Alert archive / Oklahoma / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 722, NWS Norman, OK

September 27, 2020Atoka County, Coal County, Johnston County, Oklahoma

NWS Norman, OK issued this severe thunderstorm warning at Sep 27, 2020, 8:48 PM CDT for Atoka County, Coal County, Johnston County, Oklahoma. It was in force for 42 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: Sep 27, 2020, 8:48 PM CDT (01:48 UTC)
Expired: Sep 27, 2020, 9:30 PM CDT
In force: 42 min
Issued by: NWS Norman, OK
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Atoka County, OK, Coal County, OK, Johnston County, OK

The radar

The Norman radar (KTLX), 133 km from the middle of the area, began a volume at 01:48 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

Fort Worth, TX (KFWD), launched 00:00Z, 1.8 hours before the alert went out and 198 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: 2643 J/kg
Mixed-layer CIN: -80 J/kg
Mixed-layer LCL: 1322 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 132 m²/s²
0-3 km storm-relative helicity: 248 m²/s²
Significant tornado parameter: 1.2
Supercell composite: 17.2

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 Norman, OK wrote its last area forecast discussion before this severe thunderstorm warning went out at Sep 27, 6:10 PM CDT, 2 hours 38 minutes earlier.

Area forecast discussion, Sep 27, 6:10 PM CDT, 2 hours 38 minutes before

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Hazardous weather outlook, Sep 27, 6:54 PM CDT, 1 hour 54 minutes before

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In the hours before

Local storm report, Sep 27, 5:33 PM CDT, 3 hours 15 minutes before

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Local storm report, Sep 27, 5:38 PM CDT, 3 hours 10 minutes before

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The office that day

Everything else NWS Norman, OK issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 27, 7:00 PM CDT	Special Weather Statement	OUN	Pontotoc	30 min
Sep 27, 7:30 PM CDT	Special Weather Statement	OUN	Pontotoc	30 min
Sep 27, 8:02 PM CDT	Special Weather Statement	OUN	Pontotoc	28 min
Sep 27, 8:31 PM CDT	Special Weather Statement	OUN	Coal	44 min
Sep 27, 9:21 PM CDT	Severe Thunderstorm Warning	OUN	Atoka, Bryan	54 min

Nearby

Severe Thunderstorm Warnings in Oklahoma, 2020 Every severe thunderstorm warning 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.