Storm Updates: Oklahoma and High Plains Slight Risk — Sunday, September 20, 2026

This is a live Sunday afternoon snapshot of U.S. local-storm activity as of Sunday, September 20, 2026. The organized pulse is still the Storm Prediction Center Slight Risk over central and eastern Oklahoma and from eastern Colorado into far western Kansas. As of 2013 UTC, no convective watches are valid. Overnight Severe Thunderstorm Watches 670, 671, and 672 have expired. Restoration exposure this afternoon and evening is damaging wind and large hail on the Oklahoma and High Plains Slight Risk, leftover interior water where Midwest and Ohio Valley cells trained last night, and a local Florida flash-flood polygon that is not the national headline.

These are county- and ZIP-scale thunderstorms, not a mainland hurricane landfall. Conditions change fast. Verify with the National Weather Service for the specific county or ZIP before you roll.

What is live this afternoon

The SPC 2000 UTC Day 1 Convective Outlook, issued 0244 PM CDT Sunday, September 20, 2026 and valid 202000Z–211200Z, holds a Slight Risk of severe thunderstorms across parts of central and eastern Oklahoma and from eastern Colorado into far western Kansas. The official summary: thunderstorms with severe wind gusts and large hail remain possible this afternoon and evening across those two corridors. Isolated severe gusts and hail are also possible in parts of the southern Plains and from the Ozarks eastward into the Ohio Valley. The 20Z update said the forecast remained generally on track with only minor adjustments.

No watches are currently valid. The most recently issued watch was Severe Thunderstorm Watch 672. Mesoscale Discussion 2316, issued 0149 PM CDT Sunday and valid through 2115 UTC, covers northeast and eastern Colorado, far western Kansas, and southwest Nebraska. Language is severe potential, watch possible, with a 60 percent watch-issuance probability. Isolated storms over northeast Colorado, large hail probable, a few severe gusts possible by early evening. Most probable peak hail size in that MD is 1.50 to 2.50 inches. Most probable peak wind gust 55 to 70 mph.

The Weather Prediction Center Day 1 Excessive Rainfall Outlook, updated 1602 UTC Sunday and valid 16 UTC September 20 through 12 UTC September 21, keeps Slight Risks over portions of the Midwest and Ohio Valley and over the northern High Plains. The 16Z update trimmed the northern edge of the Midwest Slight (northern Illinois, southern Iowa, northern Missouri) and kept the better confidence farther east into the Upper Ohio Valley, where antecedent 24-hour totals already ran 1 to 2 inches areal average and 3 to 4 inches locally. A separate Slight pocket remains focused over southwest South Dakota and the Black Hills on upslope flow and Saturday’s leftover wet ground.

Hotspot 1 — Central and eastern Oklahoma

This is one of the two Slight Risk contours on the 2000 UTC outlook. A surface low sits over central Oklahoma along a cold front that arcs from northeast Oklahoma into southwest Oklahoma and back through the central Texas Panhandle. A shortwave trough is moving into western Oklahoma. The airmass ahead of the front is warm, moist, and moderately buoyant. Mid-level flow is stronger across Oklahoma than across Texas, which is why the organized severe corridor is drawn here rather than over the more disorganized Texas cells. Primary threat language is damaging gusts of 55 to 65 mph, with hail in the stronger cores.

Cities and counties to watch: Tulsa, Broken Arrow, Muskogee, Shawnee, Ardmore, and the rest of the central and eastern Oklahoma Slight contour. Oklahoma City sits near the western edge of the broader risk language even when it is not the center of the Slight.

Restoration read: wind and hail first. Stage tarps, generators, and roof tarping before dark. Photograph roofs in remaining daylight only if it is safe. Do not treat this as a statewide outbreak. It is a corridor.

Hotspot 2 — Eastern Colorado into far western Kansas and southwest Nebraska

This is the other Slight Risk plus MD 2316. Easterly low-level flow north of the surface front is holding 50s F dewpoints across eastern Colorado. Heating plus cool temperatures aloft support moderate destabilization. Storm coverage is expected to stay isolated to widely scattered because of cooler surface temperatures and leftover inhibition, but any storm that matures is favored to be supercellular. Primary severe hazard on the outlook is large hail of 1 to 2.5 inches. Isolated severe gusts are possible. Some lingering severe risk may develop over southeast Colorado late this evening and spread into the Oklahoma Panhandle overnight.

Cities and counties to watch: the Palmer Divide and northeast Colorado, Lamar and the High Plains counties, far western Kansas, and southwest Nebraska where left-split cells can throw hail. Local Severe Thunderstorm Warnings already fired this afternoon in Dundy and Chase Counties, Nebraska.

Restoration read: hail and isolated wind. This is a few strong cells, not a line. Staff it as spot jobs — broken shingles, cracked skylights, vehicle and siding hits — not a regional CAT.

Hotspot 3 — Midwest and Ohio Valley flood leftovers, plus a Florida polygon

WPC keeps a Slight excessive-rainfall risk on last night’s rain axis from central Illinois and east-central Missouri into the Upper Ohio Valley. Antecedent ground is already wet. Training or backbuilding later this evening and overnight could add 2 to 4 inches in the better cores. River and flash-flood products this morning and midday covered eastern Iowa (Quad Cities, Cedar Rapids, Kalona and the English River), the Parkersburg–Athens Ohio River corridor, Charleston and Huntington, Washington County, Pennsylvania, and eastern Ohio counties including Belmont, Guernsey, Harrison, Jefferson, and Tuscarawas. The Des Plaines River near Russell, Illinois, has a new Flood Warning for minor flooding from this afternoon until further notice.

A separate local Flash Flood Warning this afternoon covers southwestern Suwannee County, Florida, with 2 to 3 inches already down. That is a North Florida urban and low-water-crossing desk, not the Slight Risk story.

Restoration read: yesterday’s water is already a ticket in Iowa, Ohio, West Virginia, and western Pennsylvania. Today’s new water, if it verifies, is more of the same corridor plus a standalone Florida polygon. Do not send the Oklahoma hail crew to the Ohio River without checking which county still has a warning.

Just hit

Saturday night’s Severe Thunderstorm Watches 670 (Kansas, Oklahoma, Texas), 671 (Colorado, Kansas), and 672 (Kansas, Missouri) are closed. Those are already on the books as wind and hail tickets across the central Plains and Lower Missouri Valley. Overnight and this morning’s Flash Flood Warnings along the Iowa–Illinois line and the Ohio River are extraction and drying work, not a new watch. This afternoon’s new work, if it verifies, is the Oklahoma wind corridor and High Plains hail cells under MD 2316.

Pulse table

What this means for restoration teams

Oklahoma wind at 55 to 65 mph is roof, siding, gutter, and tree-on-structure work. High Plains hail of 1 to 2.5 inches is shingle and auto work in a few counties, not a multi-state CAT. Midwest and Ohio Valley water from Saturday night is already inside some buildings. That mold clock started this morning, not this evening.

For teams near the Oklahoma Slight or the Colorado–Kansas MD: stage before the first warning, not after. Property owners should photograph damage in daylight if it is safe, call the carrier, and start extraction the same night if water is inside. For teams on the Iowa and Ohio River leftovers: you are already on yesterday’s tickets. Check which gauge is still in flood before you drive.

What this is not

This is not a regional derecho and not a U.S. mainland hurricane landfall. Tropical Storm Fay is in the far eastern Atlantic near 34.4°N, 32.7°W and is not a U.S. land threat this afternoon. Tropical Storm Odalys and Tropical Depression Seventeen-E are over the eastern Pacific, well offshore. The work tonight, if it comes, will be scattered: a wind swath through an Oklahoma county, hail on the High Plains, leftover water in an Iowa or Ohio River town. That is the local-storm pattern this desk should staff.

Looking ahead

Monday’s SPC Day 2 Convective Outlook, issued 1137 AM CDT Sunday, is a Marginal Risk from Mississippi to the central and southern Appalachians. Official summary: a few instances of damaging gusts are possible across the central and southern Appalachians to northern and central Mississippi. Coverage is isolated to widely scattered. Shear is expected to stay weak. Watch the next Storm Tracker update rather than assuming today’s Slight is Monday’s story.

Sources and how to verify

Primary sources, all date-stamped Sunday, September 20, 2026: NOAA Storm Prediction Center 2000 UTC Day 1 Convective Outlook; SPC current watches page (no watches valid as of 2013 UTC); Mesoscale Discussion 2316; Weather Prediction Center Day 1 Excessive Rainfall Outlook updated 1602 UTC; National Hurricane Center public page as of 2120 UTC; National Weather Service watch/warning text including Pittsburgh, Charleston, Chicago, La Crosse, and Tallahassee products. Morning desk for this calendar day: Storm Updates: Oklahoma and High Plains Slight Risk — Sunday, September 20, 2026 (Morning).

Check weather.gov for the county warning, spc.noaa.gov for the outlook, watches, MDs, and LSRs, and WPC excessive rainfall for the flood overlay.

Informational only — not an official weather warning. Follow local authorities and the National Weather Service. Turn around, don’t drown.