...The Ingredients for a Major Tornado Outbreak... 

Meteorological conditions came together Sunday May 4th, 2003, to produce the major tornado outbreak across southeast Kansas and the Missouri Ozarks.   Meteorological elements to produce a major severe weather event were in place and included a very moist and unstable airmass, strong lift and strong wind shear.  The following information will provide a brief synopsis of these ingredients that produced the outbreak of destructive and deadly tornadoes.

sfc_21z_050403.jpg (215476 bytes)Sunday May 4th started off relatively cool and damp as the area remained north of a warm front that stretched across northern Oklahoma and Arkansas.  A very moist and unstable airmass was located south of the front.   The warm front lifted northeast during the day as a strong surface low developed and tracked across Kansas.  Warmer air surged north during the day with temperatures rising into the 70s across southeast Kansas and far southwest Missouri by mid afternoon.  Temperatures north of the warm front remained in the low to mid 60s.    

sfc_pres_dew_21z_050403.jpg (326466 bytes)Meanwhile, a dry line surged east into eastern Kansas during the afternoon marking the boundary of very dry air to the west where dewpoints were in the 30s to the very moist air to the east where dewpoints were near 70 degrees.  

 

 

 

 

 

  Visible Satellite        Radar Reflectivity

vis_2115z_050403.jpg (196064 bytes)  ref_21z_050403.jpg (270932 bytes)

         415 PM                          422 PM 

 

vis_2215z_050403.jpg (201343 bytes)  ref_22z_050403.jpg (267657 bytes)

         515 PM                            457 PM 

 

vis_2315z_050403.jpg (214357 bytes)  ref_23z_050403.jpg (294148 bytes)

         615 PM                          607 PM 

 

vis_2345z_050403.jpg (232167 bytes)  ref_00z_050403.jpg (295131 bytes)

       645 PM                            657 PM

 

ir_01z_050503.jpg (242846 bytes)  ref_01z_050403.jpg (225021 bytes)

     755 PM                              753 PM

 

Thunderstorms developed rapidly around 3 PM across east central Kansas just ahead of the approaching surface low.  Explosive thunderstorm development continued south along the dry line 

the remainder of the afternoon as mid level temperatures cooled ahead of the advancing 

upper level disturbance.  

 

 

 

The storms quickly developed supercell characteristics across eastern Kansas.  Three dominant supercells formed as the storms moved into southwest Missouri.    

 

 

 

 

These supercells produced long tracked, 

destructive and deadly tornadoes. Once the supercells developed, they raced eastward at 45 mph. 

 

Lift 

 

An intense upper level jet stream streaked across the southern Plains while a strong upper level disturbance lifted northeast from the central Rockies into central Plains.  Upper level diffluence provided strong vertical lift.    

 

This jet streak is noted by the drying (orange colors) on the water vapor imagery to the far right.  Winds at 250 mb or ~35,000 ft. were ~ 125 kts, 75 kts at 500 mb or ~18000 ft.

ruc_50h_wind_21z_050403.jpg (354201 bytes)  wv_50H_2115z_050403.jpg (311062 bytes)

25H_wind_21z_050403.jpg (330772 bytes)  wv_25H_2115z_050403.jpg (345463 bytes)

 

 

500_030505_00.gif (35902 bytes) The 00z (7 PM) 500 mb analysis depicts the upper disturbance pushing northeast across the central Plains. 

 

 

 

 

250_030505_00.gif (43984 bytes)The 00z ( 7 PM ) 250 mb analysis showed the strong jet stream streaking into the region.  

 

 

 

 

 

Instability

 

The upper air soundings below taken at the NWS office in Springfield show the evolution of the atmosphere between 1 and 7 PM.  This data provides a profile of temperature, moisture, wind direction and speed from which instability and wind shear values can be calculated. 

 

 

sounding_18z_050403.jpg (223370 bytes)  sounding_21z_050403.jpg (224106 bytes)  sounding_00z_050403.jpg (216221 bytes)

         18z (1 PM)                  20z (3 PM)                  00z (7 PM)

 

A wedge of very unstable air developed between the warm front and approaching dry line.  Lifted indices approached minus 10 and CAPES were near 4000 j/kg near the Kansas border by late afternoon. 

 

 

LI_00z_050503.jpg (274910 bytes)  cape_00z_050503.jpg (381368 bytes)  

       Lifted Index                      Cape

 

 

Wind shear

 

Wind shear is the change in wind direction and/or speed with height.  Strong wind speed and directional shear was in place May 4th.  Surface winds out of the southeast turned to the south then southwest through the mid and upper levels of the atmosphere.  This turning with height combined with the strong instability supported the development of rotating thunderstorms called supercells.  

 

 

wind_shear_00z_050503.jpg (180858 bytes)  helicity_00z_050503.jpg (324477 bytes)    

        wind profile                helicity


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