May 3rd - 4th 1999 Tornado Outbreak

From the evening of Monday, May the 3rd, to the afternoon of May the 4th, a tornado outbreak occurred in the County Warning Areas (CWA) of the Tulsa National Weather Service Office.

The map below diagrams preliminary tornado track information from this event, based on NWS areal surveys, NWS ground surveys, assesments by emergency officials and media accounts. These data remain preliminary and are still being correlated with each other and radar archives. Times noted below represent the touchdown time. Location specifics are still being worked out in some cases. Special thanks goes to the Washington County Arkansas Judges Office and the Oklahoma Civil Air Patrol for their assistance with the areal surveys.

 tornado tracks map

A total of 16 tornadoes occurred in the Tulsa CWA, with an additional 29 tornadoes reported in the Norman CWA, bringing the Oklahoma total to 45. See the NWS Norman webpage for details concerning tornadoes in their area.

Overpasses are NOT protection! - Click here to read first hand accounts of the terror beneath a Moore, OK overpass. After video from Kansas in 1991, many people beleive that overpasses over great protection. Remember that each situation is different and all overpasses are not the same. It is best to move away from the tornado or run quickly to a nearby building. One of the greatests hazards in recent years is people stopping at overpasses and not clearing the traffic lane, stopping others from escaping and hindering emergency vehicles. When you make a decision to seek shelter in an overpass, you are climbing into the stronger winds. If you can not tuck yourself back into the concrete and steel structure of the overpass, your NOT protected.

Mobile Doppler Radar Data - Strongest tornado in the outbreak was rated F5 in the Oklahoma City Metro Area. Mobile Doppler radar from the National Severe Storms Labratory (NSSL), called Doppler on Wheels (DOW), measured near ground winds of 318 mph. Continued evaluation of the data is occurring. If the reading passes scientific evaluation, it will be the fastest wind speed ever recorded.

F-Scale Questions - The NSSL DOW measurement of 318 mph is the top end of the F5 scale. The F-Scale is a rating given to tornadoes based on the damage they do, and provides a crude estimate of the wind speeds in a tornado. The scale was developed by the late Ted Fujita and runs from 0 to 12, zero being the weakest. Little has been said about F6 and above, becasue it was thought that tornado wind speeds at the surface would not exceed 318 mph. A major question concerning the DOW measurement is whether or not its considered a surface wind speed. How high can a wind be measured before its considered above ground? A first guess would be 10 meters or about 30 feet. This is a standard height for NWS wind measuring equipment and would be about the depth that two story homes would experience.

The F-Scale rating is typically a highly subjective estimate and is complicated by differences in structure design and quality.

 

The Fujita Scale (note that in Feb. 2007, the Enhanced Fujita Scale was implemented)

F0 less than 73 mph Minor Damage
F1 73 to 112 mph Moderate Damage - Peels surface off roofs; windows broken; trailor houses pushed or overturned; trees on soft ground uprooted; some trees snapped; moving autos pushed off the road.
F2 113 to 157 mph Considerable Damage - Roof torn off frame houses leaving strong upright walls standing; weak structures or outbuildings demolished; trailor houses demolished; railroad boxcars pushed over; large trees snapped or uprooted; light-object missiles generated; cars blown off highway; block structures and walls badly damaged.
F3 158 to 206 mph Severe Damage - Roofs and some walls torn off well-constructed frame houses; some rural buildings completely demolished or flattened; trains overturned; steel framed hanger-warehouse type structures torn; cars lifted off the ground and may roll some distance; most trees in forest uprooted, snapped or leveled; block structure often leveled.
F4 207 to 260 mph Devastating Damage - Well-constructed frame house leveled, leaving piles of debris; structure with weak foundation lifted, torn, and blown some distance; trees debarked by small flying debris; sandy soil eroded and gravels fly high in the wind; cars thrown some distance or rolled considerable distance finally to disintegrate; large missiles generated.
F5 261 to 318 mph Incredible Damage - Strong fram houses lifted clear off foundation and carried considerable distance to disintegrate; steel-reinforced concrete structures badly damaged; automobiles-sized missiles fly through the distance of 100 yards or more; trees debarked completely; incredible phenomena can occur.
F6 319 to 379 mph Inconceivable Damage - Large objects such as storage tanks and automobiles will fly through a long distnace; home foundations ripped from ground. Assessment of tornadoes in these categories is feasible only through detailed survey involving engineering and areodynamical calculations as well as meteorological models of tornadoes.
F7 - F12 380 mph to the Speed of Sound Not expected to occurr!

NWS Norman Radar Data - The Oklahoma Climate Survey (OCS), headed by Dr. Ken Crawford, has provided great radar data from the Oklahoma City area tornadoes. To view the data, first you must download their browser plugin. Then follow this link to the data. You will see that you can also download the images in QuickTime format too, however, using the plugin will allow you to manipulate the data, as emergency managers do in real-time using live data feeds from the OCS's OK-FIRST project.  (*please contact the OCS for current links to this information)

NEXRAD Images of the Tulsa - Sapulpa Storm

radar image

 

radar image

Storm Spotter Audio and Pictures of the tornado entering Tulsa

nighttime image  nighttime image

Left: Tornado (dimly visible) moving into west Tulsa. Right: Power lines explode as they are torn from poles.

c Steve Piltz, 1999

Click here to download a short wave file with spotter audio.

Note - Amateur radio station WA5LVT is the NWS Net Control.

Tornado Damage in west Tulsa

west Tulsa damage

Church near Union Blvd and I-44 in the Carbondale area of west Tulsa.

 

Damage in Sapulpa

Sapulpa damage

Mobile home damage just south of Highway 66 in Sapulpa.

 

Tanger Mall Damage near Stroud, OK

 Tanger mall damage

Long Track OK-AR Tornado 5/4/99

radar image

Adair County Oklahoma 5/4/99

tree damage

F3 damage in extreme southeast Adair County Oklahoma...5 miles west of Natural Dam Arkansas from the tornado on 5/4/99. Rating tornadoes from just tree damage is extremely subjective and complicated further by not being able to reach the area with a ground team. However it can be seen that every tree in a hard-wood forest is down.

Cove Creek, AR 5/4/99

church damage

Church at Cove Creek, (Washington Co. SW of Fayetteville) AR - pushed off its foundation by the tornado on 5/4/99. (Photo supplied by John Gibson, Washington Co. Judge's Office)

Last updated: 5/14/99


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