textproduct: Norman

KEY MESSAGES

Updated at 1240 PM CDT Wed Sep 30 2026

- Periods of heavy rain are expected from this afternoon through at least Thursday morning. Flash flooding is possible in southern Oklahoma and western north Texas.

- Chance of severe storms this afternoon and evening.

- Cooler temperatures heading into the weekend.

NEAR TERM

(Wednesday and Wednesday night) Issued at 211 AM CDT Wed Sep 30 2026

A day/night of impactful weather is expected across the CWA. Thunderstorms, heavy rainfall, and a chance for severe weather (primarily a conditional tornado risk) will occur across much of the area.

Regional radar observations depict a large stratiform band with embedded thunderstorms across eastern New Mexico and the Texas panhandle. Model guidance suggests that this wave is not the one that will reach into our area - storm redevelopment will occur in the eastern panhandle/western Oklahoma closer to daybreak. Either way, the impact is the same: we anticipate a cluster of showers and thunderstorms to move northeastward across western and northern Oklahoma during the morning hours. Portions of that area have received heavy rainfall over the last week and thus there will be a low-to-medium risk for flooding of streams, low-water crossings, and poor-draining roads.

The primary wave of storms with the greatest chance for flooding and severe weather will begin this afternoon and last through the nighttime period. Storms will initially develop in western north Texas and western Oklahoma within the warm sector and over time grow upscale into an MCS. With the approach of the trough, 500 mb flow will become increasingly meridional, signaling a decrease in forward progression of that MCS. This will bring areas in the path of the line under heavy precipitation for 1-3 hours. Under those circumstances, flash flooding is likely in parts of western north Texas and southern Oklahoma this evening and tonight. The northward extent of the MCS remains in question with contradictory solutions in model guidance. This is of particular importance to flood-prone areas such as Lawton, OKC, and Stillwater, who have wide ranges of potential outcomes from "deluge" to "disappointingly low rain totals".

The severe risk is also worth watching, though uncertainties abound. Two potential regimes for severe weather exist. The first is along the dryline late in the afternoon in western Oklahoma. The degree of destabilization and lingering subsidence from this morning's showers and storms will act to make the potential for supercells quite conditional. On the other hand, the dry slot's approach will steepen mid-level lapse rates, and sufficient wind shear will exist in the area for supercells to develop. If (and this is a big if) supercells were to develop, the primary severe weather risk would be tornadoes. The second severe regime runs from western north Texas to southern Oklahoma with the MCS. Lapse rates will be very poor and deep-layer flow will be meridional, so from a parameter perspective these storms will not be working from a favorable environment.

Meister

SHORT TERM

(Thursday through Friday night) Issued at 211 AM CDT Wed Sep 30 2026

Rain continues in the forecast across much of the area during the day on Thursday. While flash flooding does not look to be as likely or as widespread, the antecedent conditions will favor further cases of excessive rainfall.

The basis for Thursday's rain event will be the approach of the upper-level low. While the low will be weakening on its approach, sufficient vorticity/cooling aloft will occur for instability to return, particularly across northern Oklahoma closer to the cooler 500 mb temperatures. This will be the basis for scattered thunderstorms to redevelop in the afternoon. Storms will be slow- moving with heavy rainfall rates. Sufficient shear exists for the organization of updrafts, but there's enough uncertainty that it will probably be best to wait until after tonight's MCS to try to assess any potential severe weather risk.

As the upper low lifts northeastward out of the area, a cold front will crash southward into the area late Thursday evening and Thursday night. This will bring much cooler air into the CWA. If the front had occurred last week, we'd probably have a crisp and sunny Friday, but with all of the lingering moisture on the ground, widespread stratus development seems like a given. That will keep temperatures to a much more fall-like 70-80 range across the CWA. Lingering rain chances will continue across southern Oklahoma into Friday afternoon/evening as the tropical airmass remains there the longest.

Meister

LONG TERM

(Saturday through Tuesday) Issued at 211 AM CDT Wed Sep 30 2026

Several near-to-slightly-cooler-than-normal days await us for the upcoming weekend. Though the ridge will build back in over the Southern Rockies, enough weakness in the ridge will exist for us to feel the full extent of a prolonged period of northwest flow over the Central Plains. That will keep northerly surface winds perhaps as long as Monday evening in our area. Lingering rain chances are expected mostly southeast of I-44 on Saturday, but the rest of the weekend and into Monday looks much drier.

The one constant in 2026 has been that any cooldown can't last long, and sure enough, guidance and our gridded forecast are starting to warm back up beginning next Tuesday. Fortunately, it looks like we'll be doing "October warm" instead of "July warm", with temperatures rebounding into the 80s at most sites. For those in search of more good news, model trends beyond the official long-term period do suggest that we'll be seeing more frontal intrusions in the first half of October.

Meister

AVIATION

(18Z TAFS) Issued at 1240 PM CDT Wed Sep 30 2026

Showers and storms are expected to increase later this afternoon and this evening across western OK and western north TX and spread eastward over the rest of the area tonight. Heavy rain, low vis/ceilings, and gusty winds are possible in the vicinity of thunderstorms. Otherwise, expect a mix of VFR and MVFR ceilings today and tonight, with some potential for IFR ceilings by Thursday morning but uncertainty was too high to include at this time. Winds will be from the south/southeast and will be gusty at times.

PRELIMINARY POINT TEMPS/POPS

Oklahoma City OK 68 81 63 73 / 80 70 50 30 Hobart OK 68 85 63 74 / 50 30 20 20 Wichita Falls TX 69 85 65 78 / 100 40 30 30 Gage OK 62 79 55 69 / 20 40 50 10 Ponca City OK 66 77 60 71 / 70 70 60 20 Durant OK 70 83 67 81 / 100 100 80 70

OUN WATCHES/WARNINGS/ADVISORIES

OK...Flood Watch from 4 PM CDT this afternoon through Thursday afternoon for OKZ023>032-037>048-050>052.

TX...Flood Watch from 4 PM CDT this afternoon through Thursday afternoon for TXZ085-086-088>090.