Alert archive / Oklahoma / Severe Thunderstorm Warnings in 1999
Severe Thunderstorm Warning 101, NWS Tulsa, OK
NWS Tulsa, OK issued this severe thunderstorm warning at Apr 21, 1999, 10:11 PM CDT for Pawnee County, Oklahoma. It was in force for 64 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
- Apr 21, 1999, 10:11 PM CDT (03:11 UTC)
- Expired
- Apr 21, 1999, 11:15 PM CDT
- In force
- 64 min
- Issued by
- NWS Tulsa, OK
- Area
- Whole counties; the outline is the Mesonet’s reconstruction
County Pawnee County, OK
The radar
The Norman radar (KTLX), 116 km from the middle of the area, began a volume at 03:11 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 21, 10:45 PM CDT | Hail 0.88 | Pawnee, OK | There were two reports of nickel-sized hail near Pawnee...one report from in Pawnee and the other report from 5 miles north of Pawnee. An unknown source indicated golfball-sized hail just north of Pawnee. Additionally, 50 mph winds accompanied this storm. |
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 |
|---|---|---|---|
| Apr 21, 6:00 PM CDT | Tornado Watch | SPC | 6 hr |
The nearest sounding before it
Norman, OK (KOUN), launched 00:00Z, 3.2 hours before the alert went out and 131 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.
- Mixed-layer CAPE
- 1907 J/kg
- Mixed-layer CIN
- -135 J/kg
- Mixed-layer LCL
- 1058 m above ground
- 0-6 km bulk shear
- 45 kt
- 0-1 km storm-relative helicity
- 233 m²/s²
- 0-3 km storm-relative helicity
- 210 m²/s²
- Significant tornado parameter
- 0.9
- Supercell composite
- 5.5
The text
As transmitted, in the capitals the NWS used until 2016.
999 WUUS54 KTSA 220313 RRA SVRTUL OKC117-220415- BULLETIN - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE TULSA OK 1011 PM CDT WED APR 21 1999 THE NATIONAL WEATHER SERVICE IN TULSA HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... PAWNEE COUNTY IN NORTHEAST OKLAHOMA * UNTIL 1115 PM CDT * AT 1010 PM CDT A SEVERE THUNDERSTORM WAS LOCATED 15 MILES WEST OF PAWNEE...MOVING EAST AT 35 MPH. * SOME LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... SKEDEE... PAWNEE...MARAMEC...HALLETT AND BLACKBURN HAIL TO THE SIZE OF QUARTERS AND WIND GUSTS TO 60 MPH CAN BE EXPECTED IN THE WARNED AREA. A TORNADO WATCH IS ALSO IN EFFECT. TORNADOES CAN DEVELOP SUDDENLY FROM SEVERE THUNDERSTORMS. BE ALERT FOR RAPIDLY CHANGING WEATHER CONDITIONS. LAT...LON 3641 9721 3623 9720 3619 9637 3642 9661
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 21, 9:33 PM CDT, 38 minutes earlier.
Area forecast discussion, Apr 21, 9:33 PM CDT, 38 minutes before
EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE TULSA OK 933 PM CDT WED APR 21 1999 STORMS STILL DEVELOPING ON SW FLANK OF LINE ALONG SURFACE BOUNDARY FROM NEAR EMPORIA KS TO PONCA CITY BACK TO NEAR CLINTON. CAP IS WEAKENING STORMS AS THEY MOVE EASTWARD HOWEVER... AND THERE IS SOME QUESTION ABOUT HOW FAR EAST THEY WILL MAKE IT. SEVERE WX AND HEAVY RAINFALL A DEFINITE POSSIBILITY WITH TRAINING STORMS. FOR NOW WILL UP POPS TO LIKELY IN ZONES W/NW OF TULSA AND INCREASE POPS ELSEWHERE OVER NE OKLAHOMA. WILL MONITOR RADAR TRENDS AND MAY DECIDE TO ISSUE FLASH FLOOD WATCH IF HEAVY RAIN LOOKS AS THOUGH IT WILL MAKE IT INTO WESTERN ZONES. 00Z RUC DEEPENS SURFACE LOW OVER WC OKLAHOMA WITH BOUNDARY EXPECTED TO REMAIN STATIONARY. CAP IS EXPECTED TO LIMIT CONVECTION IN E/S PART OF THE AREA OVERNIGHT...SO WILL LEAVE 10-20% POPS THERE. IF ONGOING PRECIP PERSISTS OUTFLOW BOUNDARY WILL PUSH FURTHER SE THAN RUC SHOWS SURFACE FEATURES AND COULD BECOME FOCUS FOR DEVELOPMENT LATER TONIGHT AND THURSDAY. WONT TINKER WITH LATER PERIODS THIS UPDATE BUT MAY TAKE A LOOK AT OTHER 0Z MODELS AND CHOOSE TO UPDATE AGAIN PRIOR TO MIDNIGHT. /13 AR...NONE. OK...TORNADO WATCH UNTIL MIDNIGHT FOR ZONES OKZ054>055...OKZ059...OKZ064>065.
The office that day
Everything else NWS Tulsa, OK issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 21, 10:44 PM CDT | Tornado Warning | TSA | Pawnee | 31 min |
| Apr 21, 10:54 PM CDT | Tornado Warning | TSA | Osage | 36 min |
| Apr 21, 11:29 PM CDT | Severe Thunderstorm Warning | TSA | Pawnee | 46 min |
| Apr 21, 11:46 PM CDT | Severe Thunderstorm Warning | TSA | Creek | 44 min |
| Apr 22, 12:07 AM CDT | Severe Thunderstorm Warning | TSA | Osage, Tulsa | 53 min |
| Apr 22, 12:30 AM CDT | Severe Thunderstorm Warning | TSA | Nowata, Rogers, Washington | 45 min |
| Apr 22, 1:03 AM CDT | Severe Thunderstorm Warning | TSA | Craig, Mayes | 42 min |
| Apr 22, 1:22 AM CDT | Severe Thunderstorm Warning | TSA | Delaware, Ottawa | 38 min |
| Apr 22, 3:07 PM CDT | Severe Thunderstorm Warning | TSA | Osage, Washington | 38 min |
| Apr 22, 3:39 PM CDT | Severe Thunderstorm Warning | TSA | Nowata, Washington | 36 min |
| Apr 22, 3:55 PM CDT | Tornado Warning | TSA | Nowata, Washington | 35 min |
| Apr 22, 4:25 PM CDT | Tornado Warning | TSA | Craig | 35 min |
| Apr 22, 4:52 PM CDT | Severe Thunderstorm Warning | TSA | Nowata | 38 min |
| Apr 22, 5:01 PM CDT | Tornado Warning | TSA | Craig | 29 min |
| Apr 22, 5:14 PM CDT | Tornado Warning | TSA | Delaware, Ottawa | 46 min |
| Apr 22, 5:27 PM CDT | Tornado Warning | TSA | Craig | 33 min |
| Apr 22, 5:28 PM CDT | Severe Thunderstorm Warning | TSA | Rogers, Tulsa | 47 min |
| Apr 22, 5:37 PM CDT | Severe Thunderstorm Warning | TSA | Rogers | 53 min |
| Apr 22, 5:55 PM CDT | Severe Thunderstorm Warning | TSA | Mayes, Rogers, Wagoner | 50 min |
| Apr 22, 6:00 PM CDT | Severe Thunderstorm Warning | TSA | Craig, Delaware | 45 min |
| Apr 22, 6:33 PM CDT | Tornado Warning | TSA | Mayes, Rogers, Wagoner | 42 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.