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Tropical Storm Lorena Discussion Number   6
NWS National Hurricane Center Miami FL       EP152019
400 PM CDT Wed Sep 18 2019

Visible satellite imagery has continued to show an improvement in
banding around the center of Lorena this afternoon.  Bands now wrap
completely around the center, but there have been no recent
microwave images to see if an eye has developed.  The increase in
organization has led to higher objective satellite intensity from
UW/CIMSS, and a blend of the SAB and ADT estimates yields an initial
intensity of 60 kt.  Additional strengthening is likely, and Lorena
is forecast to become a hurricane tonight while it moves over warm
water with low shear conditions. The storm is predicted to move very
close to or over the southwestern coast of Mexico later tonight and
early Thursday, and the remainder of the intensity forecast will
depend on how much land interaction occurs and the eventual
structure of the storm afterward. If Lorena moves to the right of
the official forecast, more significant weakening is likely and the
storm would struggle to re-strengthen later in the period.  The new
NHC track forecast shows slightly less interaction of the core of
the cyclone with land, and assumes Lorena will be able to continue
strengthening while the shear remains low and it moves over very
warm waters southeast of the Baja California peninsula.

Lorena is moving northwestward or 320/11 kt.  The track guidance
remains about the same as before, with the ECMWF taking the center
inland over southwestern Mexico while most of the remainder of the
guidance keeps it just offshore.  The NHC forecast is slightly west
of the previous advisory through 24 hours, but continues to show the
center passing very close to southwestern Mexico.  After that time,
a narrow mid-level ridge is forecast to build to the north of
Lorena, and this should lead to a west-northwestward motion with
Lorena passing near or just south of the southern tip of the Baja
Peninsula.  The NHC track forecast is in best agreement with the
HFIP corrected consensus.

Due the potential for land interaction within the next 12-24 hours,
there is greater than usual uncertainty in both the track and
intensity forecast for Lorena through day 5.

Key Messages:

1. Lorena is forecast to become a hurricane and move dangerously
close to the coast of southwestern Mexico tonight and Thursday.
A hurricane warning is in effect and preparations to protect life in
property should be rushed to completion.

2. 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.

3. Lorena could threaten the southern portion of the Baja
California peninsula as a hurricane this weekend, but the forecast
is more uncertain due to the potential for land interaction tonight
and Thursday.  Residents should ensure that their hurricane plan is
in place as watches may be required tonight or Thursday.


FORECAST POSITIONS AND MAX WINDS

INIT  18/2100Z 17.9N 104.4W   60 KT  70 MPH
 12H  19/0600Z 19.2N 105.3W   70 KT  80 MPH
 24H  19/1800Z 20.1N 106.2W   70 KT  80 MPH
 36H  20/0600Z 20.7N 107.2W   75 KT  85 MPH
 48H  20/1800Z 21.2N 108.3W   80 KT  90 MPH
 72H  21/1800Z 22.5N 110.8W   85 KT 100 MPH
 96H  22/1800Z 24.5N 113.0W   60 KT  70 MPH
120H  23/1800Z 26.6N 115.0W   40 KT  45 MPH

$$
Forecaster Brown

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