This is a live Thursday morning snapshot of U.S. local-storm activity as of early Thursday, September 17, 2026. Overnight convection left trees and wires down in western and north-central Ohio and quarter-to-half-dollar hail in eastern Utah and mid-Missouri. The Storm Prediction Center 1300 UTC Day 1 outlook holds a Marginal Risk of isolated severe wind gusts and hail across parts of Utah and Idaho into southwest Montana, plus a second Marginal over the central High Plains. No convective watches are valid. The Weather Prediction Center Day 1 Excessive Rainfall Outlook holds Slight Risks over portions of the north-central Plains and Midwest and over the southwestern U.S. There is no named tropical cyclone threatening U.S. land.
These are county- and ZIP-scale thunderstorms and flash-flood pulses, not a mainland hurricane landfall. Restoration exposure this morning is leftover wind and hail from last night plus a new afternoon hail/wind corridor in the Intermountain West and a water ticket on the Dakotas, Wyoming Front Range, and leftover Southwest terrain. Conditions change fast. Verify with the National Weather Service for the specific county or ZIP before you roll.
What is live this morning
SPC issued the 1300 UTC Day 1 Convective Outlook at 0730 AM CDT. Valid 171300Z–181200Z. Headline: thunderstorms with isolated severe wind gusts and hail will be possible over parts of the Intermountain West this afternoon and evening. A few strong to severe gusts may also occur across portions of the central High Plains. Risk-area population centers listed by SPC include Salt Lake City, West Valley City, Provo, West Jordan, and Orem. Categorical risk is Marginal only. No Slight Risk. No tornado probabilities in the 1300 UTC package. The Ohio Valley Marginal from Wednesday is off the map this morning. Poor lapse rates aloft and extensive cloud cover keep severe-wind probabilities below 5 percent from the Midwest through the Mid-Atlantic.
Current convective watches: none. Most recently issued watch remains Severe Thunderstorm Watch 669, already expired days ago. SPC watch page last updated 0849 UTC Thursday: no watches currently valid. That is the overnight close. Do not treat 669 as a live product.
WPC Day 1 excessive-rainfall language valid 12Z Thursday through 12Z Friday has two Slight Risk corridors. One covers a high-end Slight across much of South Dakota, expanding toward Sioux Falls and into southwestern Minnesota and northwest Iowa, and west-southwest to the Cheyenne, Wyoming region east of the Laramie Range. The other holds Slight Risk over New Mexico and eastern Arizona into the San Juans and western Colorado, with Marginal coverage into the Salt Lake corridor and southeastern Idaho. Wednesday’s Moderate Risk over southern and central Arizona is no longer the live upgrade. It is the just-hit and burn-scar follow-through desk.
Hotspot 1 — Utah, Idaho, and southwest Montana
A closed mid/upper-level low over northern California this morning will drift east across the northern Intermountain region. A 40–50 kt southwesterly mid-level jet and difluence aloft overspread the northern Great Basin this afternoon. SPC’s uncertainty is instability under morning cloud and ongoing rain. Upper-40s to low-50s dewpoints are already in place. Some guidance still builds 1000–1250 J/kg of MLCAPE over southeast Idaho and northern Utah if heating punches through. If that happens, a focused corridor of greater hail and wind potential exists because deep-layer shear is strong enough for supercells. Otherwise the threat is isolated hail and gusty winds with cells and small clusters across the northern Great Basin.
Overnight LSRs already put quarter-size hail at Huntington in Emery County and at East Carbon and Sunnyside in Carbon County. That is the same Salt Lake City forecast office that will own this afternoon’s cells.
Restoration read: hail first if discrete cells fire over the Wasatch Front and southeast Idaho. Wind second. Stage roof and auto-glass survey capacity in the Salt Lake–Provo–Boise belt before late afternoon, not after the first warning. Flash-flood risk on this corridor is Marginal to isolated, not the organized Dakotas ticket.
Hotspot 2 — Central High Plains and the Dakotas water corridor
Between the West Coast upper low and Southeast ridging, minor mid-level perturbations lift northeast from the Southwest toward the central High Plains by evening. SPC expects additional storms from northeast Colorado into western Nebraska late afternoon. Modest mid-level lapse rates should limit updraft intensity. Sufficient shear still allows a small cluster or two with isolated severe gusts spreading east-northeast through the evening. That is the wind overlay on top of WPC’s water story.
WPC is more organized here than SPC. A tropical-origin shortwave ejecting out of Arizona will pivot through the central Rockies and into the northern Plains tonight. Precipitable-water anomalies approach the 95th–99th percentile from South Dakota into southern Minnesota by the end of the period. Discussion language includes 2–4 inches, locally higher, with HREF neighborhood probabilities of greater than 2 inches at 50–80 percent across a large High Plains swath. The centroid of greater-than-3-inch probabilities sits just east and southeast of Rapid City into Badlands National Park. The Slight Risk was expanded east toward Sioux Falls for the last 6–8 hours of the forecast.
Restoration read: water first from the Wyoming Front Range across western and central South Dakota into southwest Minnesota and northwest Iowa tonight into Friday morning. Wind second if High Plains clusters organize. Do not send one crew to both a Cheyenne gust and a Rapid City wash without checking which county has a warning now.
Hotspot 3 — Southwest terrain leftover plus Ohio just-hit
The shortwave that drove Wednesday’s Arizona Moderate flood risk is leaving. WPC still keeps a Slight Risk over New Mexico and eastern Arizona into the San Juans and Sacramentos. Guidance still prints 1–3 inches on the Sangre de Cristos, San Juans, and interior New Mexico terrain. Sacramento Mountains burn-scar sensitivity remains in the discussion as locally Moderate impacts embedded inside a higher-end Slight. That is runoff on ground that already took water Wednesday, not a new Moderate upgrade.
Ohio is off today’s SPC Marginal. It is the just-hit desk. Overnight LSRs from the 16/1200Z–17/1159Z window include multiple trees down in Versailles and Piqua, a snapped hardwood onto a home awning in Darke County, barn sheet-metal loss and a blown silo near West Alexandria in Preble County, and trees and wires southeast of Mansfield in Richland County. NWS Cleveland had severe thunderstorm warnings into mid-evening Wednesday for Richland, Ashland, Holmes, and Knox counties. Those products are expired. The trees are still on the lines.
Just hit
SPC preliminary storm reports for the 16/1200Z–17/1159Z window show no tornadoes. Hail: 1.00 inch at Huntington, Emery County, Utah; 1.00 inch at East Carbon and Sunnyside, Carbon County, Utah; 1.00 to 1.25 inches near Linn Creek, Camden County, Missouri, with two-foot-diameter limbs down. Wind: downed power lines in Mesa, Maricopa County, Arizona; trees in Versailles, Darke County, and Piqua and Lockington, Miami County, Ohio; a snapped pole and large limb near Broken Arrow, Tulsa County, Oklahoma; a power line and a condo-garage roof near Osage Beach and Linn Creek, Missouri; barn roofing and a grain silo near West Alexandria, Preble County, Ohio; trees and wires southeast of Mansfield.
Today’s 17/1200Z cycle has no tornado, hail, or wind reports yet as of this morning desk. That is expected. The Intermountain and High Plains threats are an afternoon and evening problem.
Wednesday afternoon’s Storm Tracker already covered the Ohio Valley Marginal and the Arizona Moderate flood risk while they were live. This morning’s desk treats Ohio wind and Arizona washes as aftermath and moves the live outlook west and north.
Pulse table
| Region | Main threats | SPC / NWS / WPC level | Status this morning |
|---|---|---|---|
| UT / ID / SW MT | Isolated hail and severe gusts; possible supercells if CAPE builds | SPC Marginal | Afternoon–evening cells |
| NE CO / western NE / High Plains | Isolated severe gusts | SPC Marginal | Late afternoon clusters |
| WY Front Range / SD / SW MN / NW IA | Flash flood, 2–4″ swaths | WPC Slight (high-end over SD) | Today’s organized water ticket |
| NM / E AZ / San Juans / Sacramentos | Flash flood, burn-scar debris flow | WPC Slight; leftover from Wed Moderate | Diurnal terrain cells |
| Western / north-central OH | Trees, wires, barn and roof damage | LSRs overnight; warnings expired | Just-hit |
| Emery / Carbon UT; Camden MO | Quarter to half-dollar hail | LSRs overnight | Just-hit / same offices own today’s risk |
| Atlantic / Gulf vs. U.S. mainland | No named cyclone | NHC: no tropical cyclones | Quiet on the mainland coast |
What this means for restoration teams
Isolated severe hail on the Wasatch Front is a roof and auto-glass survey ticket if cells verify over Salt Lake, Provo, or southeast Idaho. Isolated High Plains gusts are tree, siding, and gutter work in a thin corridor. The organized ticket today is water from the Wyoming Front Range across South Dakota into southwest Minnesota and northwest Iowa tonight. Flash flooding on leftover Arizona–New Mexico terrain is wet drywall and a same-night extraction clock if water is inside a structure that already took rain Wednesday. Ohio trees-on-wires from last night are a separate staffing problem from this afternoon’s West.
For teams near the Intermountain Marginal: stage before mid-afternoon local. Property owners should photograph damage in daylight if it is safe, call the carrier, and start extraction the same night if water is inside. Turn around, don’t drown on High Plains and Southwest washes.
What this is not
This is not a Slight Risk severe day, not a live convective watch, and not a U.S. mainland hurricane landfall. NHC reports no tropical cyclones in the Atlantic, eastern Pacific, or central Pacific as of this morning. Edouard is already in the archive. The work, if it verifies, will be scattered: a hail swath through a Utah or Idaho county, a gust cluster on the High Plains, and heavier rain over South Dakota terrain tonight.
Looking ahead
SPC Day 2 (Friday) holds Marginal Risk across parts of the northern Intermountain West, the central Great Plains into the southern middle Missouri Valley, and the Carolina–Georgia Piedmont. WPC’s Day 1 water corridor over the Dakotas is the bridge into that Plains Marginal. The next Storm Tracker update should re-check the 1630 UTC Day 1 outlook and any new watches rather than assuming this morning’s Marginal stays the last word.
Sources and how to verify
Primary sources: NOAA Storm Prediction Center Sep 17, 2026 1300 UTC Day 1 Convective Outlook (Gleason/Mead); current convective watches (none valid; last issued Watch 669); SPC preliminary storm reports for 20260916 1200 UTC–20260917 1159 UTC; Weather Prediction Center Day 1 Excessive Rainfall Outlook and discussion (Kleebauer); National Weather Service warning text including Cleveland OH, Salt Lake City, Springfield MO, and Phoenix/Flagstaff/Tucson overnight flood products now expired; National Hurricane Center 800 AM EDT Tropical Weather Outlook, September 17, 2026.
Check weather.gov for the county warning, spc.noaa.gov for the outlook, watch, and LSRs, and WPC excessive rainfall for the flood overlay. Prior desk: Wednesday, September 16 afternoon Storm Updates.
Informational only — not an official weather warning. Follow local authorities and the National Weather Service. Turn around, don’t drown.