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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you can send it my way...we'll drain.

ya'll have a good thursday.
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Looks like they sent it to my house in Macon.

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401. IKE
I see what's happening. Drier air is moving in...

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400. IKE
Rain is just about over here for now. So much for that forecast of "several inches possible".
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399. IKE
Quoting aquak9:
0.44? not bad so far. Better than 4.44.

We're at 0.10. Just a sweet, breezy, overcast morning.


LOL...don't need 4.44...or what's left of my yard doesn't.


Quoting severstorm:
Morning all, Hey Ike how ya doin? Nice and warm down here in w c fl finally. Looks like some really nasty weather coming to this area tonight and friday.


Doing fine this morning.
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Morning all, Hey Ike how ya doin? Nice and warm down here in w c fl finally. Looks like some really nasty weather coming to this area tonight and friday.
Member Since: November 25, 2007 Posts: 0 Comments: 959
0.44? not bad so far. Better than 4.44.

We're at 0.10. Just a sweet, breezy, overcast morning.
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396. IKE
Radar glitch....

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395. IKE
I'm at .44 inches of rain so far today. Light to moderate rain falling now..60.3 degrees outside.

I noticed the dogwood trees in town are blooming. Spring is here:)
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394. IKE
Quoting aquak9:
G'morning ya'll.

Ike- are ya floating yet? it only hold eleven inches! we can see the old pollen lines on ours.

PhatKat- yep the radars were blanking out last night. Very frustrating.


They canceled the flash flood watch west of me. Still under one here but...it ain't happening.

I had .22 inches of rain yesterday. I'll go look at today's total...so far.
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G'morning ya'll.

Ike- are ya floating yet? it only hold eleven inches! we can see the old pollen lines on ours.

PhatKat- yep the radars were blanking out last night. Very frustrating.
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392. IKE
Quoting Phatkhat:
Was trying to watch the progress of Arkansas storms - and hoping like crazy for no tornadoes. Thankfully they went around. I'm only maybe 20 miles from Quitman.

But I kept getting blanks in the radar, and the storm track arrows didn't show. Anyone else having a problem? It wasn't just Little Rock's radar. Same problem at other cities.


Yeah...it's the same problem on the Mobile,AL and Red Bay,FL. radars. Appears to be on all of them.
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It might be time to buy a swamp buggy.

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Debating GW on this blog is incredibly frustrating a stupid, you might as well be arguing over religion I have an opinion but none of you be impacted by it.

Southern hemisphere is heating up, they haven't had a storm in around 20 days
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Quoting centex:
Yes, because so many do not get it, public service. When the tropics light up I give my thoughts. But ignore the science quack opinions, gives you a better point of reference. Good to know who the quacks are.There are alot quacks and need to know who they are. Anti science is far to popular here.


well Im gonna tell you now that insulting someone is not a good way to try to get them to agree with you, quack
Member Since: June 28, 2006 Posts: 25 Comments: 8360
388. HadesGodWyvern (Mod)
Fiji Meteorological Services
Tropical Disturbance Summary
TROPICAL DEPRESSION 13F
18:00 PM FST March 11 2010
===================================

At 6:00 AM UTC, Tropical Depression 13 (998 hPa) located at 14.5S 168.5E is reported as slowly moving. Position FAIR based on infrared/visible imagery with animation and peripheral observations. Sea surface temperature is around 30C.

Convection remains persistent in the last 12 hours. Organization remains fairly good. System lies along a monsoon trough and under an upper ridge, in low to moderate shear environment. Global models have picked up the system and moves it westward over the next 24-48 hours with some intensification.

Potential for this system to form into a significant tropical cyclone within the next 24-48 hours is LOW TO MODERATE.
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Was trying to watch the progress of Arkansas storms - and hoping like crazy for no tornadoes. Thankfully they went around. I'm only maybe 20 miles from Quitman.

But I kept getting blanks in the radar, and the storm track arrows didn't show. Anyone else having a problem? It wasn't just Little Rock's radar. Same problem at other cities.
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386. HadesGodWyvern (Mod)
Fiji Meteorological Services
Tropical Disturbance Advisory #3
TROPICAL DEPRESSION 14F
18:00 PM FST March 11 2010
======================================

A TROPICAL CYCLONE ALERT IS NOW IN FORCE FOR WALLIS AND FUTUNA.

A STRONG WIND WARNING IS NOW IN FORCE FOR WALLIS AND FUTUNA.


At 6:00 AM UTC, Tropical Depression 14 (1002 hPa) located at 11.0S 174.7W has 10 minute sustained winds of 20 knots. Position POOR based on hourly GMS/GOES enhanced infrared imagery with animation. The depression is reported as moving west-southwest at 7 knots.

Organization gradually improving. Primary bands to east and west consolidating and beginning to wrap around low level circulation center. Convection along both bands cooling. Low level circulation lows exposed to southwest of low level circulation center in last visible imagery due to southwest shear. System lies in a diffluent environment. Sea surface temperature is around 30C. Outflow good to east and north, developing elsewhere. System steered west southwest by northeast deep layer mean flow.

Dvorak analysis based on 0.35 wrap on LOG10 spiral yielding DT 2.0

Dvorak Intensity: T2.0/2.0/D1.0/24HRS

Global models agree on west southwest track and intensification.

Forecast and Intensity
========================
12 HRS: 11.3S 175.9W - 25 knots (Tropical Depression)
24 HRS: 11.9S 177.2W - 30 knots (Tropical Depression)
48 HRS: 14.0S 179.2W - 50 knots (CAT 2)

The Next Tropical Disturbance Advisory On TD 14F Will Be Issued At Around 14:30 PM UTC...
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Quoting KEEPEROFTHEGATE:
339. atmoaggie 3:36 AM GMT on March 11, 2010
Quoting Chicklit:
GOLFBALL TO HEN EGG SIZE HAIL REPORTED.
ahhh...you're right.
I suppose that is to clarify they weren't robin-sized eggs.

Or ostrich...ouch.
Action: Quote | Ignore User


how would you like football basketball beachball size hail


lol

And then there are beachballs. Ouch.....
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Quoting centex:
Yes

Which earns you an iggy. And yes I'm a scientist
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382. HadesGodWyvern (Mod)
Seychelles Meteorological Services
Tropical Disturbance Advisory Number NINE
DEPRESSION SUR TERRE. FORMER HUBERT (13-20092010)
10:00 AM Réunion March 11 2010
====================================

At 6:00 AM UTC, Overland Depression, Former Hubert (998 hPa) located at 20.5S 48.1E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The storm is reported as moving northwest at 3 knots.

Dvorak Intensity:

Gale-Force Winds
=================
within the center

Near Gale-Force Winds
=====================
120 NM from the center extending up to 280 NM in the northeast quadrant

Forecast and Intensity
=====================
12 HRS: 20.8S 46.1E - (Depression sur terre)
24 HRS: 22.0S 44.6E - (Depression sur terre)
48 HRS: 24.7S 41.6E - 20 knots (Perturbation Tropicale)
72 HRS: 24.6S 38.8E - 20 knots (Perturbation Tropicale)

Additional Information
=======================
According to multispectral satellite imagery, Former Cyclone Hubert still shows a rather good configuration with convection wrapping around the low level center.

System should maintain a general westward then southwestward track on the northwestern edge of the subtropical high pressures. Therefore, it is expected to remain overland for the next 24 hours and go out overseas with a very weak circulation. If it happens, potential for re-intensification appears to be poor due to increasing northwestserly shear. This forecast is based on the most availble numerical weather prediction models.
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Quoting tornadodude:


is this all you ever post about???
Yes, because so many do not get it, public service. When the tropics light up I give my thoughts. But ignore the science quack opinions, gives you a better point of reference. Good to know who the quacks are.There are alot quacks and need to know who they are. Anti science is far to popular here.
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Quoting centex:
Guys/Gals, we really need to call the far right sceptics on the political jargon I see each week on this blog. Normally I post it on the CC blog. I say this because we can't believe your tropical opinion when you take a far right stance on CC/GM which is ony a political stance and no basis in science.


is this all you ever post about???
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting Seastep:
It's not about what I say. It is about the data.

I don't listen to others, other than to trigger a "ok, I'll look."

Just seeking the facts.

Listening to others doesn't cut it. I verify.

All science, not just climatologists.

Bedtime.
sorry not pinging you, goodnight
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It's not about what I say. It is about the data.

I don't listen to others, other than to trigger a "ok, I'll look."

Just seeking the facts.

Listening to others doesn't cut it. I verify.

All science, not just climatologists.

Bedtime.
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Hi centex.

Were you able find any research that is not simply number of sunspots?
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Goodnight. Just waiting on a malware cleanup on my FIL's system.
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well bed time for me looks like mostly rain event now lets see what first light brings
Member Since: July 15, 2006 Posts: 174 Comments: 54459
i always take care only use when need be
Member Since: July 15, 2006 Posts: 174 Comments: 54459
As long as you don't post red, it's all good.

But, when you do, it will catch my attention.

I like it, if appropriately applied.

Share the same concerns as others on abuse.

Not worried about you.
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its making it interesting i guess or maybe different
Member Since: July 15, 2006 Posts: 174 Comments: 54459
You're having fun with that, aren't you, KOTG. ;)

Unobtrusive and appropriately applied.
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804

WHXX04 KWBC 110138

CHGQLM

ATTENTION...NATIONAL HURRICANE CENTER



NCEP COUPLED GFDL HURRICANE MODEL FORECAST MADE FOR



TROPICAL STORM INVEST 90Q



INITIAL TIME 18Z MAR 10



DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT

REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD

NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC

OFFICIAL FORECAST.





FORECAST STORM POSITION



HOUR LATITUDE LONGITUDE HEADING/SPEED(KT)



0 -29.8 46.7 100./ 6.0

6 -29.7 46.1 86./ 5.4

12 -30.2 45.6 133./ 6.4

18 -31.0 44.4 124./13.4

24 -32.0 43.0 125./15.8

30 -32.9 41.4 120./15.3

36 -33.8 39.5 115./19.0

42 -35.2 36.7 117./26.7

48 -37.2 33.4 121./33.2

54 -39.7 29.7 124./38.1

60 -42.7 25.2 123./44.7



STORM DISSIPATED AT 60 HRS AT THE ABOVE PSN
Member Since: July 15, 2006 Posts: 174 Comments: 54459
365. xcool
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GT. I remember. Georgetown. Visiting?
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Quoting GTcooliebai:
Hey anyone in here live in Pinellas County? Did you feel that shaking early in the afternoon I think around 3PM. My windows in the house started rattling at least twice.


My guess is there are plenty from there.

Did something happen? Explosions somewhere?

And, I thought you were from central or south America, no?
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Hey anyone in here live in Pinellas County? Did you feel that shaking early in the afternoon I think around 3PM. My windows in the house started rattling at least twice.
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Quoting JRRP:

the Azores High was pretty strong 2006
and that helped the SST were below average


Or it was the cause of the SSTs...stronger trade winds, more evaporative cooling of SST.

Winds have almost everything to do with SST variation in the MDR.
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359. JRRP
me voy a mi cama
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358. JRRP
Quoting StormW:


The maps show the position of the ITCZ (InterTropical Convergence Zone). This is where the SE and NE Trades meet. When the ITCZ is further north in a hurricane season, the chances of cyclone development along the ITCZ becomes greater, as the ITCZ has more of a chance to "buckle" and throw out a disturbance. You can see in the 2006 picture as compared to the same time for 2010, the relative position of the ITCZ is further north. In fact, I personally don't look for it to be as far north as it is till around, oh let's say June. One thing that partially dictates it's position is the strength of the A/B High, which you can see at the moment is much, much weaker as compared to the 2006 graphic.

You said it
lol..
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339. atmoaggie 3:36 AM GMT on March 11, 2010
Quoting Chicklit:
GOLFBALL TO HEN EGG SIZE HAIL REPORTED.
ahhh...you're right.
I suppose that is to clarify they weren't robin-sized eggs.

Or ostrich...ouch.
Action: Quote | Ignore User


how would you like football basketball beachball size hail


lol
Member Since: July 15, 2006 Posts: 174 Comments: 54459
355. JRRP
Quoting FirstCoastMan:
What does the difference between the two maps represent,and how does it affect this years hurricane season?

the Azores High was pretty strong 2006
and that helped the SST were below average

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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.