Alert archive / Oklahoma / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 166, NWS Norman, OK

April 26, 1999Cleveland County, McClain County, Oklahoma

NWS Norman, OK issued this severe thunderstorm warning at Apr 26, 1999, 5:14 PM CDT for Cleveland County, McClain County, Oklahoma. It was in force for 31 min. 2 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
Apr 26, 1999, 5:14 PM CDT (22:14 UTC)
Expired
Apr 26, 1999, 5:45 PM CDT
In force
31 min
Issued by
NWS Norman, OK
Area
Whole counties; the outline is the Mesonet’s reconstruction

Counties Cleveland County, OK, McClain County, OK

The radar

The Norman radar (KTLX), 27 km from the middle of the area, began a volume at 22:17 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.

What was reported inside it

TimeReportWhereRemark
Apr 26, 5:20 PM CDTHail 0.75Purcell, OK
Apr 26, 5:35 PM CDTHail 1Lexington, 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.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Apr 26, 3:30 PM CDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Norman, OK (KOUN), launched 12:00Z, 10.2 hours before the alert went out and 13 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, Norman, OK at 12:00Z on 1999-04-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 518 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, Norman, OK at 12:00Z on 1999-04-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 58 square meters per square second.19395878Sfc1 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
518 J/kg
Mixed-layer CIN
-59 J/kg
Mixed-layer LCL
644 m above ground
0-6 km bulk shear
46 kt
0-1 km storm-relative helicity
58 m²/s²
0-3 km storm-relative helicity
54 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5

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.

NWS Norman, OK wrote its last area forecast discussion before this severe thunderstorm warning went out at Apr 26, 3:30 PM CDT, 1 hour 44 minutes earlier.

Area forecast discussion, Apr 26, 3:30 PM CDT, 1 hour 44 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
330 PM CDT MON APR 26 1999

MESONET INDICATES NUMEROUS BOUNDARIES OVER THE STATE WHICH WILL ACT
AS TRIGGERS FOR CONVECTIVE DEVELOPMENT THIS AFTERNOON INTO EARLY
EVENING. MAIN OUTFLOW BOUNDARY RUNS FROM FREEDOM TO TALOGA TO BINGER
THEN EAST TO NORMAN TO SEMINOLE. AIR TO THE NORTH AND EAST OF
BOUNDARY APPEARS TO HAVE RECOVERED LESS DURING THE DAY SINCE RAIN
OCCURRED INTO EARLY AFTERNOON OVER NORTH CENTRAL ZONES. A SECOND
BOUNDARY RUNS FROM CHICASHA TO DUNCAN TO WAURIKA WHICH HAS A WEAK
DRYLINE TYPE APPEARANCE. BEST CELLS APPEAR TO BE FIRING NEAR TRIPLE
POINT OF DRYLINE AND OUTFLOW BOUNDARY. FEEL ANY CONVECTION WILL
BRING MAINLY A HAIL THREAT WITH GUSTY WINDS A SECONDARY THREAT.
CELLS WILL DIMINISH AT SUNSET.

OTHERWISE...MODELS ARE FAIRLY SIMILAR IN SHORT TERM WITH MOVING
SURFACE LOW FROM OKLAHOMA SLOWLY INTO MISSOURI AND STALLING THERE.
SHORT WAVE RIDGE ALOFT BUILDS IN BEHIND CURRENT SHORTWAVE RESULTING
IN WEAK SURFACE RIDGING OVER THE STATE...MAKING FOR A SETTLED TWO
DAY PERIOD.

IN EXTENDED...MRF/CANADIAN/ECMWF KEEP NEXT CUTOFF JUST WEST WITH
HINT OF UPPER DIFLUENT/POSSIBLY DIVERGENT FLOW OVER OR JUST TO THE
WEST OF CWA. UNCERTAIN ABOUT HOW MUCH MOISTURE WILL BE AVAILABLE FOR
PRECIP IN THE EXTENDED SINCE MODELS INDICATE LARGE SURFACE HIGH WILL
TEND TO KEEP EAST TO SOUTHEAST RECYCLED FLOW IN LOWER LAYERS.  KEPT
A CHANCE OF PRECIP IN THE EXTENDED EACH DAY. WITH LITTLE TEMPERATURE
CHANGE.

33 / D FLOYD

.OUN...
OK...NONE
TX...NONE.

In the hours before

Local storm report, Apr 26, 3:34 PM CDT, 1 hour 40 minutes before
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Local storm report, Apr 26, 3:34 PM CDT, 1 hour 40 minutes before
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Local storm report, Apr 26, 3:43 PM CDT, 1 hour 31 minutes before
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Local storm report, Apr 26, 3:43 PM CDT, 1 hour 31 minutes before
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Local storm report, Apr 26, 5:01 PM CDT, 13 minutes before
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Local storm report, Apr 26, 5:01 PM CDT, 13 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Apr 26, 9:11 AM CDTFlash Flood WarningOUNHughes, Pontotoc, Pottawatomie, Seminole3 hr
Apr 26, 9:11 AM CDTFlash Flood WarningOUNCoal3 hr
Apr 26, 3:19 PM CDTSevere Thunderstorm WarningOUNGrady, McClain41 min
Apr 26, 3:54 PM CDTSevere Thunderstorm WarningOUNCleveland, McClain51 min
Apr 26, 4:19 PM CDTSevere Thunderstorm WarningOUNPottawatomie41 min
Apr 26, 4:40 PM CDTSevere Thunderstorm WarningOUNCanadian, Grady35 min
Apr 26, 4:46 PM CDTSevere Thunderstorm WarningOUNCleveland, McClain29 min
Apr 26, 5:21 PM CDTSevere Thunderstorm WarningOUNSeminole24 min
Apr 26, 5:42 PM CDTSevere Thunderstorm WarningOUNHughes, Pontotoc, Seminole33 min
Apr 26, 5:48 PM CDTSevere Thunderstorm WarningOUNCleveland, McClain, Pottawatomie42 min
Apr 26, 5:56 PM CDTFlash Flood WarningOUNSeminole3 hr
Apr 26, 6:14 PM CDTSevere Thunderstorm WarningOUNHughes46 min
Apr 26, 6:31 PM CDTSevere Thunderstorm WarningOUNDewey, Major34 min

Nearby

Severe Thunderstorm Warnings in Oklahoma, 1999Every severe thunderstorm warning in 1999

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; radar from the NEXRAD Level II archive.