Alert archive / Oklahoma / Severe Thunderstorm Watches in 2015
Severe Thunderstorm Watch 77
The Storm Prediction Center issued this severe thunderstorm watch at Apr 18, 2015, 6:31 PM CDT for 44 counties in Oklahoma. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 18, 2015, 6:31 PM CDT (23:31 UTC)
- Expired
- Apr 19, 2015, 12:11 AM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 44 counties
Alfalfa County, OK, Atoka County, OK, Beckham County, OK, Blaine County, OK, Bryan County, OK, Caddo County, OK, Canadian County, OK, Carter County, OK, Cleveland County, OK, Coal County, OK, Creek County, OK, Custer County, OK, Dewey County, OK, Garfield County, OK, Garvin County, OK, Grady County, OK, Grant County, OK, Greer County, OK, Hughes County, OK, Jefferson County, OK, Johnston County, OK, Kay County, OK, Kingfisher County, OK, Kiowa County, OK, Lincoln County, OK, Logan County, OK, Love County, OK, Major County, OK, Marshall County, OK, McClain County, OK, Murray County, OK, Noble County, OK, Okfuskee County, OK, Oklahoma County, OK, Osage County, OK, Pawnee County, OK, Payne County, OK, Pontotoc County, OK, Pottawatomie County, OK, Seminole County, OK, Stephens County, OK, Washita County, OK, Woods County, OK, Woodward County, OK
The radar
The Norman radar (KTLX), 36 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 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
- 2%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 5%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
16 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 18, 6:35 PM CDT | Severe Thunderstorm Warning | OUN | Carter, Garvin, Murray | 40 min |
| Apr 18, 6:38 PM CDT | Severe Thunderstorm Warning | OUN | Canadian, Cleveland, Grady, McClain, Oklahoma | 52 min |
| Apr 18, 6:44 PM CDT | Severe Thunderstorm Warning | OUN | Jackson, Kiowa, Washita | 31 min |
| Apr 18, 6:56 PM CDT | Severe Thunderstorm Warning | OUN | Custer, Washita | 19 min |
| Apr 18, 7:00 PM CDT | Severe Thunderstorm Warning | OUN | Major, Woodward | 22 min |
| Apr 18, 7:09 PM CDT | Severe Thunderstorm Warning | OUN | Blaine, Caddo, Canadian, Custer, Dewey, Kingfisher and 1 more | 51 min |
| Apr 18, 7:10 PM CDT | Severe Thunderstorm Warning | OUN | Dewey, Ellis, Roger Mills | 50 min |
| Apr 18, 7:12 PM CDT | Severe Thunderstorm Warning | OUN | Garvin, Murray | 48 min |
| Apr 18, 7:24 PM CDT | Severe Thunderstorm Warning | OUN | Cleveland, Lincoln, McClain, Oklahoma, Pottawatomie, Seminole | 51 min |
| Apr 18, 7:32 PM CDT | Severe Thunderstorm Warning | OUN | Beckham, Roger Mills | 28 min |
| Apr 18, 7:57 PM CDT | Severe Thunderstorm Warning | OUN | Beckham, Roger Mills | 48 min |
| Apr 18, 8:07 PM CDT | Severe Thunderstorm Warning | OUN | Major, Woodward | 38 min |
| Apr 18, 8:25 PM CDT | Severe Thunderstorm Warning | OUN | Alfalfa, Grant | 50 min |
| Apr 18, 8:36 PM CDT | Severe Thunderstorm Warning | OUN | Dewey, Major, Woodward | 39 min |
| Apr 18, 8:43 PM CDT | Severe Thunderstorm Warning | OUN | Major, Woods, Woodward | 32 min |
| Apr 18, 8:45 PM CDT | Severe Thunderstorm Warning | OUN | Beckham, Custer, Dewey, Roger Mills, Washita | 30 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Norman, OK (KOUN), launched 12:00Z, 11.5 hours before the alert went out and 50 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1320 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- 11 m²/s²
- 0-3 km storm-relative helicity
- -8 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 17, 7:26 PM CDT | Mesoscale Discussion | SPC | Texas | 2 hr |
| Apr 18, 12:45 PM CDT | Mesoscale Discussion | SPC | Alfalfa, Blaine, Canadian, Garfield, Grant, Kingfisher and 4 more | 60 min |
| Apr 18, 1:52 PM CDT | Mesoscale Discussion | SPC | Alfalfa, Beckham, Blaine, Caddo, Canadian, Comanche and 19 more | 113 min |
| Apr 18, 2:27 PM CDT | Tornado Watch | SPC | Alfalfa, Beckham, Blaine, Caddo, Comanche, Cotton and 16 more | 6 hr |
| Apr 18, 4:07 PM CDT | Mesoscale Discussion | SPC | Garfield, Grant, Kay, Kingfisher, Lincoln, Logan and 5 more | 2 hr |
| Apr 18, 6:03 PM CDT | Mesoscale Discussion | SPC | Alfalfa, Beckham, Blaine, Caddo, Comanche, Cotton and 13 more | 87 min |
| Apr 18, 6:21 PM CDT | Mesoscale Discussion | SPC | Canadian, Carter, Cleveland, Garvin, Grady, Hughes and 11 more | 84 min |
Nearby
Severe Thunderstorm Watches in Oklahoma, 2015Every severe thunderstorm watch in 2015
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.