Alert archive / Missouri / Frost Advisories in 2020

Frost Advisory 7, NWS St. Louis, MO

October 15, 202029 counties in Missouri; 17 counties in Illinois

NWS St. Louis, MO issued this frost advisory at Oct 15, 2020, 3:35 AM CDT for 29 counties in Missouri; 17 counties in Illinois. It took effect at Oct 16, 2020, 3:00 AM CDT. It was in force for 6 hr.

The area

The counties it named.

The facts

Issued: Oct 15, 2020, 3:35 AM CDT (08:35 UTC)
In effect from: Oct 16, 2020, 3:00 AM CDT
Expired: Oct 16, 2020, 9:00 AM CDT
In force: 6 hr
Issued by: NWS St. Louis, MO

All 46 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, Madison County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Pike County, IL, Randolph County, IL, Saint Clair County, IL, Washington County, IL, Audrain County, MO, Boone County, MO, Callaway County, MO, City of Saint Louis, 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 Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Shelby County, MO, Warren County, MO, Washington County, MO

The radar

The St Louis radar (KLSX), 18 km from the middle of the area, began a volume at 08:38 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, 8.6 hours before the alert went out and 241 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 3124 m above ground
0-6 km bulk shear: 66 kt
0-1 km storm-relative helicity: 391 m²/s²
0-3 km storm-relative helicity: 441 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 frost 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 frost advisory went out at Oct 15, 12:57 AM CDT, 2 hours 38 minutes earlier.

Area forecast discussion, Oct 15, 12:57 AM CDT, 2 hours 38 minutes before

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Hazardous weather outlook, Oct 14, 6:49 PM CDT, 8 hours 46 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Oct 15, 2:08 PM CDT	Freeze Warning	LSX	Crawford, Franklin, Gasconade, Iron, Jefferson, Madison and 4 more	19 hr

Nearby

Frost Advisories in Missouri, 2020 Frost Advisories in Illinois, 2020 Every frost advisory in 2020

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.