[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 280236
TCDAT3

Hurricane Lorenzo Discussion Number  22
NWS National Hurricane Center Miami FL       AL132019
1100 PM AST Fri Sep 27 2019

Lorenzo's cloud pattern has continued to deteriorate this evening.
A series of SSMI and GMI microwave overpasses revealed inner core
erosion, particularly in the south portion.  The images also showed
a significant south to north vertical tilt of the cyclone,
indicative of the moderate southwesterly shear undercutting the
impressive upper-tropospheric diffluent flow.  A blend of all the
available subjective and objective satellite intensity estimates, as
well as an earlier SATCON analysis, yields an initial intensity of
105 kt for this advisory.

Lorenzo will remain over warm oceanic sea surface temperatures for
the next 3 days.  Nonetheless, the stiff southwesterly shear should
inhibit strengthening, although there is a slight chance of
short-term fluctuations in intensity caused by eyewall replacement
cycles.  Beyond the 72 hour period, Lorenzo is expected to encounter
stronger mid-latitude westerlies, move over cooler waters, and
undergo extratropical transition as it interacts with a baroclinic
zone moving over the central north Atlantic.  The NHC forecast is an
update of the previous advisory and is based on a blend of the HFIP
Corrected Consensus and Florida State Superensemble intensity
models.

The aforementioned microwave images also indicate that Lorenzo has
been moving a little to the left of track, and the initial motion is
estimated to be north-northwestward, or 335/8 kt. The song remains
the same, no change in the track forecast philosophy. Lorenzo should
turn northward and then northeastward during the next few days as it
moves around the western periphery of a mid-tropospheric ridge
anchored over the eastern Atlantic.  Around mid-period, Lorenzo is
forecast to accelerate toward the northeast, in the mid-latitude
westerly flow, in response to a deep-layer major shortwave trough
approaching from the north-central Atlantic.  The track forecast has
been adjusted slightly to the left of the previous one and is close
to the various consensus aids.

The wind radii have been adjusted using 2308 UTC METOP-B
scatterometer data.  The forecast wind radii, beyond the 48 hour
period, is based primarily on the RVCN global consensus.


FORECAST POSITIONS AND MAX WINDS

INIT  28/0300Z 20.8N  44.1W  105 KT 120 MPH
 12H  28/1200Z 21.9N  44.5W  105 KT 120 MPH
 24H  29/0000Z 23.7N  44.5W  100 KT 115 MPH
 36H  29/1200Z 25.4N  44.1W  100 KT 115 MPH
 48H  30/0000Z 27.0N  43.4W   95 KT 110 MPH
 72H  01/0000Z 30.7N  41.3W   95 KT 110 MPH
 96H  02/0000Z 36.5N  34.6W   90 KT 105 MPH
120H  03/0000Z 45.5N  22.9W   75 KT  85 MPH...POST-TROP/EXTRATROP

$$
Forecaster Roberts
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