[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 112058
TCDAT2

Tropical Storm Barry Discussion Number   6
NWS National Hurricane Center Miami FL       AL022019
400 PM CDT Thu Jul 11 2019

Barry has become a little better organized since the last advisory,
with a convective band forming closer to the center in the southern
semicircle and the central pressure falling to near 1003 mb.
However, the strongest winds are still 70 nm or more from the
center, and there are several cloud swirls rotating around the mean
center.  The initial intensity remains 35 kt based on earlier
aircraft and scatterometer data, but it is possible this is a little
conservative.

The initial motion is 275/4.  Barry is being steered by a weak low-
to mid-level ridge to the north, and a weakness in the ridge is
forecast to develop during the next 24-48 h.  This should allow the
cyclone to turn northwestward and eventually northward.  However,
there remains a large spread in the track guidance.  The HWRF and
HMON forecast Barry to move generally northward across southeastern
Louisiana, while the UKMET and the UKMET ensemble mean take the
cyclone to the upper Texas coast.  The GFS, ECMWF, and Canadian
models lie between these extremes.  There was a slight westward
shift in the guidance envelope since the last advisory, which
resulted in the consensus models being close to the previous NHC
forecast track.  As a result, the new forecast track is similar to
the previous track, and it calls for the center of Barry to make
landfall on the central Louisiana coast between 36-48 h.  After
72 h, the cyclone should recurve northeastward as it enters the
mid-latitude westerlies.

Barry is still being affected by northerly shear, and GOES-16
airmass imagery indicates mid- to upper-level dry air coming from
the northeast has spread over the low-level center.  So far, this
has not stopped the development, and the guidance is in good
agreement that intensification will continue.  Thus, the new
intensity forecast is similar to the previous one in calling for
intensification until landfall.  While not explicitly shown in the
forecast, there is a significant chance that Barry will be a
hurricane when it makes landfall between 36-48 h in agreement with
the HWRF and GFS models.  After landfall, Barry should weaken as it
moves through the Mississippi Valley, and it is forecast to become
a remnant low by 96 h.


Key Messages:

1. There is a danger of life-threatening storm surge inundation
along the coast of southern and southeastern Louisiana where a Storm
Surge Warning is in effect. The highest storm surge inundation is
expected between the Mouth of the Atchafalaya River and Shell Beach.
Residents in these areas should listen to any advice given by local
officials.

2. The slow movement of Barry will result in a long duration heavy
rainfall and flood threat along the central Gulf Coast and inland
through the lower Mississippi Valley through the weekend into early
next week. Flash flooding and river flooding will become
increasingly likely, some of which may be significant, especially
along and east of the track of the system.

3. Hurricane conditions are expected along a portion of the coast of
Louisiana, where a Hurricane Warning has been issued.  Residents in
these areas should rush their preparations to completion, as
tropical storm conditions are expected to arrive in the warning area
by Friday morning.

FORECAST POSITIONS AND MAX WINDS

INIT  11/2100Z 27.8N  89.3W   35 KT  40 MPH
 12H  12/0600Z 27.9N  89.8W   45 KT  50 MPH
 24H  12/1800Z 28.3N  90.5W   50 KT  60 MPH
 36H  13/0600Z 29.0N  91.3W   60 KT  70 MPH
 48H  13/1800Z 30.0N  91.7W   60 KT  70 MPH...INLAND
 72H  14/1800Z 32.5N  92.0W   30 KT  35 MPH...INLAND
 96H  15/1800Z 35.0N  91.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  16/1800Z 37.5N  89.0W   20 KT  25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Beven
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