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Tropical Storm Lorena Discussion Number   2
NWS National Hurricane Center Miami FL       EP152019
400 PM CDT Tue Sep 17 2019

A pair of ASCAT passes sampled the circulation of Lorena earlier
this afternoon and showed multiple 40-45 kt wind vectors. Based on
that data, the initial wind speed has been increased to 45 kt for
this advisory. Lorena's cloud structure has improved somewhat
during the afternoon, though Dvorak-based wind estimates are still
notably lower than the ASCAT winds.

The track models have come into much better agreement, and there has
been a large shift eastward in the track guidance. However, since
the NHC track forecast was previously on the east side of the
guidance envelope, only a slight eastward shift was made to the
official forecast. Lorena is still expected to move generally
northwestward for the next day or two, and should move over or very
near the southwestern coast of Mexico by late Wednesday or early
Thursday. If the circulation survives its interaction with land, it
should continue to head northwestward, perhaps toward the Baja
California peninsula. That said, this portion of the forecast is
highly conditional, and Lorena may end up just dissipating over the
high terrain of Mexico. The NHC track forecast is now very close to
TVCN and HCCA, especially through 72 h, and confidence in the track
forecast has increased.

The tropical storm has strengthened, and conditions appear favorable
for additional slow strengthening. Once the circulation approaches
the coast of Mexico, its intensity will become closely tied to its
track. If Lorena moves inland, it will likely weaken quickly and
could dissipate entirely shortly thereafter. If it stays offshore,
it could maintain its strength and even intensify further as it
moves away from the coast of Mexico later this week, as shown by the
HWRF, DSHP, and LGEM models. The NHC intensity forecast is
consistent with the track forecast, and therefore shows Lorena
weakening due to land interaction after 48 h, but is below the
intensity consensus since a number of those models keep the cyclone
farther from the coast.

Key Messages:

1. Lorena is forecast to cause heavy rain over portions of the
Mexican states of Guerrero, Michoacan, Colima, and Jalisco during
the next few days. This rainfall may produce life-threatening flash
flooding and mudslides.

2. Tropical storm conditions are expected along a portion of the
southwestern coast of Mexico by late Wednesday.


FORECAST POSITIONS AND MAX WINDS

INIT  17/2100Z 14.6N 101.3W   45 KT  50 MPH
 12H  18/0600Z 15.7N 102.3W   50 KT  60 MPH
 24H  18/1800Z 17.3N 103.3W   55 KT  65 MPH
 36H  19/0600Z 18.5N 104.1W   55 KT  65 MPH
 48H  19/1800Z 19.2N 104.8W   55 KT  65 MPH...NEAR THE COAST
 72H  20/1800Z 20.5N 106.5W   40 KT  45 MPH
 96H  21/1800Z 22.0N 109.5W   35 KT  40 MPH
120H  22/1800Z 23.5N 112.0W   35 KT  40 MPH

$$
Forecaster Zelinsky

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