Storm Summaries | Ceaseless Wind

A Mini Bowing Thunderstorm Line

Meteorologist Ted Keller posted this in Extreme Weather, Storm Summaries, The Ozarks on August 15th, 2010

Storm Reports as of 10:35 Sunday

A cluster of thunderstorms which started in Kansas Saturday evening, crossed into Missouri and left a swath of wind damage!

The bowing refers to the shape of the mini line of storms as it advances. This is shown clearly in the embedded loop of radar from early Sunday morning (below).

This line produced scattered wind damage reports from southern Crawford County in Kansas into Dade and eventually Greene County. There were lots of reports of small limbs down and outdoor objects such as potted plants “displaced”. The Springfield National Weather Service reported a wind gust to 51 ph at 2:10 am. There were likely some severe wind gusts (59 mph or higher ) with this storm line. Several minor power outages were reported with this storm line as well.

Storm Reports Collected by the National Weather Service

PRELIMINARY LOCAL STORM REPORT…SUMMARY
NATIONAL WEATHER SERVICE SPRINGFIELD MO
633 AM CDT SUN AUG 15 2010..TIME…   …EVENT…      …CITY LOCATION…     …LAT.LON…
.DATE…   ….MAG….      ..COUNTY LOCATION..ST.. …SOURCE….
            ..REMARKS..1224 AM     TSTM WND DMG     4 SW FRONTENAC          37.41N 94.73W
08/15/2010                   CRAWFORD           KS   LAW ENFORCEMENT            FRONT PORCH PULLED FROM HOUSE. TIME ESTIMATED.1224 AM     TSTM WND DMG     2 S PITTSBURG           37.38N 94.70W
08/15/2010                   CRAWFORD           KS   LAW ENFORCEMENT            FOUR TREES REPORTED DOWN ON THE SOUTH SIDE OF PITTSBURG.
            TIME ESTIMATED.0140 AM     TSTM WND GST     LOCKWOOD                37.39N 93.95W
08/15/2010 E60.00 MPH       DADE               MO   LAW ENFORCEMENT            50 TO 60 MPH WIND GUST ESTIMATED BY DEPUTY IN THE CITY OF
            LOCKWOOD.0140 AM     TSTM WND GST     GREENFIELD              37.42N 93.84W
08/15/2010 E60.00 MPH       DADE               MO   LAW ENFORCEMENT

            50 TO 60 MPH WIND GUST ESTIMATED AT THE DADE EOC.0145 AM     TSTM WND DMG     GREENFIELD              37.42N 93.84W
08/15/2010                   DADE               MO   LAW ENFORCEMENT            SEVERAL TREES DOWN IN GREENFIELD…A FEW WITH A DIAMETER
            UP TO 18 INCHES.

0145 AM TSTM WND DMG LOCKWOOD 37.39N 93.85W
08/15/2010 DADE MO LAW ENFORCEMENT

TWO TREES DOWN ACROSS THE ROAD NEAR THE INTERSECTION OF
HIGHWAYS 160 AND 39.

0200 AM     TSTM WND GST     EVERTON                 37.34N 93.70W
08/15/2010 E60.00 MPH       DADE               MO   LAW ENFORCEMENT

            50 TO 60 MPH WIND GUSTS ESTIMATED BY SPOTTER IN EVERTON.

0210 AM     NON-TSTM WND GST 5 SSE WILLARD           37.23N 93.40W
08/15/2010 M51.00 MPH       GREENE             MO   OFFICIAL NWS OBS

            51 MPH WIND GUST WITH THE OUTFLOW BOUNDARY AHEAD OF MAIN
            COMPLEX OF THUNDERSTORMS.

0217 AM     NON-TSTM WND GST NIXA                    37.04N 93.29W
08/15/2010 E50.00 MPH       CHRISTIAN          MO   AMATEUR RADIO

            50 MPH WIND GUST WITH THE PASSAGE OF THE OUTFLOW
            BOUNDARY.

0255 AM TSTM WND DMG SSE STRAFFORD 37.27N 93.12W
08/15/2010 GREENE MO AMATEUR RADIO

            10 FOOT SECTION OF WOOD FENCING BLOWN DOWN…A FEW TREE
            LIMBS UP TO THREE INCHES IN DIAMETER BLOWN DOWN. TIME
            ESTIMATED.

0258 AM TSTM WND DMG 2 WNW FAIR GROVE 37.39N 93.19W
08/15/2010 GREENE MO AMATEUR RADIO

FOUR INCH DIAMETER DOGWOOD TREE BLOWN DOWN.

0300 AM TSTM WND DMG 1 N STRAFFORD 37.29N 93.12W
08/15/2010 GREENE MO AMATEUR RADIO

14 INCH DIAMETER TREE DOWN ON POWER LINE. PART OF FARM
ROAD 84 BLOCKED IN THIS AREA.

0318 AM NON-TSTM WND GST AVA 36.95N 92.66W
08/15/2010 M38.00 MPH DOUGLAS MO AMATEUR RADIO

38 MPH WIND GUST MEASURED WITH OUTFLOW BOUNDARY PASSAGE.
FLAG POLE AT AVA POLICE DEPARTMENT BLOWN DOWN.

Severe Storms

Yazoo City, MS Tornado/Outbreak April 24, 2010

Meteorologist Ted Keller posted this in Severe Storms, Storm Summaries on July 29th, 2010

3D rotation at 12:14

: SPC Storm Reports

This was outbreak of tornadoes with one predominate storm, the long-tracked supercell which struck Yazoo City, MS.

The track of the main tornado with this cell has been measured atjust over 149 miles in Mississippi. This storm did produce additional tornadoes in Mississippi and after it tracked into Alabama. The surveys are still preliminary from all of the affected National Weather Service offcies. The official report on the first tornado out of the Jackson, MS National Weather Service office can be found here.

Portions of the Ozarks were affected back on February 5th, 2008 by the end of a very long-track tornado, the longest in recent history.

Outbreaks like this and long-track tornadoes are fairly rare. It takes a list of parameters to line up in space and time just right to produce this type of weather. One little thing, such as another thunderstorm forming or slight differences in the the wind or instability along the path of the storm can break the situation down and cause tornadoes to break up.

Forecast Discussion

Waterlogged!

Meteorologist Ted Keller posted this in Forecast Discussion, Storm Summaries on May 16th, 2010

: Rainfall May 9-16th

We have seen a great deal of rain over the last few days! Areas to the north of Springfield have witnessed over 5″ of rain over the last seven days!

Springfield went to 5.40″ for May as of last night surpassing our normal value of rainfall for May which is 4.57″

The forecast calls for more storms mid-week. An areal flood warning remains in effect for much of the area.

Storm Summaries

Early Morning Twisters

Meteorologist Ted Keller posted this in Storm Summaries on May 13th, 2010

Thursday morning produced a tornado-baring thunderstorm which traveled from Newton to Wright Counties which the National Weather Service confirms producing three tornadoes including an EF1 in Monett.

At about 7 am, a tornado moved across the southern portion of Monett, MO where it did EF0 damage until it crossed highway 60 where EF1 damage was surveyed. A Pizza Hut sustained heavy damage. A weak second tornado briefly downed down near Hurley in Stone country. The thunderstorm produced a third tornado about an hour later rated EF0 which traveled between Sparta and Bruner in northeastern Christian County.

Pizza Hut in Monett. Photo by Megan Korpella.

The thunderstorm line began showing signs of turning on a scale much larger than a tornado. The twist can be seen in the radar image just over Monett at around 7:01 am. The tighter circulation that a doppler radar could have detected was not present at this same time. There was some bad data in the doppler output which could have masked the spin. Reports of damage started to be received from Monett and as the rotation move ENE, it was tornado-warned for Christian and Greene County at around 7:30 am.

The same rotational area produced a second tornado in Christian county around 8 am. This tornado was a bit weaker rated at EF0.

Here are the images (Thanks Jim Sellars and Storm Lab):

Radar echoes for Monett at 7:01 am and Sparta at 8:04 am.

SRV echoes for Monett at 7:01 am and Sparta at 8:04 am

The storm may have been helped into producing a tornado because it followed a boundary of cooler air sent southward from heavy rain and storms last night to the north and northwest of Springfield. Such boundaries can often locally enhance the “spin” that a thunderstorm updraft ingests, making it more likely to spin up a tornado.

A complete report and some detailed tornado track maps can be found at the Springfield National Weather Service Office web page.

Severe Storms

A Wild Outbreak of Tornadoes

Meteorologist Ted Keller posted this in Severe Storms, Storm Summaries on May 11th, 2010

No Place on Earth

can put the ingredients together for an outbreak of tornadoes quite like the central U.S. and the outbreak of May 10th, 2010 certainly reminds us of this fact.

Rope Tornado Near Yukon, OK. Photo by Chris Novy.

The outbreak came together as extremely unstable air was pulled northward ahead of a dry line. At the same time, a very strong but compact area of intense air level winds (shortwave/jet max) moved over the area.

The alignment of the upper level winds and unstable air was going to last for only about six hours and in a relatively small area. But in that time and space frame, numerous supercell thunderstorms quickly evolved, most into tornado-barring cells.

At this writing, the National Weather Service in Norman, Oklahoma has indentified ten areas where tornadoes likely tracked on this day. More tornadoes occurred in Kansas and northeastern Oklahoma. This will be refined more as survey crews finish their painstaking task. The death toll stands at five.

NWS Reviews:

The Set Up

Low Wall Cloud, Multiple Vorticies. Photo by Allan Detrich.

It was a situation typical to the Great Plains but with the volume cranked way up. It starts when a “trough” of low pressure develops over the western U.S. This encourages steady southerly winds to blow over the central U.S. drawing humid air from the Gulf of Mexico northward. On this day the dew points, a measure of moisture in the atmosphere, were quite high and this humidity helps to make the air unstable. In fact, all else being equal, higher dew points will generally lead to more violent storms.

Unstable air is produced whenever you can warm the air at or near the surface of the earth while keeping things relatively cool aloft. Moisture adds to the instability because when water vapor condenses back into visible cloud droplets, the energy in took to evaporate this water is released into the atmosphere.

Now on top of all of this, the jet stream winds, fueled mostly by differences in temperature from south to north, were howling! These winds do several things. The overall increase in wind speed with increasing height provides structure for developing thunderstorms and allows them to become “supercells”. Also, the speed and directional changes in the wind close to the earth’s surface provide a spinning which the updrafts of a thunderstorm inherit.

Sometimes, the “wind shear” can be too strong and developing storms will get “sheared” off. The winds on the outbreak day were strong enough to be a concern for this happening BUT the instability was so strong that the updrafts which make up a thunderstorm rose violently and were able to survive, even flourish, in this environment!

Chasing These Storms

The wind speeds were very high in the atmosphere leading to storms traveling over 60 mph! This “storm motion” made these storms difficult to chase. Still, there were some shots. The multiple-vortex tornado shot by Andy Gabrielson is stunning!

Some local chaser friends of mine Jason Blum, Dave Toner and Cody Hudson got themselves into a dangerous situation near Arkansas City, KS. Their vehicle goes down a steep embankment. Then the tornado passes nearly on top of them!

The Ozarks Missed This

Some may wonder since weather moves from west to east why the Ozarks didn’t see at least a weaker version of what happened out west, especially considering how fast the jet stream was. The answer is that we were in much more stable air. I watched as these storms literally fell apart while racing eastward. The fast jet stream winds actually outpaced the ability to draw unstable air out ahead of the system. Later on, we actually did have a tornado warning or two west and northwest of Springfield but this was mostly due to the incredible wind shear working on even the weakest updraft to see if can be coaxed into rotating.

Storm Chasing

Storm Chase Results from May 1st

Meteorologist Ted Keller posted this in Storm Chasing, Storm Summaries on May 4th, 2010

A high risk for severe thunderstorms and long-tracked tornadoes existed for much of central and eastern Arkansas the afternoon of May 1st, 2010. I went down there to chase this event. When storms started firing, there were lots of them, most ended up tornado-warned. Folks were anticipating the worst. But in the end, very few tornadoes were produced.

Here’s my account of the chase and a bit about why so few tornadoes occurred on this day despite much anticipation.

We drove down via Willow Springs, MO to see the damage caused by an EF1 tornado Friday evening. The Hillbilly Junction sustained roof damage as did an antique store just up a hill and to the east. This was the last of five tornadoes produced by a supercell which started in Boone County, Arkansas.

We were a caravan of three with Dustin Elkins and Bo Hessee also driving. We eventually wove our way down to White Hall which is just north of Pine Bluff. Here, other chaser friends of ours had gathered including Dena Sanders and Brian DePriest. The Tornado Intercept Vehicle (TIV) was there as were other chasers.

Boundary Moving Slowing North This Day

Of much interest early on was the very obvious boundary visible on radar stretching WSW/ENE south of Little Rock. It was thought that this boundary would be able to supply more focused and localized storm relative helicity to storms forming along it. Indeed several storms west of Little Rock did appear to have an increase in rotation while crossing this boundary. But the storm motion was taking them across and not along this feature. If a storm could have traveled along it, it might have produced the longer-track type of tornado which was feared on this day.

Storms became very numerous in southern Arkansas by the 6 o’clock hour. In fact, too numerous really. It became difficult to know which storm to chase! We initially decided to get northeast of the Arkansas River toward the flat rice lands in and around Stutgartt. But as supercells became tornado-warned in southern Arkansas, we decided to change the plan, back track a bit and try to get one of the southern storms. While on the way, storms started firing north and south of Pine Bluff which eventually became tornado-warned. The decision of the day was to not chase these storms and instead press on to the most southeast of all of the supercells which was going to cross highway 65 near Gould, AR. The reasons we didn’t pursue the Pine Bluff storms were 1) we would have to travel back through the city of Pine Bluff, 2) the river crossing were limited and 3) there was too much rain, drizzle and just plain bad visibility east of these storms.

Radar Image w/Mesocyclone Indicator at 7:46 pm

So, on down highway 65 we traveled. We were racing against dark really. We got into position ahead of the well defined cell which had a great hook echo. One more adjustment southeast to Gould was required due to the slight right turn the storm (and many supercells) started to take.

We saw some great formations and a likely wall cloud but as the storm passed just to our west, no tornado ever formed. Reed Timmer and the Dominator crew was coming though Gould and we followed them briefly north chasing the same storm but eventually the chase was abandoned.

I’m waiting on the archived SPC data for this day to appear but I suspect that the reason more tornadoes were not generated on this day were due to low values of low level rotation and generally weaker than needed low level winds.

I am compiled a video log of the chase which should be finished by Thursday.