Alert archive / Illinois / Severe Thunderstorm Warnings in 2003

Severe Thunderstorm Warning 1, NWS Chicago, IL

March 19, 2003Grundy County, Will County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Mar 19, 2003, 5:50 PM CST for Grundy County, Will County, Illinois. It was in force for 40 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Mar 19, 2003, 5:50 PM CST (23:50 UTC)
Expired: Mar 19, 2003, 6:30 PM CST
In force: 40 min
Issued by: NWS Chicago, IL
Area: Counties, with a storm outline in the text

Counties Grundy County, IL, Will County, IL

The radar

The Chicago radar (KLOT), 28 km from the middle of the area, began a volume at 23:50 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 11.8 hours before the alert went out and 139 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 450 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 70 m²/s²
0-3 km storm-relative helicity: 69 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Chicago, IL wrote its last area forecast discussion before this severe thunderstorm warning went out at Mar 19, 1:54 PM CST, 3 hours 56 minutes earlier.

Area forecast discussion, Mar 19, 1:54 PM CST, 3 hours 56 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
154 PM CST WED MAR 19 2003

PRELIMINARY DISCUSSION FOR 4 PM ZONES/GRIDS

AT 19Z NUMEROUS SHOWERS OVER FAR N TIER COUNTIES AND NEW
BAND OF SHOWERS MOVING N THRU THE S COUNTIES WITH THE STRONG
VORT LOBE. NO LIGHTING IN ANY AT THIS TIME EXCEPT NR STL.  STRONG
WARM FRONT JUST S OF STL.

THE LOBE PASSES N OF AREA 06-08Z. AFTER LOBE PASSES DEPENDING
ON MODEL -20/-22C TEMPS AT 500 OVER AREA BY O6Z AND -22/-24 FOR
THURSDAY. 700/500 LAPSE RATES OF 7 TO 7.5 ALSO SO BECOME UNSTABLE
ALOFT WITH THE LOBE PASSAGE. ANY PRECIP AFTER LOBE PASSAGE
WOULD DEFINITELY BE A MIX OF RW/TRW. LOOKS LIKE SOME MINOR VORTS
MOVE THRU BUT MAIN TROF LINE MOVES E OF AREA BY THURSDAY 12Z AS
NEW VORT DROPS DOWN FROM MN. NW 1/2 AREA UNDER THE VORT FIELD
BY 00Z FRIDAY AND THEN THRU NIGHT ALL SECTIONS. BY 12Z SATURDAY
850 DOWN TO -4C.

BACK TO BASIC ZONAL FLOW OVER ALL CONUS BY 12Z MONDAY.

WITH VERY COLD LAKE WILL SLOW DOWN WARM FRONTAL MOVEMENT TONIGHT
AND TOMORROW. MODELS CAN NOT HANDLE THIS FULLY IN LOWEST
LAYERS. BUT FRONT WILL BE VERY SHALLOW WITH STRONG PUSH OF WARM
AIR JUST ALOFT. ONCE WARM FRONT THRU COLD FRONT NOT THRU TIL
LATE THURSDAY NIGHT.

ETA TEMPS LOOK WAY TOO WARM TOMORROW. TEMPS OVERALL TRICKY AS A
FEW HOURS OF SUN COULD REALLY SEND THEM UP. WITH FRONT COMING N
TONIGHT OVERNIGHT LOWS WILL BE EVE TEMPS THEN SLOWLY CLIMB.

.CHI...NONE

AF

AVIATION DISCUSSION FOR 18Z TAFS...
FIRST WAVES OF PRECIP CONTINUING TO MOVE NORTH AND OUT OF TAF
AREAS. NEXT BAND SEEN ON RADAR ACROSS CENTRAL ILLINOIS. TIMING IS
FOR ARRIVAL IS MID-AFTERNOON. THOUGH NO LIGHTNING STRIKES WITHIN
LOT 88D RANGE COMPOSITE DATA INDICATED 40 DBZ RETURNS. AN
ADDITIONAL INSTAB ENOUGH TO INCLUDE CHC TSTMS AS BAND MOVES
THROUGH.

SEQUENCE OF EVENTS FOR REMAINDER OF TAF PERIOD LOOKS OK -- TIMING
IS LESS CERTAIN. AFTER THIS AFTERNOON PRECIP, CHC CONTINUES
THROUGH AROUND MIDNIGHT OR JSUT AFTER. BY THAT TIME TAFS APPEARS
IN SYSTEM DRY SLOT WITH CIGS ICREASING TO VFR AND VSBYS OK. WILL
HAVE TO WAIT UNTIL SUFRFACE LOWS MOVES INTO IL THURSDAY AM FOR
RETURN TO MVFR CIGS.

.CHI...NONE

Hazardous weather outlook, Mar 19, 3:30 PM CST, 2 hours 20 minutes before

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Nearby

Severe Thunderstorm Warnings in Illinois, 2003 Every severe thunderstorm warning in 2003

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.