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Tropical Storm Kate Discussion Number  11
NWS National Hurricane Center Miami FL       AL102021
500 PM AST Mon Aug 30 2021
 
The low-level center of Kate is exposed in visible satellite imagery
this afternoon. Its deep convection collapsed late this morning, and
the sheared tropical cyclone is now only producing a small area of
convection over 60 n mi east of its center. A partial 1321 UTC
ASCAT-B pass still showed numerous 30-kt wind vectors in the eastern
semicircle, even with little to no active convection. The initial
intensity is conservatively lowered to 35 kt for this advisory.
 
The subtropical jet stream across the central Atlantic will continue
to impart strong west-northwesterly vertical wind shear on Kate
during the next day or so. If the struggling tropical cyclone can
survive these hostile conditions, some modest strengthening could
occur later this week over warm SSTs of 28 deg C or so. However, the
lack of mid-level moisture in the surrounding environment may limit
convective development even under these more favorable conditions,
and there is no guarantee that Kate will survive that long. In fact,
simulated satellite imagery from the GFS and ECMWF suggest that Kate
may continue to only produce sporadic bursts of convection over the
next couple of days, which jeopardizes its chances of surviving
through the week. The official NHC intensity forecast has been
adjusted downward based on the latest guidance trends and the
uncertainties discussed above. Minor fluctuations in intensity could
occur over the next 24-36 h as convective pulsing causes the
cyclone's intensity to hover around tropical-storm-force strength.
 
Kate is moving a little faster toward the north, or 355/9 kt, within
a weakness in the subtropical ridge. A northward motion is expected
to continue through early Tuesday. The subtropical ridge is expected
to become reestablished over the central Atlantic Tuesday night into
Wednesday, which should turn Kate toward the northwest through
midweek. Thereafter, Kate is forecast to accelerate northward or
north-northeastward ahead of an approaching deep-layer trough that
will move across the western Atlantic late this week. Assuming Kate
is still around by day 5, the cyclone is forecast to become absorbed
by a larger extratropical low near Atlantic Canada.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  30/2100Z 22.7N  50.9W   35 KT  40 MPH
 12H  31/0600Z 23.7N  50.7W   30 KT  35 MPH
 24H  31/1800Z 24.7N  50.7W   30 KT  35 MPH
 36H  01/0600Z 25.8N  51.1W   35 KT  40 MPH
 48H  01/1800Z 27.0N  52.1W   35 KT  40 MPH
 60H  02/0600Z 28.4N  53.5W   40 KT  45 MPH
 72H  02/1800Z 30.1N  54.7W   40 KT  45 MPH
 96H  03/1800Z 34.5N  55.0W   40 KT  45 MPH
120H  04/1800Z...DISSIPATED
 
$$
Forecaster Reinhart
 
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