000
WTNT41 KNHC 290237
TCDAT1

TROPICAL STORM JOAQUIN DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL112015
1100 PM EDT MON SEP 28 2015

Satellite images indicate that the shower and thunderstorm activity
associated with the depression has increased and become better
organized during the past several hours.  In addition, the low-level
center now appears to have moved closer to the convection than it
was earlier. The latest Dvorak classifications from TAFB and SAB
were 2.5/35 kt, and the initial intensity is set at that value,
making the cyclone Tropical Storm Joaquin.  This intensity analysis
also agrees with the reconnaissance aircraft data from earlier today
that showed winds just under tropical-storm force.

The center of Joaquin has been moving southwestward during the last
several hours, but it is expected to begin moving slowly westward
overnight.  This westward track is forecast to continue for a couple
of days while a mid-level ridge remains to the north of the storm.
After that time, a trough is anticipated to amplify over the eastern
United States, which should cause Joaquin to turn northward and
accelerate.  There is considerable spread in the models, mainly due
to the timing of when and how fast the storm makes the northward
turn, due to differences in the evolution of the trough.  In
general, the guidance envelope has shifted southward for the first
couple of days and then westward after that time.  The official
track forecast has been adjusted accordingly, but additional
southward and westward adjustment may be needed in subsequent
advisories.

Northwesterly shear of about 20 kt is currently affecting Joaquin,
causing most of the thunderstorm activity to be located to the
southeast of the center.  The shear is expected to lessen some
during the next couple of days, which in combination with warm water
and high relative humidity values should allow Joaquin to
strengthen.  The official intensity forecast is raised from the
previous one, but is lower than the intensity model consensus at
days 3-5.

FORECAST POSITIONS AND MAX WINDS

INIT  29/0300Z 26.7N  70.4W   35 KT  40 MPH
 12H  29/1200Z 26.9N  71.0W   40 KT  45 MPH
 24H  30/0000Z 27.1N  72.0W   40 KT  45 MPH
 36H  30/1200Z 27.2N  72.8W   45 KT  50 MPH
 48H  01/0000Z 27.4N  73.4W   50 KT  60 MPH
 72H  02/0000Z 28.6N  74.0W   55 KT  65 MPH
 96H  03/0000Z 32.4N  74.0W   55 KT  65 MPH
120H  04/0000Z 38.0N  74.0W   55 KT  65 MPH

$$
Forecaster Cangialosi