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TROPICAL STORM KATE DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122015
400 AM EST TUE NOV 10 2015

Kate's convective structure hasn't changed much from the previous
advisory.  The center is located beneath a small central dense
overcast with broken banding over the northeastern quadrant.  The
initial intensity remains 50 kt based on a blend of Dvorak numbers
of T3.5/55 kt from TAFB and T3.0/45 kt from SAB.  A NOAA P-3
aircraft recently reached Kate, and on its first pass through the
center it reported peak 700-mb flight-level winds of 45 kt and
surface winds between 40-45 kt.  In addition, the central pressure
has fallen to 1003 mb.  The plane will be making a few more passes
through the center during the next couple of hours.

Although vertical shear is forecast to increase during the next
couple of days and Kate will be moving over water colder than 26C
within the next 12-24 hours, all of the reliable intensity models
indicate that the cyclone should strengthen and reach hurricane
strength by 36 hours, if not sooner.  After 36 hours, the shear is
expected to increase to nearly 50 kt, which should cause Kate to
become post-tropical.  One significant change on this cycle is that
the 00Z GFS, UKMET, Canadian, and to some extent the ECMWF now show
Kate becoming the dominant low pressure area over the north Atlantic
in a few days instead of being absorbed by a separate extratropical
low.  Therefore, the updated NHC is now extended beyond 48 hours,
showing Kate as a growing extratropical low over the north Atlantic
on days 3-5.

Kate is accelerating northward with an initial motion of 010/15 kt.
The cyclone is forecast to turn northeastward and east-northeastward
and accelerate further through Wednesday as it becomes embedded in
the mid-latitude westerlies.  Kate is likely to slow down around
day 3 when it becomes extratropical, but it should resume a faster
northeastward motion toward the far north Atlantic on days 4 and 5.
The new NHC track forecast is primarily an update of the previous
forecast through 48 hours, and the extended extratropical portion
beyond day 3 is generally a blend of the GFS and ECMWF models.

FORECAST POSITIONS AND MAX WINDS

INIT  10/0900Z 28.8N  75.8W   50 KT  60 MPH
 12H  10/1800Z 31.0N  73.7W   55 KT  65 MPH
 24H  11/0600Z 33.9N  68.3W   60 KT  70 MPH
 36H  11/1800Z 36.6N  60.7W   65 KT  75 MPH
 48H  12/0600Z 39.2N  54.0W   65 KT  75 MPH...POST-TROPICAL
 72H  13/0600Z 43.0N  48.5W   55 KT  65 MPH...POST-TROP/EXTRATROP
 96H  14/0600Z 46.0N  39.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  15/0600Z 53.0N  27.0W   45 KT  50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Berg

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