Alert archive / Missouri / Heat Advisories in 2007

Heat Advisory 1, NWS St. Louis, MO

August 20, 2007City of Saint Louis, Missouri

NWS St. Louis, MO issued this heat advisory at Aug 20, 2007, 3:54 PM CDT for City of Saint Louis, Missouri. It took effect at Aug 21, 2007, 12:00 PM CDT. It was in force for 4 hr.

The area

The counties it named.

The facts

Issued
Aug 20, 2007, 3:54 PM CDT (20:54 UTC)
In effect from
Aug 21, 2007, 12:00 PM CDT
Expired
Aug 21, 2007, 3:46 PM CDT
In force
4 hr
Issued by
NWS St. Louis, MO

County City of Saint Louis, MO

The radar

The St Louis radar (KLSX), 43 km from the middle of the area, began a volume at 20:54 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

Springfield, MO (KSGF), launched 12:00Z, 8.9 hours before the alert went out and 370 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-pSkew-T log-p diagram, Springfield, MO at 12:00Z on 2007-08-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 671 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Springfield, MO at 12:00Z on 2007-08-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 225 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
671 J/kg
Mixed-layer CIN
-30 J/kg
Mixed-layer LCL
560 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
225 m²/s²
0-3 km storm-relative helicity
254 m²/s²
Significant tornado parameter
0.6
Supercell composite
8.4

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 Aug 20, 3:29 PM CDT, 25 minutes earlier.

Area forecast discussion, Aug 20, 3:29 PM CDT, 25 minutes before
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Hazardous weather outlook, Aug 20, 6:11 AM CDT, 9 hours 43 minutes before
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Nearby

Heat Advisories in Missouri, 2007Every heat advisory 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.