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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Oh snap....mini-hurricane headed our way. There's no way to tell how heavy the snow within this mesoscale low is. It is showing up on radar so it could be pretty potent. Bracing myself....just 5 more inches and my 60-inch snowstake will disappear for the first time since I've had it.

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Quoting Levi32:
Japanese model agrees pretty well with the Euro, calling for neutral ENSO conditions by April and May, and reaching solid central-neutral by June.




A La Nina is supposed to develop in August
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My wife just sent me a message:

http://www.foxnews.com/weather/2010/03/10/hurricanes/

It says that US will see more hurricanes in 2010…

Good News for my hurricane hunting husband!!!
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Quoting atmoaggie:

What's with the CAPS?

I know the causeway had reduced speed limits northbound and convoys southbound earlier - full fog restrictions.

just didn't think to turn caps off. my bad. thanks for the info, and yes sun is in st. tammany it takes about 5 minutes to drive through. if you blink you'll miss it. hahaha
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Quoting SQUAWK:


Oh yeah. Sun, it is just north of Bush and just south of Rio.

lol!!
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Quoting atmoaggie:

Hehe. Sun is a town in northern St. Tammany parish. (or is it southern Washington parish?)

Feels like the surface of the sun, usually, for 10 months of the year, though.


Oh yeah. Sun, it is just north of Bush and just south of Rio.
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This has been a long time comin'
Spruce Creek Fly-In, Daytona Beach, Florida (PWS)
Updated: 2 sec ago
75.9 °F Scattered Clouds
Humidity: 56% Dew Point: 59 °F
Wind: 2.0 mphfrom the ESE
Wind Gust: 7.0 mph
Pressure: 29.96 in (Falling)
Heat Index: 78 °F
Visibility: 10.0 miles
UV: 7 out of 16
Perfect weather today in ECFL.
Member Since: July 11, 2006 Posts: 14 Comments: 11141
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

NORTHERN AND CENTRAL TEXAS
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Quoting atmoaggie:

Hehe. Sun is a town in northern St. Tammany parish. (or is it southern Washington parish?)

Feels like the surface of the sun, usually, for 10 months of the year, though.


Never heard of it. Leaned something today.
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Japanese model agrees pretty well with the Euro, calling for neutral ENSO conditions by April and May, and reaching solid central-neutral by June.

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Quoting StormChaser81:


Well it's a couple thousand degrees and you might need a fire proof suite, I would also bring some SPF 1000 or higher for the sun burn or scorch.

Haha!
Member Since: August 17, 2009 Posts: 0 Comments: 249
Quoting StormChaser81:


Well it's a couple thousand degrees and you might need a fire proof suite, I would also bring some SPF 1000 or higher for the sun burn or scorch.

Hehe. Sun is a town in northern St. Tammany parish. (or is it southern Washington parish?)

Feels like the surface of the sun, usually, for 10 months of the year, though.
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A bunch of hail reports around Dallas. Almost all about quarter-sized.

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Quoting sarahjola:
I AM HEADED TO SUN TODAY. JUST WANTED TO KNOW WHAT TO BE PREPARED FOR. THANKS!
WHO DAT!!!


Well it's a couple thousand degrees and you might need a fire proof suite, I would also bring some SPF 1000 or higher for the sun burn or scorch.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting sarahjola:
I AM HEADED TO SUN TODAY. JUST WANTED TO KNOW WHAT TO BE PREPARED FOR. THANKS!
WHO DAT!!!

What's with the CAPS?

I know the causeway had reduced speed limits northbound and convoys southbound earlier - full fog restrictions.
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I AM HEADED TO SUN TODAY. JUST WANTED TO KNOW WHAT TO BE PREPARED FOR. THANKS!
WHO DAT!!!
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Quoting CycloneOz:


...and don't bother to do so, unless you need to take a nap.
Quoting SQUAWK:


You did not miss much.


Advice duly noted :) I shall steer clear of that film.
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Quoting Levi32:


Never seen that movie...lol.


You did not miss much.
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Quoting Levi32:


Never seen that movie...lol.


...and don't bother to do so, unless you need to take a nap.
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NWS NOLA/BR not doing the weekly test today...so don't expect to hear one.

Public Information Statement:

...Weekly NOAA Weather Radio test postponed...

The weekly test has been postponed due to inclement weather expected
today and will be done tomorrow...Thursday March 11th...2010 at 11am
CST.

We apologize for any inconvenience.
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Quoting CycloneOz:


Too bad you weren't filming a remake of "Ice Station Zebra." What a waste of a good blizzard! :p :D


Never seen that movie...lol.
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My great-grandfather was a sea captain who sailed from Liverpool to Buenos Aires back in the late 1800s. One of the stops along the way was the port city of Rio Grande, Brazil, just south of where that cyclone is right now. One of the stories handed down in my family was that he always feared the approach to Rio Grande more than any other part of the voyage due to the unpredictable weather there.
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Quoting sarahjola:
IS THERE GOING TO BE BAD WEATHER TODAY IN SOUTHEAST LOUISIANA?

I am of the opinion that most of the rough stuff will stay to our north...a line from Fort Polk, Alex, Hattiesburg. This is based on the RUC forecasts showing the high CAPE values staying north of that line. We could still get the scattered stong T-storm, but I think they will be few and far between.

BUT, is a possibility (please don't go ignore it because I said the above).
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Quoting Levi32:
Good morning all.

Dawn is upon us and it looks like we scored a few more inches of snow overnight, and it is now snowing for the 49th straight hour. The 28 straight hours of blizzard conditions ended late last night as winds have calmed down, but a mesoscale low continues to toy with us this morning, keeping light snow falling. Things should finally wind down today, and snow should cease altogether by this evening.

We are now at approximately 46 inches of new snow and still counting.



Too bad you weren't filming a remake of "Ice Station Zebra." What a waste of a good blizzard! :p :D
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IS THERE GOING TO BE BAD WEATHER TODAY IN SOUTHEAST LOUISIANA?
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Good morning all.

Dawn is upon us and it looks like we scored a few more inches of snow overnight, and it is now snowing for the 49th straight hour. The 28 straight hours of blizzard conditions ended late last night as winds have calmed down, but a mesoscale low continues to toy with us this morning, keeping light snow falling. Things should finally wind down today, and snow should cease altogether by this evening.

We are now at approximately 46 inches of new snow and still counting.

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RUC data further into the run shows a very good hodograph for nadoes in South Central Arkansas. This for 6 pm CST:



Hope awareness and brain cells are in abundance there today.
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26. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 5235
Hurricane Forecasters Bring Preparedness Message to Atlantic, Mexico and Caribbean
Public invited to tour Air Force Reserve “Hurricane Hunter” aircraft



NOAA and the U.S. Air Force Reserve will host a series of public events from March 18 to 27 in six coastal communities in Bermuda, Mexico and the Caribbean to urge residents to prepare for the upcoming hurricane season.

Tours of the Air Force Reserve Command’s WC-130J “hurricane hunter” aircraft will be available to residents and have an opportunity to meet U.S. National Hurricane Center director Bill Read; deputy director Ed Rappaport; senior hurricane specialist Lixion Avila; Tropical Analysis and Forecast Branch meteorologist Jorge Aguirre-Echevarria; and personnel from the 53rd Weather Reconnaissance Squadron of the 403rd Wing.


Locations and times for public tours are listed below (all times are local):

•Friday, March 19: Bermuda; 11:00 a.m. to 4:00 p.m.

•Monday, March 22: Mazatlan, Mexico; 11:00 a.m. to 3:00 p.m.

•Tuesday, March 23: Merida, Mexico; 1:00 p.m. to 4:00 p.m.

•Wednesday, March 24: San Salvadore, El Salvadore, 1:00 p.m. to 4:00 p.m.

•Friday, March 26: Antigua; 11:00 a.m. to 3:00 p.m.

•Saturday, March 27: Roosevelt Roads, Puerto Rico; 9:00 a.m. to 4:30 p.m.

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With that big of a "slight" region, I expect we'll see a few radiosondes at 18 Z. (in about 2 hours)

Should be interesting.
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Little Rock is the middle of the highest CAPE by 2 pm according to the latest RUC run, though.



This looks very capable:



Shear not exactly perfect for nado generation:

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Jackson and Lake Charles look ripe in the 12 Z soundings. Lake Charles has some shear, Jackson very little.

Jackson:



Lake Charles:

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Good Talk,

The animations in PowerPoint do get tricky sometimes.

Thanks
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Great lecture Dr. M; thanks for plugging the Blog............... :)
Member Since: August 8, 2006 Posts: 0 Comments: 8701
SPC report of hail this morning near Dallas...

...in the face of a monster inversion ?!?



(Unless you guys warmed some 15 C since 6 CST)

Add on: Hmmm, I guess evap cooling with precip could drop the temp of the pbl, which would allow for *some* buoyancy...seems like a reach, though.
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I see a face. It's sticking out it's tongue! :p

Winter weather mocking us...

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Climate:

Houston reached 80 degrees yesterday the first time we have seen 80 since November 15, 2009…now that is impressive this far south and gives a testament to just how cold this winter has been. The area has just suffered through one of the coldest winter periods on record and the month of February averaged significantly below normal. Houston recorded its 5th coldest February on record (6.9 degrees below average), Hobby its 3rd (8.4 degrees below average) and College Station its 5th (7.8 degrees below average). Victoria tied for its 2nd coldest February on record! Houston only had 2 days of temperatures above average during the entire month. From the period of Dec 1-Feb 28th (meteorological winter) Houston suffered its 6th coldest winter ever and the coldest since 1977-1978, Galveston its 5th coldest winter ever, and College Station its 6th coldest winter ever. Additionally, at Corpus Christi, the number of days that were at or above 70 in February 2010 was only 4…last year there were 26 with the average being 12.
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Morning all, Hey jeff9641 i have to hand it to you. you have been telling all about the severe wx coming to c fl thur and fri. And now it looks like a great poss. Great call!!!!
Member Since: November 25, 2007 Posts: 0 Comments: 956
Bastardi forecasts an active 2010 Atlantic hurricane season.

Link
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Brazil Meteorological Services blog
=========================================

A cyclone very rare, extraordinary scientific point of view to our regional climate, still classified subtropical officially by the United States, but by our analysis has already evolved into tropical, acting in the coastline of Rio Grande do Sul. The latest data from called best track system, dawn, accuse it positioned to 29.5 degrees south latitude and 48 degrees longitude, very close to the previous six hours 29.9 degrees South and 48.1 ° West. Means that the center of the cyclone little changed position at dawn, a little to the North and Northwest. Already the satellite images, which provide an idea more updated, allege that the tropical cyclone began to depart more vigorously to the East, away more continent now daybreak.
Member Since: May 24, 2006 Posts: 50 Comments: 44424
Good Morning everyone. The Dallas-Ft Worth, TX area is under a Severe Thunderstorm Watch. Look who's coming in for "brunch"!!
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Seychelles Meteorological Services
Tropical Disturbance Advisory Number SIX
TEMPETE TROPICALE MODEREE HUBERT (13-20092010)
16:00 PM Réunion March 10 2010
====================================

At 12:00 PM UTC, Moderate Tropical Storm Hubert (998 hPa) located at 20.9S 49.1E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The storm is reported as moving west southwest at 6 knots.

Dvorak Intensity: T3.0

Gale-Force Winds
=================
15 NM from the center

Near Gale-Force Winds
=====================
35 NM from the center

Forecast and Intensity
=====================
12 HRS: 21.3S 47.9E - (Depression sur terre)
24 HRS: 21.5S 46.8E - (Depression sur terre)

Additional Information
=======================
The moderate tropical storm Hubert has been named by the Madagascar Meteorological Services at 1200z. MSLP has been adjusted 4 hPa higher than normal to take into account the high environmental pressure (set to 1013 hPa). Convection still remains quite fluctuating. The central dense overcast visible this morning has faded and a curve band feature takes place. Microwave imagery (TRMM at 0854z) shows a beginning of banding eye that justify the moderate tropical storm stage. With landfall expected to occur on the Malagasy coast next night (between Mananjary and Mahanoro), the system could rapidly decrease beyond 36 hrs.
Member Since: May 24, 2006 Posts: 50 Comments: 44424
NAM


GFS



LOOKS LIKE A SEVERE SOUTHEASTERN THREAT FOR FRIDAY....Keep your eyes to the sky in these Areas
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Member Since: September 2, 2007 Posts: 178 Comments: 20439
12Z update on 90Q

SL 90 2010031012 BEST 0 297S 476W 40 1000 LO


SAB has dvorak 2.0 as a tropical system, TAFB has dvorak 2.5 as a subtropical system.

SL 90 201003101145 2980S 4750W SAB 2020 ///// MET8 CSC T
SL 90 201003101145 2990S 4760W TAFB 2525 ///// MET8 CSC S
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Looks very Tropical for now i would say!

Member Since: September 2, 2007 Posts: 178 Comments: 20439
Thank you very much for posting on 90Q. Who will issue forecasts on this system?
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Thank You Dr. and Good Luck this morning; will be interesting to see how the severe weather patterns emerge over the next several weeks and whether April will bring a greater threat based upon the relative position of the jet stream and warmer temps.
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Very interesting stuff Down South. When one compares the last event in 2004 that was also a rough year In the North Hemp. Atlantic also..........HEMMM.....lets hope there it was just by chance the last time.
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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.

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