Dangerous tornado outbreak expected Saturday; Gulf of Mexico SSTs warmest on record

By: Dr. Jeff Masters , 2:57 PM GMT on April 13, 2012

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A dangerous tornado outbreak is expected on Saturday over the Plains, says NOAA's Storm Prediction Center (SPC). Warm, moist air flowing northwards from a Gulf of Mexico that has record-warm waters will collide with cold air funneling down from Canada, creating a highly unstable air mass capable of creating strong thunderstorm updrafts. An impressive upper-level low, accompanied by a jet stream with 105 - 125 mph winds at middle levels of the atmosphere, will create plenty of wind shear, giving the air the spin it needs to form tornadoes. SPC has has issued their highest level of alert, a "High Risk," for much of Oklahoma, Kansas, and Nebraska for Saturday. Included in the "High Risk" area are the cities of Wichita, Oklahoma City, and Lincoln. This is the second time SPC has issued a "High Risk" forecast this year; the first "High Risk" forecast came for the March 2 tornado outbreak, which killed 41 people and did $1.5 - $2 billion in damage. It is very unusual for SPC to issue a "High Risk" forecast more than a day in advance of a suspected tornado outbreak; according to Wikipedia, today's "High Risk" forecast is only the second time SPC has ever done this. The other instance was for the April 6 - 8, 2006 tornado outbreak focused over Tennessee, which generated 73 tornadoes that killed 13 and did $1.5 billion in damage. People living in the threatened area need to pay close attention on Saturday to this dangerous severe weather situation.


Figure 1. Severe weather risk for Saturday, April 14, 2012, from NOAA's Storm Prediction Center.

Gulf of Mexico water temperatures the warmest on record
Temperatures in the states bordering the Gulf of Mexico were the 3rd - 7th warmest on record during the first three months of 2012, according to NOAA's National Climatic Data Center. This allowed Sea Surface Temperatures (SSTs) in the Gulf of Mexico (25 - 30°N, 85 - 90°W) to climb to 1.4°C (2.5°F) above average during March 2012, according to a wunderground analysis of the Hadley Centre SST data set. This is the warmest March value on record for the Gulf of Mexico, going back over a century of record keeping. During the first two weeks of April, Gulf of Mexico waters remained about 1.5°C above average, putting April on pace to have the warmest April water temperatures on record. Only one year in the past century has had April water temperatures in the Gulf of Mexico more than 1.1°C above average; that year was 2002 (1.4°C above average.) All that record-warm water is capable of putting record amounts of water vapor into the air, since evaporation increases when water is warmer. Because moist air is less dense than dry air, this warm, moist air flowing northwards from the Gulf of Mexico into the developing storm system over the Plains will be highly unstable once it encounters cold, dry air aloft. The record-warm waters of the Gulf of Mexico are a key reason for the high risk of severe weather over the Plains this weekend.


Figure 2. Departure of Sea Surface Temperature (SST) from average for April 12, 2012, as computed by NOAA/NESDIS. SSTs in the Gulf of Mexico are at their warmest levels on record for this time of year.

Follow Weather Underground on twitter for the latest on this potential severe weather outbreak.

Jeff Masters

April Storms (llpj04)
this storm greeted me as I came out of the grocery store, chased me home and got to my driveway the same time I did.
April Storms
Lightning Up the Pond - Oklahoma (mbryan777)
Last night we had a pretty spectacular lightning storm. I put the camera on the tripod in time-lapse mode and laid on my back on the hillside above the pond taking in an amazing show. When it got more exciting than I was comfortable with, I ran for the house.
Lightning Up the Pond - Oklahoma

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1207. Patrap
Dodge City
NEXRAD Radar

Base Reflectivity 0.50° Elevation
Range 124 NMI

Member Since: Posts: Comments:
Quoting RTSplayer:


I think 7p.m.

the GFS and Canadian seems to think this is going to be almost non-stop till tomorrow evening, at least on the last runs.

I think the low is still 7 or 8mb away from peak forecast intensity.

The worst of it should be from 7p.m. central to about 7a.m. central.


ok cool
Member Since: Posts: Comments:
Odd that the storm in Iowa is producing tornadoes... at least comparatively with the much better atmosphere to the west and southwest. It must be interacting with the warm front to help spin-up the surface-based vorticity. I can't imagine it staying around too long as it gets further east, away from the best CAPE.
Member Since: September 28, 2002 Posts: 5 Comments: 3193
Quoting Tazmanian:
when sould things get going in OK


I think 7p.m.

the GFS and Canadian seems to think this is going to be almost non-stop till tomorrow evening, at least on the last runs.

I think the low is still 7 or 8mb away from peak forecast intensity.

The worst of it should be from 7p.m. central to about 7a.m. central.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
I think we might have more storms develop later this evening/tonight along the convergent area when a bunch of the energy from out west ejects into the plains.



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Quoting 1900hurricane:
Every single cell along this line in this frame is tornado warned!




That line up almost looks military.
You people out there under these things sure need all the divine assistance and luck you can get.
Ive been around for a long time and Ive never seen anything this "awesome forming,"
Good luck everybody affected and stay safe, we need you alive and kicking for the future!
Member Since: Posts: Comments:
1200. KEEPEROFTHEGATE (Mod)
Quoting Tazmanian:
when sould things get going in OK
as the sun sets and turns to a nightime sky
Member Since: July 15, 2006 Posts: 171 Comments: 53839
Look at that storm in Iowa!
Member Since: February 11, 2012 Posts: 83 Comments: 7786
Quoting IceCoast:


Haha, well one can always learn. EHI is calculated from the equation EHI=(Cape x Helicity)/160,00. It's basically a composite number of instability and helicity that can be used to forecast supercells.


What's cape and helicity sorry:/
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1174 ChillinInTheKeys: When the threat for damage caused by severe convection is unusually high, the Storm Prediction Center (SPC) enhances the wording of its convective watch product with the following statement:
THIS IS A PARTICULARLY DANGEROUS SITUATION
.

Phrases like "THIS IS A PARTICULARLY DANGEROUS SITUATION" and "TORNADO ON THE GROUND" should be the only thing printed in All CAPITOL lettering.
As is, NWS bosses are going way out of their way to not-prevent harm by burying the important points in a blizzard of difficult-to-read lettering.
And WMO "rules" ain't a good reason, it's just a crummy excuse to continue with the same ol', same ol'.
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I'm back... Did I miss anything real big?
Member Since: February 11, 2012 Posts: 83 Comments: 7786
1194. ncstorm
2046 1 S RUSH CENTER RUSH KS 3845 9931 BRIEF TORNADO TOUCHDOWN JUST SOUTH OF THE TOWN OF RUSH CENTER. (DDC

From the SPC
Member Since: August 19, 2006 Posts: 13 Comments: 15299
when sould things get going in OK
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Quoting IceCoast:


Haha, well one can always learn. EHI is calculated from the equation EHI=(Cape x Helicity)/160,00. It's basically a composite number of instability and helicity that can be used to forecast supercells.

And here it is in real time:

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I don't think des Moines is gonna get the worst of this one, it's going to get some rain etc but not the worst part.
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Quoting Ameister12:
Uh-oh.


That might be debris.

Hail core out ahead, and very heavy return in the hook.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Tornado Reported by Law Enforcement on the IA storm, Take Cover!!!


SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
351 PM CDT SAT APR 14 2012

IAC001-003-121-175-142115-
/O.CON.KDMX.TO.W.0002.000000T0000Z-120414T2115Z/
UNION IA-MADISON IA-ADAIR IA-ADAMS IA-
351 PM CDT SAT APR 14 2012

...A TORNADO WARNING REMAINS IN EFFECT FOR NORTHEASTERN ADAMS...
SOUTHEASTERN ADAIR...SOUTHWESTERN MADISON AND NORTHWESTERN UNION
COUNTIES UNTIL 415 PM CDT...

AT 347 PM CDT...LOCAL LAW ENFORCEMENT REPORTED A TORNADO. THIS
TORNADO WAS LOCATED 9 MILES SOUTH OF GREENFIELD...OR 10 MILES
NORTHWEST OF CRESTON...MOVING EAST AT 45 MPH.

LOCATIONS IMPACTED INCLUDE...
MACKSBURG.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IMMEDIATELY SEEK SHELTER IN A BASEMENT...
OR IN AN INTERIOR ROOM OF A REINFORCED BUILDING. STAY AWAY FROM
WINDOWS.

IF YOU ARE OUTSIDE...IN A MOBILE HOME...OR IN A VEHICLE...SEEK
SHELTER IN A NEARBY REINFORCED BUILDING. AS A LAST RESORT...FIND THE
LOWEST SPOT AVAILABLE AND COVER YOUR HEAD.

HEAVY RAINFALL MAY HIDE THIS TORNADO. TAKE COVER NOW. IF YOU WAIT TO
SEE OR HEAR IT COMING...IT WILL BE TOO LATE TO GET TO A SAFE PLACE.

&&

LAT...LON 4135 9418 4118 9409 4110 9455 4121 9461
TIME...MOT...LOC 2051Z 253DEG 40KT 4119 9440

$$

SKOW
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Uh-oh.
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Quoting weatherh98:


It looks bad buti don't know what it's saying hahaha


The higher the number is the more likely tornadoes and severe hail storms will form, and the stronger they are likely to be.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Quoting weatherh98:


It looks bad buti don't know what it's saying hahaha


Haha, well one can always learn. EHI is calculated from the equation EHI=(Cape x Helicity)/160,00. It's basically a composite number of instability and helicity that can be used to forecast supercells.
Member Since: Posts: Comments:
Quoting 1900hurricane:
Iowa cell is back in commission!



That Iowa cell looks just as bad as all the storms in KS/OK.
Member Since: July 22, 2010 Posts: 1 Comments: 3842
I wonder how long the Iowa storm is going to romp around. It's pretty much the only storm in the area.

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that des moines cell looks very strong
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1180. Speeky
this could be a big one
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Iowa cell is back in commission!



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I do much better with hurricanes
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Quoting TropicalAnalystwx13:
Alrighty then. I don't think that's too good.



It looks bad buti don't know what it's saying hahaha
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Tornado Warning Adair, Iowa

here's the vortex signature.

0 D4 Adair IA 68 dBZ 34,000 ft. 59 kg/m² 100% Chance 100% Chance 2.50 in. 27 knots WSW (249)

Tornado with severe hail.



Headed directly for Des Moines, Iowa
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Tornado Warning now on the cell SW of Des Moines IA. Don't know why they cancelled the sever thunderstorm warning on it the last ~10 minutes, it was pretty obvious it was going to cycle.



TORNADO WARNING
IAC001-003-121-175-142115-
/O.NEW.KDMX.TO.W.0002.120414T2047Z-120414T2115Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
347 PM CDT SAT APR 14 2012

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* TORNADO WARNING FOR...
SOUTHEASTERN ADAIR COUNTY IN SOUTHWEST IOWA...
NORTHEASTERN ADAMS COUNTY IN SOUTHWEST IOWA...
SOUTHWESTERN MADISON COUNTY IN SOUTH CENTRAL IOWA...
NORTHWESTERN UNION COUNTY IN SOUTH CENTRAL IOWA...

* UNTIL 415 PM CDT

* AT 342 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS
STORM WAS LOCATED 10 MILES SOUTH OF GREENFIELD...OR 11 MILES
NORTHWEST OF CRESTON...AND MOVING EAST AT 45 MPH.

* LOCATIONS IMPACTED INCLUDE...
ORIENT AND MACKSBURG.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A DANGEROUS STORM. IMMEDIATELY SEEK SHELTER IN A BASEMENT...
OR IN AN INTERIOR ROOM OF A REINFORCED BUILDING. STAY AWAY FROM
WINDOWS.

IF YOU ARE OUTSIDE...IN A MOBILE HOME...OR IN A VEHICLE...SEEK
SHELTER IN A NEARBY REINFORCED BUILDING. AS A LAST RESORT...FIND THE
LOWEST SPOT AVAILABLE AND COVER YOUR HEAD.

&&

LAT...LON 4135 9418 4118 9409 4110 9455 4121 9461
TIME...MOT...LOC 2047Z 253DEG 40KT 4119 9446

$$

SKOW
Member Since: Posts: Comments:
A good read on PDS Watches...

"When the threat for damage caused by severe convection is unusually high, the Storm Prediction Center (SPC) enhances the wording of its convective watch product with the following statement:
THIS IS A PARTICULARLY DANGEROUS SITUATION".

Link
Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:
I'm already getting tired and the main event has not even started yet.

The main energy hasn't even reached the high risk area yet. Wait until 21Z-0Z.


It's times like these that you gotta wake up!
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Alrighty then. I don't think that's too good.

Member Since: July 6, 2010 Posts: 113 Comments: 32056
West of Woodward:



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Quoting Ameister12:
More supercells are forming further south. This outbreak is going to get worse.

They're even coming out of Texas now!



UGH, why did I have to work today??? I could be chasing right now!!!
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Cumulus still building to the south along the dry line. More storms to come.




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1168. wxmojo
The crazy talk weather modification is correlating with severe weather patterns amazingly well.

askwhy333.minus.com/muVSRK7DY
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1167. ncstorm
So far..

Member Since: August 19, 2006 Posts: 13 Comments: 15299
Well defined funnel cloud near Rush Center.
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http://content.wdtinc.com/popout/index.php?M=10164& C=20226&O=10090 MIDSCAR developoing tornado

http://content.wdtinc.com/popout/index.php?M=1016 4&C=20226&O=10317 same developing tornado different angle
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Best all day.
Member Since: July 22, 2010 Posts: 1 Comments: 3842
Member Since: June 1, 2010 Posts: 0 Comments: 159
The cell north of Greensburg has consistently has some really wicked rotation with it.





It also might be rain-wrapped with that second cell almost on top of it. That one could be a doozy!
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Wow. These storm are amazing.
Member Since: July 22, 2010 Posts: 1 Comments: 3842
FLOOD ADVISORY
NATIONAL WEATHER SERVICE SAN JUAN PR
436 PM AST SAT APR 14 2012

PRC025-031-063-127-139-142330-
/O.NEW.TJSJ.FA.Y.0128.120414T2036Z-120414T2330Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/
CAGUAS PR-GURABO PR-SAN JUAN PR-TRUJILLO ALTO PR-CAROLINA PR-
436 PM AST SAT APR 14 2012

THE NATIONAL WEATHER SERVICE IN SAN JUAN HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY
FOR THE FOLLOWING MUNICIPALITIES...

IN PUERTO RICO
CAGUAS...GURABO...SAN JUAN...TRUJILLO ALTO AND CAROLINA

* UNTIL 730 PM AST

* AT 431 PM AST...DOPPLER RADAR INDICATED HEAVY RAIN ACROSS THE
IN PARTS OF THE ADVISORY AREA. RAIN RATES OF 1 TO 1.5 INCH PER HOUR
IS BEING OBSERVED WITH THESE SHOWERS. THIS WILL RESULT IN URBAN
FLOODING AS WELL AS QUICK RIVER RISES IN AREAS OF THESE
MUNICIPALITIES.

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

&&

LAT...LON 1846 6608 1842 6595 1827 6594 1816 6605

$$

ER
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More supercells are forming further south. This outbreak is going to get worse.
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1158. Speeky
Quoting hurricanehunter27:
Wow the Storm west of Greensburg has a wallcloud that is almost on the ground. Skip Talbot has it.


Looks like a monster of a storm
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1139 ScottLincoln: I almost couldn't believe the statistic...50% of tornado emergencies dont even have an actual tornado hit the place mentioned in the wording, let alone a big, destructive tornado. I'm sure that suggests to some a credibility issue...

What I don't get is MidWest folks gettin' all panicky "Y'all better move outta there!" when they hear a report of a 50% probability of a strong earthquake hitting a California town sometime in the next 40years.
Yet if there's a 50% chance of a tornado hitting their own town in the next several hours, it's all "Yeh, yeh." and a trip to a coffee shop for some gossip.
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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.