Alert archive / Missouri / Special Weather Statements in 2018

Special Weather Statement, NWS St. Louis, MO

May 20, 2018Knox County, Missouri

NWS St. Louis, MO issued this special weather statement at May 20, 2018, 1:47 AM CDT for Knox County, Missouri. It was in force for 43 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: May 20, 2018, 1:47 AM CDT (06:47 UTC)
Expired: May 20, 2018, 2:30 AM CDT
In force: 43 min
Issued by: NWS St. Louis, MO

County Knox County, MO

The radar

The Quad Cities radar (KDVN), 197 km from the middle of the area, began a volume at 06:47 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

Davenport, (KDVN), launched 00:00Z, 6.8 hours before the alert went out and 202 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: 98 J/kg
Mixed-layer CIN: -38 J/kg
Mixed-layer LCL: 1692 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 23 m²/s²
0-3 km storm-relative helicity: 40 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement 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 special weather statement went out at May 19, 10:43 PM CDT, 3 hours 4 minutes earlier.

Area forecast discussion, May 19, 10:43 PM CDT, 3 hours 4 minutes before

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Hazardous weather outlook, May 19, 4:36 PM CDT, 9 hours 11 minutes before

Hazardous Weather Outlook
National Weather Service Saint Louis MO
436 PM CDT Sat May 19 2018

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-201200-
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-Saint Clair IL-Monroe IL-Knox MO-
Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls MO-Pike MO-Boone MO-
Audrain MO-Moniteau MO-Cole MO-Osage MO-Callaway MO-Montgomery MO-
Lincoln MO-Gasconade MO-Warren MO-Saint Charles MO-Franklin MO-
Saint Louis MO-Saint Louis City MO-Jefferson MO-Crawford MO-
Washington MO-Saint Francois MO-Sainte Genevieve MO-Iron MO-
Madison MO-Reynolds MO-
436 PM CDT Sat May 19 2018

This hazardous weather outlook is for portions of eastern and
central Missouri as well as west central and southwest Illinois.

.DAY ONE...Tonight

A few severe thunderstorms will be tonight across central and
eastern Missouri as well as west central Illinois. Damaging winds
and large hail will be the main threats with these storms.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Strong to severe thunderstorms are possible again Sunday and
Sunday evening.

The chance of thunderstorms will continue each day through
Friday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report any severe weather to the
National Weather Service.

Tilly

In the hours before

Local storm report, May 19, 8:00 PM CDT, 5 hours 47 minutes before

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Special weather statement, May 19, 8:15 PM CDT, 5 hours 32 minutes before

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Local storm report, May 19, 8:47 PM CDT, 5 hours before

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Special weather statement, May 20, 1:47 AM CDT, 0 minutes before

Special Weather Statement
National Weather Service St Louis MO
147 AM CDT SUN MAY 20 2018

MOZ018-200730-
Knox MO-
147 AM CDT SUN MAY 20 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN KNOX COUNTY UNTIL 230 AM
CDT...

At 146 AM CDT, Doppler radar was tracking a strong thunderstorm 9
miles southeast of Greentop, moving east at 30 mph.

Nickel size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations impacted include...
Colony, Greensburg and Baring.

LAT...LON 4030 9195 4020 9195 4023 9235 4030 9235
TIME...MOT...LOC 0646Z 270DEG 25KT 4028 9241

Britt

The office that day

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

Issued	Product	Office	Counties	Lasted
May 19, 7:39 PM CDT	Special Weather Statement	LSX	Osage	66 min
May 19, 8:15 PM CDT	Special Weather Statement	LSX	Crawford, Gasconade	75 min
May 20, 8:40 AM CDT	Special Weather Statement	LSX	Cole, Osage	65 min
May 20, 9:05 AM CDT	Severe Thunderstorm Warning	LSX	Gasconade, Osage	40 min
May 20, 9:23 AM CDT	Severe Thunderstorm Warning	LSX	Crawford, Gasconade	22 min
May 20, 9:44 AM CDT	Severe Thunderstorm Warning	LSX	Franklin, Gasconade, Warren	33 min
May 20, 6:16 AM CDT	Severe Thunderstorm Warning	LSX	Bond, Macoupin, Madison, Montgomery	46 min
May 20, 6:35 AM CDT	Severe Thunderstorm Warning	LSX	Bond, Fayette, Montgomery	40 min
May 20, 7:12 AM CDT	Special Weather Statement	LSX	Fayette	33 min

Nearby

Special Weather Statements in Missouri, 2018 Every special weather statement in 2018

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.