Alert archive / Oklahoma / Severe Thunderstorm Warnings in 1987

Severe Thunderstorm Warning 255, NWS Norman, OK

July 17, 1987Caddo County, Grady County, Oklahoma

NWS Norman, OK issued this severe thunderstorm warning at Jul 17, 1987, 4:54 PM CDT for Caddo County, Grady County, Oklahoma. It was in force for 51 min. 3 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Jul 17, 1987, 4:54 PM CDT (21:54 UTC)
Expired: Jul 17, 1987, 5:45 PM CDT
In force: 51 min
Issued by: NWS Norman, OK
Area: Whole counties

Counties Caddo County, OK, Grady County, OK

The radar

The WSR-88D network and its archive begin in 1991, so there is no radar volume for this alert.

What was reported inside it

Time	Report	Where
Jul 17, 5:15 PM CDT	Thunderstorm Wind 0	Grady, OK
Jul 17, 5:30 PM CDT	Hail 0.75	Caddo, OK
Jul 17, 5:30 PM CDT	Hail 1	Grady, OK

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in. Storm Data before 1996 records only tornadoes, thunderstorm wind and hail.

The nearest sounding before it

Fort Sill, OK (KFSI), launched 12:00Z, 9.9 hours before the alert went out and 55 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: 955 J/kg
Mixed-layer CIN: -8 J/kg
Mixed-layer LCL: 574 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 281 m²/s²
0-3 km storm-relative helicity: 259 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 4.8

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

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.

In the hours before

Local storm report, Jul 17, 4:12 PM CDT, 42 minutes before

STORM REPORT
NATIONAL WEATHER SERVICE OKLAHOMA CITY OK
411 PM CDT FRI JUL 17 1987

TIME    COUNTY         REPORT
408 PM  COMANCHE       WINDS GREATER THAN 70 MPH IN INDIAHOMA.

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 17, 3:20 PM CDT	Severe Thunderstorm Warning	OUN	Comanche, Kiowa	40 min
Jul 17, 3:57 PM CDT	Tornado Warning	OUN	Comanche	33 min
Jul 17, 4:34 PM CDT	Tornado Warning	OUN	Comanche, Kiowa, Tillman	31 min
Jul 17, 5:13 PM CDT	Severe Thunderstorm Warning	OUN	Caddo, Comanche, Grady	47 min
Jul 17, 5:56 PM CDT	Severe Thunderstorm Warning	OUN	Garvin, Grady, McClain	49 min
Jul 17, 6:15 PM CDT	Severe Thunderstorm Warning	OUN	Cleveland, McClain	60 min
Jul 17, 6:37 PM CDT	Severe Thunderstorm Warning	OUN	Pottawatomie	53 min
Jul 17, 6:43 PM CDT	Severe Thunderstorm Warning	OUN	Garvin, Grady	32 min

Nearby

Severe Thunderstorm Warnings in Oklahoma, 1987 Every severe thunderstorm warning in 1987

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive.