OKLAHOMA · OKLAHOMA COUNTY
Building on the Literal Heart of Tornado Alley
Oklahoma City sits on the central Oklahoma plains where violent tornadoes form more often than anywhere on Earth. Design wind speeds run 115-125 mph under the Oklahoma Uniform Building Code's adoption of ASCE 7.
CENTRAL OKLAHOMA PLAINS
Why Oklahoma City Carries the Nation's Most Violent Tornado Record
No other major metro stacks EF5 strikes the way central Oklahoma does. ASCE 7 speeds come from synoptic winds, but OKC's exposure is defined by the storms that bracket it.
May 3, 1999 · F5
The Bridge Creek-Moore tornado produced the highest wind speed ever measured on Earth via mobile Doppler radar.
BRIDGE CREEK-MOOREMay 20, 2013 · EF5
The Moore tornado ran 1.3 miles wide on a 17-mile path eight miles south of downtown OKC, killing 24.
MOORE EF5Highest Frequency
Oklahoma County averages roughly 11 tornadoes a year, the densest cadence of any county in the United States.
OKLAHOMA COUNTYDerechos & Giant Hail
Organized thunderstorm complexes drive 70-90 mph straight-line winds, with 2-inch hail battering envelopes each spring.
SEVERE CONVECTIONASCE 7-22 · CHAPTER 32 TORNADO LOADS
Two Storms, Two Load Paths: Synoptic Wind and Tornado Provisions
ASCE 7-22 added Chapter 32, the first national tornado-load standard. For OKC's risk profile, the spirit of those provisions matters as much as the basic wind map.
Basic Wind Map
Risk Category II sits at 115-125 mph (3-second gust). Higher categories read a longer return-period map, so loads rise with the risk class, not a fixed multiplier.
115-125 MPHChapter 32 Qualitative
Tornado loads apply to Risk Category III and IV buildings in tornado-prone regions. They layer a separate tornado pressure check on top of the standard wind design.
RISK III & IVShelters & Safe Rooms
Post-2013 Moore, schools and essential facilities pair the calc with ICC 500 / FEMA P-361 shelter design and PE-sealed verification.
ICC 500 · FEMA P-361Velocity pressure, OKC baseline. Using qz = 0.00256 Kz Kzt Kd Ke V² at V = 120 mph, Kz = 0.70 (Exposure B, ≤30 ft), Kzt = 1.0 flat plains, Kd = 0.85, Ke = 1.0 yields roughly 26 psf before pressure coefficients. Open-plains sites default to Exposure C, which raises Kz to 0.85+ and pushes pressures well above the urban-core baseline.
TERRAIN · ASCE 7 SECTION 26.7
Reading Exposure on the Open Great Plains
Downtown and inner OKC can qualify as Exposure B, but the metro's open terrain pushes most sites toward the more demanding Exposure C.
Exposure B — Urban Core
Downtown, Midtown, and Nichols Hills with dense buildings under 30 ft extending 800+ ft upwind read as Exposure B.
DOWNTOWN · MIDTOWNExposure C — Open Plains
Developing suburbs in Moore, Norman, Edmond, Yukon, and Mustang sit on open prairie. When in doubt, the conservative Exposure C governs.
MOST METRO SITESPERMIT WORKFLOW · OKLAHOMA COUNTY
What an OKC Permit Set Has to Prove
Six checkpoints carry a central-Oklahoma project from code edition to a stamped, permit-ready report.
Adopted Code
Oklahoma UBC via OUBCC adopts the IBC, which references ASCE 7 for wind.
IBC + ASCE 7Design Speed
Confirm 115-125 mph for Risk Cat II at the project address.
115-125 MPHRisk Category
Classify per Table 1.5-1; schools and essential facilities climb the speed map.
TABLE 1.5-1Exposure
Default Exposure C on open plains; document B only where terrain supports it.
B / CTornado Provisions
For Risk III/IV, address ASCE 7-22 Ch 32 plus shelter standards.
CH 32PE Seal & Report
Submit PE-sealed calcs to OKC Development Services for permit review.
PERMIT-READYAvoid the classic OKC misses: assuming Exposure B on open prairie, skipping tornado-shelter provisions for schools, or running an outdated ASCE 7 edition. Roofs must also resist 2-inch-plus hail alongside wind uplift.
OFFICIAL OKC RESOURCES
Code & Licensing Authorities
The three official sources every OKC wind-load submittal should reference.
NEARBY & STATEWIDE
Across the Oklahoma City Metro
Moore, Norman, Edmond, Yukon, and Mustang share OKC's 115-125 mph speeds and open-plains exposure. Zoom out to statewide and Tornado Alley context.
Oklahoma Statewide
Full Oklahoma wind-load requirements and code adoption.
STATE PAGETornado Alley Safety
How wind-load design responds across the corridor.
CORRIDORASCE 7-22 Chapter 32
The national tornado-load provisions, explained.
CH 32 GUIDEWind Speed by Location
Look up design speeds anywhere in the country.
LOOKUP| City | Risk Cat II Speed | Tornado Risk |
|---|---|---|
| Oklahoma City, OK | 115-125 mph | Extreme — 1999 F5 & 2013 EF5 Moore |
| Wichita, KS | 115-120 mph | High — Tornado Alley |
| Kansas City, MO/KS | 110-120 mph | High — Tornado Alley |
| Dallas, TX | 105-115 mph | Moderate — corridor edge |
START YOUR OKC CALCULATION
Permit-Ready Loads for the Tornado Alley Epicenter
Enter an Oklahoma City address and get the 115-125 mph velocity, Exposure B/C, Risk Category adjustments, and PE-ready output in one pass.