Tag: tornadoes

Tornado Chasing: Our Elevation Of Insanity

seymour tornadoI am upset by the deaths of three tornado chasers Friday in Oklahoma. These were people who knew how to find tornadoes. They also knew how to avoid them. Their deaths are a tragedy, but I’m not sure the word accident applies. They were where they shouldn’t have been and they knew it.

The same applies to The Weather Channel’s Mike Bettes and crew who survived after their SUV was tossed a few hundred yards and destroyed.

Here’s the problem. Tornado chasing has become an extreme sport!

In the past I’ve written about weather live shots from hurricanes. Dangerous. Foolhardy. It sends the absolute worst message to the public we try and protect.

Until now I drew an exception for tornadoes. I’d never heard of a death or accident involving a tornado chaser. Knowing where not to be is fairly easy.

Chasing was something I wanted to do. That no longer holds.

More and more, TV glorifies people doing stupid things. This goes well beyond MTV’s groundbreaking “Jackass.” I’ve seen divers in the Bering Sea getting oxygen from garden hoses while wearing wet suits held together with duct tape! Now this.

Is this behavior 100% TV driven? Probably not, but TV is certainly part of the equation.

I mourn this loss of life. I mourn our elevation of insanity as entertainment.

Weatherwise Tuesday Looks Bad Too

Storm Prediction Center May 20 2013 1730 UTC Day 2 Convective Outlook

This information is current as of Tuesday morning at midnight. When you look for a forecast, look for current information.

todayTerrible day today in the Southern Plains. 18 reported tornadoes. Around 100 reports of large hail. Nearly two dozen children killed at school. Thirty others dead as well.

The storms were well forecast. The area was warned. Some storms are beyond simple defenses.

Folks who live in Oklahoma hear warnings all the time. I suppose it’s easy to dismiss them and think, as has always been the case for most people, the storm will hit someone else. That was especially true because Monday’s severe weather set up in about the same place as Sunday–unusual.

mcd0741Tonight concern is centered from the Missouri bootheel through Eastern Illinois and Western Indiana plus a little corner of Kentucky and Tennessee. Tuesday it will be Northeast Texas (maybe the Dallas metroplex) into Northern Louisiana and Southern Arkansas under-the-gun.

Here’s the lead from the Storm Prediction Center’s tech discussion. Read what you can. I’ll follow with a translation to English.

CURRENT INDICATIONS ARE THAT PRE-FRONTAL CONVECTION DURING THE DAY 1 OVERNIGHT HOURS WILL RESULT IN OUTFLOW BOUNDARIES LOCATED WITHIN THE WARM SECTOR AT THE START OF THE PERIOD…AND THESE ARE EXPECTED TO PROVIDE AN ADDITIONAL FOCUS FOR SUBSEQUENT THUNDERSTORM REDEVELOPMENT DURING THE DIURNAL HEATING CYCLE ON TUESDAY.

A front is moving in from the west tonight. Thunderstorms will fire up ahead of it. Cold air, outflow from the storm, will pour down from the cloudtops.

The cold air will dislodge warm parcels near the ground which will keep the thunderstorm cycle alive.

Here in Connecticut we sometimes see storms refire from outflow, but there’s little skill in predicting which exact one. That’s why most watches and warnings you get from real people (like on TV) will talk more about general conditions than saying, “If you live on Flugle Street hit the basement now.”

We can nowcast these cells, not forecast them.

Tuesday in the Lower Midwest will be muggy. Overhead the jet stream will run a moderate speed, helping to draw parcels of humid air skyward from the surface.

ALTHOUGH LOW-LEVEL WINDS WILL GENERALLY BE AOB 20-25 KT…FORECAST SOUNDINGS INDICATE WINDS WILL INCREASE AND VEER WITH HEIGHT IN RESPONSE TO THE PROGRESSIVE SHORT WAVE TROUGH…PROVIDING SUFFICIENT VERTICAL SHEAR FOR ORGANIZED CONVECTIVE STRUCTURES INCLUDING A FEW SUPERCELLS TO DEVELOP. VERY LARGE HAIL…DAMAGING WIND GUSTS…AND POSSIBLY A FEW TORNADOES WILL BE POSSIBLE…ESPECIALLY WHERE BOUNDARY INTERACTIONS MAY ENHANCE LOW LEVEL SHEAR/SRH. ACTIVITY IS EXPECTED TO GROW UPSCALE BY EVENING WITH SEVERAL QLCS/S FORMING WHICH MAY RESULT IN AN INCREASE IN WIND DAMAGE POTENTIAL. ACTIVITY IS THEN EXPECTED TO WEAKEN GRADUALLY BY 03-6Z AS THE SHORT WAVE TROUGH LIFTS NEWD AWAY FROM THE REGION AND DIURNAL COOLING BEGINS TO STABILIZE THE BOUNDARY LAYER.

There won’t be much wind on the ground, but it will increase and change direction as it climbs. Wind shear is part of the formula for supercells.

The discussion mentions QLCSs, Quasi-Linear Convective Systems. These are storms which pack a line of damaging winds on the leading edge. Maybe you heard me mention “bow echoes” on TV? That’s part of the QLCS life cycle.

The worst times for storms will be Tuesday afternoon and evening with things finally simmering down before midnight.

Tornadoes are nasty. They often pack stronger winds than the strongest hurricanes. The whole concept of safety in a tornado is more relative than absolute. Tornadoes can grow stronger than any of our prep, as happened today.

I watched a man interviewed on CNN tonight. He carried all his worldly possesions in a laundry basket. He felt terrible for those who suffered more. He considered himself lucky tonight in Oklahoma.

I just can’t imagine.

Where To Find Tornado Info

SPC’s site is a nerd’s delight! It is loaded with maps, charts and numbers. All the secrets are hidden in plain sight if you know where to look.

From the Ohio Valley south this is an explosive night! Over 50 tornado touchdowns have been reported so far and the day is far from over. There is a continuous line of Tornado Watches from Central Ohio to the Florida Panhandle!

I sent texts to two friends in the Nashville area. I told them the storms near them deserve respect. They get it.

If you’re interested in severe weather the best place to go is the Storm Prediction Center‘s own site. Severe weather forecasting has benefited from digital technology and instant communications more than any other forecast discipline.

SPC’s site is a nerd’s delight! It is loaded with maps, charts and numbers. All the secrets are hidden in plain sight if you know where to look.

The SPC homepage is built around a map with rollover menu. No clicking necessary. Just mosue from menu item to menu item to see the map instantly populated with data.

Clicking the mesoanalysis tab opens another map with the country divided into zones. Some zones are fixed by geography. Others float in response to current or soon-to-be-current conditions. Each can be filled with the parameters most useful in predicting severe storms.

As the weather progresses and new storms look likely SPC issues Mesoscale Discussions. In these discussions forecasters lay out their thinking behind the watches to come. These are often very technical and cloaked in arcane terminology and even more obscure abbreviations.

I’ve been doing this nearly 30 years and I still scratch my head from time-to-time!

SUPERCELLS MOVING THROUGH ERN KY WILL CONTINUE THROUGH AN ENVIRONMENT VERY FAVORABLE FOR STRONG TO VIOLENT TORNADOES AS THE LLJ STRENGTHENS TO IN EXCESS OF 60 KT. LAST VWP DATA FROM JACKSON KY INDICATE VERY LARGE 0-1 KM HODOGRAPHS WITH STORM RELATIVE HELICITY ON THE ORDER OF 800 M2/S2 AND 500 J/KG MLCAPE. THESE PARAMETERS ALONG WITH THE DISCRETE NATURE OF THE CONVECTION WILL CONTINUE TO PROMOTE A THREAT OF TORNADOES…VERY LARGE HAIL AND DAMAGING WIND NEXT FEW HOURS.

That one I understood entirely.

SPC is also the keeper of the storm reports. What’s listed is often unverified and subject to revision, but still a good indicator of what’s going on. There are over 300 reports today including tornadoes!

When tornadoes are on the ground or severe storms are spotted the responsibility gets moved to local Weather Service offices. Following details becomes more random and difficult since offices cover oddly shaped areas. The Storm Prediction Center still watches, but with more of a hands off attitude.

If this site would have existed when I was growing up I might have never left the house!

I Keep Track Of The Weather

“Southeastward moving.” That’s the scare line for me. Our strongest storms move northwest to southeast.

I don’t know how other people do their jobs, but I keep track of the weather while I’m off-the-clock. The atmosphere has a rhythm. You want to stay in the rhythm. I look at maps, usually briefly, all the time.

The Storm Prediction Center just issued Moday’s national outlook. We’re squarely inside the “slight risk” area for severe storms.

Slight doesn’t sound bad, but it’s better than 50/50 if you’re in the slight risk area you will get a severe weather box later in the day! I’ve been doing this a long time. There is a rhythm.

I’m going to post SPC’s technical discussion, but feel free to skip this section. It’s full of jargon and technical terms plus nearly all the Weather Service bulletins are all caps. Sorry.

…NORTHEAST STATES/NEW ENGLAND…
EASTERN CANADIAN UPPER TROUGH WILL DIG SOUTHEASTWARD OVER QUEBEC/EASTERN ONTARIO TOWARD NEW ENGLAND/NORTHEAST STATES THROUGH TONIGHT…WITH ASSOCIATED COOLING/STRENGTHENING CYCLONIC FLOW ALOFT AS FAR SOUTH AS THE MID-ATLANTIC STATES. WITH RELATIVELY STEEP LAPSE RATES/SUFFICIENT CAPE BY AFTERNOON…MULTIPLE SOUTHEASTWARD-MOVING BANDS OF STRONG/SEVERE TSTMS SHOULD DEVELOP/INCREASE THIS AFTERNOON…WITH SUCH DEVELOPMENT FOCUSED IN VICINITY OF A SURFACE TROUGH ACROSS NEW ENGLAND/NEAR THE EASTERN SEABOARD AND/OR ALONG ONE OR MORE SOUTHEASTWARD MOVING WEAK COLD FRONTS ACROSS THE NORTHEAST/NEW ENGLAND. SUSTAINED MULTICELLS ALONG WITH A FEW SUPERCELLS CAN BE EXPECTED…WITH DAMAGING WINDS/SEVERE HAIL AS THE PRIMARY HAZARDS.

“Southeastward moving.” That’s the scare line for me. Our strongest storms move northwest to southeast. In the Plains the strongest storms head to the northeast.

SPC also says the biggest risks are strong winds and large hail. Tornadoes seem unlikely, though you can have comparable damage from microbursts.

The Rapid Refresh model which did well on timing this past Friday shows the system entering Connecticut early afternoon. It will build as it heads in our direction. The computer readout resembles a snowball which grows as it rolls downhill.

This isn’t the last time I’ll look at maps before going to work today.

Another Tornado Outbreak

I am as perplexed by this vicious season as much as anyone. I understand the atmospheric set-up. That part’s no surprise.

You will be excused if you don’t hit the Storm Prediction Center website especially on this idyllic day in Connecticut. They are expecting more doom and destruction in the Midwest. It’s scary. It’s sad.

Here’s how they set the plate. The following outlook was issued long before any watches or warnings. Consider it a general heads up!

PUBLIC SEVERE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1226 PM CDT WED MAY 25 2011

…MAJOR TORNADO AND SEVERE WEATHER OUTBREAK EXPECTED OVER PARTS OF
THE LOWER MISSISSIPPI…MID MISSISSIPPI…AND LOWER OHIO VALLEYS
THIS AFTERNOON AND TONIGHT…

THE NWS STORM PREDICTION CENTER IN NORMAN OK IS FORECASTING THE
DEVELOPMENT OF NUMEROUS TORNADOES…WIDESPREAD DAMAGING WINDS…AND
LARGE HAIL OVER PARTS OF THE LOWER MISSISSIPPI…MID
MISSISSIPPI…AND LOWER OHIO VALLEYS THIS AFTERNOON AND TONIGHT.

THE AREAS MOST LIKELY TO EXPERIENCE THIS ACTIVITY INCLUDE

CENTRAL AND EASTERN ARKANSAS
CENTRAL AND SOUTHERN ILLINOIS
CENTRAL AND SOUTHERN INDIANA
WESTERN KENTUCKY
CENTRAL AND EASTERN MISSOURI
NORTHERN MISSISSIPPI
WESTERN TENNESSEE

The map I’ve attached show how tornado watches stand as I type this. Obviously those will pop on-and-off through the night.

I am as perplexed by this vicious season as much as anyone. I understand the atmospheric set-up. That part’s no surprise.

The question is why are all the factors gelling so often this year?

Bad luck? Probably.

At this point I’m dismissing any tie-in between this severe weather and global warming. You can’t easily connect anecdotal events with climate.

I am closely watching our chances for severe weather Friday and Monday.

Something I Didn’t Know About The Tornado Numbers

A change of methodology means tornado reports are inflated when compared to prior years.

I was reading Reddit when I came upon this. A change in methodology means tornado reports are inflated when compared to prior years.

[T]he NWS changed its policy regarding duplicate severe weather reports this year.

It should be noted that duplicate preliminary reports are NO LONGER purged from the data set. As a consequence, it is not possible to compare this preliminary data to previous years’ data. In the past, possible duplicate reports were culled based on time and proximity. This is not the case anymore.

The old rule of thumb was ~15% of preliminary reports were duplicates. Based on the preliminary v. final numbers so far this season it is possible that up to 65% of these preliminary reports are duplicates.

On March 8, 2011, the SPC removed space/time filtering on incoming National Weather Service (NWS) Local Storm Reports (LSRs). This filtering had been used by SPC in an attempt to reduce duplicate reports and limit artificially inflated initial estimates of severe weather events when many reports arrived for the same event. Space/time filtering is no longer being applied to decoded NWS LSRs and this approach is consistent with NWS storm-based verification methods.

You probably already know the number of weak tornadoes reported has gone up over time as ‘chasing’ has made fewer of them unobserved.

Tornado Prediction From The Experts

Like a hot air balloon as long as the parcels remain warmer than their surroundings they’ll continue to rise. As described by SPC the Midwest has an added feature this weekend–the jet!

There’s a big severe weather outbreak still underway this weekend. At least one Iowa town was flattened yesterday with 31 tornadoes reported overall. Today it’s ‘only’ six. The evening is young. Three Four tornado watches and one severe thunderstorm watch are up as I type.

The prevailing wisdom is tornadoes form during a clash between warm moist and cool dry air. That’s a situation likely to exist in the Midwest every spring.

However, if you listen to the experts from the Storm Prediction Center you’ll see there’s more. Tech stuff first. I’ll translate after you read it.

SCATTERED VIGOROUS STORMS ARE ONGOING…FROM NEAR THE DEEP SURFACE CYCLONE CENTER MIGRATING ACROSS NORTHWEST WISCONSIN…SOUTHWARD TO THE VICINITY OF A 90 KT SOUTHWESTERLY 500 MB JET AXIS ACROSS SOUTHWEST WISCONSIN. AN EMBEDDED SPEED MAXIMUM IS IN THE PROCESS OF NOSING ACROSS THE UPPER MISSISSIPPI VALLEY TOWARD THE UPPER GREAT LAKES REGION…WITH A REGION OF ENHANCED UPPER DIVERGENCE CONTRIBUTING TO CONVECTIVE DEVELOPMENT.

  • Deep surface cyclone is a low pressure system at ground level.
  • 90 kt southwesterly 500mb jet axis means there’s a wind blowing between 110-115 mph at approximately 18,000 feet. The exact height isn’t important.
  • Enhanced upper divergence means as the wind is moving by it’s spreading out.
  • Convective development means thunderstorms born of air moving upward in the atmosphere

These conditions paint a serious situation because of how thunderstorms form and what make them strong (sometimes strong enough to spawn tornadoes).

In a thunderstorm parcels of relatively warm air rise into a colder atmosphere. Like a hot air balloon as long as the parcels remain warmer than their surroundings they’ll continue to rise. As described by SPC the Midwest has an added feature this weekend–the jet!

A strong jet streak will help rising air ascend even faster and make the situation much more volatile. Divergence means additional air will need to be sucked up from below to fill an increasingly large atmospheric void. It’s a scary and vicious cycle.

The good news is this severe weather is exceptionally well forecast. It’s tough to believe anyone in the bullseye doesn’t know what’s going on.

The bad news is sometimes there’s just nowhere to hide.