Alert archive / Oklahoma / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 113, NWS Norman, OK

May 4, 2001Stephens County, Oklahoma

NWS Norman, OK issued this severe thunderstorm warning at May 4, 2001, 6:24 PM CDT for Stephens County, Oklahoma. It was in force for 51 min. 1 report came from inside the area while it was in force.

The area

The outline the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties, with what was reported inside it.

The facts

Issued: May 4, 2001, 6:24 PM CDT (23:24 UTC)
Expired: May 4, 2001, 7:15 PM CDT
In force: 51 min
Issued by: NWS Norman, OK
Area: Whole counties; the outline is the Mesonet’s reconstruction

County Stephens County, OK

What was reported inside it

Time	Report	Where	Remark
May 4, 7:20 PM CDT	Tornado F0	Amber, OK	This tornado was observed by two storm chasers and developed in a field east of Highway 92, then tracked north-northwest, eventually crossing Highway 92. No damage was observed or reported.

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.

Issued	Product	Office	Lasted
May 4, 2:00 PM CDT	Tornado Watch	SPC	6 hr

The nearest sounding before it

Norman, OK (KOUN), launched 12:00Z, 11.4 hours before the alert went out and 85 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: 225 J/kg
Mixed-layer CIN: -67 J/kg
Mixed-layer LCL: 928 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: 8 m²/s²
0-3 km storm-relative helicity: -10 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WUUS54 KOUN 042326
SVROKC

OKC137-050015-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE NORMAN OK
624 PM CDT FRI MAY 4 2001

THE NATIONAL WEATHER SERVICE IN NORMAN HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  STEPHENS COUNTY IN SOUTHERN OKLAHOMA

* UNTIL 715 PM CDT

* AT 624 PM CDT...DOPPLER RADAR DETECTED A LINE OF SEVERE 
THUNDERSTORMS JUST TO THE WEST AND NORTHWEST OF DUNCAN... MOVING 
EAST AT 25 MPH. 

* LOCATIONS IN THE WARNING INCLUDE BRAY...DUNCAN...EMPIRE CITY AND
  MARLOW

WINDS IN EXCESS OF 70 MPH ARE POSSIBLE WITH THESE STORMS. 

SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES WITH NO ADVANCE WARNING.
MOVE IMMEDIATELY TO A STORM SHELTER... BASEMENT OR STURDY BUILDING IF
A TORNADO IS SIGHTED.

THESE THUNDERSTORMS ARE CAPABLE OF PRODUCING PARTICULARLY DAMAGING
WINDS. MOBILE HOMES AND HIGH PROFILE VEHICLES ARE ESPECIALLY
SUSCEPTIBLE TO HIGH WINDS AND MAY BE OVERTURNED. MOVE TO A STURDY
BUILDING AND STAY AWAY FROM WINDOWS.

LAT...LON 3472 9803 3438 9815 3450 9777 3467 9771

CJS

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 May 4, 2:02 PM CDT, 4 hours 22 minutes earlier.

Area forecast discussion, May 4, 2:02 PM CDT, 4 hours 22 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
202 PM CDT FRI MAY 4 2001

VERY ACTIVE WX PATTERN TO PERSIST ACROSS MUCH OF THE FORECAST AREA
THRU THE WEEKEND.  UPPER LOW TO OUR WEST HAS MOVED ONLY SLOWLY SEWD
THRU THE PAST 24 HRS AND IS NOW LOCATED OVR NERN AZ.  MEANWHILE..
UPPER LOW OVR BAJA HAS BEGUN TO SHEAR OUT AND IS ACCOMPANIED BY AN
80+ KT SPEED MAX NOSING INTO SW TEX ATTM.

HAVE BEEN WATCHING THE SITUATION FOR THIS AFTERNOON/EVENING WITH
INCREASING INTEREST ALL MORNING.  PARAMETERS FOR A SVR WX EPISODE
THIS EVENING APPEAR TO BE COMING TOGETHER ACROSS THE SRN SECTIONS OF
THE FA ATTM. SUBTROPICAL SPEED MAX IS ENHANCING DEEP LAYER
SHEAR..AND AS LOW LEVEL FLOW BACKS THRU THE AFTERNOON SHEAR WILL
ONLY GET BETTER..ESP 0-1KM.  DESPITE WEAKER LAPSE RATES..CAPES ARE
APPROACHING 2000 J/KG WITH LOW BOUNDARY LAYER T/TD SPREADS.  THIS
ENVIRONMENT IS NOT THAT DISSIMILAR TO A FEW DAYS LAST OCTOBER THAT
PRODUCED SEVERAL SMALL TORNADIC SUPERCELLS..AND WUDNT BE SURPRISED
TO SEE SOMETHING SIMILAR TODAY.  SEVERAL CELLS IN NC TEX ARE ALREADY
EXHIBITING LOW LEVEL ROTATION IN EXCESS OF 40 KTS - AND LATEST KFDR
VAD WIND PROFILE LOOKS TO BE VERY SUPPORTIVE OF SUPERCELLS.

EXPECT CONVECTION TO EVOLVE INTO AN MCS THAT WILL SWEEP MUCH OF THE
ERN 2/3 OF THE FA OVERNITE.  SOME LOCALLY HEAVY RAINFALL IS
LIKELY..BUT EXPECT HEAVIEST AMOUNTS TO THE EAST OF LAST NITE.  MUCH
OF CENTRAL OK HAS NOT SEEN MUCH RAIN FOR NEARLY 2 WEEKS AND SHUD BE
ABLE TO HANDLE FARILY DECENT RAINS WITHOUT MUCH TROUBLE..SO DO NOT
PLAN ON A FLASH FLOOD WATCH ATTM.  WILL LIKELY LET WATCH FOR WRN CWA
EXPIRE WITH AFTERNOON PACKAGE ISSUANCE.

MORNING CONVECTION EXPECTED TO MOVE EAST OF THE AREA IN TIME TO
ALLOW RECOVERY ON SAT AFTERNOON..AND AS UPPER SYSTEM BRUSHES ACROSS
INSTABILITY AXIS SAT AFT/EVE..ANOTHER ROUND OF SVR IS LIKELY. /SEE
LATEST SWODY2 FOR DETAILS/ 12Z ETA IS EVEN MORE DEFINITIVE THAN YDAY
IN SWINGING A TRAILING SHORTWAVE TROF INTO THE SRN PLAINS SUN
AFT/EVE..AND THIS LOOKS INCREASINGLY LIKE ROUND 3 FOR SVR AS
FRONT/DRYLINE WILL STILL BE IN THE AREA WITH HEALTHY INSTABILITY YET
AGAIN IN PLACE BY 00Z MON.

FRONT FINALLY LOOKS TO CLEAR THE AREA ON MONDAY WITH LOW LEVEL
RIDGING BUILDING INTO THE AREA.  WE ARE STILL SOMEWHAT SKEPTICAL ON
HOW FAR FRONT WILL BE ABLE TO PUSH SWD SINCE MEDIUM RANGE MODELS ALL
HINT AT SOME SORT OF MID LEVEL TROFFING HANGING IN THE AREA FOR MUCH
OF THE WEEK.  SEEMS AS THOUGH TSTORM CHANCES WILL RETURN TO WRN
SECTIONS THURS/FRI IN WEAK DRYLINE REGIME..AND MAY NEED TO MONITOR
TUES/WED FOR POPS AS WELL IF MOISTURE DOES NOT GET SCOURED OUT
CLEANLY BY FRONT ON MONDAY.
 MILLER

FIRST CUT AT NUMBERS..
OKC   62  77  61  80 /   +  60  70  40
HBR   60  80  58  83 /  60  40  60  40
SPS   61  80  62  84 /   +  60  60  40
GAG   56  80  53  83 /  40  40  60  40
PNC   62  77  61  80 /   +  60  60  40
DUA   64  77  64  79 /  60  80  60  60

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

In the hours before

Special weather statement, May 4, 1:00 PM CDT, 5 hours 24 minutes before

OKZ004>048-050>052-TXZ083>090-042000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
100 PM CDT FRI MAY 4 2001

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT ACROSS PORTIONS OF CENTRAL AND SOUTHERN OKLAHOMA AND WESTERN
NORTH TEXAS. THE SLIGHT RISK AREA WILL BE SOUTH AND WEST OF A LINE
FROM SAYRE... TO CLINTON... TO OKLAHOMA CITY... TO MADILL. ALTHOUGH
LARGE HAIL AND STRONG WINDS WILL BE THE PRIMARY THREATS... ISOLATED
TORNADOS WILL ALSO BE POSSIBLE. THERE IS ALSO A POSSIBILITY OF HEAVY
RAINFALL ACROSS WESTERN OKLAHOMA AND WESTERN NORTH TEXAS THROUGH
TONIGHT.

AN UPPER LEVEL LOW PRESSURE AREA NEAR THE FOUR CORNERS AREA WILL
MOVE SLOWLY EAST THIS AFTERNOON AND TONIGHT. DISTURBANCES ALOFT
ASSOCIATED WITH THIS FEATURE WILL MOVE OVER TEXAS AND OKLAHOMA
THROUGH TONIGHT AND CONTINUE THE PERIODS OF SHOWERS AND
THUNDERSTORMS.

AS AN UPPER DISTURBANCE APPROACHES THE AREA LATE THIS AFTERNOON AND
EVENING... THE VERTICAL WIND PROFILE WILL BECOME MORE FAVORABLE FOR
SEVERE THUNDERSTORMS. EXTENSIVE CLOUD COVER ACROSS THE REGION DURING
MUCH OF THE DAY HAS LIMITED THE INSTABILITY. HOWEVER... INCREASING
LOW LEVEL MOISTURE...COMBINED WITH A FEW BREAKS IN THE CLOUDS LATER
THIS AFTERNOON... MAY PROVIDE ADEQUATE INSTABILITIES TO SUPPORT A
FEW SEVERE THUNDERSTORMS.

MEANWHILE... THE PERSISTENCE OF SHOWERS AND THUNDERSTORMS ACROSS
WESTERN PORTIONS OF OKLAHOMA AND NORTH TEXAS WILL PRODUCE SCATTERED
HEAVY RAINS.

&&

EMERGENCY MANAGERS AND SPOTTER GROUPS IN SOUTHERN OKLAHOMA AND
WESTERN NORTH TEXAS SHOULD BE PREPARED FOR POSSIBLE SEVERE WEATHER
OPERATIONS THIS AFTERNOON AND TONIGHT.

CJS

Local storm report, May 4, 4:15 PM CDT, 2 hours 9 minutes before

LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
415 PM CDT FRI MAY 04 2001

TIME (CDT) .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0405 PM    GRANDFIELD                OK   TORNADO
05/04/01   TILLMAN                        PD RPTD BRIEF TOUCHDOWN ON
                                          WEST SIDE OF TOWN. TREE AND
                                          POWER LINE DAMAGE.

TL

Local storm report, May 4, 5:19 PM CDT, 1 hour 5 minutes before

LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
519 PM CDT FRI MAY 4 2001

TIME (CDT) .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0512 PM    5 N COOKIETOWN            OK   .88 INCH HAIL
05/04/01   COTTON                         HAM RADIO REPORT

LANE

Local storm report, May 4, 5:31 PM CDT, 53 minutes before

LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
531 PM CDT FRI MAY 4 2001

TIME (CDT) .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0300 PM    3 NE OKLAUNION            TX   TORNADO
05/04/01   WILBARGER                      BRIEF TOUCHDOWN
                                          SEVERAL TREES UPROOTED
                                          SHED DESTROYED
  b                                        REPORTED BY VERNON FIRE

LANE

Local storm report, May 4, 6:07 PM CDT, 17 minutes before

LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
607 PM CDT FRI MAY 4 2001

TIME (CDT) .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0536 PM    3 SE GERONIMO             OK   TORNADO
05/04/01   COMANCHE                       BRIEF TOUCHDOWN
                                          HAM RADIO REPORT

0548 PM    4 SW PUMPKIN CENTER       OK   TORNADO
05/04/01   COMANCHE                       MULTI-VORTEX TORNADO
                                          REPORTED BY BROADCAST
                                          MEDIA

0600 PM    HULEN                     OK   80 MPH WIND GUST
05/04/01   COTTON                         (ESTIMATED)
                                          HAM RADIO REPORT

LANE

The office that day

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

Issued	Product	Office	Counties	Lasted
May 4, 4:12 PM CDT	Tornado Warning	OUN	Cotton	33 min
May 4, 4:45 PM CDT	Tornado Warning	OUN	Cotton	30 min
May 4, 5:12 PM CDT	Tornado Warning	OUN	Cotton	33 min
May 4, 5:30 PM CDT	Tornado Warning	OUN	Comanche	30 min
May 4, 5:57 PM CDT	Tornado Warning	OUN	Comanche, Stephens	33 min
May 4, 6:07 PM CDT	Severe Thunderstorm Warning	OUN	Grady	38 min
May 4, 6:43 PM CDT	Severe Thunderstorm Warning	OUN	Grady	47 min
May 4, 6:49 PM CDT	Severe Thunderstorm Warning	OUN	Jefferson	26 min

Nearby

Severe Thunderstorm Warnings in Oklahoma, 2001 Every severe thunderstorm warning in 2001

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.