May 3, 2021 Preliminary Severe Weather Recap

A series of severe thunderstorms produced tornadoes, large hail, and damaging winds across central Illinois on May 3rd. Preliminary information regarding the event can be found on the "Reports" tab below. The meteorological summary and event photos will be updated over the next few days.

Reports

Meteorology

Radar and Satellite

Photos

Details regarding the tornadoes that occurred across central Illinois on May 3rd can be seen below. A list of all severe weather reports (including hail and damaging wind) is included after the damage survey information.


    
                        

101

NOUS43 KILX 312011

PNSILX

ILZ027>031-036>038-040>057-061>063-066>068-071>073-010815-



Public Information Statement

National Weather Service Lincoln IL

311 PM CDT Sat Aug 31 2024



...A LOOK AHEAD AT SEPTEMBER CLIMATOLOGICAL DATA...



Normals are for the period 1991-2020.



...TEMPERATURES...        SPRINGFIELD           PEORIA

Normal high/low           80/56                 78/56

  Sep  1 normals          84/61                 83/62

  Sep 30 normals          75/50                 73/51



Month record high         102 on 9/01/2011#     104 on 9/05/1899

Month record low           31 on 9/30/1899#      24 on 9/28/1942



Normal occurrences of...

  Highs 90 or above       4                     3

  Highs 32 or below       0                     0

  Lows  32 or below       0                     0

  Lows   0 or below       0                     0



...PRECIPITATION...

Normal liquid equivalent  2.88                  3.48

  Greatest month total   15.16 in 1926         13.09 in 1961

  Least month total      Trace in 1979          0.03 in 1979

  Greatest 24-hour        5.12 on 9/26/1959     4.11 on 9/13/1961



Normal snowfall           0.0                   0.0

  Greatest month total   Trace in 1942          1.0 in 1942

  Least month total       0.0 in many years     0.0 in many years

  Greatest 24-hour       Trace on 9/25-26/1942  1.0 on 9/25/1942



...DEGREE DAYS (BASE 65)...

Normal heating            61                    66

Normal cooling            151                   137



...FREEZE DATES...

Normal first freeze       October 21            October 15

Earliest first freeze     9/20/1991             9/20/1991



CLIMATOLOGICAL OUTLOOK FOR THE NEW MONTH:



   Temperatures --- No favored trend -- Use Climatology

   Precipitation -- Below Normal favored



# - Last of several occurrences



$$



25

A list of all storm reports that occurred across central Illinois on May 3rd can be seen below:

PRELIMINARY LOCAL STORM REPORT...SUMMARY...CORRECTED
NATIONAL WEATHER SERVICE LINCOLN IL
1122 PM CDT MON MAY 3 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0455 PM     HAIL             3 SSE BLUFF SPRINGS     39.95N 90.33W
05/03/2021  E1.50 INCH       CASS               IL   COCORAHS         



0504 PM     HAIL             VIRGINIA                39.95N 90.21W
05/03/2021  E1.50 INCH       CASS               IL   PUBLIC           

            RELAYED BY BROADCAST MEDIA. DAMAGE TO CARS. 

0505 PM     TORNADO          3 S VIRGINIA            39.91N 90.21W
05/03/2021                   CASS               IL   TRAINED SPOTTER  

            ON GROUND IN OPEN FIELD. DIME SIZED HAIL. 

0515 PM     HAIL             4 WSW NEWMANSVILLE      39.98N 90.08W
05/03/2021  E1.00 INCH       CASS               IL   FIRE DEPT/RESCUE 

            RELAYED BY ASHLAND FIRE. 

0527 PM     TORNADO          2 WNW PLEASANT PLAINS   39.88N 89.95W
05/03/2021                   SANGAMON           IL   STORM CHASER     

            CORRECTION TO PREVIOUS REPORT OF TORNADO 3 N 
            ASHLAND. 

0532 PM     HAIL             3 S PETERSBURG          39.97N 89.85W
05/03/2021  E1.00 INCH       MENARD             IL   AMATEUR RADIO    



0532 PM     TSTM WND DMG     3 S PETERSBURG          39.97N 89.85W
05/03/2021                   MENARD             IL   AMATEUR RADIO    

            POWER POLES BLOWN DOWN INTO FIELD. 

0610 PM     TORNADO          1 ESE DAWSON            39.85N 89.45W
05/03/2021                   SANGAMON           IL   PUBLIC           

            BRIEF TOUCHDOWN NEAR I-72. 

0612 PM     TSTM WND DMG     3 N DAWSON              39.90N 89.46W
05/03/2021                   SANGAMON           IL   TRAINED SPOTTER  

            POWER POLES DOWNED. 

0614 PM     TORNADO          1 NW MECHANICSBURG      39.82N 89.41W
05/03/2021  UF1              SANGAMON           IL   TRAINED SPOTTER  

            CORRECTS PREVIOUS TORNADO REPORT FROM 1 NW 
            MECHANICSBURG. 

0718 PM     HAIL             1 S MACON               39.70N 89.00W
05/03/2021  E1.00 INCH       MACON              IL   PUBLIC           



0728 PM     HAIL             5 WSW ROSAMOND          39.35N 89.25W
05/03/2021  E2.00 INCH       CHRISTIAN          IL   TRAINED SPOTTER  



0824 PM     TSTM WND DMG     CHARLESTON              39.48N 88.18W
05/03/2021                   COLES              IL   EMERGENCY MNGR   

            TREE BLOWN DOWN. 


&&

$$

The following is a technical overview of the meteorological conditions that occurred during the May 3rd severe weather event across central Illinois.

On Monday, May 3rd, thunderstorms developed along a cold front in north central Missouri and progressed into west central Illinois by mid-afternoon. Widespread cloud cover was in place across central Illinois through much of the morning and afternoon, but clouds diminished ahead of the cold front. In areas where the sun came out ahead of the front, temperatures climbed into the upper 70s. Dew point temperatures were in the mid-60s, resulting in a moderately unstable environment with around 1500 J/kg of mixed-layer convective available potential energy (MLCAPE). This instability combined with 35-45 knots of deep layer wind shear was supportive of severe weather. The angle between the shear vectors and the cold front was greater than 45 degrees, allowing for the development of supercells. The first image below shows the surface observations as of 22z/5pm, with the cold front pushing into west central Illinois. The second image shows the MLCAPE as of 22z/5pm. Note the lack of blue shading across central Illinois indicating the atmosphere is unstable and ready for thunderstorm development in the presence of a forcing mechanism (in this case, the forcing mechanism was the cold front). The second image shows the shear vectors at the same time.

The tornado threat was enhanced by a mesoscale convective vortex (MCV), an area of spin in the atmosphere that formed as a result of thunderstorms the previous day across Kansas/Nebraska, which tracked across north-central Missouri then northeastward across the Illinois River Valley. This MCV contributed to a surface wind shift, from southwesterly to southeasterly, ahead of the cold front. This localized wind shift increased the low-level wind shear, which increased the tornado potential.

Several severe thunderstorms developed along the cold front and moved through central Illinois. The strongest storm tracked from Cass County east-southeastward towards Coles County. That storm produced at least four tornadoes and up to 2" hail (hen egg sized). (See the "Reports" tab for complete details regarding the location of tornadoes). All four tornadoes occurred primarily in open fields, and a tornado rating could not be assigned due to the lack of damage. The other severe thunderstorms produced large hail, but did not produce tornadoes. Overall, damage reports from the event were fairly limited. Power poles were blown down in Sangamon County, however, it is believed this damage was caused by straight line winds. Ping pong ball sized hail caused damage to vehicles in Virginia, IL. An observer five miles north of Buffalo, IL, reported that enough half-inch sized hail stones fell to cover the ground in hail.

Satellite Loop

Visible and IR satellite loop showing storm initiation in north-central Missouri during the late morning hours of May 3rd. As it moves eastward, a line of thunderstorms quickly develops and strengthens upon reaching the Illinois border with cold cloud tops (orange colors) indicating persistent updrafts. Additional cells develop southward into the favorable storm environment while the line progresses across the state. After sunset, storms begin to lose energy and weaken as they approach the Indiana border.

Closer Look at Tornadic Storm

The loop below is a base reflectivity animation focusing on the supercell that went on to produce 5 tornados in central Illinois. This radar loop shows the early stages of this storm and spans 16 minutes from 4:41-4:57 PM local time. In this loop, red boxes indicate a severe thunderstorm warning and the purple box indicates a tornado warning.

Photos of the thunderstorms across central Illinois. This section will be updated. If you have photos of the storms that you would like for us to include in the event summary, send us a tweet at @NWSLincolnIL with your picture, location, and permission to use your photo.