Unusual Chantal Disorganized, but has 65 mph Winds

By: Dr. Jeff Masters , 8:06 PM GMT on July 09, 2013

Share this Blog
72
+

Unusual Tropical Storm Chantal has strengthened a bit more as it speeds west-northwestwards at 26 mph away from the the Lesser Antilles Islands. Sustained winds of 38 mph, gusting to 52 mph, were observed at Martinique at 10 am AST as the storm passed. However, an automated weather station at the airport measured sustained winds of 60 mph, gusting to 78 mph, according to an official with Meteo-France. The Associated Press reported that Chantal ripped the roofs off of several homes on neighboring Dominica. An Air Force hurricane hunter aircraft measured top winds at their 1,000' flight level of 89 mph at 12:55 pm AST. Top winds seen by the aircraft's SFMR instrument were about 65 mph, in a small area east of Chantal's center. The Hurricane Hunters have departed Chantal, and the next plane is due in the storm at 8 pm EDT. Chantal's winds are unusually high considering the storm's high central pressure of 1006 mb and disorganized appearance on satellite imagery. Chantal is fighting dry air associated with the Saharan Air Layer (SAL), as seen on water vapor satellite loops. This dry air is creating strong thunderstorm downdrafts that are robbing Chantal of moisture and energy. Visible satellite loops show the outflow boundaries of these thunderstorm downdrafts at the surface, spreading to the northwest of Chantal. Martinique Radar shows a large area of heavy rain that is not well-organized, lying mostly to the west of the Lesser Antilles Islands.


Figure 1. MODIS image of Chantal taken at approximately 1 pm EDT Tuesday, July 9, 2013. At the time, Chantal had top winds of 65 mph, but looked very disorganized, due to high wind shear and dry air. Dry air is creating strong thunderstorm downdrafts that are robbing Chantal of moisture and energy. Outflow boundaries from these downdrafts are spreading out to the northwest of Chantal, as seen on this satellite image. Image credit: NASA.

An small-scale easterly jet creating high shear in Chantal
Chantal is not very impressive on satellite images, with a modest amount of heavy thunderstorms that are not well-organized. Only a small amount of upper-level outflow is visible. The reason for Chantal's rather disorganized appearance can be found by looking at this morning's balloon sounding from Guadaloupe. This island was just northwest of the center of Chantal when the balloon was launched at 8 am EDT. The sounding showed typical easterly trade winds at the surface of 12 knots (14 mph.) However, the winds rose quickly aloft, with a jet of easterly winds of 35 - 53 knots between 800 - 600 mb (about 7,000 - 15,000'.) But, by the time the ballon hit 500 mb (18,000'), the winds had died down to 15 knots. A change of wind speed from 12 knots to 53 knots and back down to 15 knots from the surface to 500 mb is a tremendous amount of wind shear, which will make it very difficult for a tropical storm to keep the surface center aligned with the upper level center. The traditional measure of wind shear, the difference in wind between 200 mb and 850 mb, was 44 knots in this morning's Guadaloupe sounding, but was a much higher 56 knots from 200 mb to 700 mb. The powerful easterly wind jet was not apparent at any of the other balloon soundings this morning at adjacent islands (Barbados, Puerto Rico, Saint Martin), and demonstrates that there is a lot going on the atmosphere at small scales we cannot see which makes intensity forecasting of tropical cyclones very challenging. Thanks go to Jason Dunion of NOAA's Hurricane Research Division for pointing out this morning's interesting Guadaloupe sounding.

Forecast for Chantal
Chantal will have difficulty intensifying much more before hitting Hispaniola on Wednesday afternoon. In their 11 am EDT wind probability forecast, NHC gave Chantal a 29% chance of becoming a hurricane before hitting Hispaniola. Working against intensification will be the high wind shear from the strong mid-level easterly jet discussed above, plus the fast forward speed of the storm--tropical storms moving faster than 20 mph in the deep tropics usually have trouble intensifying. In addition, the Eastern Caribbean is an area where the trade winds accelerate, helping drive sinking air that discourages tropical storm intensification. Dry air will also slow down the intensification process. Interaction with the high mountains of Hispaniola and high wind shear may be able to destroy Chantal by Thursday. The 2 pm EDT Tuesday wind shear forecast from the SHIPS model calls for shear to rise to the high range, 20 - 35 knots, Tuesday night through Friday. On Saturday, when Chantal is expected to be in the Bahamas, moderate wind shear of 10 - 20 knots is predicted. If Chantal survives until Saturday, it will then have the opportunity to re-strengthen. The latest 12Z run of the European model (ECMWF) dissipates Chantal as it crosses Hispaniola. The 12Z run of the American GFS model has Chantal barely surviving.

Chantal's fast west-northwest forward speed of 26 mph will slow to 20 mph by Wednesday morning and then 10 mph by Thursday night, as the storm "feels" the presence of a trough of low pressure over the U.S. East Coast. This trough will steer Chantal to the northwest and then north-northwest across Hispaniola and into the Bahamas. The trough of low pressure pulling Chantal northwards is expected to lift out the the northeast over the weekend, leaving Chantal behind off the coast of Florida. High pressure will likely build in, potentially forcing Chantal westwards into the Florida or Southeast U.S. coast, with a possible Sunday landfall.

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

Sign In or Register Sign In or Register

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 936 - 886

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54Blog Index

Convection is finally starting to rebuild
Member Since: Posts: Comments:
Quoting 924. HighPressureLarry:
its over for chantral..pressure is not falling at all


Just because it's not falling right now doesn't mean it won't fall later
Member Since: Posts: Comments:
Quoting 917. Stormchaser121:

There it is again!


A surprisingly good analogue for Chantal, at least for the Martinique to Savannah part.

Member Since: Posts: Comments:
I think there is a convective burst...
Member Since: Posts: Comments:
Chantal looks like she wants to make another run at a CDO this evening. Convection is expanding and deepening over the center currently. CIMMS still shows good convergence/divergence so she should be able to maintain. Shear is currently 20kts over the center.

Member Since: Posts: Comments:
Quoting 914. Dakster:


Only digitals.

Notice that all of the storms that have historically formed at this time, in the area of chantal all have different tracks. Granted, none have gone out to sea -


That's an ominous observation. Wonder who's gonna get it..?
Member Since: Posts: Comments:
Storm has moved wsw or wobbled.
Member Since: Posts: Comments:
Quoting 924. HighPressureLarry:
its over for chantral..pressure is not falling at all


Poor gal. At least spell her name right before you poof her!
Member Since: Posts: Comments:
Hi all. It seems Chantal is struggling. I have also noticed the cone has shifted east so I imagine the models concur.
Member Since: Posts: Comments:
And for some reason, my comment got put inside the quote box and I couldn't correct it.
Member Since: Posts: Comments:


Good symmetrical inflow still.
Member Since: Posts: Comments:
its over for chantral..pressure is not falling at all
Member Since: Posts: Comments:
So far, the Hurricane Hunters have only been sampling the northern half of the storm, so don't expect to see westerly winds here. If once they get south of the 14.9N or so mark and Hurricane Hunters do not discover true westerly winds, then we would have an open system and no longer a true tropical cyclone.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
Hello everyone!

Long time member, seasonal commentator, from Fort Lauderdale Beach.

Chantal is the most disorganized 65mph TS that I've seen in many years. If it weren't for the observations and HH data this wouldn't much more than a typical disturbance with a 20% chance of development.

Looks can be deceiving so it must be watched either way as it heads WNW.
Member Since: Posts: Comments:
Quoting 913. GrandCaymanMed:


This storm keeps fooling me...Madame Chantal wants to be really unpredictable.


Well, you have to pay attention to the entirety of the advisory, because the center fix is not an absolute. It is presented with a margin of error, which was previously 30nautical miles with the coc, which is basically plus or minus half a degree in any compass direction.
Member Since: Posts: Comments:
looks like it may miss Hispaniola to the west
Member Since: Posts: Comments:
Quoting 915. Tazmanian:
recon findings so far is bearly holding on too TS and am still not seeing march in a way of a W wind


They are going to be out there for about another 5 1/2 hours, so plenty of time to investigate the whole system.
Member Since: Posts: Comments:
OOPS, sorry on the above, newbie learning the blog ropes! :)

Meant to quote the "below 15" part...
Member Since: Posts: Comments:

There it is again!
Member Since: September 2, 2011 Posts: 0 Comments: 1149
Quoting 910. Capeverde5:



Please put responses OUTSIDE the blockquote tags. I don't want your comments being incorrectly displayed as mine, due to moderation...issues.

Thanks.
Member Since: Posts: Comments:
Quoting 909. slavicthunder:
Chantal = a storm with no analogs.


Only digitals.

Notice that all of the storms that have historically formed at this time, in the area of chantal all have different tracks. Granted, none have gone out to sea -
Member Since: Posts: Comments:
Quoting 907. RTSplayer:


Still south of the 5pm advisory.

So the storm actually went 0.1s and 1.4w since the 5pm.


Now latitude is probably within the margin of error of the 5pm anyway, so we can safely say it's just due west. Regardless, the 8pm needs to be corrected for accuracy.


This storm keeps fooling me...Madame Chantal wants to be really unpredictable.
Member Since: Posts: Comments:
Quoting 799. floridaT:
the fact that its moving so fast (26 mph) makes the north side winds really only 34mph . I think thats why we are so amazed at the wind speed.
Does the forward sped increase the sustained wind speed? I think I remember reading that is why Wilma was so destructive on the east coast of Florida. Does that make sense?
Member Since: Posts: Comments:
Chantal is up against her first real battle...wind shear
Member Since: Posts: Comments:
Quoting 876. RTSplayer:


I think they missed it to the north, based on the wind barbs direction.

Also, they may have had a bad approach angle for the cell with max winds. Give it time, this is only the first pass, after all.



If that is a trend and not just a jog or reformation, that puts sticky wicket in the forecast!
Member Since: Posts: Comments:
Chantal = a storm with no analogs.
Member Since: Posts: Comments:
The ATCF update really doesn't matter, the NHC will use whatever recon finds.
Member Since: Posts: Comments:
Quoting 891. nrtiwlnvragn:
AL, 03, 2013071000, , BEST, 0, 151N, 651W, 50, 1009, TS


Still south of the 5pm advisory.

So the storm actually went 0.1s and 1.4w since the 5pm.


Now latitude is probably within the margin of error of the 5pm anyway, so we can safely say it's just due west. Regardless, the 8pm needs to be corrected for accuracy.
Member Since: Posts: Comments:
Quoting 898. HurricaneAndre:
no 50 kts, 60 mph.


oops, sorry about that. I read it wrong
Member Since: Posts: Comments:
Quoting 895. MechEngMet:


Been meaning to ax you... Zactly what is in Hurlo's cooler there?


He's from New Orleans. Hurricanes of course!
Member Since: Posts: Comments:
Quoting 895. MechEngMet:


Been meaning to ax you... Zactly what is in Hurlo's cooler there?


Don't know if I REALLY want to know the answer to that question.
Member Since: Posts: Comments:
Quoting 896. Hurricanes101:


thats knots, 60 mph


Plus there are alot more passes to go before the next advisory
Member Since: Posts: Comments:
Quoting 894. weatherlover94:


looks like we are dropping to 50 mph at 11:00
50 knots. 60 mph is possible at 11:00 pm.
Member Since: August 1, 2011 Posts: 28 Comments: 8119
Quoting SLU:
The last few visible frames did show a closed circulation. I expect that the RECON will still find westerlies. Quite remarkable. This really is a storm unlike what we've grown accustomed to in the past.



reminds me a bit like Isaac from last year. The HH'er have NW and NE winds, lets see what they find in the next pass. Do we have a troll??
Member Since: Posts: Comments:
Chantal will struggle for the next 48 hours.
Member Since: Posts: Comments:
Chantal may just have to tangle with Cuba
Member Since: Posts: Comments:
Quoting 894. weatherlover94:


looks like we are dropping to 50 mph at 11:00
no 50 kts, 60 mph.
Member Since: Posts: Comments:
Quoting 894. weatherlover94:


looks like we are dropping to 50 mph at 11:00


thats knots, 60 mph
Member Since: Posts: Comments:
Quoting 859. Patrap:
Hurricane Preparation 2013

It's time to dust off that family disaster plan, or in many cases, create one.

Keeping your family safe during a hurricane starts with proper planning. One in six Americans live along the eastern seaboard or the Gulf of Mexico, making hurricane preparation a must for many and their families.








Evacuation Considerations for the Elderly, Disabled and Special Medical Care Issues



Your Evacuation Plan


Disaster Supplies Kit


NOAA Alert Weather Radio's


"Think outside the Cone"
hurricanebuddy.com


Been meaning to ax you... Zactly what is in Hurlo's cooler there?
Member Since: Posts: Comments:
Quoting 891. nrtiwlnvragn:
AL, 03, 2013071000, , BEST, 0, 151N, 651W, 50, 1009, TS


looks like we are dropping to 50 mph at 11:00
Member Since: Posts: Comments:
Center is in the vicinity of the lil red ball that recently developed.

Member Since: Posts: Comments:
Patrap = You forgot about the dangers of leeches after the storm. They will be out in droves.

The blood sucking parasites usually offer to do work for you and want to be paid up front. Then they run away with your money.
Member Since: Posts: Comments:
AL, 03, 2013071000, , BEST, 0, 151N, 651W, 50, 1009, TS
Member Since: Posts: Comments:
Quoting 884. RTSplayer:


Yeah, as I just pointed out, that would agree with the assumption that the HH passed by the CoC on the north side, and it means the storm has actually taken a significant southerly wobble by about 0.3 degrees since the 5pm advisory. If this verifies, it means the 8pm advisory is garbage.
I saw that wobble too.
Member Since: Posts: Comments:
Quoting 870. nrtiwlnvragn:
RADAR FIX PSBL CENTER 14.9N 65.25W. POOR RADAR PRESENTATION, MET ACCURACY 10NM

Link


looks like I may be correct


Quoting 879. FIUStormChaser:



Based on what? The National Hurricane Center has trained meteorologists, and people who consult the top experts to determine the general direction of a system. Yes the National Hurricane may be off fifty miles to the right or left but not 200+ miles. Until you have reasonable evidence you will only be subjected to critism on this blog. Chances are Chantel will dissipate over Haiti and pull an Ernesto.

you will learn don't worry you will see
Member Since: June 13, 2009 Posts: 2 Comments: 12818
Quoting 884. RTSplayer:


Yeah, as I just pointed out, that would agree with the assumption that the HH passed by the CoC on the north side, and it means the storm has actually taken a significant southerly wobble by about 0.3 degrees since the 5pm advisory. If this verifies, it means the 8pm advisory is garbage.


Chances are there is no center of circulation anymore.
Member Since: Posts: Comments:
Member Since: Posts: Comments:

Viewing: 936 - 886

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54Blog Index

Top of Page

About

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

Local Weather

Partly Cloudy
45 °F
Partly Cloudy

JeffMasters's Recent Photos

Carrot Nose in Danger
Deep Snow in Brookline, MA
Sunset at Fort DeSoto
New Years Day Sunset in Death Valley