Tropical Depression KATE (Text)

Tropical Depression Kate Discussion Number  18
NWS National Hurricane Center Miami FL       AL102021
1100 AM AST Wed Sep 01 2021
It has been difficult to pinpoint where the low-level circulation of 
Kate is this morning. After last night's diurnal convective maximum, 
the remaining convection has taken on a very disorganized structure, 
with a mid-level vortex being left behind to the south, while 
deeper, but more outflow driven convection is racing off to the 
north, ahead of the estimated low-level center position. A recently 
received 1211 UTC ASCAT-A pass indicated that Kate's low-level 
circulation is still closed, but just barely. The scatterometer wind 
data supports maintaining the current intensity at 30-kt, which also 
agrees with the latest subjective and objective Dvorak estimates.
The estimated motion is continuing off to the north-northwest, at 
340/9 kt. Kate appears to now be primarily steered by the low-level 
flow around a subtropical ridge located to its east. A general 
north-northwest motion is expected to continue today, followed by a 
turn to the north and north-northeast around the periphery of this 
ridge. The latest NHC track guidance has been adjusted a bit right 
of the previous track, shifting towards the latest consensus 
guidance (TVCN) that can still track the cyclone beyond 24 hours.
A 0958 UTC SSMIS microwave pass suggested that the better organized 
structure observed last night has decayed, with the low- and 
mid-level centers quite misaligned. Vertical wind shear diagnosed by 
SHIPS is now between 15-20 kt out of the north. This shear is likely 
contributing to the vortex tilt, while also helping to import very 
dry mid-level air, preventing Kate's convective activity from 
organizing.  The bulk of the intensity guidance is in agreement that 
gradual spin down of the low-level circulation will occur over the 
next several days, with the deterministic ECMWF model suggesting 
Kate could open up to a trough as soon as tomorrow. The latest NHC 
intensity forecast makes Kate a remnant low in 36 hours, with 
dissipation after 48 hours. However, given the current structure, 
this could occur sooner than forecast.
INIT  01/1500Z 26.8N  52.3W   30 KT  35 MPH
 12H  02/0000Z 27.9N  52.7W   25 KT  30 MPH
 24H  02/1200Z 29.6N  53.1W   25 KT  30 MPH
 36H  03/0000Z 31.1N  53.2W   20 KT  25 MPH...POST-TROP/REMNT LOW
 48H  03/1200Z 32.4N  52.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 60H  04/0000Z...DISSIPATED
Forecaster Papin

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Page last modified: Friday, 31-Dec-2021 12:09:24 UTC