Unusual Chantal Disorganized, but has 65 mph Winds

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

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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

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One thing for sure..lil "Chantral" fired up the blog !
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1035. ackee
well chantal is one weird storm high pressure yet with winds of 50mph and it racing 29mph it may be that the Bermuda High IS Getting strong add that to the how fast chantal is moving now I am guessing that may be the reason the storm may track further west that what was expected
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new tstorms and heavy rain back in the center!!
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1032. Patrap
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Quoting 1016. Dakster:


And a Cat 3 thru South Florida too?


Maybe a cat 1 ....giving a 20% chance of that happening right now
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Quoting 1010. MiamiHurricanes09:
Pretty "interesting" wind shifts.



utterly confused on why this is happening.. need an ASCAT or something right now
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Quoting 941. GTstormChaserCaleb:
Yep there it is just blew up in the last frame and westbound she goes.



Holy carp. She is, and we got a snap of her eye.

11 TWO is going to have to explain this.
Member Since: August 4, 2007 Posts: 0 Comments: 3254
1027. sar2401
Quoting weatherlover94:


in about 5 days as it nears its final landfall

When it makes its final landfall where? Only three models want to keep it alive until then, and they show Florida, Georgia, and South Carolina as possible landfalls. None of them show them as a 70mph storm by then either.
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Chantal is very much alive and kicking , just give her time to evolve, just remember what John Hope the Hurricane guru said , developes east of the islands , the storm won't die , it may struggle where it is , but west of Haiti , watch out she could explode . My thinking over middle of Cuba , then all bets are off east or west of Florida as a major , that is if she survives tonight , and early Wednesday , Chantal will probally surprise us all , she's made it thus far .
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Member Since: August 9, 2011 Posts: 26 Comments: 8605
1024. will40
Quoting 1021. Dakster:


I stand corrected then.


ty i accept your correction
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1023. Patrap
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She looks to be moving due west.
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1021. Dakster
Quoting 1004. will40:


i didnt say the last recon


I stand corrected then.
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Quoting 1009. Grothar:



I told you people 3 days ago Chantal was going to move over Hispaniola then move through the Windward Passage into the Bahamas and very possibly Florida. :)

What more do you want???? I need my rest.


The exact latitude, longitude and pressure in mb for its landfall! And time in ZULU.
Member Since: August 9, 2011 Posts: 26 Comments: 8605
Quoting 996. GTstormChaserCaleb:
Chantal is like that sports team you never count out, could be down 0-3 in a series and comeback and win it 4-3.
like our 2004 Red Sox
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1018. Patrap
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1017. Matt74
Quoting 975. sar2401:

You said what exactly? That Chantal would move more westerly, as she has done for her entire history, regardless of model persistence? Exactly how far west do you think she will go? There was never any doubt in my mnd that she would go further west than the models said but if you're implying that she will get to the Caymans, or even Jamaica, I would still call you a wishcaster.
Might as well call him a wishcaster cause he's definitely wanting a cayman/Jamaica hit.
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1016. Dakster
Quoting 1009. Grothar:



I told you people 3 days ago Chantal was going to move over Hispaniola then move through the Windward Passage into the Bahamas and very possibly Florida. :)

What more do you want???? I need my rest.


And a Cat 3 thru South Florida too?
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Quoting 1000. weathermanwannabe:
Good Evening. Nice convective burst over the COC at the moment. This evening into tommorow morning and d-max will be her opportunity to shine before the encounter with Haiti.......Then the real forecast dilemas might begin when she reemerges.


Let's see what recon has to say. If this West or WWWSWWW jog/motion/reposition/relocation pans out she may never see much of Haiti.
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Quoting 999. BaltimoreBrian:
Caleb 971--I posted that a while ago. It seems that the HWRF latches on to a weak westward tracking vorticity and ignores the main part of Chantal which it treats as a new system.
The models just seem messed up right now and don't know what in the world they are doing, well I know one thing for sure Chantal knows where she is going, she's just making us follow her lead. :P
Member Since: June 30, 2013 Posts: 12 Comments: 8305
Quoting 986. fredric1979:






She's may be trying to bounce back


Conditions this evening are looking to be the best they have been thus far for strengthening. Being relatively convectionally challenged most of the day it's no surprise the pressures have come up. I wouldn't be surprised if it did open up briefly this afternoon and reformed the center further to the S. We will see what the evening holds. Recon should show falling pressures and increasing winds as the flight goes on this evening.
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Here we go, Patrap
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1011. GetReal
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Pretty "interesting" wind shifts.

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1009. Grothar
Quoting 746. GeoffreyWPB:
We need Grothar's analysis. Let's see if we can get him in...




I told you people 3 days ago Chantal was going to move over Hispaniola then move through the Windward Passage into the Bahamas and very possibly Florida. :)

What more do you want???? I need my rest.
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1008. Patrap
At 00:57:30Z (last observation), the observation was 211 miles (339 km) to the SSE (168°) from San Juan, Puerto Rico (USA).

Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 10th day of the month at 00:57Z
Date: July 10, 2013
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Storm Number: 03
Storm Name: Chantal (flight in the North Atlantic basin)
Mission Number: 3
Observation Number: 14

00:57:30Z 15.433N 65.383W 842.2 mb
(~ 24.87 inHg) 1,613 meters
(~ 5,292 feet) 1014.5 mb
(~ 29.96 inHg) - From 143° at 21 knots
(From the SE at ~ 24.1 mph) 16.1°C
(~ 61.0°F) 13.6°C
(~ 56.5°F) 25 knots
(~ 28.7 mph) 39 knots
(~ 44.8 mph) 9 mm/hr
(~ 0.35 in/hr) 32.8 knots (~ 37.7 mph)
156.0%
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor
HDOB Observations
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Quoting 994. Dakster:


1009.5 is less than 1006 from the last recon. O_o


was also recorded with flight level winds of about 15-20 knots, wasnot the center
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Quoting 1002. canehater1:



Hmmm. That XTRP Model sure is an outlier.....


stop that...lol
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1005. Patrap
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1004. will40
Quoting 994. Dakster:


1009.5 is less than 1006 from the last recon. O_o


i didnt say the last recon
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TROPICAL WAVES...
A TROPICAL WAVE IS OVER THE EASTERN ATLC EXTENDING FROM 15N20W
TO 06N21W MOVING W-SW NEAR 15 KT. THE WAVE IS EMBEDDED WITHIN A
HIGH MOIST ENVIRONMENT WITHIN THE MONSOON TROUGH AXIS. SAL DRY
AIR IS TO THE N OF THIS WAVE AND CURRENTLY SPREADS OVER A LITTLE
PORTION OF ITS AXIS N OF 14N. A CLUSTER OF MODERATE CONVECTION
WITH EMBEDDED THUNDERSTORMS IS WITHIN 216 NM EAST OF THE AXIS
FROM 11N-14N. SCATTERED MODERATE CONVECTION IS WITHIN 200 NM
WEST OF THE AXIS FROM 08N-14N.
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Quoting 948. MiamiHurricanes09:
And the models have shifted a little bit back to the east. [TVCN] Still west of the NHC plot.




Hmmm. That XTRP Model sure is an outlier.....
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Quoting 991. sar2401:

The end of which period?


in about 5 days as it nears its final landfall
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Good Evening. Nice convective burst over the COC at the moment. This evening into tommorow morning and d-max will be her opportunity to shine before the encounter with Haiti.......Then the real forecast dilemas might begin when she reemerges.
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Caleb 971--I posted that a while ago. It seems that the HWRF latches on to a weak westward tracking vorticity and ignores the main part of Chantal which it treats as a new system.
Member Since: August 9, 2011 Posts: 26 Comments: 8605
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Chantal is like that sports team you never count out, could be down 0-3 in a series and comeback and win it 4-3.
Member Since: June 30, 2013 Posts: 12 Comments: 8305
Miami
NEXRAD Radar

Velocity Azimuth Display Wind Profile ° Elevation
Range 124 NMI

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Quoting 988. will40:
1009.5 mb
(~ 29.81 inHg)

down at least a lil


1009.5 is less than 1006 from the last recon. O_o
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there is more model spread in where it might go this evening and that is bothersome and is going to make it even more difficult to forecast
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What affect will the ULL have on Chantal? The ULL looks the be moving west to wsw.
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Quoting weatherlover94:
Chantel has weakened to a 60 mph tropical storm and the intensity is dropping it still to a 40 mph tropical storm then coming back close to a 70 mph storm at the end of the period.

The end of which period?
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Quoting HighPressureLarry:
Chantral is dead


No, she is very much alive. The names Ernesto and Isaac ring a bell to me.

Ernesto...


Isaac...


Keep your powder dry before you take it out to use it,,, or it might not go poof, but you will.
Member Since: September 30, 2007 Posts: 9 Comments: 15935
989. HadesGodWyvern (Mod)


Super Typhoon (130 knots JTWC estimate)
Member Since: May 24, 2006 Posts: 51 Comments: 45307
1009.5 mb
(~ 29.81 inHg)

down at least a lil
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Quoting 932. ProgressivePulse:
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.







She's may be trying to bounce back
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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.