May 18 Hamel, Illinois Chase
by John Farley


Although I knew this could be an excellent chase day, especially to my north in central Illinois, my chasing opportunities were severely limited. Due to work, I could not get out until around 5:00 - by which time St. Louis city and county were under a tornado warning, and most of Illinois and eastern Missouri were under tornado watches. The cell responsible for the warning - the first in a lined-up group of 3 supercells in the St. Louis area - was crossing into Illinois just northwest of Edwardsville as I hurried home from work just before 5:00. In addition, severe thunderstorm warnings were out for Madison and southern Macoupin Counties based on both of the first two cells.

5:00 - Out the door. I grabbed my gear and headed up I-55 one exit to Hamel.

5:05 - Driving up I-55 toward Hamel, I could see rain/hail shafts and a brief lowering under updraft to my west. This was the second storm in the progression of 3 moving through the area. The first storm - the one that caused the earlier tornado warning in St. Louis Co., was to my north, to the north and, increasingly, northeast of Hamel.

5:15-5:20 - I exited the freeway and found a place to view the storm from 140 at the Hamel exit, just east of Hamel. Looking to my NNW through a little rain from second storm, I could see a wide but not particularly low wall cloud under updraft of the storm first storm, the precipitation core of which was now northeast of Hamel. The wall cloud formed a long inflow tail on the side toward the storm's core, then the wall cloud rapidly lowered toward the ground. It quickly developed a nice RFD (rear flank downdraft) slot. Here is a video capture which shows both the lowering and the RFD slot nicely. But due to rain falling from the next storm, I could not see if there was rotation, and trees kept me from seeing exactly how close it really was to the ground, though at this point it was down as far as I could see. It may have been a funnel cloud, but because I could not verify rotation I cannot say it was more than a very low wall cloud. Additionally, the lowering seemed to form from or near the earlier inflow tail, which would argue against a funnel cloud. On the other hand, it rapidly lowered as the RFD slot cut around the wall cloud. I do not think it was a tornado, because there were no reports of tornadoes or of wind damage in that immediate area. In any case, it formed and dissipated within 5 minutes. Rain then obscured this area of the storm.

5:20 - 5:30 - As rain and maybe a little hail from the storm to the SW caught up to my position, I blast east on 140. Precip is coming from SSE. Then I turn S on 4 to get position on SW storm. I see RFB and intense precip core w/some hail shafts to my W and WNW; a very impressive rainfoot evident. I watched this from about 5:30 to 5:40. At that time, a small lowering - I thought outflow-related - forms on leading edge of storm S of heaviest precip. I followed the storm east on Fruit Road to where it T-intersects with Schwartz Rd. I took that a mile north to Niggle Rd. which I took east to 160. I cut north on 160 to 140 and followed 140 east until I reached the road S. to Pochahantas around or a little after 6:00. Between 5:40 and 6:00 the precip outran the lowering, which then took on a more wall-cloud looking structure. By now the lowering was under the updraft, which was very leaned over to NE (but it still had very hard towers) due to strong upper winds/speed shear. What appeared to be a hail shaft formed behind the wall cloud feature, which had become a little less pronounced by the time of this picture. (It would alternately increase and decrease in size from about 5:40 to nearly 6:00. Around 6:00 or a little before, an apparent clear slot, indicating the formation of a rear flank downdraft, cut around where the wall cloud had been, but around this time the wall cloud either disappeared in rain or dissipated, since all I could see where it had been was an area of precipitation. At this time, as had been the case for the entire chase, I was inflow to the storm - I was never overtaken by outflow, and at times the inflow was quite strong; I would estimate 30 mph or more at times. As it was now after 6:00 and the storm was still screaming off to ENE at 50+ MPH, I broke off the chase, in part for possibility of intercepting another storm with a warning in STL Co. (The third cell in the cluster) I proceeded W on I-70 then on IL-143. As it turns out, by 6:00 the whole complex of thunderstorms was dying out, as it apparently moved into more stable air or too far from the cold front. There were no tornadoes reported in the area, but scattered reports of large hail and straight-line wind damage in the STL area.

I drove in sunshine and anvil rain from Marine back to Edwardsville. It appeared to rain out of a clear, blue sky, as the anvil from the southwesternmost of the 3 storms raced over me and off to my northeast in the jet stream winds. I was home by around 6:45. Total chase distance: about 65 miles.

Here are 3 radar images of these storms (reflectivity). Note that the first two storms are displaying something of a hook echo, particularly at 5:00 p.m.:

5:00 p.m. (CDT) radar image
5:30 p.m. radar image
6:00 p.m. radar image

Below are a mesoscale discussion from SPC on these storms, the warnings on the storms, and the local storm reports from the St. Louis NWS.

Comments to John Farley, jfarley@siue.edu

Return to Severe Weather Observations Page

5/18 Chase443
ACUS3 KMKC 182142
SWOMCD
MKC MCD 182141
MOZ000-ILZ000-190000-

SPC MESOSCALE DISCUSSION #0832 FOR ..ERN MO/CENTRAL IL..
CONCERNING...SEVERE THUNDERSTORM POTENTIAL...REF WW 305.

LINE OF WIDELY SCATTERED SUPERCELL THUNDERSTORMS HAVE DEVELOPED
ALONG SURFACE COLD FRONT NEAR STL. LATEST SURFACE ANALYSIS
INDICATES WINDS IN THE BLV AREA ARE SLIGHTLY MORE BACKED THAN IN
SURROUNDING REGIONS...ENHANCING LOW LEVEL SHEAR AND CONVERGENCE
WITH ACTIVITY NEAR STL/ALN. 3KM HELICITY VALUES AROUND 200 M2/S2
AND CAPE VALUES OVER 3000 J/KG APPEAR FAVORABLE FOR CONTINUED
SEVERE STORMS WITH POTENTIAL FOR ISOLATED TORNADOES.

OTHER ISOLATED SUPERCELL STORMS HAVE FORMED WEST OF PIA. THESE
STORMS ARE JUST SOUTH OF SURFACE WARM FRONT AND IN REGION OF STRONG
DYNAMIC LIFT. THESE STORMS WILL POSE THREAT OF LARGE HAIL AND
ISOLATED TORNADOES FOR THE NEXT FEW HOURS AS THEY TRACK
NORTHEASTWARD INTO NORTHEAST IL.

NEW WATCH WILL LIKELY BE REQUIRED AHEAD OF THESE STORMS OVER PARTS
OF EASTERN IL AND NORTHERN IND WITHIN THE NEXT 1-2 HOURS.

..HART.. 05/18/00

...PLEASE SEE WWW.SPC.NOAA.GOV/ FOR GRAPHIC PRODUCT...

Severe Thunderstorm Warning355
WUUS53 KLSX 182112
SVRSTL
ILC013-083-117-119-182200-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
412 PM CDT THU MAY 18 2000

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
SOUTHWESTERN MACOUPIN COUNTY IN CENTRAL ILLINOIS
NORTHWESTERN MADISON COUNTY IN SOUTHWEST ILLINOIS
JERSEY COUNTY IN WEST CENTRAL ILLINOIS
SOUTHERN CALHOUN COUNTY IN WEST CENTRAL ILLINOIS

* UNTIL 500 PM CDT

* AT 412 PM CDT...WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE
THUNDERSTORM 7 MILES SOUTH OF BRUSSELS..MOVING NORTHEAST AT 25 MPH.

* LOCATIONS THAT WILL BE AFFECTED...
GRAFTON
ELSAH
BRIGHTON

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MPH...
DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR YOUR
PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME
OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE INTO
AREAS WHERE WATER COVERS THE ROAD.

A TORNADO WATCH IS ALSO IN EFFECT FOR THE WARNED AREA. REMEMBER...
SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES WITH LITTLE OR NO ADVANCE
WARNING.

LAT...LON 3889 9062 3893 9043 3891 9025 3888 8994
3922 9017 3910 9070

Tornado Warning401
WFUS53 KLSX 182117
TORSTL
MOC183-189-182145-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
416 PM CDT THU MAY 18 2000

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* TORNADO WARNING FOR...
ST. CHARLES COUNTY IN EAST CENTRAL MISSOURI
NORTHERN ST. LOUIS COUNTY IN EAST CENTRAL MISSOURI

* UNTIL 445 PM CDT

* AT 416 PM CDT...WEATHER SERVICE DOPPLER RADAR INDICATED A TORNADO 2
MILES SOUTHEAST OF NEW MELLE...MOVING EAST AT 30 MPH.

* LOCATIONS IN THE PATH...
DARDENNE PRAIRIE
O'FALLON
CHESTERFIELD
ST. PETERS
BRECKENRIDGE HILLS

IF YOU ARE IN A VEHCILE...LEAVE IT IMMEDIATELY AND GO TO A STRONG
BUILDING. DO NOT USE YOUR CAR TO TRY TO OUTRUN A TORNADO. CARS ARE
EASILY TOSSED AROUND BY TORNADO WINDS. IF NO STRUCTURE IS NEARBY...
SEEK SHELTER IN A DITCH OR LOW SPOT.

LAT...LON 3875 9098 3858 9090 3866 9030 3896 9028
3884 9092

Severe Thunderstorm Warning248
WUUS53 KLSX 182147
SVRSTL
ILC117-119-MOC183-189-182230-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
443 PM CDT THU MAY 18 2000

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
SOUTHERN MACOUPIN COUNTY IN CENTRAL ILLINOIS
EASTERN ST. CHARLES COUNTY IN EAST CENTRAL MISSOURI
NORTHERN ST. LOUIS COUNTY IN EAST CENTRAL MISSOURI
MADISON COUNTY IN SOUTHWEST ILLINOIS

* UNTIL 530 PM CDT

* AT 443 PM CDT...WEATHER SERVICE DOPPLER RADAR INDICATED TWO
SEVERE THUNDERSTORMS. ONE WAS NEAR ST. CHARLES AND THE SECOND WAS
5 MILES NORTHWEST OF ALTON. BOTH STORMS ARE MOVING EAST NORTHEAST
AT 40 MPH.

* LOCATIONS THAT WILL BE AFFECTED...
BUNKER HILL
ALTON
STAUNTON
FLORRISANT
PORTAGE DE SIOUX

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MPH...
DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR YOUR
PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME
OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE INTO
AREAS WHERE WATER COVERS THE ROAD.

LAT...LON 3888 9058 3868 9049 3867 8973 3928 8970
3927 9016 3900 9015

Severe Thunderstorm Warning150
WUUS53 KLSX 182220
SVRSTL
ILC005-135-182300-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
518 PM CDT THU MAY 18 2000

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
MONTGOMERY COUNTY IN CENTRAL ILLINOIS
NORTHERN BOND COUNTY IN SOUTH CENTRAL ILLINOIS

* UNTIL 600 PM CDT

* AT 518 PM CDT...WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE
THUNDERSTORM 8 MILES WEST OF WALSHVILLE..MOVING EAST AT 35 MPH.

* LOCATIONS THAT WILL BE AFFECTED...
HILLSBORO
LITCHFIELD
GREENVILLE
GOVERNOR BOND LAKE
COFFEEN LAKE

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MPH...
DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR YOUR
PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME
OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE INTO
AREAS WHERE WATER COVERS THE ROAD.

A TORNADO WATCH IS ALSO IN EFFECT FOR THE WARNED AREA. REMEMBER...
SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES WITH LITTLE OR NO ADVANCE
WARNING.

LAT...LON 3921 8972 3902 8972 3891 8955 3886 8927
3936 8929 3936 8954

Severe Thunderstorm Warning492
WUUS53 KLSX 182233
SVRSTL
ILC119-182300-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE ST LOUIS MO
531 PM CDT THU MAY 18 2000

THE NATIONAL WEATHER SERVICE IN ST LOUIS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
EASTERN MADISON COUNTY IN SOUTHWEST ILLINOIS

* UNTIL 600 PM CDT

* AT 531 PM CDT...WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE
THUNDERSTORM OVER WORDEN..MOVING EAST AT 45 MPH.

* LOCATIONS THAT WILL BE AFFECTED...
NEW DOUGLAS
LIVINGSTON
ALHAMBRA

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MPH...
DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR YOUR
PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME
OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE INTO
AREAS WHERE WATER COVERS THE ROAD.

A TORNADO WATCH IS ALSO IN EFFECT FOR THE WARNED AREA. REMEMBER...
SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES WITH LITTLE OR NO ADVANCE
WARNING.

SVS from KLSX 



149 
WWUS34 KSTL 182253
SVSSTL
ILZ060-064-100-182300-

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE ST LOUIS MO
551 PM CDT THU MAY 18 2000

...A SEVERE THUNDERSTORM WARNING CONTINUES FOR MONTGOMERY AND 
NORTHERN BOND COUNTIES UNTIL 600 PM CDT...

AT 551 PM CDT...WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE
THUNDERSTORM OVER NEW DOUGLAS. THIS STORM WAS MOVING EAST AT 40 MPH.

THE SEVERE THUNDERSTORM HAS MOVED EAST OF EASTERN MADISON 
COUNTY...SO THE WARNING HAS BEEN CANCELLED.

A TORNADO WATCH IS ALSO IN EFFECT FOR SOUTHWEST ILLINOIS UNTIL 11 PM 
CDT. REMEMBER...SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES WITH 
LITTLE OR NO ADVANCE WARNING.
LSR from KLSX 


311 
WWUS30 KSTL 190227
LSRSTL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
925 PM CDT WED MAY 17 2000

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0323 PM    WENTZVILLE                MO   .75 INCH HAIL          
05/18/00   ST CHARLES                     DIME SIZED HAIL REPORTED 
                                          BY WENTZVILLE POLICE 

0410 PM    OTTERVILLE                IL   1.75 INCH HAIL         
05/18/00   JERSEY                         GOLFBALL SIZED HAIL 
                                          REPORTED BY SPOTTER 

0420 PM    O FALLON                  MO   65 MPH TSTM GUST       
05/18/00   ST CHARLES                     ESTIMATED 60 TO 70 MPH 
                                          WINDS AT INTERSECTION OF 
                                          HIGHWAYS K AND N REPORTED 
                                          BY A SPOTTER

0425 PM    NEW MELLE                 MO   65 MPH TSTM GUST       
05/18/00   ST CHARLES                     ESTIMATED 65 MPH WINDS 
                                          REPORTED BY NEW MELLE 
                                          POLICE...APPROXIMATE TIME 

0439 PM    BRIDGETON                 MO   .88 INCH HAIL          
05/18/00   ST LOUIS                       NICKEL SIZED HAIL REPORTED 
                                          BY SPOTTER 

0440 PM    ST CHARLES                MO   .75 INCH HAIL          
05/18/00   ST CHARLES                     DIME SIZED HAIL REPORTED 
                                          BY SPOTTER 

0445 PM    BRIGHTON                  IL   1 INCH HAIL            
05/18/00   MACOUPIN                       1 INCH HAIL REPORTED BY 
                                          SPOTTER 

0452 PM    FLORISSANT                MO   .75 INCH HAIL          
05/18/00   ST LOUIS                       DIME SIZED HAIL REPORTED 
                                          BY SPOTTER 

0452 PM    HAZELWOOD                 MO   1 INCH HAIL            
05/18/00   ST LOUIS                       ONE INCH HAIL REPORTED BY 
                                          SPOTTER 

0505 PM    2 S MANCHESTER            MO   WIND DAMAGE            
05/18/00   ST LOUIS                       TREES DOWNED BY HIGH WINDS 
                                          NEAR INTERSECTION OF BIG 
                                          BEND AND HANNA ROADS 
                                          REPORTED BY SPOTTER

0700 PM    REDFORD                   MO   WIND DAMAGE            
05/18/00   REYNOLDS                       TREES AND POWERLINES 
                                          DOWNED ON ROUTE K 
                                          SOUTHEAST OF REDFORD. 

0730 PM    2 SE ANNAPOLIS            MO   TORNADO                
05/18/00   IRON                           TORNADO REPORTED BY DEPUTY 
                                          SHERIFF BETWEEN ANNAPOLIS
                                          AND VULCAN.   SEVERAL
                                          HOUSES ON ROUTE 49 DAMAGED
                                          WITH TREE AND POWER LINES
                                          DOWNED.

BRITT/TRUETT