ATL: HENRI - Remnants - Discussion

[cycloneye]

TROPICAL STORM HENRI DISCUSSION NUMBER 10
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082015
500 AM AST FRI SEP 11 2015

Overall, Henri's cloud pattern has become slightly better organized
since the last advisory. While nearly all of the cyclone's deep
convection is still located well to the northeast of the center, a
relatively new convective burst over this area has grown in coverage
and cloud tops have cooled. Subjective Dvorak classifications
remain below tropical storm strength, but the initial intensity held
at 35 kt due to the cyclone's increasing forward speed and somewhat
improved satellite presentation.

Southerly shear appears to be diminishing over the cyclone, as has
been forecast by the large-scale models. The lower shear could
allow for some additional intensification to take place during the
next 12 hours or so while it remains over warm-enough waters.
However, the continued presence of dry air in the near-storm
environment and Henri's disorganized appearance suggest that any
intensification should be negligible. After the cyclone crosses the
northern wall of the Gulf Stream in less than 18 hours,
substantially lower sea surface temperatures and increasingly stable
air should induce weakening soon after that. A plausible alternate
scenario, presented by some of the global models, is that Henri
could degenerate into a trough later today. The cyclone or its
remnants are forecast to undergo extratropical transition in about
36 hours, with the system likely to be absorbed by a larger
extratropical cyclone by 72 hours. The new intensity forecast is
very similar to the previous one.

The initial motion estimate is 010/14. Henri is expected to
accelerate north-northeastward and then northeastward during the
next day or so as it encounters the fast-paced 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 adjusted to the left of the previous forecast and lies on the
right side of the guidance envelope.

The latter part of this forecast, when the storm is expected to be
post-tropical, is partially based on guidance provided by NOAA's
Ocean Prediction Center.


FORECAST POSITIONS AND MAX WINDS

INIT 11/0900Z 36.2N 60.3W 35 KT 40 MPH
12H 11/1800Z 39.0N 59.3W 40 KT 45 MPH
24H 12/0600Z 43.0N 56.4W 40 KT 45 MPH
36H 12/1800Z 46.5N 52.0W 35 KT 40 MPH...POST-TROP/EXTRATROP
48H 13/0600Z 48.9N 45.9W 35 KT 40 MPH...POST-TROP/EXTRATROP
72H 14/0600Z...ABSORBED

$$
Forecaster Kimberlain

[wxman57]

Visible satellite reveals that Henri appears to lack a circulation. Looks like an open wave.

[cycloneye]

Still alive.

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

[wxman57]

Still alive in name only. There are squalls producing 35kt winds but no circulation center.

[wxman57]

Bones says "good riddance"...

[HurricaneBelle]

au revior, Henri

WTNT43 KNHC 112033
TCDAT3

REMNANTS OF HENRI DISCUSSION NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082015
500 PM AST FRI SEP 11 2015

Henri is no longer a tropical cyclone. Visible images clearly show
that Henri lacks a well-defined center, with scatterometer and
satellite data also suggesting the circulation has degraded into a
southeast-to-northwest oriented trough. The scatterometer did show
a small area of 35-kt winds, so that intensity is kept.

The remnants of Henri are expected to trek northeastward then
eastward over the North Atlantic and should transition into an
extratropical low on Saturday. Future information on this system
can be found in High Seas Forecasts issued by the National Weather
Service Ocean Prediction Center...under AWIPS header NFDHSFAT1 and
WMO header FZNT01 KWBC.


FORECAST POSITIONS AND MAX WINDS

INIT 11/2100Z 40.0N 58.5W 35 KT 40 MPH...REMNANTS OF HENRI
12H 12/0600Z...DISSIPATED

[HurricaneBelle]

A little Henri history:

All the Henris have been weak tropical storms (1985, 2003, 2009, 2015) with the exception of 1979's version, which was a Cat 1 hurricane in the Bay of Campeche but dissipated in the Gulf without making landfall.

There was no Henri in 1997, an El Nino year, and technically there was no Henri in 1991 but the unnamed hurricane that formed from "the perfect storm" would have been Henri had it been named.

[floridasun78]

ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT FRI SEP 11 2015

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center has issued the last advisory on the
remnants of Tropical Storm Henri, which has dissipated several
hundred miles south of Newfoundland.

1. A large area of disorganized showers and thunderstorms continues
near the northern Leeward Islands and the Virgin Islands in
association with the remnants of Tropical Storm Grace. Upper-level
winds are not expected to be favorable for redevelopment of this
system during the next several days. However, heavy rain and gusty
winds are possible across portions of the northern Leeward Islands,
the Virgin Islands, Puerto Rico, and Hispaniola as the system moves
west-northwestward at 15 to 20 mph.
* Formation chance through 48 hours...low...near 0 percent
* Formation chance through 5 days...low...near 0 percent