Alert archive / Missouri / Heat Advisories in 2009

Heat Advisory 2, NWS St. Louis, MO

June 21, 200926 counties in Missouri; 15 counties in Illinois

NWS St. Louis, MO issued this heat advisory at Jun 21, 2009, 2:24 PM CDT for 26 counties in Missouri; 15 counties in Illinois. It was in force for 6 days.

The area

The counties it named.

The facts

Issued: Jun 21, 2009, 2:24 PM CDT (19:24 UTC)
Expired: Jun 27, 2009, 7:00 PM CDT
In force: 6 days
Issued by: NWS St. Louis, MO

All 41 counties

Adams County, IL, Bond County, IL, Brown County, IL, Calhoun County, IL, Clinton County, IL, Fayette County, IL, Greene County, IL, Jersey County, IL, Macoupin County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Pike County, IL, Randolph County, IL, Washington County, IL, Audrain County, MO, Boone County, MO, Callaway County, MO, Cole County, MO, Crawford County, MO, Franklin County, MO, Gasconade County, MO, Iron County, MO, Jefferson County, MO, Knox County, MO, Lewis County, MO, Lincoln County, MO, Madison County, MO, Marion County, MO, Moniteau County, MO, Monroe County, MO, Montgomery County, MO, Osage County, MO, Pike County, MO, Ralls County, MO, Reynolds County, MO, Saint Francois County, MO, Sainte Genevieve County, MO, Shelby County, MO, Warren County, MO, Washington County, MO

The radar

The St Louis radar (KLSX), 23 km from the middle of the area, began a volume at 19:26 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, 7.4 hours before the alert went out and 245 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: 899 J/kg
Mixed-layer CIN: -57 J/kg
Mixed-layer LCL: 885 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 113 m²/s²
0-3 km storm-relative helicity: 103 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 4.4

Open this sounding in Storm Lab

What forecasters said that day

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

NWS St. Louis, MO wrote its last area forecast discussion before this heat advisory went out at Jun 21, 2:18 PM CDT, 6 minutes earlier.

Area forecast discussion, Jun 21, 2:18 PM CDT, 6 minutes before

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Hazardous weather outlook, Jun 21, 4:50 AM CDT, 9 hours 34 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ST LOUIS MO
450 AM CDT SUN JUN 21 2009

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-221000-
GREENE IL-MACOUPIN IL-MONTGOMERY IL-BOND IL-FAYETTE IL-CLINTON IL-
MARION IL-WASHINGTON IL-RANDOLPH IL-ADAMS IL-BROWN IL-PIKE IL-
CALHOUN IL-JERSEY IL-MADISON IL-ST. CLAIR IL-MONROE IL-KNOX-LEWIS-
SHELBY-MARION-MONROE-RALLS-PIKE-BOONE-AUDRAIN-MONITEAU-COLE-OSAGE-
CALLAWAY-MONTGOMERY-LINCOLN-GASCONADE-WARREN-ST. CHARLES-FRANKLIN-
ST. LOUIS-ST. LOUIS CITY-JEFFERSON-CRAWFORD-WASHINGTON-
ST. FRANCOIS-STE. GENEVIEVE-IRON-MADISON-REYNOLDS-
450 AM CDT SUN JUN 21 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN AND
CENTRAL MISSOURI AS WELL AS WEST CENTRAL AND SOUTHWEST ILLINOIS.

.DAY ONE...TODAY AND TONIGHT

THE COMBINATION OF HIGH TEMPERATURES IN THE MID 90S AND HUMID
CONDITIONS WILL CAUSE AFTERNOON HEAT INDICES TO CLIMB TO AROUND
105 DEGREES THIS AFTERNOON IN THE ST. LOUIS METROPOLITAN AREA
WHERE AN EXCESSIVE HEAT WARNING HAS BEEN ISSUED.

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER PARTS OF THE
AREA TODAY. THE STRONGEST STORMS COULD PRODUCE WIND GUSTS UP TO 50
MPH.

MODERATE RIVER FLOODING IS OCCURRING ALONG THE MISSISSIPPI RIVER
AT CHESTER. SEE THE APPROPRIATE FLOOD STATEMENT FOR SPECIFIC
DETAILS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THE HEAT WILL CONTINUE TO BUILD ACROSS THE REGION WITH AFTERNOON
HEAT INDEX READINGS ABOVE 100 DEGREES MOST OF THIS WEEK. THE ST.
LOUIS METROPOLITAN AREA WILL BE HOTTER BECAUSE OF THE URBAN HEAT
ISLAND...WITH AFTERNOON HIGHS IN THE UPPER 90S AND HEAT INDEX
READINGS OF 105 DEGREES OR GREATER. THE EXCESSIVE HEAT WARNING
CONTINUES THROUGH WEDNESDAY EVENING.

ISOLATED THUNDERSTORMS ARE EXPECTED OVER WEST CENTRAL AND SOUTH
CENTRAL ILLINOIS ON MONDAY AFTERNOON. SEVERE WEATHER IS NOT
EXPECTED AT THIS TIME.

MODERATE RIVER FLOODING WILL CONTINUE ALONG THE MISSISSIPPI RIVER
AT CHESTER THROUGH MONDAY. SEE THE APPROPRIATE FLOOD STATEMENT
FOR SPECIFIC DETAILS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT.

&&

FOR A GRAPHICAL VERSION OF THIS INFORMATION SEE OUR
WEBPAGE AT (LOWERCASE)... HTTP://WWW.WEATHER.GOV/LSX/?N=HWO1

BRITT

The office that day

Everything else NWS St. Louis, MO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 21, 3:40 AM CDT	Excessive Heat Warning	LSX	Saint Charles, Saint Louis, City of Saint Louis	7 days

Nearby

Heat Advisories in Missouri, 2009 Heat Advisories in Illinois, 2009 Every heat advisory in 2009

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.