Alert archive / Oklahoma / Severe Thunderstorm Watches in 2012

Severe Thunderstorm Watch 202

April 28, 201219 counties in Oklahoma

The Storm Prediction Center issued this severe thunderstorm watch at Apr 28, 2012, 11:52 PM CDT for 19 counties in Oklahoma. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Apr 28, 2012, 11:52 PM CDT (04:52 UTC)
Expired: Apr 29, 2012, 5:00 AM CDT
In force: 5 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

Counties Adair County, OK, Cherokee County, OK, Craig County, OK, Creek County, OK, Delaware County, OK, Mayes County, OK, McIntosh County, OK, Muskogee County, OK, Nowata County, OK, Okfuskee County, OK, Okmulgee County, OK, Osage County, OK, Ottawa County, OK, Pawnee County, OK, Rogers County, OK, Sequoyah County, OK, Tulsa County, OK, Wagoner County, OK, Washington County, OK

The radar

The Tulsa radar (KINX), 42 km from the middle of the area, began a volume at 04:52 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 SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 20%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 40%
One or more hailstones of 2 inches or more: 10%
Six or more combined severe hail and wind reports: 60%

Warnings issued inside it

4 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Apr 29, 1:00 AM CDT	Severe Thunderstorm Warning	TSA	Osage, Pawnee	45 min
Apr 29, 1:43 AM CDT	Severe Thunderstorm Warning	TSA	Creek, Pawnee	30 min
Apr 29, 2:43 AM CDT	Severe Thunderstorm Warning	TSA	Creek, Osage, Pawnee	32 min
Apr 29, 4:29 AM CDT	Severe Thunderstorm Warning	TSA	Osage, Tulsa, Washington	46 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

Mesoscale Discussion 619Apr 29, 1:53 AM CDT

The nearest sounding before it

Lamont, OK (KLMN), launched 00:00Z, 4.9 hours before the alert went out and 144 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: 167 J/kg
Mixed-layer CIN: -203 J/kg
Mixed-layer LCL: 868 m above ground
0-6 km bulk shear: 64 kt
0-1 km storm-relative helicity: 58 m²/s²
0-3 km storm-relative helicity: 228 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.2

Open this sounding in Storm Lab

The text

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

973 
WWUS20 KWNS 290452
SEL2
SPC WW 290452
OKZ000-291000-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 202
NWS STORM PREDICTION CENTER NORMAN OK
1155 PM CDT SAT APR 28 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

       NORTHEAST OKLAHOMA

EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 1155 PM
UNTIL 500 AM CDT.

HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60
STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES NORTHEAST OF
BARTLESVILLE OKLAHOMA TO 15 MILES WEST SOUTHWEST OF MUSKOGEE
OKLAHOMA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 200...WW 201...

DISCUSSION...SCTD SUSTAINED STORMS/POSSIBLE SUPERCELLS EXPECTED TO
MOVE E TO ENE FROM CNTRL OK INTO NE OK THROUGH EARLY SUN...ALONG AND
N OF WEAK FRONT STALLED WSW-ENE ACROSS REGION.  ACTIVITY WILL BE
SUPPORTED BY MODEST LOW LVL WAA AND ASCENT IN RIGHT ENTRANCE REGION
OF JET STREAK MOVING ENE FROM NM.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 25030.


...CORFIDI

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 28, 10:36 PM CDT	Tornado Watch	SPC	Caddo, Canadian, Cleveland, Comanche, Cotton, Garvin and 11 more	3 hr
Apr 28, 10:54 PM CDT	Mesoscale Discussion	SPC	Caddo, Canadian, Cleveland, Comanche, Cotton, Grady and 4 more	2 hr
Apr 29, 1:37 AM CDT	Mesoscale Discussion	SPC	Alfalfa, Beckham, Blaine, Custer, Dewey, Garfield and 8 more	23 min
Apr 29, 1:53 AM CDT	Mesoscale Discussion	SPC	Adair, Cherokee, Craig, Creek, Delaware, Kay and 12 more	2 hr
Apr 29, 3:13 AM CDT	Mesoscale Discussion	SPC	Beckham, Custer, Dewey, Roger Mills	92 min
Apr 29, 2:22 PM CDT	Mesoscale Discussion	SPC	Cimarron	113 min
Apr 29, 5:10 PM CDT	Severe Thunderstorm Watch	SPC	Beaver, Cimarron, Harper, Texas	8 hr
Apr 29, 5:51 PM CDT	Mesoscale Discussion	SPC	Alfalfa, Canadian, Craig, Creek, Garfield, Grant and 17 more	2 hr

Nearby

Severe Thunderstorm Watches in Oklahoma, 2012 Every severe thunderstorm watch in 2012

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.