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 819 
 WTNT43 KNHC 102033
 TCDAT3
 
 TROPICAL STORM HENRI DISCUSSION NUMBER   8
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082015
 500 PM AST THU SEP 10 2015
 
 Henri continues to struggle with most of its deep convection well
 removed to the northeast of the center.  In fact, it is taking on
 some characteristics of a subtropical cyclone with recent
 scatterometer data indicating that the radius of maximum winds has
 increased to a rather high value of 120 n mi.  The initial wind
 speed will remain 35 kt on the basis of 30-35 kt winds observed in
 partial scatterometer pass that missed the area that likely
 has the strongest winds.
 
 Southerly shear is still forecast to relax overnight near Henri,
 which theoretically could result in intensification during the next
 day or so before the cyclone moves over cold water on Saturday.
 However, dry air aloft persists near the storm and the overall cloud
 pattern is quite disorganized. The unfavorable factors are starting
 to outweigh the favorable conditions, so the official intensity
 forecast is reduced from the previous one, a little below the model
 consensus.  Extratropical transition is expected within 2 days due
 to strong shear and very cold water.  A reasonable alternative
 solution provided by some of the global models is that the cyclone
 stays weak and opens up into a trough during the day on Friday.
 
 Henri is moving faster to the north, now about 13 kt.  The storm
 should continue to accelerate northward tonight and northeastward
 tomorrow due to it encountering faster steering from the subtropical
 ridge.  After that time, an even faster northeastward and then
 eastward motion is predicted when the cyclone becomes embedded in
 the mid-latitude flow.   The guidance has trended to the left
 with the track of Henri, perhaps due to a weaker forecast
 representation of the storm.  The NHC forecast is shifted in that
 direction, although remains on the right side of the guidance
 envelope.  If it survives, the cyclone should become absorbed by a
 larger extratropical low by day 4 over the far North Atlantic.
 
 The latter part of this forecast, when the storm is expected to be
 post-tropical, is based on guidance provided by NOAA's Ocean
 Prediction Center.
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  10/2100Z 33.9N  60.7W   35 KT  40 MPH
  12H  11/0600Z 36.1N  60.3W   40 KT  45 MPH
  24H  11/1800Z 39.7N  59.1W   40 KT  45 MPH
  36H  12/0600Z 43.5N  56.5W   40 KT  45 MPH
  48H  12/1800Z 46.8N  51.8W   40 KT  45 MPH...POST-TROP/EXTRATROP
  72H  13/1800Z 48.5N  36.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
  96H  14/1800Z...DISSIPATED
 
 $$
 Forecaster Blake
 
 
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