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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304. Skyepony (Mod)
Click this & animate the last 8 frames.. the low in the central part of US sucks in the severe low out of the SW to dance as it establishes a good tap to the ITCZ down deep in the Pacific.
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303. xcool
i buy g
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My sister and her husband picked the wrong week to be in Clinton Arkansas buying farmland. Clinton is NW of Little Rock:
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Quoting Skyepony:
nrtiwlnvragn~ Just doesn't seem like the big low over South America is there & that looks more right inverted. Didn't know the nest moved that far south. Does kinda almost look like running the model on the disorganized blob ~32N38W.


They should be able to move the nest in the HWRF similar to the GFDL for 90Q.
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300. Skyepony (Mod)
nrtiwlnvragn~ Just doesn't seem like the big low over South America is there & that looks more right inverted. Didn't know the nest moved that far south. Does kinda almost look like running the model on the disorganized blob ~32N38W.
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hey guys check it out

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341
NWUS54 KSHV 110148
LSRSHV

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

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

0748 PM HAIL LAWSON 33.20N 92.48W
03/10/2010 E2.00 INCH UNION AR LAW ENFORCEMENT

GOLFBALL TO HEN EGG SIZE HAIL REPORTED.


&&

Member Since: July 15, 2006 Posts: 174 Comments: 54370
Member Since: July 15, 2006 Posts: 174 Comments: 54370
Quoting Skyepony:


I think they may have ment to. Like the whole thing is inverted, forget the land & pretend Antarctica is at the top. The other way & it would go off the map too quick.


Not sure of that, the nest is movable and it showed the low currently over the US. The GFDL graphics should be showing up soon, the text just came out:

HOUR: .0 LONG: -46.74 LAT: -29.78 MIN PRESS (hPa): 994.62 MAX SURF WIND (KNOTS): 47.12
HOUR: 6.0 LONG: -46.12 LAT: -29.74 MIN PRESS (hPa): 995.20 MAX SURF WIND (KNOTS): 39.72
HOUR: 12.0 LONG: -45.62 LAT: -30.21 MIN PRESS (hPa): 995.40 MAX SURF WIND (KNOTS): 40.85
HOUR: 18.0 LONG: -44.39 LAT: -31.04 MIN PRESS (hPa): 993.62 MAX SURF WIND (KNOTS): 37.33
HOUR: 24.0 LONG: -42.95 LAT: -32.04 MIN PRESS (hPa): 991.71 MAX SURF WIND (KNOTS): 42.20
HOUR: 30.0 LONG: -41.44 LAT: -32.90 MIN PRESS (hPa): 990.09 MAX SURF WIND (KNOTS): 37.25
HOUR: 36.0 LONG: -39.46 LAT: -33.84 MIN PRESS (hPa): 985.73 MAX SURF WIND (KNOTS): 41.18
HOUR: 42.0 LONG: -36.70 LAT: -35.25 MIN PRESS (hPa): 984.50 MAX SURF WIND (KNOTS): 43.80
HOUR: 48.0 LONG: -33.39 LAT: -37.24 MIN PRESS (hPa): 983.22 MAX SURF WIND (KNOTS): 44.00
HOUR: 54.0 LONG: -29.69 LAT: -39.73 MIN PRESS (hPa): 982.04 MAX SURF WIND (KNOTS): 45.45
HOUR: 60.0 LONG: -25.18 LAT: -42.65 MIN PRESS (hPa): 979.73 MAX SURF WIND (KNOTS): 43.79

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292. Skyepony (Mod)
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Quoting atmoaggie:

Trying to make a newer version of the Navy's COAMPS model run on my cluster. Losing hair in the process. Quitting 'till the morning...unless I slap my forehead on the way home.

(There are a lot of things the Navy, FNMOC, and NAVO do very well. Coupled atmosphere/ocean model documentation isn't one of them.)


Are you serious? I thought you were kidding when you said you were going to do that. Still looking into the buoy fiasco. They whole thing is making less sense. There are some links I might send you this week on question and answer blog on the different systems.
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290. Skyepony (Mod)
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Quoting xcool:
lmao i'm big time geeks haha


Wh ch s your favor te show?

I'll buy an i.
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Member Since: July 15, 2006 Posts: 174 Comments: 54370
287. xcool
lmao i'm big time geeks haha
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Quoting atmoaggie:
1 'nado and 1 wind report at SPC...57 hail reports.


mainly hail threat
winds come later overnight maybe
may in fact diminsh to a rain event overnight after midnight
till morn then tomorrow another run of weather
Member Since: July 15, 2006 Posts: 174 Comments: 54370
Quoting Levi32:


You guys are funny lol.


Hey Levi, didn't you ever notice that the blog gets quiet at 6:59 and starts up again around 7:59. Most be all us geeks watching the Wheel and Jeopardy. LOL
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284. xcool
Wheel of Fortune rock,
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283. Skyepony (Mod)
Quoting nrtiwlnvragn:
HWRF was run on 90Q but looks like they forgot to put the negative on the longitude.


I think they may have ment to. Like the whole thing is inverted, forget the land & pretend Antarctica is at the top. The other way & it would go off the map too quick.
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1 'nado and 1 wind report at SPC...57 hail reports.

Member Since: August 16, 2007 Posts: 6 Comments: 12463
Quoting Levi32:
The blog is dead in the middle of the afternoon? With severe weather to boot? Wow lol.

Trying to make a newer version of the Navy's COAMPS model run on my cluster. Losing hair in the process. Quitting 'till the morning...unless I slap my forehead on the way home.

(There are a lot of things the Navy, FNMOC, and NAVO do very well. Coupled atmosphere/ocean model documentation isn't one of them.)
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Quoting PcolaDan:


ssshhhhhh Taking an after dinner nap. ;) 6:30 here.
Quoting Grothar:


SHHHH! Wheel of Fortune is on.


You guys are funny lol.
Member Since: November 24, 2005 Posts: 635 Comments: 26654
Quoting NRAamy:
grothar!!!!

yo!!!!!!

:)


Amy, How has your weather been. We are expecting the 80's tomorrow. Just hope we don't get any big storms.
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Quoting Levi32:
The blog is dead in the middle of the afternoon? With severe weather to boot? Wow lol.


SHHHH! Wheel of Fortune is on.
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Quoting Grothar:
Hey JJ

Atmo and I always joke with each other. I put that phrase "I don't want to be difficult" just as a little joke between us. Maybe I shouldn't have put in on the blog. He is a scientist and I am sure knows about the blinking lights phenomenon. But thanks for posting that article anyway. It might help some people.


Hawk!!!
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Quoting NRAamy:
dashboard cow man is back!!!!!!!!!

:)


Yea, well, my retirement guy wasn't having any luck, :)
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Hi guys I am getting really happy as the days go by try to think why
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Here's the MODIS true-color image of the mesoscale polar low that hit us this morning as a grand finale of the epic 5-day, 1-2 punch of snow that has dropped 48 inches of snow at my house. The storm is now FINALLY over, after 58 straight hours of snowfall and 28 straight hours of blizzard conditions during the 2nd round.

Member Since: November 24, 2005 Posts: 635 Comments: 26654
Member Since: July 15, 2006 Posts: 174 Comments: 54370
grothar!!!!

yo!!!!!!

:)
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HWRF was run on 90Q but looks like they forgot to put the negative on the longitude.
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dashboard cow man is back!!!!!!!!!

:)
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Quoting Levi32:
The blog is dead in the middle of the afternoon? With severe weather to boot? Wow lol.


ssshhhhhh Taking an after dinner nap. ;) 6:30 here.
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The blog is dead in the middle of the afternoon? With severe weather to boot? Wow lol.
Member Since: November 24, 2005 Posts: 635 Comments: 26654
Hey JJ

Atmo and I always joke with each other. I put that phrase "I don't want to be difficult" just as a little joke between us. Maybe I shouldn't have put in on the blog. He is a scientist and I am sure knows about the blinking lights phenomenon. But thanks for posting that article anyway. It might help some people.
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265: Isn't that for this morning?

RUC figures the CAPE to be about like so as of 6 pm CST:

(Yellow is 2000 )
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Member Since: July 15, 2006 Posts: 174 Comments: 54370
Quoting twhcracker:
this is twice now someone posted a "tornado warning" about a "severe thunderstorm capable of producing a tornado". i thought a tornado warning meant an actual tornado was headed your way, and not just a potential for one?

Ummm, those come directly from the NWS offices...they issue a warning if radar signatures indicate a likely rotation detected at cloud level. A lot of false warnings occur.

This will get better with the dual-pole radars...coming soon.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Quoting twhcracker:
this is twice now someone posted a "tornado warning" about a "severe thunderstorm capable of producing a tornado". i thought a tornado warning meant an actual tornado was headed your way, and not just a potential for one?


This has been a bone of contention with me also. Wrote a long winded entry on the blog here a while back about it. But I'll post them anyways for my area until they come up with a new method. (Need another level in my opinion)
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506

WOUS20 KWNS 102234

WWASPC

SPC WW-A 102235

LAZ000-TXZ000-102340-



STATUS REPORT ON WW 24



THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA.



..MEAD..03/10/10



ATTN...WFO...SHV...



&&



STATUS REPORT FOR WS 24



SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS



LAC013-015-017-021-027-031-043-049-059-061-069-073-081-085-111-

119-127-102340-



LA

. LOUISIANA PARISHES INCLUDED ARE



BIENVILLE BOSSIER CADDO

CALDWELL CLAIBORNE DE SOTO

GRANT JACKSON LA SALLE

LINCOLN NATCHITOCHES OUACHITA

RED RIVER SABINE UNION

WEBSTER WINN

$$





TXC005-067-073-183-203-315-347-365-401-403-405-419-423-459-499-

102340-



TX

. TEXAS COUNTIES INCLUDED ARE



ANGELINA CASS CHEROKEE

GREGG HARRISON MARION

NACOGDOCHES PANOLA RUSK

SABINE SAN AUGUSTINE SHELBY

SMITH UPSHUR WOOD

$$





THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE

REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL

INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES

CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.

$$
Member Since: July 15, 2006 Posts: 174 Comments: 54370
this is twice now someone posted a "tornado warning" about a "severe thunderstorm capable of producing a tornado". i thought a tornado warning meant an actual tornado was headed your way, and not just a potential for one?
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Quoting atmoaggie:

Whoa, there! I wasn't doubting the phenomena...I was mocking Grother's use of the phrase "I don't want to be difficult".
Yeah, sure ATMO. You just like picking on Peoples...jk I hope you are doing good.:)
Member Since: September 27, 2007 Posts: 1 Comments: 21416
TORNADO WARNING
MSC041-153-110000-
/O.NEW.KMOB.TO.W.0003.100310T2309Z-100311T0000Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE MOBILE AL
509 PM CST WED MAR 10 2010

THE NATIONAL WEATHER SERVICE IN MOBILE HAS ISSUED A

* TORNADO WARNING FOR...
NORTHERN GREENE COUNTY IN SOUTHEAST MISSISSIPPI...
SOUTHEASTERN WAYNE COUNTY IN SOUTHEAST MISSISSIPPI...

* UNTIL 600 PM CST

* AT 509 PM CST...NATIONAL WEATHER SERVICE RADAR INDICATED A SEVERE
THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 4 MILES EAST OF
NEELY...OR ABOUT 8 MILES WEST OF LEAKESVILLE...MOVING NORTHEAST AT
30 MPH.

* THE TORNADO WILL BE NEAR...
JONATHAN BY 515 PM CST...

THE SAFEST PLACE TO BE DURING A TORNADO IS ON THE LOWEST FLOOR OF A
STURDY BUILDING...PREFERABLY IN AN INTERIOR HALLWAY OR A ROOM SUCH AS
A CLOSET OR BATHROOM. IF POSSIBLE...GET UNDER A WORKBENCH OR OTHER
PIECE OF STURDY FURNITURE. USE BLANKETS OR PILLOWS TO COVER YOUR BODY
AND ALWAYS STAY AWAY FROM WINDOWS.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 800 PM CST WEDNESDAY EVENING
FOR SOUTHWESTERN ALABAMA AND SOUTHEAST MISSISSIPPI.

LAT...LON 3154 8869 3144 8845 3112 8864 3117 8879
TIME...MOT...LOC 2309Z 206DEG 25KT 3120 8868

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Quoting JJ:

Whoa, there! I wasn't doubting the phenomena...I was mocking Grother's use of the phrase "I don't want to be difficult".
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Quoting Grothar:


Looks like Spring has Sprung. Hope they don't last. It was a quiet February for tornadoes now this.
El-Nino making itself known one last time before departure. I really hope that this years predictions on the 2010 Hurricane season do not come to fruition. We are still recovering from past disasters.
Member Since: September 27, 2007 Posts: 1 Comments: 21416
New warning:

THE NATIONAL WEATHER SERVICE IN MOBILE HAS ISSUED A

* TORNADO WARNING FOR...
NORTHERN GREENE COUNTY IN SOUTHEAST MISSISSIPPI...
SOUTHEASTERN WAYNE COUNTY IN SOUTHEAST MISSISSIPPI...

* UNTIL 600 PM CST

* AT 509 PM CST...NATIONAL WEATHER SERVICE RADAR INDICATED A SEVERE
THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 4 MILES EAST OF
NEELY...OR ABOUT 8 MILES WEST OF LEAKESVILLE...MOVING NORTHEAST AT
30 MPH.

* THE TORNADO WILL BE NEAR...
JONATHAN BY 515 PM CST...

THE SAFEST PLACE TO BE DURING A TORNADO IS ON THE LOWEST FLOOR OF A
STURDY BUILDING...PREFERABLY IN AN INTERIOR HALLWAY OR A ROOM SUCH AS
A CLOSET OR BATHROOM. IF POSSIBLE...GET UNDER A WORKBENCH OR OTHER
PIECE OF STURDY FURNITURE. USE BLANKETS OR PILLOWS TO COVER YOUR BODY
AND ALWAYS STAY AWAY FROM WINDOWS.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 800 PM CST WEDNESDAY EVENING
FOR SOUTHWESTERN ALABAMA AND SOUTHEAST MISSISSIPPI.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
255. JJ
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)


Regarding seizure disorders and blinking lights:
http://trace.wisc.edu/peat/photosensitive.php
"What can stimulate photosensitive seizures?

Certain flashing lights, images, and repetitive patterns may cause seizures in persons with photosensitive seizure disorder. Strobe lights, flicker of bright light through leaves, and sunlight flashing off of a series of windows are examples of known stimuli. Some people are known to be affected by the raster rate of cathode ray tube televisions, especially in Europe, where the standard is 50 Hz. Video content, whether on television, film, in computer games, or on the web, may include unsafe flicker, colors, or high-contrast patterns that induce seizure. For example, in 1997 a Pokémon episode broadcast in Japan showed a sequence of flickering images which triggered seizures in hundreds of children."

try putting seizure disorders blinking lights
into google.
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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

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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.