[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 301502
TCDAT3

Hurricane Lorenzo Discussion Number  33
NWS National Hurricane Center Miami FL       AL132019
1100 AM AST Mon Sep 30 2019

Lorenzo continues to maintain its strength.  A cloud filled eye is
evident in infrared satellite imagery, while convection is
attempting to wrap around a break in the southern portion of the
hurricane. This is indicating that for the time being, the cyclone
is fighting off some of the dry air entraining into it from the
southwest.  The subjective Dvorak intensity estimates from TAFB and
SAB remain at 90 kt, which will be the initial intensity for this
advisory.

Lorenzo continues north-northeastward, now at 13 kt, around the
northwestern periphery of a subtropical ridge. Over the next couple
of days Lorenzo will be accelerated northeastward by increasing
southwesterly flow ahead of a mid-latitude trough amplifying across
the central Atlantic. This motion should take the core of Lorenzo
near or just west of the western Azores late Tuesday and early
Wednesday. The forecast track confidence is high through 72 hours,
but decreases significantly thereafter, as forecast models continue
to differ on their handling of the steering flow. By that time, the
steering flow may break down as the trough to the west of Lorenzo
de-amplifies, while an extratropical low quickly approaches from the
west. Some of the forecast models turn Lorenzo north ahead of the
approaching low as they begin to interact, other solutions turn
Lorenzo or its remnants to the east in the westerlies, with
limited interaction with this low. The official forecast track is
very close to the previous one and to the consensus aids, which lies
in between these two scenarios.

Lorenzo should gradually weaken over the next couple of days while
drier air continues to get pulled into the circulation and the
system moves over progressively cooler waters. After 48 hours, the
interaction with the approaching trough, an associated cold front,
and very strong southwesterly shear will help transition Lorenzo
into an extratropical low. This transition is expected to be
complete by 72 hours. The low is then expected to either dissipate
or become absorbed by another extratropical low by day 5. The
official forecast intensity is very similar to the previous one,
and is in good agreement with the consensus aids.

Key Messages:

1.  Lorenzo is expected to bring hurricane and tropical storm force
winds to the Azores beginning Tuesday night, and these conditions
will continue into Wednesday.  Hurricane and Tropical Storm Warnings
are now in effect for the Azores.

2.  Large swells generated by Lorenzo will continue to spread across
much of the north Atlantic basin during the next few days.  These
swells will produce life-threatening surf and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT  30/1500Z 30.0N  42.6W   90 KT 105 MPH
 12H  01/0000Z 31.7N  41.5W   85 KT 100 MPH
 24H  01/1200Z 34.5N  38.6W   80 KT  90 MPH
 36H  02/0000Z 38.1N  34.3W   75 KT  85 MPH
 48H  02/1200Z 43.3N  28.0W   70 KT  80 MPH
 72H  03/1200Z 53.5N  17.8W   60 KT  70 MPH...POST-TROP/EXTRATROP
 96H  04/1200Z 58.2N  11.4W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  05/1200Z...DISSIPATED

$$
Forecaster Latto
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