Alert archive / Oklahoma / Severe Thunderstorm Warnings in 1997

Severe Thunderstorm Warning 82, NWS Tulsa, OK

April 20, 1997Okmulgee County, Oklahoma

NWS Tulsa, OK issued this severe thunderstorm warning at Apr 20, 1997, 6:33 PM CDT for Okmulgee County, Oklahoma. It was in force for 42 min. 1 report 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 20, 1997, 6:33 PM CDT (23:33 UTC)
Expired: Apr 20, 1997, 7:15 PM CDT
In force: 42 min
Issued by: NWS Tulsa, OK
Area: Whole counties

County Okmulgee County, OK

The radar

The Tulsa radar (KINX), 69 km from the middle of the area, began a volume at 23:35 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

Time	Report	Where	Remark
Apr 20, 6:40 PM CDT	Hail 0.75	Morris, 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 nearest sounding before it

Norman, OK (KOUN), launched 12:00Z, 11.6 hours before the alert went out and 138 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: 1896 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 37 m²/s²
0-3 km storm-relative helicity: 77 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 
TTAA00 KTUL 202335 RRA
SVRTUL
OKC111-210015-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE TULSA OK
633 PM CDT SUN APR 20 1997
 
THE NATIONAL WEATHER SERVICE IN TULSA HAS ISSUED A
SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL  715 PM CDT
FOR PEOPLE IN THE FOLLOWING LOCATION...
 
IN NORTHEAST OKLAHOMA
 
   ...EASTERN OKMULGEE COUNTY
 
AT 630 PM...RADAR SHOWED A SEVERE THUNDERSTORM 4 MILES NORTHEAST OF THE
CITY OF OKMULGEE. THE STORM WAS MOVING EAST AT 30 MPH. THE STORM
WILL MOVE INTO EASTERN OKMULGEE COUNTY TO THE NORTH OF ERAM AND
MORRIS.
 
HAIL TO THE SIZE OF DIMES AND WIND GUSTS TO 60 MPH CAN BE EXPECTED
IN THE WARNED AREA.
 
DURING THE STORM MOVE INDOORS AND STAY AWAY FROM WINDOWS.
TO PROTECT YOURSELF FROM LIGHTNING DO NOT USE THE TELEPHONE
OR HAND HELD ELECTRICAL APPLIANCES...UNLESS IN AN EMERGENCY.
MOTORISTS SHOULD BE ALERT FOR WATER ON ROADWAYS AND NEVER
DRIVE ONTO A FLOODED ROAD.
 
KEEP TUNED TO THISZ STATION FOR THE LATEST WEATHER BULLETINS.

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 Tulsa, OK wrote its last area forecast discussion before this severe thunderstorm warning went out at Apr 20, 3:36 PM CDT, 2 hours 57 minutes earlier.

Area forecast discussion, Apr 20, 3:36 PM CDT, 2 hours 57 minutes before

EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
335 PM CDT SUN APR 20 1997

SFC LO CONTG TO DEEPEN THRU THE AFTN AND LTCD JUST NW EMP KS AT 20Z.
SFC FNT/TROF EXTNDG FRM LO DOWN TO OSAGE/PAWNEE CONTIES IN NWRN PART
OF FA...THEN ON TWRD S-CNTL OK.  GUSTY SWLY SFC WNDS CONTG OUT AHD
OF BNDRY WITH DEWPTS IN THE 50S.  AMS HAS CONTD TO BCM INCRSLY
UNSTBL..BUT MOISTR RMNS SHALLOW.  MAIN THREAT OF BIG STMS THIS EVNG
STILL APPEARS TO BE SE KS/SW MO CLOSER TO SFC LO WHICH COULD THEN
AFFECT FAR NE OK AND NW AR.  WL CARRY HIGHEST POPS THOSE LCTNS...BUT
WL CONT TO MAINTAIN AT LEAST LO POPS ACRS REMAINDER OF FA AHD OF
ADVANCING FNT/TROF.  SFC LO WL CONT TO TRACK TO THE ESE OR SE ENDING
THREAT OF PRECIP MOST AREAS BY LATE EVNG.  HWVR SRN PORTION OF FNT
COULD HANG UP OVR SRN ZNS.

THRU REMAINING PDS UNSETTLED WX WL CONT THRU MUCH OF THE WEEK
AS WL RMN BASICALLY IN A RATHER QUICK MOVG NWLY FLOW PTRN.  PTRN
WL BE A LTL LESS AMPLIFIED ACRS THE COUNTRY...BUT WL STILL CONT TO
SEE SERIES OF S/WVS MOVG THRU THE PLNS WITH TIMING PBLMS BTWN
VARIOUS MDLS.  FOR NOW WL TEND TO BROADBRUSH SLGT CHC/CHC POPS
THRU LATER PDS.

PRELIM NUMBERS:  TUL 53/73/51/70 2233  BVO 49/73/48/70 1233
                 FSM 54/75/50/71 4233  FYV 49/68/47/68 5233
...04...         MLC 54/77/51/71 3233  IDB 57/76/50/72 4233
                                       BYV 47/68/45/68 5233
.TUL...
OK...NONE.
AR...NONE.

In the hours before

Special weather statement, Apr 20, 1:00 PM CDT, 5 hours 33 minutes before

OKZ054>076-ARZ001-002-010-011-019-029-211200-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
100 PM CDT SUN APR 20 1997

ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE LATE THIS AFTERNOON AND
EARLY TONIGHT ACROSS PARTS OF NORTHEAST OKLAHOMA AND NORTHWEST
ARKANSAS.  THIS RISK OF SEVERE STORMS IS ALONG AND NORTH OF A LINE
FROM MULBERRY ARKANSAS TO TAHLEQUAH TO SOUTH COFFEYVILLE OKLAHOMA.

AT NOON A NEARLY STATIONARY FRONT EXTENDED FROM HUNTSVILLE ARKANSAS
TO NEAR JOPLIN TO NEAR A SURFACE LOW PRESSURE CENTER JUST NORTHWEST
OF EMPORIA KANSAS.  THE ATMOSPHERE ALONG AND JUST SOUTH OF THIS
FRONT WILL BECOME INCREASINGLY UNSTABLE THIS AFTERNOON AS LOW-LEVEL
MOISTURE FLOWS INTO THE FRONT AND TEMPERATURES RISE TO NEAR 80.

THUNDERSTORMS ARE EXPECTED TO DEVELOP IN SOUTHEAST KANSAS BETWEEN
3 AND 5PM TODAY AS THE SURFACE LOW TRACKS TOWARD JOPLIN.  THESE
STORMS ARE EXPECTED TO BECOME SEVERE.  FORECAST WIND PROFILES AND
STORM MOTIONS SUGGEST THAT THE STRONGER STORMS MAY BECOME
SUPERCELLS WITH LARGE HAIL...DAMAGING WIND AND A RISK OF A TORNADO.
ONCE DEVELOPED THE STORMS WILL TRAVEL SOUTHEAST NEAR 30 MPH TOWARD
SOUTHWEST MISSOURI.  THESE STORMS MAY DEVELOP INTO EXTREME
NORTHEAST OKLAHOMA AND FAR NORTHWEST ARKANSAS DURING THE EVENING.
ANY SOUTHWARD SHIFT OF THE TRACK OF THE SURFACE LOW WOULD INCREASE
THE RISK OF SEVERE WEATHER IN NORTHEAST OKLAHOMA AND NORTHWEST
ARKANSAS.

EMERGENCY MANAGEMENT AGENCIES AND SKYWARN GROUPS IN THE RISK AREA
SHOULD BE READY FOR ACTIVATION AFTER 3PM.  THE THREAT FOR SEVERE
WEATHER SHOULD END IN THE RISK AREA AFTER 10PM AS TEMPERATURES COOL
AND THE MAIN UPPER SUPPORT FOR THE STORMS SHIFTS TO THE EAST.

IN ADDITION...A WEAK WIND SHIFT LINE FROM CENTRAL KANSAS INTO
SOUTHWEST OKLAHOMA AT EARLY AFTERNOON WILL SWEEP ACROSS THE REGION
DURING THE NEXT 18 HOURS.  SOUTHERLY WINDS WILL SHIFT TO
NORTHWESTERLY AS IT PASSES.  LOW-LEVEL MOISTURE IS EXPECTED TO BE
QUITE SHALLOW AS THIS FEATURE MOVES INTO NORTHEAST OKLAHOMA THIS
AFTERNOON AND THUNDERSTORM DEVELOPMENT IS NOT LIKELY.  AS THIS
FRONT REACHES WEST CENTRAL ARKANSAS AND SOUTHEAST OKLAHOMA TONIGHT
THERE IS A SOMEWHAT BETTER CHANCE OF STORM DEVELOPMENT...BUT WEAK
INSTABILITY IN THE MIDDLE OF THE NIGHT AND LACK OF STRONG LIFT
ALONG THE FRONT SUGGESTS ANY STORMS THAT MIGHT FORM SHOULD REMAIN
BELOW SEVERE LEVELS...HOWEVER EMERGENCY MANAGERS AND SKYWARN GROUPS
IN SOUTHEAST OKLAHOMA AND WEST CENTRAL ARKANSAS SHOULD MONITOR THE
LATEST INFORMATION FOR POSSIBLE UPDATES.

Special weather statement, Apr 20, 1:04 PM CDT, 5 hours 29 minutes before

OKZ054>076-ARZ001-002-010-011-019-029-211200-

EASTERN OKLAHOMA/NORTHWEST ARKANSAS THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE TULSA OK
100 PM CDT SUN APR 20 1997

ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE LATE THIS AFTERNOON AND
EARLY TONIGHT ACROSS PARTS OF NORTHEAST OKLAHOMA AND NORTHWEST
ARKANSAS.  THIS RISK OF SEVERE STORMS IS ALONG AND NORTH OF A LINE
FROM MULBERRY ARKANSAS TO TAHLEQUAH TO SOUTH COFFEYVILLE OKLAHOMA.

AT NOON A NEARLY STATIONARY FRONT EXTENDED FROM HUNTSVILLE ARKANSAS
TO NEAR JOPLIN TO NEAR A SURFACE LOW PRESSURE CENTER JUST NORTHWEST
OF EMPORIA KANSAS.  THE ATMOSPHERE ALONG AND JUST SOUTH OF THIS
FRONT WILL BECOME INCREASINGLY UNSTABLE THIS AFTERNOON AS LOW-LEVEL
MOISTURE FLOWS INTO THE FRONT AND TEMPERATURES RISE TO NEAR 80.

THUNDERSTORMS ARE EXPECTED TO DEVELOP IN SOUTHEAST KANSAS BETWEEN
3 AND 5PM TODAY AS THE SURFACE LOW TRACKS TOWARD JOPLIN.  THESE
STORMS ARE EXPECTED TO BECOME SEVERE.  FORECAST WIND PROFILES AND
STORM MOTIONS SUGGEST THAT THE STRONGER STORMS MAY BECOME
SUPERCELLS WITH LARGE HAIL...DAMAGING WIND AND A RISK OF A TORNADO.
ONCE DEVELOPED THE STORMS WILL TRAVEL SOUTHEAST NEAR 30 MPH TOWARD
SOUTHWEST MISSOURI.  THESE STORMS MAY DEVELOP INTO EXTREME
NORTHEAST OKLAHOMA AND FAR NORTHWEST ARKANSAS DURING THE EVENING.
ANY SOUTHWARD SHIFT OF THE TRACK OF THE SURFACE LOW WOULD INCREASE
THE RISK OF SEVERE WEATHER IN NORTHEAST OKLAHOMA AND NORTHWEST
ARKANSAS.

EMERGENCY MANAGEMENT AGENCIES AND SKYWARN GROUPS IN THE RISK AREA
SHOULD BE READY FOR ACTIVATION AFTER 3PM.  THE THREAT FOR SEVERE
WEATHER SHOULD END IN THE RISK AREA AFTER 10PM AS TEMPERATURES COOL
AND THE MAIN UPPER SUPPORT FOR THE STORMS SHIFTS TO THE EAST.

IN ADDITION...A WEAK WIND SHIFT LINE FROM CENTRAL KANSAS INTO
SOUTHWEST OKLAHOMA AT EARLY AFTERNOON WILL SWEEP ACROSS THE REGION
DURING THE NEXT 18 HOURS.  SOUTHERLY WINDS WILL SHIFT TO
NORTHWESTERLY AS IT PASSES.  LOW-LEVEL MOISTURE IS EXPECTED TO BE
QUITE SHALLOW AS THIS FEATURE MOVES INTO NORTHEAST OKLAHOMA THIS
AFTERNOON AND THUNDERSTORM DEVELOPMENT IS NOT LIKELY.  AS THIS
FRONT REACHES WEST CENTRAL ARKANSAS AND SOUTHEAST OKLAHOMA TONIGHT
THERE IS A SOMEWHAT BETTER CHANCE OF STORM DEVELOPMENT...BUT WEAK
INSTABILITY IN THE MIDDLE OF THE NIGHT AND LACK OF STRONG LIFT
ALONG THE FRONT SUGGESTS ANY STORMS THAT MIGHT FORM SHOULD REMAIN
BELOW SEVERE LEVELS...HOWEVER EMERGENCY MANAGERS AND SKYWARN GROUPS
IN SOUTHEAST OKLAHOMA AND WEST CENTRAL$ ARKANSAS SHOULD MONITOR THE
LATEST INFORMATION FOR POSSIBLE UPDATES.

Local storm report, Apr 20, 6:01 PM CDT, 32 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TULSA OK
601 PM CDT SUN APR 20 1997

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

0538 PM    2 SW WELCH                OK   .88 INCH HAIL
04/20/97   CRAIG

0550 PM    NARCISSA                  OK   .88 INCH HAIL
04/20/97   OTTAWA

0554 PM    3 S MIAMI                 OK   1 INCH HAIL
04/20/97   OTTAWA

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 20, 5:26 PM CDT	Severe Thunderstorm Warning	TSA	Craig	49 min
Apr 20, 5:37 PM CDT	Severe Thunderstorm Warning	TSA	Ottawa	38 min
Apr 20, 6:08 PM CDT	Severe Thunderstorm Warning	TSA	Ottawa	37 min
Apr 20, 6:45 PM CDT	Severe Thunderstorm Warning	TSA	Muskogee	45 min
Apr 20, 6:49 PM CDT	Severe Thunderstorm Warning	TSA	Wagoner	41 min

Nearby

Severe Thunderstorm Warnings in Oklahoma, 1997 Every severe thunderstorm warning in 1997

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.