 30.8N  43.1W   55 KT  65 MPH
  24H  10/0600Z 29.2N  42.5W   60 KT  70 MPH
  36H  10/1800Z 28.1N  42.0W   65 KT  75 MPH
  48H  11/0600Z 28.4N  40.5W   65 KT  75 MPH
  72H  12/0600Z 31.2N  33.8W   75 KT  85 MPH
  96H  13/0600Z 33.5N  23.0W   70 KT  80 MPH
 120H  14/0600Z 34.0N  17.0W   55 KT  65 MPH...POST-TROPICAL
 
 $$
 Forecaster Cangialosi
 
 
 
 265 
 WTNT44 KNHC 090857
 TCDAT4
 
 Hurricane Michael Discussion Number  11
 NWS National Hurricane Center Miami FL       AL142018
 400 AM CDT Tue Oct 09 2018
 
 Reports from an Air Force Reserve Hurricane Hunter aircraft a few
 hours ago indicate that Michael's strengthening has paused, with
 the maximum winds near 80 kt and a central pressure near 973 mb.
 The aircraft also reported that the eyewall had become less
 organized, which may be due to some dry air entrainment and shear.
 The latest satellite imagery shows the convective banding becoming
 better defined, and the next aircraft will shortly arrive in the
 hurricane to provide better information on whether intensification
 has resumed.
 
 The initial motion is now 345/10.  There is little change in either
 the forecast philosophy from the previous advisory, as Michael
 expected to remain caught between a deep-layer ridge centered off of
 the U.S. east coast and a highly amplitude mid-latitude trough over
 the U.S. Plains states and northern Mexico. This pattern should
 steer the hurricane north-northwestward to northward for the next 24
 h or so, followed by a turn to the northeast as Michael recurves
 into the westerlies.  Only minor tweaks have been made to the
 previous forecast track, with Michael expected to make landfall in
 the Florida Panhandle on Wednesday and cross the southeastern United
 States Wednesday night and Thursday.
 
 The large-scale models continue to forecast a decrease in the shear
 later today, and thus Michael is forecast to intensify further
 before landfall.  The new intensity forecast follows the previous
 forecast in showing Michael as a category 3 hurricane at landfall.
 The cyclone should weaken significantly as it crosses the
 southeastern United States, then it should re-intensify over the
 western Atlantic as it undergoes extratropical transition between
 72-96 h.
 
 It should be noted that the location and magnitude of peak storm
 surge flooding is very sensitive to small changes in the track,
 intensity, and structure of the hurricane. Since there is still
 uncertainty in all of these parameters, the official NHC storm surge
 forecast and watch/warning areas includes various plausible
 scenarios. Regardless of the eventual track and intensity of
 Michael, life-threatening storm surge inundation is expected along
 portions of the Florida Panhandle and Big Bend/Nature Coast, and the
 storm surge watch has been upgraded to a storm surge warning for
 parts of this area.
 
 The NOAA G-IV aircraft is currently conducting a synoptic
 surveillance mission over the Gulf of Mexico and dropsondes from
 that mission will be assimilated into the 1200 UTC numerical models
 runs.
 
 Key Messages:
 
 1. Life-threatening storm surge is likely along portions of the
 coasts of the Florida Panhandle, Big Bend, and Nature Coast, and a
 storm surge warning is in effect for these areas. Residents in these
 areas should follow all advice given by their local officials.
 
 2. A hurricane warning has been issued for portions of the Florida
 Gulf Coast, and everyone in these areas should prepare for
 life-threatening winds associated with the core of Michael.
 Damaging winds will also extend inland across portions of the
 Florida Panhandle, southern Georgia, and southeast Alabama as
 Michael moves inland.
 
 3. Heavy rainfall from Michael could produce life-threatening flash
 flooding from the Florida Panhandle and Big Bend region into
 portions of Georgia and South Carolina.
 
 4. Tropical storm conditions will continue in portions of western
 Cuba for a few more hours.
 
 5. Michael is expected to produce heavy rainfall and flash flooding
 over portions of western Cuba during the next day or so.
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  09/0900Z 24.1N  85.9W   80 KT  90 MPH
  12H  09/1800Z 25.7N  86.3W   90 KT 105 MPH
  24H  10/0600Z 27.9N  86.4W  100 KT 115 MPH
  36H  10/1800Z 29.9N  85.6W  105 KT 120 MPH
  48H  11/0600Z 32.3N  83.4W   50 KT  60 MPH...INLAND
  72H  12/0600Z 36.5N  75.5W   45 KT  50 MPH...OVER WATER
  96H  13/0600Z 42.5N  60.5W   60 KT  70 MPH...POST-TROP/EXTRATROP
 120H  14/0600Z 49.0N  40.5W   55 KT  65 MPH...POST-TROP/EXTRATROP
 
 $$
 Forecaster Beven
 
 

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