Rare “High Risk” Day

This is a big deal. “High risks” are rare, usually only a day or two each calendar year. I want to break the components for you.

Tornado

A one in three chance of a tornado occurring within 25 miles of any given point within the high risk area with potential for tornadoes of F2 or greater intensity.

Damaging Thunderstorm Winds

Very high numbers here. The hatched area is where gusts of 75 mph or more are forecast. Suffice to say it is a huge area of damaging thunderstorm winds. 

Large Hail

Hatched area is a forecast of 2″ diameter hair or bigger.

 No tornado watches are in effect at present. However, thunderstorms are developing in many areas and they will become stronger, especially this afternoon.

6am Update: Storms Evolving As Predicted

Here is the AccuWeather regional radar for Friday morning at 5:44am and, unfortunately, the storms are evolving just about as forecast. The large supercell near St. Louis has produced large hail across its entire journey across Missouri.

This is exactly as forecast three hours ago:

In fact, compare the actual regional radar (above) to the forecast regional radar (for 8am this morning, the timing is a bit off) pattern. 

In both, you have the large supercell near St. Louis, the training thunderstorms into the Ozarks and the mix of rain and snow back into Kansas. 

I expect the supercell(s) will continue to move east across Illinois within about 70 miles either side of Interstate 70 this morning and continue to produce large hail.  

At 3pm CST, there will be numerous thunderstorms throughout the Midwest and South, some of which will be producing large hail, damaging thunderstorm winds, and tornadoes.

And, as I was finishing up this posting, the NWS extended the severe thunderstorm watch across Illinois until 11am (below):

Better Ways of Finding Extreme Weather

So large, in fact, that a record for the largest hailstone in state history was set: a stone that fell in southwest Wichita had a diameter of 7.75 inches, shattering the existing record by more than 2 inches.

But Scott Blair, a meteorologist with the Topeka branch of the National Weather Service, came across something startling as he researched the Sept. 15, 2010, storm. Checking local media websites, he found photos of one massive hailstone after another.

By the time he was done, he had found eight hailstones that were larger than the previous state record hailstone, which fell in Coffeyville in 1970.

“I’m sure there was a lot more that didn’t get documented,” Blair said. “That alone shows the impressive nature of the storm.”
Thanks to social media, the storm could become a turning point in how data on severe storms is collected and in researchers’ grasp of what hailstorms can do, Blair and other experts say.


The Coffeyville stone’s record lasted more than three decades. Social media is playing a bigger and bigger role in documenting extreme weather. Details from The Wichita Eagle. 

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Huge Hail in Carolinas

From CharlotteObserver.com

It wasn’t just the Plains with severe weather Saturday. There were at least 41 areas of South Carolina and western North Carolina that received hail at least two inches in diameter. A map (blue = 1″ or larger; black diameter = hail 2″ or larger in diameter). Green is winds of 58 mph or more.

National Weather Service
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Violent Weather Possible Late Today into Monday

There is going to be a great deal of severe weather starting later today and lasting into Monday. Here is a breakdown.

3pm Saturday through 7am Sunday

Thunderstorms with large hail are possible from the Southeast (including Augusta, GA where the Master’s golf tournament is being played) into the Midwest and down into the Plains.
NWS large (≥1″) hail probabilities, hatched area ≥ 2″
College of DuPage graphic

Tornadoes are also possible in the areas indicated in red with a lesser chance in the areas in yellow. And, while not shown on this graphic, I would include northern Iowa to the Minnesota border.
Noon Sunday through 9pm Monday

Tomorrow looks like a tornado “outbreak” (defined by meteorologists as an unusually large number of tornadoes in a large geographic area) day. Here is the overall outlook for Sunday and Monday’s severe weather from my colleagues at AccuWeather:
The highest probabilities of major tornadoes Sunday are in the hatched area below:
What makes this especially hazardous is that the tornadoes will be fast-moving meaning there could be less than usual amounts of “lead time” (i.e., warning time before the tornado arrives).
So, if you live in any of the areas (including the East Monday, see the AccuWeather graphic) outlined, please pay attention to the weather. 

11:30pm Update

Tornado warning on the storm near Tonkawa, OK (arrow).

Here is the radar at 11:27pm. Storms with large hail are in southern Greenwood Co., KS and near and east of St. Joseph, MO.

Two Views of Hail at the Smith House

A flash shot:

A time lapse of the hail streaks.

I could hear the sound of the hail approaching. 4,800 without power in the Wichita area with wind gusts to 55 mph (the burnt orange color in this Doppler wind display):

Also: Tornado warning for northern Chase and Morris Co. in Kansas. The rotation seen on radar is moving toward Council Grove.

Tornado warning CANCELLED. Severe thunderstorm warning for Morris Co. (only) until 10:35pm. 

Large Hail This Evening

On a regional basis, here is a hail size map through 8:45pm CDT:

While not listed, large hail (≥1.5″) fell along the
path of the arrow

There was also large hail in the southeast part of the Wichita Metro Area:

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Hail Spike in Oklahoma

Earlier, I have explained that “hail spikes” are identify large hail nearly 100% of the time. We now have one in Oklahoma and 1.75″ in hail has been confirmed just southeast of Enid, OK. You can use this knowledge to tell whether hail is moving into your area.

UPDATE: 6:15pm. Tennis ball-sized hail associated with the
hail spike!
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The Rapid Progress in Severe Storm Forecasting

One of the topics of Warnings is the rapid progress that has been made in severe storm forecasting the last ten years. Yesterday’s hailstorms are an excellent example.

At 8:58am CDT yesterday, I posted:

The hatched area on the graphic shows the potential for hailstones 2 inches in diameter or more. The yellow line is a 30% probability and the blue line is a 45% probability of hail at least 1″ in diameter.

At 6:28pm, I posted:

Vicious hail storms swept across the region where the hail was forecast during the following four hours. Here is a map of hail reports with the sizes indicated:

Click to enlarge. Wichita is in the far lower left corner.
Downtown Kansas City toward upper right.

And, here is a closeup of the hail tracks north and south of downtown Kansas City:

With more than twelve hours of advance notice, it should have been possible to put cars in garages, bring outdoor furniture indoors, round up pets, etc. The forecast of the potential for very large hail and its location was excellent.

Weather science is making amazing strides that make our lives safer and can help prevent property losses. That is the story I tell in Warnings

Severe Storm Update, 8:45pm

Here is a look at the storms overall…

The northern end of the line of storms has weakened a little the last 30 minutes.  Very strong storms continue farther south.

The strong storm northeast of KC in Ray Co. produced large hail in the northern parts of the KC metro area. The storm now near Lawrence will affect most of the the KC area that didn’t experience the first storm. Update: 9:08pm. Golfball size hail in Stanley, Kansas, moving into south KC Metro.

Farther south, a line of strong storms extends from near Wichita into the Flint Hills.

As expected, the biggest problem has been large hail.

Green = large hail. Blue = strong winds (50 mph or higher). Black diamond = hail ≥2″ and black = winds 75 mph or more.  So far, no tornadoes reported. Tornadoes are still possible in the tornado watch area (see below) until midnight. Red is the tornado watch, blue are severe thunderstorm watches.

To give you an idea of how widespread the large hail has been, here is a plot of hail reports this evening. The “three ball” symbol = large hail. To help orient you, I have placed an arrow pointing to downtown KC.

This is my last posting on these storms.  More severe weather likely tomorrow and I’ll update everyone in the morning.

Welcome Kansas City Star readers. We welcome you to take a look around the blog. 

Tornado and Hail Spike on Radar in Pennsylvania

UPDATE: 6:39pm. Here is video of the tornado in Greensburg (Hempfield), PA (noted by the tornado symbol at left center of the radar image below). This tornado damaged a number of homes.
Associated Press reports: A possible tornado caused severe damage to about 30 western Pennsylvania homes, two schools and some businesses, but only a few minor injuries were reported, authorities said.
ORIGINAL POSTING:

Very strong thunderstorm in southwest Pennsylvania likely producing giant hail (defined by meteorologists to be 2″ in diameter or larger). Not only is the storm very reflective (whitish pink area in core of storm), it has a “hail spike.” The storm and spike (the narrowing blue-green area) are circled. When you see a spike on the side of the storm away from the radar, large hail is likely in progress.

This storm produced a damaging tornado west of Latrobe, PA. A tornado warning continues in effect.

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Hail Spike on Radar

The purple-pink echoes (circled) indicate large hail and, there is a “hail spike” southeast of the hail-bearing storm (indicated by arrows). Any time you see one of these spikes there is a very high probability of large (2″ or larger) hail.

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The Two Most Interesting Storms of the Week…

…Were the storms in New York City yesterday and in Wichita Wednesday.

With regard to the former, the question has been, “Was New York hit by a tornado?” The question will be definitely answered by the NWS today, but I believe the answer is yes. From a quick look at the radar data, there was a small but strong low pressure system embedded in a line of thunderstorms. These sometimes produce tornadoes. Assuming the NWS confirms this, I’ll have more later today.

With regard to the Wichita storm, it was unique in the way it transitioned from one producing near-record giant-sized hail to one producing small tornadoes and straight winds with gusts up to 90 mph.  I’ll be writing more about that one today, as well. Still waiting for some data and images to come in.

So, stay tuned!

Unique Way of Displaying Huge Hail

Via Facebook, 5 1/2″ hail stones displayed next to young Carson Bieberle.  Posted by Justin and Crystal Bieberle.  Much of the southwest half of the city of Wichita experienced large hail.

UPDATE 2PM Thursday:  As if these hail stones were not big enough, we had a 7.5″ stone in southwest Wichita.  Here is more from a Stormtrack posting by Mike Guekes:
The hail stone below that is pictured at 7.5 inches may have broken a new record for Kansas hailstones. The hail stone may have broken the record Diameter of any hailstone at 7.5 Inches, other stats include 15.5 Inches in circumference and 1.1 lbs. This hailstone fell near Pawnee and 119th Street in West Wichita around 6pm on September 15th, 2010. The measured circumference and weight were measured 15 hours after the event. The previous record was 5.7 Inches in Diameter, 17.6 Inches in circumference, and 1.65 lbs and fell in Coffeyville, Kansas on September 3rd, 1970.
UPDATE: 5PM Thursday. KAKE TV reports Wichita’s Auburn Hills golf course was closed today due to thousands of holes pitting the course. They expect a week for things to get back to normal.  
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