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Tropical Storm HENRI


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TROPICAL STORM HENRI DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082015
1100 AM AST FRI SEP 11 2015

Visible satellite images indicate that the surface circulation of
Henri has become rather distorted this morning. Multiple low-level
swirls can be seen in the circulation that is elongated from
southeast to northwest, with some suggestion that the cyclone may no
longer be closed in the northwestern quadrant. The intensity is
being held at 35 kt in agreement with the satellite estimate from
TAFB.

Although shear is somewhat lower over the cyclone, it appears that
the low-level structure is too poor to take advantage of the more
favorable environment. The intensity forecast has been lowered
a little to reflect the less conducive conditions. The cyclone or
its remnants are forecast to undergo extratropical transition in
about 24 hours while moving over colder water with high shear,
and the system is likely to be absorbed by a larger extratropical
cyclone by 72 hours. An alternate scenario, one that is becoming
more likely, is that Henri could degenerate into a trough later
today.

The initial motion estimate is 020/17.  Henri is expected to
accelerate north-northeastward and then northeastward during the
next day or so as it encounters increasing flow ahead of a deep
longwave trough digging into eastern North America and the western
Atlantic. The post-tropical cyclone or its remnants should then
turn east-northeastward over the north Atlantic. The new track
forecast is very similar to the previous one and near or on the
right side of the model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  11/1500Z 38.0N  59.4W   35 KT  40 MPH
 12H  12/0000Z 41.0N  57.7W   35 KT  40 MPH
 24H  12/1200Z 44.9N  54.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 36H  13/0000Z 48.0N  48.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 48H  13/1200Z 50.0N  42.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  14/1200Z...DISSIPATED

$$
Forecaster Blake

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