075 
 WTPZ42 KNHC 270250
 TCDEP2
 
 TROPICAL STORM MARTY DISCUSSION NUMBER   2
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP172015
 1000 PM CDT SAT SEP 26 2015
 
 The cyclone has become better organized during the past several
 hours with a large burst of convection recently trying to form a
 central dense overcast.  In addition, the latest microwave images
 show some structure to the inner core, along with more pronounced
 banding features south of the center.  On the basis of the increased
 organization and the latest Dvorak estimate from TAFB, the initial
 wind speed is set to 35 kt.
 
 Marty is now moving northward at about 4 kt.  A turn to the
 north-northeast is forecast on Sunday due to the storm moving around
 the western side of a weak mid-level ridge over the far eastern
 Pacific west of Central America.  While Marty will get close to
 being caught by a trough over Mexico, most of the guidance suggest
 that the cyclone will be left behind in a couple of days southwest
 of the coast of Mexico due to the trough moving away.  Marty would
 then drift west-northwestward in the low-level flow as a weaker
 cyclone. The NHC forecast has shifted eastward in the first couple
 of days, then westward at longer range with more model guidance
 showing the solution where the cyclone is left behind.  This is an
 uncertain forecast, however, and it wouldn't take much of a
 deviation for stronger winds to approach the coast.  A tropical
 storm watch could be issued for a portion of the coast of Mexico on
 Sunday morning.
 
 Marty is currently in an environment of light wind shear, high mid-
 level moisture and very warm waters.  These favorable conditions
 should last for the next 24-36 hours and promote intensification
 during that time.  While none of the deterministic guidance shows
 rapid intensification, the SHIPS-RI index shows about a 70 percent
 chance of a 25-kt increase in the first 24 hours.  The intensity
 forecast is set at the upper end of the guidance, about 5 kt above
 the previous prediction through 36 hours.  After that time, almost
 all of the global models show a significant increase in
 southwesterly shear, which should cause Marty to weaken and probably
 dissipate by day 5.  The official forecast is very close to the
 previous one and the intensity consensus after 72 hours.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  27/0300Z 13.6N 103.0W   35 KT  40 MPH
  12H  27/1200Z 14.2N 102.8W   45 KT  50 MPH
  24H  28/0000Z 14.9N 102.6W   55 KT  65 MPH
  36H  28/1200Z 15.4N 102.3W   60 KT  70 MPH
  48H  29/0000Z 15.8N 102.0W   55 KT  65 MPH
  72H  30/0000Z 16.0N 102.0W   45 KT  50 MPH
  96H  01/0000Z 16.2N 102.3W   30 KT  35 MPH
 120H  02/0000Z 16.5N 103.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
 $$
 Forecaster Blake