Tropical Storm Henri forms
The tropics spawned another October surprise today, when Tropical Storm Henri formed in the face of adverse levels of wind shear. Henri is under about 20 - 25 knots of wind shear, which ordinarily prevents rapid development like we witnessed this afternoon. However, the environment is quite moist, and Henri is over warm waters, 29°C. An ASCAT pass from 11:37am EDT showed Henri had winds of 40 mph. Satellite loops show that Henri has managed to rapidly develop a large area of intense thunderstorms with cold cloud tops in just a few hours, though the high shear is keeping any thunderstorms from developing on the west side of the center. Water vapor satellite images show that there is some dry air to Henri's northwest, and this dry air will act to slow Henri's growth some. The dry air is creating strong downdrafts that are apparent on visible satellite images as arcs of cumulus clouds spreading out from where the downdraft hits the ocean surface, along the northwest side of Henri's center.
None of the reliable global computer models showed Henri would develop, and the models all favor weakening and dissipation of Henri by Thursday, due to high wind shear of 20 - 25 knots. The official NHC forecast goes along with this scenario, but think there is a medium (30 - 50% chance) that Henri will not dissipate. By Friday, wind shear in the vicinity of Henri (or its remains) is predicted to fall to the low to moderate range. Even if Henri has dissipated by that point, regeneration into a tropical storm may occur. The track of Henri after Friday is problematic, as the storm will be in an area of weak steering currents. Several of the models favor a track to the west-southwest into the Caribbean, across Hispaniola. Residents of the Dominican Republic and Haiti should anticipate that Henri or its remains may bring flooding rains to Hispaniola by Saturday. It is also possible that Henri will get pulled northwards and recurved out to sea, and not affect the Caribbean at all, though.

Figure 1. Latest satellite image of Henri.
A little tropical weather for England
The remnant circulation of Tropical Storm Grace is currently making landfall in Southwest England. Grace's remains brought sustained winds of tropical storm force--41 mph--to one buoy off the coast last hour, and 38 mph to the Sevenstones Lightship buoy. you can track the progress of Grace via our wundermap for the region.

Figure 2. The remnant circulation of Tropical Storm Grace scoots by to the south of Ireland in this visible satellite image taken at 1pm EDT 10/06/09. Image credit: UK Met Office.
Jeff Masters
Reader Comments
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Not to attack you but I think with each storm something is learned. Grace was not suppose to develop in the cool waters but did. Henri should not have developed due to high wind shear but did. I could go on but it would take a while. I just think that "NOTHING" is text book.
at first glance, yet Erika's LLC was never curved around the LLCC, while Henri's convection is curved around the LLCC. Structurally, Henri winds.
that confuses me more :|
farther to the south?
Thanks, can I have a link?
I was walking past the mental hospital the other day,
And all the patients were outside shouting, '13...13...13.'
The fence was too high to see over, but I saw a
Little gap in the planks, so I looked through to see
What was going on...
Somebody poked me in the eye with a stick!
Then they all started shouting '14...14...14'...
good evening everyone as always nice to read your posts
well that image was from a few hours ago, so it lines up perfectly with the center we are currently seeing on shortwave imagery.
ah nice thanks for that clarification :)
I agree they add to uncertainity and excitement, also a challenge for forecasters, these are the storms that makes weathermen/women smarter imo.
NHC has in the past included pronunication in the forecast discussion. They also have a webpage on pronounciation.
Lol. Good evening. :)
Link
Select on the right hand side.
well said, you learn and open yourself to multiple possibilities.
ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM DOLLY DISCUSSION NUMBER 3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042008
1100 PM EDT SUN JUL 20 2008
DATA FROM A NOAA P3 AIRCRAFT INDICATE THAT DOLLY HAS NOT BECOME ANY
BETTER ORGANIZED THIS EVENING. INDEED...THE SYSTEM PROBABLY
DOESN'T HAVE A CLOSED SURFACE CENTER RIGHT NOW. HOWEVER...DOLLY IS
MAINTAINING VIGOROUS CONVECTION AND THE STRONGEST WINDS...AS
ESTIMATED BY THE SFMR...HAVE INCREASED TO 45 KT. SINCE DOLLY COULD
REGENERATE A CENTER AT ANY TIME...NO GOOD WOULD BE SERVED BY
HANGING ON A TECHNICALITY.
equals this: Link
why do I see a LLC on one and not on the other :|
i said the same thing =P
I think Henri LLC has been forming since 5 am this morning, just after we began receiving GOES-12 images from the eclipse.
I agree. Goes to show you, even Mother Nature can "think outside the box."
most likely becuase its two different organizations reading, organizating, displaying the data.
it could be a simple as the difference between the programming code, graphics resolution etc.
EUMETSAT must use a slightly different automatic algorithm for wind solutions.
From The Operational Use of QuikSCAT Ocean Surface Vector Winds at the
National Hurricane Center
The design of the QuikSCAT instrument results in up
to four possible wind solutions, or ‘‘ambiguities,’’ in
each wind vector cell (WVC) over which the retrieval
is performed. An ambiguity removal filter chooses a
solution (hereafter the ‘‘automated’’ solution) from
among the ambiguities in each WVC (Hoffman and
Leidner 2005). The ambiguity removal filter utilized in
the NESDIS NRT retrievals is initialized with a 6–9-h
forecast 10-m wind field from the NCEP Global Forecast
System (GFS) model. Both the automated solutions
and the ambiguities are displayable in N-AWIPS at
NHC, which is important since the ambiguities are often
manually analyzed by a forecaster to properly interpret
the QuikSCAT retrievals, especially in TCs.
Tropical cyclone center locations derived from the
automated QuikSCAT wind solutions are often unreliable,
showing large positional errors or the absence of a
closed circulation altogether. Therefore, forecasters at
NHC perform a manual analysis of all the possible wind
solutions (i.e., an ‘‘ambiguity analysis’’) in an attempt to
locate the surface circulation or determine if one exists.
This manual procedure is essentially a streamline
analysis that is performed by examining all of the possible
ambiguities, working inward toward a suspected
center and attempting to choose ambiguities that correspond
to a closed cyclonic circulation.1 The starting
point for the analysis is chosen, if possible, in a region
where either the wind direction is known from other
observations, or at points in the QuikSCAT swath that
show only two or three potential wind directions (i.e.,
two- or three-way ambiguities), implying less uncertainty
in the wind direction
Henri is "AHN ree"! Earlier, I called Henri a "she" earlier and mispronounced his name! And I am "Smarter than a 5TH grader"!
TS Henri is still firing off plenty of deep convection.
GFS SUGGEST FRONT ONLY GETS INTO NORTHERN GULF THEN
STALLS...AS HAS BEEN THE CASE SO FAR THIS FRONTAL SEASON. THE
ECMWF IS MORE AGGRESSIVE IN BRINGING THE FRONT CLEANLY THROUGH THE
COASTAL WATERS WITH CONTINTENTAL INFLUENCES OF DRIER AND COOLER
AIR. GIVEN STRENGTH OF SURFACE HIGH...THIS FRONT SHOULD HAVE MORE
INTEGRITY THAN PREVIOUS FRONTS CLOSER TO ECMWF SOLUTION. HIGH
PRESSURE THEN BUILDS AND MOVES EAST IN TIME SATURDAY THROUGH
MONDAY.
&&
.MARINE...
LIGHT ONSHORE FLOW TONIGHT AND MUCH OF WEDNESDAY WILL INCREASE TO
MODERATE LEVELS THURSDAY IN ADVANCE OF THE COLD FRONT. A WIND
SHIFT TO NORTHEAST DOES TAKE PLACE FRIDAY WITH FRONTAL PASSAGE BUT
AIR MASS WILL BE LOSING INTEGRITY IN THE PROCESS...WHICH SHOULD
BRING EAST TO SOUTHEAST WINDS BACK THROUGH THE COASTAL WATERS
SATURDAY AND SUNDAY. ONSHORE FLOW SHOULD THEN PREVAIL AT LIGHT TO
MODERATE LEVELS MONDAY THROUGH WEDNESDAY.
this confirms it GeoffreyWPB and stormpetrol
That's the infrared center
Sounds like a skit on SNL..:)
Ah I see. Nice analogy.
Atmospheric dynamics do NOT always "color between the lines"!
In math 1 + 1 always equals 2. The atmospheric dynamics may be similar but are never, ever the same. So many variables, not even a computer can accurately assess and predict an outcome.
That's why I love weather :0)!
I remember that SNL skit, "Pat"! Ha, ha, ha :0).
And her/his? date Chris. Lol.
waterwitch that was a great one. thanks for the entertainment.
Also NHC may not dissipate the storm as quickly since the track used on the latest SHIPS is the interpolated official forecast, which shows it going out to 96 hours.
It could miss Haiti, which would definitly boost its chances.
I did not had QS in 1998 and I did not know to use it until 2001, we have to go back to old fashion forecasting. It might be a bit more difficult but ASCAT has a narrower swath and the same time lapse as QS, which is a downgrade. Tonight is a perfect example. We were able to get a center without using QS and it verified per the 0000UTC, so this is what we might be in for, so start learning (not in a rude way though).
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