Yesterday’s wind damage up in Walker County at Sumiton was very significant, and caused by a “wet microburst”, a short lived wind event that is most often found in summer storms. Wet microbursts are narrow regions of very strong, straight-line winds descending from mid levels of the thunderstorm accompanied by brief intense rain. By definition, the damage is in an area 2.5 miles in diameter or less, and the high winds last five minutes or less. Needless to say, with something that small scale that doesn’t last more than a minute or two, a good warning is almost impossible. There was no severe thunderstorm warning in effect for Walker County when the damage happened, but I sure can’t blame the National Weather Service. There were probably two dozen storms on radar yesterday that looked just like that one, and all of the other ones did not produce that kind of damage.

Many people in Sumiton told us it was a tornado, but the atmospheric conditions yesterday were not adequate for a tornado to form; if you were to go up 15,000 feet, the winds were less than 10 knots. And, even at jet stream level, around 25,000 feet, winds were under 20 knots. Jet stream altitude winds during tornado outbreaks are usually over 100 knots. Those strong upper winds are usually up around the Canadian border this time of the year.

Good ingredients for wet microbursts include very high surface-based instability values and a nice layer of dry air in the mid levels of the atmosphere. As a parcel descends through the dry layer, evaporative cooling makes the air sink faster. Winds at the surface can exceed 75 mph briefly.

We will go back and look at the radar images during the microburst at Sumiton yesterday, we might be able to identify one velocity signature that would have given us a clue, but in real time it is almost impossible to identify a microburst event that lasts for only a few minutes. Just another reminder we all need to keep an eye on the sky when thunderstorms are prowling around the Alabama countryside. Even on a hot, summer afternoon....

Looks like Sumiton on US 78 just inside Walker County got hit pretty hard with strong wind from a microburst this afternoon. Mary Howell, one of our Skywatchers, took the pictures while she was out this evening. The police were trying to keep onlookers away, so she was not able to get very close. The cafe picture is on State Street just up the road from Bevil College. The flooring store is on Main Street at the intersection of State Street and Main.

A house about a block up from the flooring store had a foot or so of the edge of their roof blown up. It was just sticking up in the air. There are some apartments on State Street that are across from Bevil College that had some siding blown off. One set of bleachers at Sumiton Christian football field were blown over. Across 78 HWY from Sumiton Christian is a road that had trees down across it.

Mary also reported that there isn't a single pine tree left in the area that has any brown pine needles left on them. The needles are on the roads.

Thanks, Mary. We all appreciate the views of the damage suffered in your area.

-Brian-

A huge percentage of Alabama is without showers and thunderstorms tonight. At 9:30, there was nothing going on over the North and East part of the state. Only the SW part and a small part of West Central Alabama still has action.

The northernmost shower or storm was a small one over Pickens County. All of the main stuff is from near Livingston down into the SW part of the state.

Last night, showers and thunderstorms developed, redeveloped and redeveloped until long past midnight over the north and west part of the state. Some of them became severe and it was almost 3 am before we could settle in for a fast 4 hours of sleep.

We somewhat semi-hope that does not occur again tonight even though we realize a lot of people still need rain.

INTERESTING FEATURE FROM THE SOUTHWEST
This time of year the monsoon season gradually sets in over the Desert Southwest. They even call it that in Arizona. Moisture in the warm season gradually makes a long trek from the Caribbean and South Gulf of Mexico and some from the East pacific, northward through Mexico and finally into Arizona. During the monsoon season, thunderstorms become more frequent in places like Arizona and those storms can also kick up big dust storms.

It is interesting to look at the North American lightning detection map tonight and see a long string of thunderstorms all the way up the southern and western part of Mexico NW znd northward into Arizona.

Much of North Alabama free of thunderstorms early this evening. However, strong thunderstorms continue over parts of South Central and SW Alabama. Some of the strongest storms at 6:40 pm extended from west of Montgomery into Dallas and South Marengo County. Moving SW and producing much dangerous lightning and downpours of rain and probably some strong gusty winds.

Parts of Alabama had 100-degree heat again today. It was 101 in Demopolis before a late afternoon thunderstorm cooled the city to 79.

A ROUNDUP OF REPORTS

+ Downbursts caused damage on the southside of Birmingham and at Sumiton near the Walker-Jefferson County line. Scroll down to an earlier report for details on this.

+ Hail 3/4 to one inch in diameter at Rosalie in Jackson County this afternoon.

+ At 2:10 pm, a roof was blown off a building in Albertville damaging cars in a parking lot.

+ At Good Hope, Cullman County, trees and power lines were down. A building under construction was destroyed.

OCEAN SPRINGS
Scott McClellan, one of our regular blog readers, reported intense lightning just north of the Mississippi coastal town late today and said today was the 3rd day in a row that it caused the street lights to come on before 6 pm.

THE BIG HEAT BUBBLE
Alabama has been under the edge of it lately but the worst heat is to our west and up through the Great Plains. Here are some temperatures observed at 6 o'clock this evening, CST, so todays highs were probably higher:
107 in Wichita
107 in Lincoln, Neb.
101 in Kansas City
103 in Omaha
106 in Lawton and Altus, Okla.
105 in Oklahoma City and Stillwater
108 in Norman and Ardmore, Okla.
101 in Dallas-Fort Worth
107 in Wichita, Falls, Tex.

Overall, thunderstorms across North and central Alabama have decreased in number and intensity. However, there are exceptions.

Clusters of strong thunderstorms producing very heavy rain and dangerous lightning continued over West central Alabama mainly in Pickens and Marengo County.

Moving SW.

We will try to post a complete list of rainfall amounts from today's storms lter this evening.

* High of 101 in Demopolis today at the 3340 Skycam site. However, heavy rain late this afternoon lowered the temperature to 79.

* At 1:40 this afternoon, a downburst along 4th Avenue South in Birmingham unroofed some buildings and tore down powerlines.

* At 150 pm, another downburst caused damage at Sumiton in the east edge of Walker County, The roof and side of a building (Smiley Cafe) was torn off. Power lines were down on US 78 in front of Walmart. The roof was torn off a trailer on 5th Avenue. This report from the Walker County EMA Office.

* Possible house fire from lightning in Hoover this afternoon.

At 5 pm, most of the Greater Birmingham area was still getting a break from the storms.

Some of Central Alabama now getting a break from thunderboomers. At 4:20 most of these areas did not have any:

Jefferson County, including all of Metro Birmingham
Shelby County
Blount County
St Clair County
Walker County

Some of the main thunderstorms were:

+ Over North Tuscaloosa County
+ Northwest corner of Alabama some 20 miles west of Florence
+ West of Anniston near I-20
+ Near Talladega
+ NW Fayette County just south of Winfield (3340 Winfield Skywatcher reported some strong winds with this storm but not much rain.
+ Sumter County (strongest of all)

Everything moving SW

REPORTS
0.20 rainfall Rex Lane in Leeds area (we incorrectly said 2.00 inches earlier)
0.43 in Talladega (from 33/40 Skywatcher)
0.90 downtown Birmingham at 3340 Skycam site

The list of thunderstorms above not all-inclusive. There are a number of smaller showers and storms including some stronger ones over far South Alabama.

There are two counties in Alabama under a Severe Thunderstorm Warning:

+ Sumter County in West Alabama until 4 pm
+ Barber County, SE Alabama until 4:15

All thunderstorms moving slowly SW

RAINFALL REPORT
2.00 inches this afternoon on Rex Lane in the Leeds area
0.90 at the 3340 Skycam site, downtown Birmingham
0.53 in NE Trussville

Big slow moving thunderstorms continue across Alabama this afternoon.

They are not numerous but some are dumpring very heavy rain and producing strong winds. Earlier, there was some street flooding in parts of metro Birmingham.

At 3:25 pm, some of the strongest storms over the north half of the state were:

+ North Cullman County

+ Along Jefferson-Walker County line NW of Birmingham. Most of that storm was over in the east edge of Walker County.

+ Along the Shelby-Chilton County line along I-65.

+ Greene and Sumter County in West Alabama

+ Near Childersburg in East Central Alabama

All of the storms were moving slowly toward the SW,

Earlier, 0.90 of an inch of rain fell at the 3340 Skycam in downtown Birmingham with gusts to 44 mph. NWS estimates as much as 1 to 2 inches fell in parts of the Birmingham area.

MISSISSIPPI
Severe Thunderstorm Warnings for several South Mississippi counties. Also a Severe Thunderstorm Watc.

**No afternoon map discussion today due to active storms across Alabama**

The morning map discussion video pretty much has the situation well in hand, that is still available on iTunes and on the web:

http://www.jamesspann.com/

SHORT TERM: Summer storms on a hot afternoon in Alabama can pack quite a punch, and as Jason has mentioned here in his posts, there is potential for strong winds today, or "wet microbursts" in the most intense storms. Driving from Trinity Medical Center to our studio in Riverchase around 1:30 to 1:45, I figured winds were around 45 mph in Mountain Brook, and the power was out. And, the lightning as usual was pretty wicked.

Our SKYCAM site in downtown Birmingham atop the Daniel Building has recorded a wind gust of 44 mph.

The weather won't change much tomorrow; highs in the mid to upper 90s and widely scattered afternoon storms.

A VERY WELCOMED CHANGE: As we have mentioned here for several days, the weekend should feature a better coverage of showers and storms as an upper trough begins to form over the eastern part of the nation, and a surface front approaches Alabama from the north. And, because of the clouds and showers, the heat backs off considerably. Many spots will not reach 90 over the weekend.

And, scattered to numerous showers and storms will continue well into next week as the front slowly dissipates over North Alabana.

Going to have to keep this one short today due to active weather... I will have a long post and a fresh map discussion video posted by 7:00 a.m. tomorrow. J.B. and Jason will have short term weather updates for the rest of the evening here on the blog!