Alert archive / Illinois / Severe Thunderstorm Warnings in 2007

Severe Thunderstorm Warning 84, NWS Chicago, IL

July 18, 2007Iroquois County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Jul 18, 2007, 3:31 AM CDT for Iroquois County, Illinois. It was in force for 44 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: Jul 18, 2007, 3:31 AM CDT (08:31 UTC)
Expired: Jul 18, 2007, 4:15 AM CDT
In force: 44 min
Issued by: NWS Chicago, IL
Area: Counties, with a storm outline in the text

County Iroquois County, IL

The radar

The Chicago radar (KLOT), 98 km from the middle of the area, began a volume at 08:31 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 00:00Z, 8.5 hours before the alert went out and 93 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: 46 J/kg
Mixed-layer CIN: -310 J/kg
Mixed-layer LCL: 1165 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 124 m²/s²
0-3 km storm-relative helicity: 119 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 Jul 18, 3:11 AM CDT, 20 minutes earlier.

Area forecast discussion, Jul 18, 3:11 AM CDT, 20 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Hazardous weather outlook, Jul 17, 9:50 PM CDT, 5 hours 41 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
950 PM CDT TUE JUL 17 2007

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
181015-
WINNEBAGO-BOONE-MCHENRY-LAKE ILLINOIS-OGLE-LEE-DE KALB-KANE-
DUPAGE-COOK-LA SALLE-KENDALL-GRUNDY-WILL-KANKAKEE-LIVINGSTON-
IROQUOIS-FORD-LAKE INDIANA-PORTER-NEWTON-JASPER-BENTON-
950 PM CDT TUE
JUL 17 2007 /500 PM EDT TUE JUL 17 2007/

THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR NORTH
CENTRAL AND NORTHEAST ILLINOIS...AND NORTHWEST INDIANA.

.DAY ONE...TONIGHT.

A FLOOD WATCH IS IN EFFECT UNTIL 6 AM WEDNESDAY. THUNDERSTORMS
ARE EXPECTED TO MOVE BACK INTO THE REGION TONIGHT.  SOME STORMS
COULD PRODUCE HEAVY RAINFALL RESULTING IN FLOODING. THERE IS A
SLIGHT RISK OF SEVERE THUNDERSTORMS. A FEW STORMS COULD PRODUCE
LARGE HAIL OR DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

THERE IS A CHANCE OF THUNDERSTORMS WEDNESDAY AND THURSDAY. A SLIGHT
RISK OF SEVERE THUNDERSTORMS EXISTS ACROSS THE AREA WEDNESDAY AND
WEDNESDAY NIGHT. IN ADDITION TO ANY SEVERE THREAT THESE STORMS WILL
ALSO BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED OVERNIGHT.  ANY REPORTS OF HEAVY
RAINFALL...LARGE HAIL OR HIGH WINDS ARE APPRECIATED.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

LMZ740>745-766-181015-
WINTHROP HARBOR TO WILMETTE HARBOR IL-
WILMETTE HARBOR TO NORTHERLY ISLAND IL-
NORTHERLY ISLAND TO CALUMET HARBOR IL-
CALUMET HARBOR IL TO GARY IN-GARY INDIANA TO BURNS HARBOR-
BURNS HARBOR TO MICHIGAN CITY-
LAKE MICHIGAN, WINTHROP HARBOR IL EASTWARD TO THE MID-
POINT OF THE LAKE AND SOUTHWARD TO MICHIGAN CITY MI BEYOND 5 NM
OFFSHORE-
950 PM CDT TUE JUL 17 2007

THIS PORTION OF THE HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS
AND INDIANA WATERS OF LAKE MICHIGAN.

.DAY ONE...TONIGHT.

SCATTERED THUNDERSTORMS ARE EXPECTED LATE TONIGHT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

THERE IS A CHANCE OF THUNDERSTORMS WEDNESDAY AND THURSDAY. A SMALL
CRAFT ADVISORY MAY BE NEEDED THURSDAY.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

In the hours before

Local storm report, Jul 18, 1:01 AM CDT, 2 hours 30 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Local storm report, Jul 18, 1:11 AM CDT, 2 hours 20 minutes before

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Local storm report, Jul 18, 1:45 AM CDT, 1 hour 46 minutes before

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
145 AM CDT WED JUL 18 2007

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

1245 AM     FLASH FLOOD      POLO                    41.98N 89.58W
07/18/2007                   OGLE               IL   AMATEUR RADIO

            DIVISION AND WEST COVEN STREETS FLOODED - 2 INCHES OF
            RAIN IN POLO SINCE BEGINNING OF STORM

0126 AM     TSTM WND DMG     5 E POLO                41.98N 89.48W
07/18/2007                   OGLE               IL   AMATEUR RADIO

            LARGE TREE BRANCH BLOWN DOWN NEAR THE ENTRANCE OF WHITE
            PINES STATE PARK

0126 AM     FLOOD            5 E POLO                41.98N 89.48W
07/18/2007                   OGLE               IL   AMATEUR RADIO

            PINE CREEK OVER ITS BANKS IN WHITE PINES STATE PARK.
            FLOODING IN PARK IS BEGINNING.

0130 AM     FLASH FLOOD      AMBOY                   41.72N 89.33W
07/18/2007                   LEE                IL   LAW ENFORCEMENT

            WATER COMING UP THROUGH THE STORM DRAINS IN THE
            ROADWAYS...PER LEE COUNTY SHERIFFS OFFICE

0130 AM     FLOOD            DIXON                   41.85N 89.48W
07/18/2007                   LEE                IL   LAW ENFORCEMENT

            FLOODING OFF OF ROUTE 2 ON THE NORTHEAST SIDE OF DIXON

&&

CGITRO

Local storm report, Jul 18, 2:51 AM CDT, 40 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
251 AM CDT WED JUL 18 2007

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

1217 AM     TSTM WND DMG     DIXON                   41.85N 89.48W
07/18/2007                   LEE                IL   LAW ENFORCEMENT

            TREE DOWN AT 9TH AND HIGHLAND...RADAR TIME ESTIMATED

&&

CGITRO

The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 18, 12:13 AM CDT	Severe Thunderstorm Warning	LOT	Lee, Ogle	62 min
Jul 18, 12:49 AM CDT	Flash Flood Warning	LOT	Lee	6 hr
Jul 18, 3:24 AM CDT	Severe Thunderstorm Warning	LOT	Ford, Livingston	36 min
Jul 18, 4:22 AM CDT	Flash Flood Warning	LOT	LaSalle	6 hr
Jul 18, 7:20 AM CDT	Flash Flood Warning	LOT	Livingston	6 hr

Nearby

Severe Thunderstorm Warnings in Illinois, 2007 Every severe thunderstorm warning in 2007

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.