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Multiple Tornadic Supercells on Wednesday

10:53 am in Extreme Weather, Storm Summaries by Ted Keller

Hail near Brighton

A pre-Thanksgiving outbreak of supercell thunderstorms occurred on Wednesday the 24th in the Ozarks.  Some produced tornadoes.

It would be a challenge for me to count them from memory!  I know that several passed over the same corridor affecting portions of Vernon, Cedar, St Clair, Hickory, Polk, Dallas and Camden counties.  This was the earlier portion of the outbreak from mid afternoon through early evening. 

Damage was reported near Wheatland and Cross Timbers in Hickory County from this early round.  This was confirmed as two tornadoes today by the National Weather Service. 

Later in the evening, the supercells started shifting more to the south.  One cell starting ramping up significantly as it crossed into northwestern Greene county.  This storm continued east-northeast into southern and southeastern Polk.  This storm was responsible for multiple reports of damage near Brighton on the Greene/Polk county line. This too was confirmed as an EF1 tornado by the National Weather Service today.

Looking North from Hermitage. Photo by Ron Gamble.

A supercell started showing signs of rotation in Jasper and Newton county shortly before 8 pm.  This storm remained tornado-warned as it traveled into Lawrence county.  This was of course a concern for Greene county as it approached.  As it crossed the county and city of Springfield, multiple reports of hail from quarter to as high as ping-pong ball sized were reported.  There was also some minor wind damage.  The tornado warning picked up again as it was just leaving Greene and continued through Webster and Wright counties!

Dent county went tornado-warned for a time late in the evening followed by the final warning in Barry county just before 11 pm and into the 11 o’clock hour.

The National Weather Service has a full report on this storm.

Tornadic Supercell Near Richmond, VA!

3:42 pm in Extreme Weather, Severe Storms by Ted Keller

Tornadic supercell with a hook echo passes over the northern Richmond, VA area. Tornado report at Mechanicsville, VA.

Record Low Pressure!

4:00 pm in Did You Know?, Extreme Weather, In the News by Ted Keller

Very Deep Low 10/26/10 18z

Not since the Superstorm of 1993 has a low pressure system over the United States achieved such a low central barometric pressure!

From the National Weather Service:

“New record set today for the lowest pressure in a non-tropical storm in the mainland U.S. The massive storm system barreling across the central U.S. had a minimum central pressure of 28.24″ or 956 mb (equivalent to the minimum pressure of a Category 3 hurricane). This breaks the old record of 28.28″ (958 mb), set on …Jan. 26, 1978, during the Blizzard of 1978 (aka the Cleveland Superbomb). This is also lower than the March 1993 Superstorm (aka “The Storm of the Century”), or the “Witch of November” storm that sank the Edmund Fitzgerald in 1975, or even the Columbus Day Storm of Oct. 1962.”

Editors note: it looks like 28.21″ is the official lowest pressure of this storm.

Development of "bomb" low! Thanks NSSL!

Such intense lows at the surface of the earth are brought about in this case by a powerful jet stream wind pattern.  For lows at the surface of the earth to deepen, air must be evacuated out of the top of the low faster than it can be replaced from below.  When this is true, air molecules are removed from the column of air leading to less air pressure as measured by a barometer.  This is called hydrostatic pressure or the total weight of the air on the barometer.

Strong jet stream winds high in the atmosphere can set up a path for air to take away from the deepening low leading to a drop in pressure.

Wind at the Jet Stream Level (300mb) 12z 10/26/10

Wind and pressure are intimately related.  The deeper the low, the larger the difference in pressure or pressure gradient observed.  The stronger the pressure gradient, the faster the wind will blow.

This storm had widespread 40-50 mph wind gusts connected to it over areas of Iowa, Illinois, Minnesota and Wisconsin eariler today.  Some of the gusts near shower and thunderstorm bands reached 60-70+ mph.

Also, the storm system has spawed many tornadoes in parts of Illinois (EF2 near Peotone), Indiana and Kentucky.  At  this writing, many tornado warnings were in effect for counties in Tennesee, Kentucky and Alabama.

Link to a great write-up by the Duluth National Weather Service.

Tornadic Week

6:13 pm in Extreme Weather, Storm Summaries by Ted Keller

We’ve had a lot of noteworthy tornadoes last week in the U.S.

On Wednesday, September 15th, severe storms sprang up violently over portions of southcentral and southeastern Kansas.  Discrete supercell storms produced both tornadoes and extremely large hail. In fact, a new state record for large hail may be threatened in Kanasa as a result of these storms.  The Wichita NWS has an excellent summary of the severe weather outbreak.

Later that same evening, the individual cells merged into a severe squall line with bowing line segments as it finished moving through eastern Kansas and then headed into the Ozarks.  Shortlly before 11 pm, a weak EF0 tornado was on the ground for only one half mile about 4-5 southwest of Nixa.  The Springfield NWS has a review of the tornado as well as downbursts and heavy rain in southwest Missouri on this day.

On Thursday, September 16th, a cool front was responsible for two additional tornadic areas.  In New York City, the National Weather Service confrms two tornadoes within the city limits.  An EF0 tornado touched down in Brooklyn while an EF1 rating was attatched to a Flushing/Bayside twister in Queens.  The storm killed one person.  A link to the news story and to the NWS report.

Also on Thursday, severe thunderstorms formed in southeastern Ohio and traveled southeast into West Virginia, producing tornadoes including two EF3’s and several EF2’s.

EF0 Tornado/Wind Damage Wednesday Evening

8:24 pm in Extreme Weather, Storm Summaries by Ted Keller

The Springfield National Weather Service performed damage surveys today and determined an EF0 tornado touched down southwest of Nixa Wednesday evening.  Here is the storm report.

Additionally, a mircroburst produced wind damage west of Turners.  Several other microbursts were reported in Rogersville and near Fordland.

I have radar data processing and will update this story tomorrow.

Event summary page from the Springfield National Weather Service.

EF Rating 3 Second Gust (mph)
0 65-85
1 86-110
2 111-135
3 136-165
4 166-200
5 Over 200

Rain, Rain, Rain

9:58 am in Extreme Weather, The Ozarks by Ted Keller

With yesterday’s rain total of 1.58″, our September total jumped to 10.69″. So in one day, we moved from 7th to 4th on the all-time wettest September list for Springfield!

The years ahead of 2010 are 1975, 1986 and 1993 in 3rd, 2nd and 1st.  It would be hard to push into all-time wettest because the 1993 total is 17.46″!  That was the year of the south Ferguson flooding with massive amounts of rain falling in that section of southwest Springfield.

Springfield Wettest Septembers
17.46 1993
11.65 1986
11.36 1975
9.87 1970
9.46 1945
9.15 1962
9.03 1977
8.52 1894
8.40 1958
8.33 1926
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