Tropical Storm Henri forms

By: Dr. Jeff Masters , 9:37 PM GMT on October 06, 2009

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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


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Quoting BahaHurican:
Wow! I have had internet access problems since Friday, and looks what happens! 2 new storms!!!


You missed one heck of a weekend. I mean seriously.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
I can't wait til next week!..And I'll bet Ike can't either. Bring the cool weather on to the Southeast!
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Wow! I have had internet access problems since Friday, and looks what happens! 2 new storms!!!
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AOI

AOI

AOI

AOI


Daily Chuckles in Comments section


PARMA
Current Storm Position
Oct 6 - 18:00 UTC
Tropical Cyclone
Maximum winds of 035 knots
Gusts to 045 knots
155 degrees at 04 knots

Latitude: 18.2
Longitude: 121

MELOR
Current Storm Position
Oct 6 - 18:00 UTC
Typhoon
Maximum winds of 090 knots
Gusts to 110 knots
005 degrees at 14 knots

Latitude: 26.6
Longitude: 130.8

HENRI
Current Storm Position
Oct 6 - 21:00 UTC
Tropical Storm
Maximum winds of 40 mph
and a pressure of 1007 mb
Latitude: 17.8
Longitude: -54
Member Since: October 1, 2007 Posts: 81 Comments: 26511
It will be interesting to see if the NHC continues the cone for another 12 or 24 hours at 11:00 p.m.
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What the NHC is looking at to dissipate the storm is that large trough to northwest of Henri. As that trough advects eastward, shear will increase over the next 24 hours.
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249. xcool



Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting WxLogic:
Guys don't forget QS is starting to die little by little. I believe atmogie posted some info on it a while back so... it sure looking like NHC and/or other organization(s) are starting to look into ASCAT instead of QS as the Euro version is more reliable... IMO.


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).
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Drakoen:
The SHIPS analyzes shear at 25 knots over the system. Conditions, according to the SHIPS, should remain unfavorable for significant development over the 24 hours before upper level winds and directional shear become more conducive. Assuming the system lasts that long, it may organize further before running into the Greater Antilles.


It could miss Haiti, which would definitly boost its chances.
Member Since: September 6, 2009 Posts: 2 Comments: 3756
Quoting Drakoen:
The SHIPS analyzes shear at 25 knots over the system. Conditions, according to the SHIPS, should remain unfavorable for significant development over the 24 hours before upper level winds and directional shear become more conducive. Assuming the system lasts that long, it may organize further before running into the Greater Antilles.


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.
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just catching up.

waterwitch that was a great one. thanks for the entertainment.
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Guys don't forget QS is starting to die little by little. I believe atmogie posted some info on it a while back so... it sure looking like NHC and/or other organization(s) are starting to look into ASCAT instead of QS as the Euro version is more reliable... IMO.
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Quoting Bordonaro:


I remember that SNL skit, "Pat"! Ha, ha, ha :0).



And her/his? date Chris. Lol.
Member Since: August 15, 2008 Posts: 10 Comments: 3665
The SHIPS analyzes shear at 25 knots over the system. Conditions, according to the SHIPS, should remain unfavorable for significant development over the 24 hours before upper level winds and directional shear become more conducive. Assuming the system lasts that long, it may organize further before running into the Greater Antilles.
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Quoting GeoffreyWPB:


Sounds like a skit on SNL..:)


I remember that SNL skit, "Pat"! Ha, ha, ha :0).

Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting lakeEFX:

I agree. Goes to show you, even Mother Nature can "think outside the box."

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)!
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting tornadofan:
For those familiar with the NFL or NCAA football, when using instant replay, the video has to show irrefutable evidence to reverse the call on the field. Similarly, I believe the NHC will have to see irrefutable evidence before stating Henri has lost it's LLC.


Ah I see. Nice analogy.
Member Since: August 15, 2008 Posts: 10 Comments: 3665
Quoting StSimonsIslandGAGuy:
The storm Ruth merged with was Pat.


Sounds like a skit on SNL..:)
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Quoting nrtiwlnvragn:
AL 10 2009100700 BEST 0 181N 547W 35 1007 TS



this confirms it GeoffreyWPB and stormpetrol

That's the infrared center
Member Since: July 24, 2005 Posts: 407 Comments: 19076
06/2345 UTC 17.9N 54.4W T1.5/1.5 HENRI -- Atlantic
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AL 10 2009100700 BEST 0 181N 547W 35 1007 TS
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For those familiar with the NFL or NCAA football, when using instant replay, the video has to show irrefutable evidence to reverse the call on the field. Similarly, I believe the NHC will have to see irrefutable evidence before stating Henri has lost it's LLC.
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Quoting Weather456:


I think Henri LLC has been forming since 5 am this morning, just after we began receiving GOES-12 images from the eclipse.
Thanks weather456
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What this means, other than a fleeting at best cold front, is that this trough anyway may not make it far south enough to have any affect on Henri. Of course this is the NW GOM. The trough may swing deeper off the east coast, I don't know.

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.
Member Since: August 15, 2008 Posts: 10 Comments: 3665
Is it possible for these 2 storms to merge? Anyone?
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Quoting nrtiwlnvragn:


NHC has in the past included pronunication in the forecast discussion. They also have a webpage on pronounciation.


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.
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting Weather456:
I wonder why the two QS versions differ considering it is basically the same pass.


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
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Quoting Weather456:
I wonder why the two QS versions differ considering it is basically the same pass.


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.
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For some reason October means, develop in hostile environment. Either develops in cold water and now with high shear very Interesting.
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Quoting Weather456:
Systems like Erika and Henri are far from boring, due to the uncertain they are more interesting than clear-cut storms like Bill.

I agree. Goes to show you, even Mother Nature can "think outside the box."
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Quoting tropics21:
IMO I think there needs to be a specific period of time that the established LLC has to sustain before a tropical storm is named heck the way they are off again On again they could run out of names in a given year with 12 hour cyclones But that's just my opinion


I think Henri LLC has been forming since 5 am this morning, just after we began receiving GOES-12 images from the eclipse.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Weather456:


This was an image of 91L earlier today and met the criteria and thus was named. Whether or not it lost its LLC and became an open wave has nothing to do with earlier this afternoon.



IMO I think there needs to be a specific period of time that the established LLC has to sustain before a tropical storm is named heck the way they are off again On again they could run out of names in a given year with 12 hour cyclones But that's just my opinion
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220. JLPR
Quoting Weather456:
I wonder why the two QS versions differ considering it is basically the same pass.


i said the same thing =P
Member Since: September 4, 2007 Posts: 36 Comments: 5223
219. JLPR
if this: Link

equals this: Link

why do I see a LLC on one and not on the other :|
Member Since: September 4, 2007 Posts: 36 Comments: 5223
I wonder why the two QS versions differ considering it is basically the same pass.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Dolly lost its LLC while relocating when it was just going over the Yucatan if any of you remember. They'll keep it a TS at 11.

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
.

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216. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting stormpetrol:

I agree they add to uncertainity and excitement, also a challenge for forecasters, these are the storms that makes weathermen/women smarter imo.


well said, you learn and open yourself to multiple possibilities.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Weather456:


Thanks, can I have a link?


Link

Select on the right hand side.
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October looking to be the surprise month.
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Quoting WaterWitch11:
How I learned to mind my own business

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


Lol. Good evening. :)
Member Since: August 15, 2008 Posts: 10 Comments: 3665
Quoting CosmicEvents:

LOL...that's a good one.
.
.
I only brought up the whole pronunciation thing because the NHC started it. Today was the first time that I recall the NHC giving out proper pronunciation in a discussion.
.
.
For years, we somehow got by without the pronunciation leson, and we also managed to get by without the "idiot" colors. For most, they never get past just looking at the NHC graphical map. They don't read the discussions. So they don't understand the reasoning behind the colors. Even those of us here, who go way beyond just reading the discussion, for most, I don't think that they understand the 24-48 hour probability window that these idiot colors represent.


NHC has in the past included pronunication in the forecast discussion. They also have a webpage on pronounciation.
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Quoting Weather456:
Systems like Erika and Henri are far from boring, due to the uncertain they are more interesting than clear-cut storms like Bill.

I agree they add to uncertainity and excitement, also a challenge for forecasters, these are the storms that makes weathermen/women smarter imo.
Member Since: Posts: Comments:
209. JLPR
Quoting Weather456:


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 :)
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting JLPR:


that confuses me more :|
farther to the south?


well that image was from a few hours ago, so it lines up perfectly with the center we are currently seeing on shortwave imagery.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
How I learned to mind my own business

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
Member Since: Posts: Comments:

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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