Rare South Atlantic subtropical cyclone forms; severe weather season in U.S. underway

By: Dr. Jeff Masters , 2:10 PM GMT on March 10, 2010

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A rare weather event is underway in the South Atlantic Ocean, where the basin's 7th recorded tropical or subtropical cyclone of all-time has formed. An area of disturbed weather (Invest 90Q) off the coast of Brazil, near 30S 48W, attained a well-defined surface circulation, top wind speeds of tropical depression strength (35 mph), a warm core in the bottom portion of the atmosphere, and a cold core aloft last night. If this storm had been in the North Atlantic, there is a good chance it would have been named Subtropical Depression One. However, tropical and subtropical storms are so rare in the South Atlantic that there is no official naming of depressions or storms done. The cyclone had top winds of at least 35 mph as seen on an ASCAT pass at 7:02 am EST this morning (Figure 2), and satellite estimates of the storm's intensity topped out at 40 mph (minimum subtropical storms strength) last night. This morning, the satellite estimates are showing that the system has weakened to a 35 mph tropical depression. There is some moderate wind shear interfering with development, and sea surface temperatures are about 25°C, which is about 1°C below what is typically needed to support a tropical storm. The storm is headed eastward out to sea, and is not a threat to any land areas. The models show the storm will lose its tropical characteristics and get absorbed by a frontal system by Saturday.


Figure 1. Afternoon visible satellite image of the Brazilian Invest 90Q.


Figure 2. Satellite-measured winds from ASCAT clearly show the circulation of the cyclone in this pass from 7:02 am EST on March 10, 2010. Top winds as seen be ASCAT were 30 knots (35 mph), just below the 40 mph needed for it to be a tropical storm. Image credit: NOAA/NESDIS/ORA.

Brazil has had only one landfalling tropical cyclone in its history, Cyclone Catarina of March 2004. Catarina is one of only six known tropical or subtropical cyclones to form in the South Atlantic, and the only one to reach hurricane strength. Tropical cyclones rarely form in the South Atlantic Ocean, due to strong upper-level wind shear, cool water temperatures, and the lack of an initial disturbance to get things spinning (no African waves or Intertropical Convergence Zone exist in the proper locations in the South Atlantic to help spawn tropical storms). Today's storm is located close to where Catarina formed.

Severe weather season begins
It's March, and that means severe weather season will get underway in earnest for the Midwest U.S., and powerful spring storm systems draw warm, moist air from the Gulf of Mexico northward, to collide with cold, dry air from Canada. It's been a quiet early season, with only 42 tornadoes reported thus far this year (as of Sunday), compared to a normal 70 - 100 twisters. There was only one tornado in the U.S. in February, in a San Joaquin Valley oilfield in California two weekends ago. A year ago, there were 36 February tornadoes, and the year's deadliest tornado occurred on Feb. 10, 2009, in Lone Grove, Oklahoma, where eight people died in a storm with winds estimated at 170 mph. But thanks to a very wet winter and a continued active jet stream pattern that will pull strong storms through the Midwestern U.S. this month, expect at least an average March for severe weather. NOAA's Storm Prediction Center is forecasting a "slight" chance of severe weather across a large portion of the Mississippi Valley today, in association with a strong cold front that will be plowing through the region. Strong thuderstorms capable of generating damaging winds and large hail should develop along the front from southeast Kansas through eastern Oklahoma into NE Texas by middle/late afternoon. The storms should consolidate into broken bands and move into Missouri and and Arkansas by early evening. Isolated tornadoes are also possible in the entire "slight" risk area.


Figure 3. Severe weather forecast for today from the NOAA Storm Prediction Center.

Hurricane Hugo talk
I'm presenting a talk to a class at the University of Michigan this morning on my 1989 flight through Hurricane Hugo. You can listen in live starting at about 10:10 - 10:15 am EST by pointing your browser to http://samson.lecturetools.org/. You'll need to have Apple Quicktime installed. If all goes well, the talk will be recorded and you can view it later, as well.

Jeff Masters

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Quoting aquak9:
Hi ya'll. Really expected severe season to have started before now. But here it is, and here we are.

Yep, SW arkansas. Guess it's all gotta start somewhere.

Yeah. I suppose the relatively benign couldn't last with all of this juice in the air...
Baseball hail and power lines down at SPC reports.


http://w1.spc.woc.noaa.gov/climo/reports/today.html
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Hi ya'll. Really expected severe season to have started before now. But here it is, and here we are.

Yep, SW arkansas. Guess it's all gotta start somewhere.
Member Since: August 13, 2005 Posts: 171 Comments: 26286
Quoting hydrus:
Hi Grother, here we go with the severe weather again. A little early this year. It could get ugly tonight and tomorrow. Hope you are doing well. :)


Looks like Spring has Sprung. Hope they don't last. It was a quiet February for tornadoes now this.
Member Since: July 17, 2009 Posts: 71 Comments: 26895
251. hydrus
11:05 PM GMT on March 10, 2010
Quoting aquak9:
Lively cell moving towards Hot Springs, arkansas. MRV shows rotation in the upper levels, another stronger cell to the southwest of it as well.
It is always like this in mid-April...Oh..It is Mar-10..Hello aquack9.
Member Since: September 27, 2007 Posts: 1 Comments: 21766
250. aquak9
11:02 PM GMT on March 10, 2010
Lively cell moving towards Hot Springs, arkansas. MRV shows rotation in the upper levels, another stronger cell to the southwest of it as well.
Member Since: August 13, 2005 Posts: 171 Comments: 26286
249. Grothar
11:01 PM GMT on March 10, 2010
Quoting atmoaggie:

So far, just a classic super-cell (mostly) hail-only event. So far...not sure how much more it will turn into...

Many of the severe t-storm warnings have included no mention of dangerous winds...some do, though.




... THE NATIONAL WEATHER SERVICE IN WICHITA HAS ISSUED A SIGNIFICANT WEATHER ADVISORY FOR CHAUTAUQUA AND COWLEY COUNTIES...

AT 444 PM CST... NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM CHILOCCO TO HARDY TO 17 MILES SOUTH OF GRAINOLA... AND MOVING NORTHEAST AT 40 MPH.

PENNY TO NICKEL SIZE HAIL... AND WINDS TO 50 MPH ARE EXPECTED WITH THESE STORMS.

BE PREPARED TO TAKE SHELTER IN THE EVENT THESE STORMS INTENSIFY AND BECOME SEVERE, OR A WARNING IS ISSUED BY THE NATIONAL WEATHER SERVICE.

Member Since: July 17, 2009 Posts: 71 Comments: 26895
248. atmoaggie
10:59 PM GMT on March 10, 2010
Quoting KEEPEROFTHEGATE:

So far, just a classic super-cell (mostly) hail-only event. So far...not sure how much more it will turn into...

Many of the severe t-storm warnings have included no mention of dangerous winds...some do, though.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
247. tkeith
10:59 PM GMT on March 10, 2010
Thanks for the Severe updates everyone. Looks like my 70 years old mother is about to be in the bullseye in Ar.
Member Since: November 1, 2004 Posts: 25 Comments: 8937
246. hydrus
10:58 PM GMT on March 10, 2010
Quoting KEEPEROFTHEGATE:
now till midnight expect the worse with a slow diminish during early morning hrs
One weatherman said with the warm temperatures in Tennessee tomorrow we could have some strong storms. They have 4 main stations here and they almost always have a different forecast.
Member Since: September 27, 2007 Posts: 1 Comments: 21766
245. KEEPEROFTHEGATE (Mod)
10:55 PM GMT on March 10, 2010
Member Since: July 15, 2006 Posts: 175 Comments: 54858
243. KEEPEROFTHEGATE (Mod)
10:52 PM GMT on March 10, 2010
now till midnight expect the worse with a slow diminish during early morning hrs
Member Since: July 15, 2006 Posts: 175 Comments: 54858
242. hydrus
10:50 PM GMT on March 10, 2010
Quoting Grothar:


Hey, Hydrus. Good one! ;)
Hi Grother, here we go with the severe weather again. A little early this year. It could get ugly tonight and tomorrow. Hope you are doing well. :)
Member Since: September 27, 2007 Posts: 1 Comments: 21766
241. Grothar
10:47 PM GMT on March 10, 2010
Member Since: July 17, 2009 Posts: 71 Comments: 26895
240. Grothar
10:45 PM GMT on March 10, 2010
They are breaking out all over.

THE NATIONAL WEATHER SERVICE HAS ISSUED SEVERE THUNDERSTORM WATCH
23 IN EFFECT UNTIL 10 PM CST THIS EVENING FOR THE FOLLOWING AREAS

IN KANSAS THIS WATCH INCLUDES 3 COUNTIES

IN SOUTHEAST KANSAS

BOURBON CHEROKEE CRAWFORD

IN MISSOURI THIS WATCH INCLUDES 34 COUNTIES

IN CENTRAL MISSOURI

BENTON CAMDEN HICKORY
MARIES MILLER MORGAN
PHELPS PULASKI ST. CLAIR

IN SOUTH CENTRAL MISSOURI

DENT HOWELL OREGON
SHANNON TEXAS

IN SOUTHWEST MISSOURI

BARRY BARTON CEDAR
CHRISTIAN DADE DALLAS
DOUGLAS GREENE JASPER
LACLEDE LAWRENCE MCDONALD
NEWTON OZARK POLK
STONE TANEY VERNON
WEBSTER WRIGHT
Member Since: July 17, 2009 Posts: 71 Comments: 26895
239. KEEPEROFTHEGATE (Mod)
10:44 PM GMT on March 10, 2010
may get some baseball to softball size hail out of all this
Member Since: July 15, 2006 Posts: 175 Comments: 54858
238. xcool
10:42 PM GMT on March 10, 2010





Member Since: September 26, 2009 Posts: 2 Comments: 15684
236. KEEPEROFTHEGATE (Mod)
10:41 PM GMT on March 10, 2010
219
NWUS54 KSHV 102237
LSRSHV

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
437 PM CST WED MAR 10 2010

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..

0430 PM HAIL DOMINO 33.25N 94.11W
03/10/2010 E1.75 INCH CASS TX EMERGENCY MNGR

GOLFBALL SIZED HAIL REPORTED ALONG THE EAST SIDE OF LAKE
WRIGHT PATMAN NEAR DOMINO.

Member Since: July 15, 2006 Posts: 175 Comments: 54858
235. atmoaggie
10:41 PM GMT on March 10, 2010
21 Z sounding for Little Rock.

Yup. CAPE = 2600.


(click for full size...reduced just for jeffs and his inept explorer. Poor jeffs.)
Member Since: August 16, 2007 Posts: 6 Comments: 12463
234. Grothar
10:40 PM GMT on March 10, 2010
Quoting hydrus:
I think it is good when the warning is flashing. I might overlook it otherwise. If the whole monitor is flashing, we will get Levi. jk


Hey, Hydrus. Good one! ;)
Member Since: July 17, 2009 Posts: 71 Comments: 26895
233. KEEPEROFTHEGATE (Mod)
10:40 PM GMT on March 10, 2010
Quoting P451:
We do have quite a setup unfolding here. Water Vapor imagery:

looks like things should start taking it up a knotch or two hmmm
Member Since: July 15, 2006 Posts: 175 Comments: 54858
231. Grothar
10:36 PM GMT on March 10, 2010
Quoting P451:
We do have quite a setup unfolding here. Water Vapor imagery:



Look who's back! Hey P451. The action starts and your back.
Member Since: July 17, 2009 Posts: 71 Comments: 26895
229. hydrus
10:33 PM GMT on March 10, 2010
Quoting Levi32:


That strikes me as pretty weird...but whatever. Why would they even risk surfing the internet then if anything that flashes (and there are a lot of things on the internet that do) could give them a seizure?

I don't think it's that big of a deal. I'm not going to abuse that capability. Nothing's going to blink unless it's really urgent.
I think it is good when the warning is flashing. I might overlook it otherwise. If the whole monitor is flashing, we will get Levi. jk
Member Since: September 27, 2007 Posts: 1 Comments: 21766
227. KEEPEROFTHEGATE (Mod)
10:32 PM GMT on March 10, 2010
978
NWUS54 KSHV 102228
LSRSHV

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
428 PM CST WED MAR 10 2010

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..

0348 PM FUNNEL CLOUD TEXARKANA 33.44N 94.07W
03/10/2010 BOWIE TX EMERGENCY MNGR

FUNNEL CLOUD REPORTED ON THE NORTHWEST SIDE OF TEXARKANA.



&&
Member Since: July 15, 2006 Posts: 175 Comments: 54858
226. xcool
10:30 PM GMT on March 10, 2010
lasttime 16-7-4 .verified .
Member Since: September 26, 2009 Posts: 2 Comments: 15684
225. atmoaggie
10:30 PM GMT on March 10, 2010
So far, no severe winds reported at SPC (will change soon) and not bad winds showing on the surface obs. Also see that the dewpoints are not all that high...not as much as I expected, anyway, with Td still in the 50s for NE TX, N La, Arkansas, MS north of Jackson. (Dewpoints in blue, bottom-left of station circle)


(click for full size)
Member Since: August 16, 2007 Posts: 6 Comments: 12463
224. KEEPEROFTHEGATE (Mod)
10:29 PM GMT on March 10, 2010
155
NWUS54 KBMX 102223
LSRBMX

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
423 PM CST WED MAR 10 2010

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..

0356 PM FLOOD LOCUST FORK 33.91N 86.62W
03/10/2010 BLOUNT AL LAW ENFORCEMENT

ONE FOOT OF WATER FLOWING OVER DEAVER WALKER RD

Member Since: July 15, 2006 Posts: 175 Comments: 54858
223. Grothar
10:27 PM GMT on March 10, 2010
Interesting article on blinking lights

Link
Member Since: July 17, 2009 Posts: 71 Comments: 26895
222. Levi32
10:26 PM GMT on March 10, 2010
Quoting Hurricanes101:


I kinda figure there wasn't, I was referring to the parallels between 2004 and 2010 so far

hurricane list, south atlantic storm, etc


Ah just coincidence lol.
Member Since: November 24, 2005 Posts: 635 Comments: 26684
221. xcool
10:26 PM GMT on March 10, 2010
. StormW ;) hi
Member Since: September 26, 2009 Posts: 2 Comments: 15684
219. Hurricanes101
10:23 PM GMT on March 10, 2010
Quoting Levi32:


As far as I can tell there are no significant correlations between south and north Atlantic hurricane activity.


I kinda figure there wasn't, I was referring to the parallels between 2004 and 2010 so far

hurricane list, south atlantic storm, etc
Member Since: March 10, 2010 Posts: 1 Comments: 7874
218. KEEPEROFTHEGATE (Mod)
10:23 PM GMT on March 10, 2010

SPC TORNADO AND SEVERE THUNDERSTORM REPORTS

UNOFFICIAL - FOR OFFICIAL REPORTS, SEE PUBLICATION 'STORM DATA'

FOR 06CST WED MAR 10 2010 THRU 16CST WED MAR 10 2010



EVENT LOCATION REMARKS (CST)TIME



.....TORNADO REPORTS..........TORNADO REPORTS..........TORNADO REPORTS.....





NONE REPORTED


Member Since: July 15, 2006 Posts: 175 Comments: 54858
217. Grothar
10:23 PM GMT on March 10, 2010
Quoting atmoaggie:

I don't believe that for a second. As credible as a triple-digit dewpoint from a broken PWS in the summer...
(j/k, Gro)


YO! Have you ever known me to be difficult?? LOL
Member Since: July 17, 2009 Posts: 71 Comments: 26895
216. Levi32
10:21 PM GMT on March 10, 2010
Quoting Hurricanes101:
Wow so they named that system in the South Atlantic after all

very interesting

are the parallels to 2004 anymore abvious?


As far as I can tell there are no significant correlations between south and north Atlantic hurricane activity.
Member Since: November 24, 2005 Posts: 635 Comments: 26684
214. Levi32
10:21 PM GMT on March 10, 2010
Quoting Grothar:


I don't want to be difficult, but people with seizure disorders can have an episode if they watch a blinking light too long. They try to avoid them if possible.


That strikes me as pretty weird...but whatever. Why would they even risk surfing the internet then if anything that flashes (and there are a lot of things on the internet that do) could give them a seizure?

I don't think it's that big of a deal. I'm not going to abuse that capability. Nothing's going to blink unless it's really urgent.
Member Since: November 24, 2005 Posts: 635 Comments: 26684
213. atmoaggie
10:21 PM GMT on March 10, 2010
Well, there you go...in Bama, anyway.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
212. Hurricanes101
10:21 PM GMT on March 10, 2010
Wow so they named that system in the South Atlantic after all

very interesting

are the parallels to 2004 anymore abvious?
Member Since: March 10, 2010 Posts: 1 Comments: 7874
211. Grothar
10:20 PM GMT on March 10, 2010


Nice little image of the feature off Brazil.
Member Since: July 17, 2009 Posts: 71 Comments: 26895
210. KEEPEROFTHEGATE (Mod)
10:20 PM GMT on March 10, 2010
791
NWUS54 KBMX 102207
LSRBMX

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
407 PM CST WED MAR 10 2010

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..

0405 PM FUNNEL CLOUD 2 SW TALLADEGA 33.41N 86.12W
03/10/2010 TALLADEGA AL TRAINED SPOTTER

FUNNEL CLOUD SPOTTED ALONG HWY 275 AND RENFROE ROAD
Member Since: July 15, 2006 Posts: 175 Comments: 54858
209. atmoaggie
10:20 PM GMT on March 10, 2010
Quoting Grothar:


I don't want to be difficult, but people with seizure disorders can have an episode if they watch a blinking light too long. They try to avoid them if possible.

I don't believe that for a second. As credible as a triple-digit dewpoint from a broken PWS in the summer...
(j/k, Gro)
Member Since: August 16, 2007 Posts: 6 Comments: 12463
207. Grothar
10:17 PM GMT on March 10, 2010
Quoting Levi32:


Yeah people using IE don't know what they are missing.

I know effects can be quite annoying and I'm using mine wisely. "Tornado Warning" were the only two words I made blink in red in the warning message. I think that's more than appropriate, and hopefully nobody goes farther than that or it would get annoying instead of helping direct people's eyes to important information.


I don't want to be difficult, but people with seizure disorders can have an episode if they watch a blinking light too long. They try to avoid them if possible.
Member Since: July 17, 2009 Posts: 71 Comments: 26895
206. KEEPEROFTHEGATE (Mod)
10:17 PM GMT on March 10, 2010
...THE TORNADO WARNING FOR EAST CENTRAL TALLADEGA AND NORTHERN CLAY
COUNTIES WILL EXPIRE AT 415 PM CST...

THE WARNING HAS BEEN ALLOWED TO EXPIRE.
Member Since: July 15, 2006 Posts: 175 Comments: 54858
205. SQUAWK
10:16 PM GMT on March 10, 2010
Serious rotation near Nashville, AR.

Member Since: December 9, 2008 Posts: 0 Comments: 2498
204. atmoaggie
10:16 PM GMT on March 10, 2010
Quoting Jeff9641:


From the warning reports. I'll post in a few. Tornado outbreak is underway.

I haven't seen a nado warning that goes beyond the usual doppler radar indicated with a "could be".

Show us, please?
Member Since: August 16, 2007 Posts: 6 Comments: 12463

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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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