Severe Weather Update for Kansas/Oklahoma/Texas for Today...

Above is the latest analysis of CAPE (Convective Available Potential Energy) across the primary severe weather threat area for today.  CAPE is a measure of how unstable the atmosphere is, and the values in excess of 5,000 across Oklahoma and southwest Kansas are extreme by any measure.

A surface low pressure area is strengthening over the central Oklahoma panhandle area, with a dryling trailing off to the South and a warm front arching to the East then Southeast across central Oklahoma.

The winds are out of the East to Southeast along and immediately to either side of the warm front, which will provide favorable turning in the atmosphere to cause storms to rotate later this afternoon and evening.

Storms will likely initially form along and ahead of the dryline by late afternoon, and also along and North of the warm frontal boundary.

The latest run of the high resolution NAM model generally agrees with that scenario, as shown on the simulated radar forecast images valid at 4pm, 5pm, 6pm and 7pm today, respectively:

Tornadoes, very large hail and damaging winds will be possible with severe storms in this region today, with the highest risk located within the red and orangish-red shaded areas on the image below (which is unchanged from my earlier outlook):

Please stay weather aware in these areas - and be prepared to move to shelter quickly if threatening conditions are observed or a warning is issued.

As I mentioned in my post earlier today, graduation ceremonies and other events are abundant across the region this afternoon and evening.  If you are heading out to a public place, be sure to note your best sheltering option while entering the venue, just in case.  Many public places have signs like these to help direct you to a safe place, but be sure to identify them ahead of time, not in the heat of the moment when you're likely to be distracted:

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Significant Severe Weather, Including Tornadoes, Likely Today thru Monday...

As feared for much of the past week, a string of significant severe weather days will get underway starting today in the Plains...

The latest severe weather outlook for today is shown below:

The highest risk of significant severe weather will take place where the green (scattered severe storms) and red (significant severe storms) merge from southwestern Nebraska into much of the Western one-half of Kansas into northwestern Oklahoma.

Within this region, one or more strong and/or long track tornadoes are possible, along with very large hail in excess of 2 inches in diameter.  The significant hail threat will extend Southward into the red shaded region across northwest Texas and southwest Oklahoma as well.

The most significant severe risk for today includes the cities of North Platte, Goodland, Hays, Russell, Dodge City, Pratt, Great Bend and Woodward.

Thunderstorms are forecast to develop along and ahead of the dryline by late afternoon from western Kansas into northwestern Oklahoma.  Activity should be well underway by 7pm CDT, as depicted by this simulated radar image valid at that time via the high-resolution NAM computer model:

By that time, you can see that isolated development is also indicated over northwest Texas as well.  While one should not take the forecast radar positions as literal, it does give you a good idea as to the general areas where development is likely at a particular time.

The highest tornado potential will take place in association with any storm that is able to remain isolated and become well organized, mainly during the late afternoon through mid-evening hours.  Once the activity congeals into one or more larger clusters of storms by late evening, the tornado threat will decrease - but a pronounced large hail and damaging wind threat will continue.

Tomorrow, Sunday, continues to look particularly ominous.  This is mainly for two reasons:  (1).  the coverage and magnitude of potentially significant severe weather will increase and (2). the threat will shift Eastward into a more heavily populated region (as compared to today).

The outlook for tomorrow is shown below:

Once again, the highest risk of significant severe weather will exist within the red shaded area, including the cities of Oklahoma City, Tulsa, Wichita, Kansas City, Joplin, Omaha and Des Moines.

Strong to violent and/or long track tornadoes, very large hail and damaging winds will be a distinct possibility within this region on Sunday afternoon and evening.  This is a potentially dangerous and life threatening situation for the indicated areas, and folks living in the region or that have travel plans into the region should be on a high state of alert on Sunday afternoon and evening.

For Monday, a threat of significant severe weather will continue over the Sooner State, including the OKC and Tulsa areas once again:

If you live across the severe weather outlook areas for the next few days, please remain on a high state of alert and readiness.  Review your severe weather safety and preparedness tips ahead of time, and make sure that you've identified the best sheltering option at home, work, school, church or any other location that you may be.

I am particularly concerned with the high number of graduation ceremonies that are scheduled across the region both today and Sunday.  If you are in a large public arena or other venue, look for "Storm Shelter" or "Tornado Shelter" signs, like the ones shown below, as you enter the facility, that way you can move to a safe place quickly if severe weather threatens.  Additional sheltering tips are offered in my free Severe Weather Safety:  Seeking Shelter guide that you can download today.

Also make sure that you have a way to receive severe weather warnings no matter where you are.  There are numerous options out there today, including apps or other links that you can load directly on your smartphone.  

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The Tornado Chronicles: Granbury and Cleburne TX Tornadoes of 5-15-13...

Thus far, 16 tornadoes have been confirmed across North Texas during the late afternoon and evening hours of May 15, 2013 as several supercell storms produced multiple tornadoes and/or tornado families.  

The two strongest tornadoes took place just to the East of Granbury (in Hood County - as shown in the photo above) and in the Cleburne area (in Johnson County).

A preliminary track map for the Granbury area tornado is shown below.  the first map is a wide view, and the second is a tighter zoom on the track itself:

The tornado to the East of Granbury had a track length of 2.75 miles and the damage is preliminarily rated at EF-4 intensity, with maximum winds of 166-200 mph.  

The video below, posted to YouTube by "tsubasachan777" shows the tornado at about the time that the EF-3 to EF-4 intensity damage was being done.  WARNING: turn the volume way down - the wind is very loud as it blows across the open body of water in the foreground:

The damage from this tornado is extensive and very impressive.  Several frame built homes (not mobile or pre-manufactured homes) were wiped completely off of their foundations, which signifies high end EF-4 or low end EF-5 intensity damage (depending on how the home was originally secured to the foundation):

Numerous other homes were heavily damaged and/or completely destroyed in widespread EF-3 or EF-4 intensity damage:

A mapping of the Cleburne area tornado is not yet available (please check back to this post for updates).  The Cleburne area tornado track was 8.5 miles in length and the damage is preliminarily rated EF-3 intensity, with maximum winds of 140 mph.

At one point it is estimated that the tornado was as much as 1 mile wide, as suggested by this frightening video (as the huge tornado is illuminated by nearly continuous lightning) posted to YouTube by storm chasers Bill Ford and Mike Casey:

This is the same supercell storm that made a near "U-turn", first travelling to the South/Southeast and then turning back Northward toward the Cleburne area, producing one or more tornadoes all the while.

While it is not unsual for a severe thunderstorm to make a right or left turn over time, it is relatively rare for such a dramatic shift in direction to take place in such a short period of time as we saw near Cleburne on Wednesday evening.

Numerous homes were also heavily damaged or completely destroyed in the Cleburne area as well:

The aerial footage shot by KXAS TV is even more telling of the damage that took place in this region:

There has been some discussion since the event that it was "not forecast" or "under forecast."  While its true that the National Weather Service initially issued a Severe Thunderstorm Watch for the region on Wednesday afternoon, the watch was upgraded/converted to a Tornado Watch shortly before 6pm, roughly 60-90 minutes before the first of the stronger tornadoes started to develop.

The overall meteorological situation on Wednesday very much reminds me of the situation that we saw two years ago in the Joplin area.  The situation rapidly evolved during a relatively short period of time and became very favorable for intense tornado development over a relatively concentrated geographic area.  Unlike the situation shaping up for this weekend in the Plains, where tornadic development appears likely several days in advance, it is the type of events that took place on Wednesday night that we seek to learn more about in order to increase their longer range predictability in the future.

If you have an interest in the tornadoes that took place in the Granbury, Cleburne and North Texas areas on Wednesday, please bookmark this post and check back for updates that will be forthcoming over the next few days...as additional information is received.

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First Significant/Widespread Tornado Threat of Season This Weekend and Monday...

The 2013 severe weather season has been "slow" to evolve with regard to significant and/or widespread tornado activity, but I am afraid that's about to change this weekend, perhaps in a major way...

Below are the latest severe weather outlooks for today through Sunday, respectively:

As you can see, the threat of severe weather, with respect to both coverage and intensity, becomes stronger each day as the weekend progresses.  A similar threat will exist into Monday over much of the same area indicated in red on the Sunday outlook, while extending a bit Eastward in Missouri as well.

Today's activity will be limited to the high plains, mainly in the form of large, damaging hail and wind gusts.  An isolated tornado or two cannot be ruled out.  Most of this activity will be limited to the late afternoon and evening hours.

On Saturday, the threat will expand Eastward, particularly across the Dakotas, Nebraska and Kansas.  As the wind field increases throughout the atmosphere, the tornado risk will increase on Saturday afternoon and evening, particularly within the area shaded in green and red.  Very large hail can also be expected in these areas.

So far, the "worst" of the 3 days appears to be taking shape for Sunday.  Sunday is starting to take on characteristics of a "classic" severe weather outbreak day, with strong tornado potential across a large area, as indicated in red on the outlook map:

I am becoming increasingly concerned that one or more strong to violent and/or long track tornadoes are likely on Sunday, especially within the red shaded area.  This enhanced threat of tornadoes includes the cities of Tulsa, Joplin, Kansas City, Omaha and Des Moines.

If you live anywhere within the severe weather outlook areas for this weekend, and especially within the red shaded areas for Saturday and Sunday, please keep a very close eye on the weather.  Take a few moments ahead of time to ensure that your severe weather safety kit is stocked, and identify your best sheltering option in case threatening weather is observed or a warning is issued for your area.

"Stay tuned" for more information over the next few days...

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Severe Weather Back on the Table for This Weekend...

After a quiet few days, the threat of severe weather is expected to ramp up for this coming weekend...

Below are the severe weather outlooks for Saturday and Sunday, respectively:

All modes of severe weather will be possible in the indicated areas, from large hail and damaging winds to a few tornadoes.

The primary threat will take place from mid to late afternoon into the early nighttime hours each day.

It's been a relatively quiet spring so far in most of these areas, so please take a few moments this week to review your severe weather safety procedures, restock your emergency supplies and plan out your best sheltering options for the weekend.  That way you'll be all ready to go if severe weather impacts your area.

Stay tuned for more information over the coming days...

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Large Hail, Some Significant, Likely Today thru Friday...

After a severe weather "drought" (relatively speaking) over the last several days, the southern and central Plains are about to become active again today through Friday, with some risk of severe weather also extending East into the Ohio Valley Region as well.

The latest severe weather outlook for today is shown below, which includes a threat primarily to the West of the Oklahoma City and Wichita areas:

A cluster of thunderstorms moved East/Southeast along the Oklahoma/Kansas border area overnight and early this morning.  The decaying thunderstorm activity has laid down several outflow boundaries across southern Kansas as well as western and central Oklahoma.  One or more of these boundaries may serve to focus thunderstorm development late this afternoon and evening, in addition to development that is expected to take place further West along a surface dryline.

Large hail is likely with the activity today and early tonight, some of which may exceed 2 inches in diameter, especially within the green shaded area on the above image.  Damaging winds and a few isolated tornadoes are also possible.

A pronounced threat of large to very large hail appears to be taking shape for tomorrow afternoon and evening.  At this time the threat is expected to include the OKC Metro area, the DFW Metroplex and the Hill Country to the West of the Austin / San Antonio corridor along I-35:

Scattered strong to severe storms are also forecast to move East/Northeast into the Midwest and Ohio Valley Region Thursday afternoon and evening, with large hail the primary threat once again.

By Friday afternoon and evening, a threat of severe storms will settle Southeastward into the Austin/San Antonio area in Texas, on Northeastward into portions of the Ohio Valley and Northeast:

At this time there not any signals that "scream" tornado potential in association with activity in a particular area nor on a particular day.  The thing to watch (as is often the case) will be for any storms that are able to remain isolated and become well organized before being taken over by larger lines or clusters.

If you live across the indicated areas, please remain alert and make sure to have a way to receive severe weather warnings and updates.  Be sure to identify your best sheltering option, that way you can move there quickly if threatening weather is observed or a warning is issued for your area.

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Large Tornado in Emilia Romagna Italy Today...

A large tornado struck the Emilia Romagna region of Italy earlier today (local time).  The above video was recently posted on YouTube and the still photo below was posted on twitter:

One of the same supercell thunderstorms also produced very large hail across the area (which is not typical of this region):

The radar snapshot below shows the same types of supercell thunderstorm signatures across northern Italy today that we'd typically see here in the central U.S.!

...and a related visible satellite picture shows "overshooting tops" on at least 3 storms, which signifies very large hail (as confirmed by the picture above):

You can read more about the event here.

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