135 
WTPZ43 KNHC 070850
TCDEP3

Tropical Storm Kristy Discussion Number   2
NWS National Hurricane Center Miami FL       EP132018
200 AM PDT Tue Aug 07 2018

Satellite images indicate that the cyclone has rapidly become better
organized, with a distinct curved band pattern now apparent. A
timely scatterometer pass indicated peak winds of 40-45 kt, so the
initial wind speed is set to 45 kt.  Continued intensification is
forecast while the storm remains over warm waters with light or
moderate shear. While there is no guidance indicating anything but
slow strengthening, some caution should be advised since Kristy has
already overachieved.  The wind speed forecast is raised from the
previous one, and is close to the HFIP corrected consensus.
Weakening should start by day 4 as the storm moves over cooler
waters.

Kristy appears to be moving at 265/10 kt. Model guidance is in
decent agreement on a subtropical ridge holding steady to the north
of the cyclone for a day or so, causing a westward motion.  After
that time, the agreement becomes quite poor due to large
uncertainties over how fast the ridge erodes, partially due to the
circulation of Hurricane John.  The GFS shows a fast erosion and a
turn to the north and northeast of Kristy, while the ECMWF keeps the
ridge in place, leading to the models being a "mere" 1200 miles
apart on the day-5 forecast of Kristy.  Interestingly, the model
consensus didn't change much, so I've decided to keep the forecast
basically the same, with the caveat that this is obviously a
low-confidence prediction.


FORECAST POSITIONS AND MAX WINDS

INIT  07/0900Z 14.3N 125.1W   45 KT  50 MPH
 12H  07/1800Z 14.3N 126.5W   50 KT  60 MPH
 24H  08/0600Z 14.5N 128.2W   55 KT  65 MPH
 36H  08/1800Z 14.9N 129.4W   60 KT  70 MPH
 48H  09/0600Z 15.6N 130.2W   65 KT  75 MPH
 72H  10/0600Z 17.5N 130.5W   65 KT  75 MPH
 96H  11/0600Z 19.5N 131.0W   55 KT  65 MPH
120H  12/0600Z 22.0N 133.0W   45 KT  50 MPH

$$
Forecaster Blake