Alert archive / Illinois / Mesoscale Discussions in 2004
Mesoscale Discussion 239
The Storm Prediction Center issued this mesoscale discussion at Mar 28, 2004, 2:43 PM CST for 9 counties in Illinois; Kenosha County, Wisconsin. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 28, 2004, 2:43 PM CST (20:43 UTC)
- Expired
- Mar 28, 2004, 4:45 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
Counties Cook County, IL, DuPage County, IL, Grundy County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Lake County, IL, Livingston County, IL, Will County, IL, Kenosha County, WI
The radar
The Chicago radar (KLOT), 19 km from the middle of the area, began a volume at 20:46 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, 8.7 hours before the alert went out and 185 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1307 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 298 m²/s²
- 0-3 km storm-relative helicity
- 304 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
728 ACUS11 KWNS 282044 SWOMCD SPC MCD 282043 INZ000-ILZ000-WIZ000-282245- MESOSCALE DISCUSSION 0239 NWS STORM PREDICTION CENTER NORMAN OK 0243 PM CST SUN MAR 28 2004 AREAS AFFECTED...NERN IL...THE CHICAGO METRO AREA CONCERNING...CONVECTIVE TRENDS VALID 282043Z - 282245Z THUNDERSTORM ACTIVITY MAY INCREASE LATE THIS AFTERNOON WITH POTENTIAL FOR GUSTY WINDS...BUT NEED FOR WW IS NOT CURRENTLY ANTICIPATED. DESPITE WEAK LOW-LEVEL CONVERGENCE ALONG PRE-FRONTAL WIND SHIFT... SLOW INCREASE IN CONVECTIVE DEVELOPMENT IS ONGOING IN NARROW BAND WEST OF THE MILWAUKEE AND CHICAGO METROPOLITAN AREAS. FURTHER INCREASE IN INTENSITY SHOULD OCCUR NEXT FEW HOURS IN RESPONSE TO LOW-LEVEL FRONTOGENETIC FORCING...AND A GRADUAL WEAKENING OF CONVECTIVE INHIBITION ON LEADING EDGE OF STRONGER MID-LEVEL HEIGHT FALLS. INITIAL CLOUD TO GROUND LIGHTNING ACTIVITY HAS OCCURRED IN CONVECTION TO THE SOUTHWEST OF MILWAUKEE...AND THUNDERSTORMS APPEAR LIKELY TO BECOME MORE NUMEROUS THROUGH LATE AFTERNOON. WEAK INSTABILITY...WITH MEAN MIXED LAYER CAPE ON THE ORDER OF 500 J/KG OR LESS...WILL LIMIT VIGOR OF UPDRAFTS IN DEVELOPING LINE OF STORMS. HOWEVER...WARM AND RELATIVELY DEEP MIXED BOUNDARY LAYER ...EVIDENT IN LATEST SURFACE OBSERVATION AROUND THE CHICAGO METROPOLITAN AREA...WILL ENHANCE POTENTIAL FOR DOWNWARD MOMENTUM TRANSFER IN DOWNDRAFTS. THOUGH SOUTHERLY LOW-LEVEL JET AXIS IS NOW DEVELOPING EASTWARD ACROSS LAKE MICHIGAN...30 TO 40 KT FLOW IN LOWEST KILOMETER OR TWO ABOVE SURFACE PROVIDES POTENTIAL FOR A FEW SURFACE GUSTS APPROACHING OR BRIEFLY EXCEEDING SEVERE LIMITS. WITH DEVELOPING LINE ORIENTED PARALLEL TO DEEP LAYER SOUTHERLY FLOW...ONLY SLOW EASTWARD PROGRESS ACROSS THE CHICAGO AREA IS EXPECTED THROUGH 29/00Z. ..KERR.. 03/28/2004 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...LOT...ILX...MKX... 41668749 41048761 40618830 40538883 41058867 41568852 42328839 42638841 42788821 42748789 42688778
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 28, 12:18 PM CST | Mesoscale Discussion | SPC | Monroe, Randolph | 117 min |
Nearby
Mesoscale Discussions in Illinois, 2004Mesoscale Discussions in Wisconsin, 2004Every mesoscale discussion in 2004
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.