819 
 WTNT41 KNHC 082051
 TCDAT1
 
 SUBTROPICAL STORM ANA DISCUSSION NUMBER   4
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012015
 500 PM EDT FRI MAY 08 2015
 
 Ana is in the latter stages of tropical transition with curved deep
 convection closer to the center, with some evidence of a shrinking
 radius of maximum winds.  Still, the convection isn't particularly
 deep, and an upper-level low remains basically on top of the
 cyclone.  Ana will remain a subtropical cyclone on this advisory,
 but it would not be surprising if the aircraft mission this evening
 found enough tropical characteristics to signal a transition to
 a tropical storm.  The maximum winds are kept at 40 kt, which is a
 blend of the satellite classifications from TAFB and SAB.
 
 Ana continues to meander beneath a blocking ridge along the U.S.
 east coast.  While the overall ridge pattern shifts slowly eastward,
 the western part of the ridge is forecast to build slightly over the
 Ohio Valley tomorrow.  This will help steer Ana more to the
 northwest, and model guidance continues to be in good agreement in
 bringing Ana to the coast of the Carolinas in about two days.  Only
 a small eastward adjustment was required to the previous forecast
 track near the time of landfall.  A strong trough should then cause
 Ana to move more quickly to the north and east late Sunday and into
 early next week.   Extratropical transition should be complete by 96
 hr due to interaction of Ana with the trough and the cold waters of
 the North Atlantic.
 
 Some intensification of Ana is still possible since the cyclone
 remains parked over the Gulf Stream with cold upper-level
 temperatures promoting more convection than one would expect given
 the marginally warm waters.  However, there is quite a bit of dry
 air around the storm, which seems to be limiting convection. Some
 weakening of Ana seems probable on Sunday due to the storm's motion
 over cooler shelf waters. The latest NHC forecast is close to
 the previous one, near or slightly above the model consensus. Most
 of the global models show a little bit of strengthening of Ana in
 its extratropical phase, so the intensity was raised at 96 and 120
 hr.
 
 
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  08/2100Z 31.7N  77.4W   40 KT  45 MPH
  12H  09/0600Z 31.9N  77.6W   45 KT  50 MPH
  24H  09/1800Z 32.3N  77.9W   45 KT  50 MPH
  36H  10/0600Z 33.0N  78.4W   40 KT  45 MPH
  48H  10/1800Z 33.6N  78.7W   35 KT  40 MPH
  72H  11/1800Z 36.0N  77.0W   30 KT  35 MPH...INLAND
  96H  12/1800Z 40.5N  69.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 120H  13/1800Z 46.0N  50.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 
 $$
 Forecaster Blake