586 
 WTPZ44 KNHC 012034
 TCDEP4
 
 TROPICAL STORM ISELLE DISCUSSION NUMBER   5
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092014
 200 PM PDT FRI AUG 01 2014
 
 Iselle has a well-defined structure in visible imagery and at times
 seems to have been trying to form an eye.  However, the convective
 pattern as observed in infrared satellite imagery has been a little
 ragged and not as well structured.  Dvorak estimates from TAFB and
 SAB are now unanimously T3.5/55 kt, but final-T estimates from the
 UW-CIMSS ADT have actually dropped to T3.1/47 kt since this
 morning.  Based on these numbers, as well as a 50-kt estimate from
 a recent ASCAT-B pass, the initial intensity is held at 55 kt.
 
 The strengthening trend may be taking a temporary respite, but
 environmental conditions should support further intensification
 during the next 2-3 days.  Modest northerly shear appears to be
 impinging on the storm, but that shear is expected to diminish in a
 day or two.  By that time, thermodynamic conditions will become a
 little more marginal as Iselle approaches the 26C sea surface
 temperature isotherm.  The intensity models are in fairly good
 agreement in showing modest strengthening, although the peak
 intensities have decreased a bit.  Based on the latest guidance,
 the updated NHC intensity forecast shows Iselle reaching a maximum
 intensity of 70 kt in 36-48 hours.
 
 The track models are also in good agreement, showing very little
 spread during the first 3 days.  The subtropical ridge to the north
 of Iselle should keep the cyclone on a west-northwestward track
 during that time.  Iselle's forward speed is then expected to slow
 down on days 3 and 4 as it gets impeded by a mid-level ridge near
 Hawaii, and then speed up again on day 5 when the ridge slides
 eastward.  No significant changes were required to the official
 track forecast, and the NHC points continue to lie very close the
 model consensus TVCE.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  01/2100Z 14.5N 126.4W   55 KT  65 MPH
  12H  02/0600Z 14.9N 127.7W   60 KT  70 MPH
  24H  02/1800Z 15.4N 129.5W   65 KT  75 MPH
  36H  03/0600Z 15.9N 131.3W   70 KT  80 MPH
  48H  03/1800Z 16.3N 133.2W   70 KT  80 MPH
  72H  04/1800Z 16.6N 136.3W   65 KT  75 MPH
  96H  05/1800Z 16.9N 138.7W   60 KT  70 MPH
 120H  06/1800Z 17.5N 143.0W   50 KT  60 MPH
 
 $$
 Forecaster Berg