textproduct: Norman

KEY MESSAGES

Updated at 211 PM CDT Tue Oct 13 2026

- Severe thunderstorms possible this evening and tomorrow afternoon/evening night primarily along and northwest of I-44.

- Multiple rounds of heavy rain expected between now and Thursday morning with an increasing flash flood risk.

- Colder and drier airmass arrives late Thursday, with weather becoming cool and pleasant by the weekend.

NEAR TERM

(Rest of today and tonight) Issued at 211 PM CDT Tue Oct 13 2026

Near-term forecast concerns: Record high temperature potential this afternoon, severe storms this afternoon and evening, flood risk increasing toward daybreak.

Discussion: Our fall storm begins late this evening and tonight. Prior to that, heating toward record temperatures has been interrupted somewhat by the development of moist advection stratus this morning, particularly along and southeast of I-44 within a corridor of 73-75 dewpoints. Still, breaks in cloud cover (and total sunshine in northern/western Oklahoma) have warmed temperatures into the mid-to-upper 80s by early afternoon. With 4-6 more degrees of warming, we'll reach those low-to-mid 90s that were anticipated for much of the area.

By the peak of diurnal heating, storm development will be ongoing across southern Kansas along a slowly-sinking cold front. While this activity will remain just to our north this evening, can't rule out thunderstorms/heavy rain in far northern Oklahoma. The more certain zone for storms this evening will be across western Oklahoma and western north Texas as convection develops and moves east off of the dryline. Deep-layer shear of 50 knots will support updraft organization, though initially weak low-level shear will tend to lead to upscale growth into clusters by the time storms arrive in our area this evening. The severe risk will be somewhat limited by nocturnal stabilization, though dewpoints in the upper 60s to low 70s will keep the boundary layer from fully decoupling. In all likelihood, we will see several severe thunderstorms capable of damaging winds and perhaps one or two storms with favorable storm/LLJ interactions to contain a tornado risk.

This line will move eastward tonight, likely weakening as it approaches I-35 and moves into higher 500 mb heights. By late tonight, the low-level jet will be matured and veering across the I- 40 corridor in western Oklahoma. This will trigger warm advection storms to redevelop within an extremely tropical (PWATS of 2.0 to 2.25 inches) airmass before or around daybreak. The severe risk will be limited with those storms (though can't rule out low-level rotation within any more pristine airmass pockets), but very heavy rainfall and flooding will start to become more prominent.

Meister

SHORT TERM

(Wednesday through Thursday night) Issued at 211 PM CDT Tue Oct 13 2026

Short-term forecast concerns: Escalating flood risk from Wednesday morning through Thursday morning, severe risk Wednesday afternoon into Wednesday night, cold front arrival with falling temperatures on Thursday.

Discussion: Environment is set up for impactful flash flooding somewhere in our area tomorrow morning through Thursday morning. How impactful, what location, and specific timing remain the biggest questions. The upper-level low will be slow to lift northeastward; tomorrow morning it will be near the Four Corners, and by Thursday afternoon it will just be leaving Colorado into Nebraska as the polar jet absorbs it. Because of this, a surface low will develop and take the rough track of (an extremely weak) panhandle hook from southeast Colorado to northern Oklahoma to eastern Iowa. All of this synoptically speaks to why we should expect the cold front to be slower to move south despite repeated convective reinforcement as persistent height falls counteract it.

Into this environment we will see several rounds of thunderstorms from Wednesday morning through Thursday morning. The round tomorrow morning will be driven by the decaying LLJ. There may be break before more storms in the afternoon as instability increases south of the front, or the two rounds may just end up merging. Regardless, more storms will form along and north of the cold front and last through Wednesday evening. This seems to be the period of greatest severe potential through this event, particularly along the front near/after sunset as the low-level jet again ramps up. Any bowing structures or discrete supercells in this extremely tropical airmass would be capable of wet microbursts and/or brief tornadoes. Our expectation is that those pockets of pristine, untouched warm sector will continue to shrink as the night goes on, reducing near-surface instability and the severe risk.

However, the flash flood risk will only continue to increase with each round of thunderstorms. REFS/HREF guidance both suggest a final round of thunderstorms as the trough begins to kick out and the low- level jet veers early Thursday morning. This pattern (veered LLJ/favorable propagation vectors, extreme PWATs, weak instability, rather slow storm motions, prior thunderstorms) checks all of the boxes for flash flooding. The location of this axis/MCS is still in question, with the NAM somewhat surprisingly much to the northwest of the remaining guidance. The consensus of convection-allowing models would put that rainfall axis near or just northwest of I-44 from about Hobart to Stillwater. This flash flood risk looks like it will be maximized for the Thursday morning commute.

It's worth noting that the official QPF gridded forecast that we receive from the WPC is rather bearish on rainfall amounts. This guidance shows about 1-3 inches of rain falling in a box bounded by Alva, Arnett, Wichita Falls, and Seminole. Often times, our gridded forecast runs hot compared to reality (for example, two weeks ago our forecast was initializing at 3-5 inches of rain across most of the area which was well above what the median storm total ended up being). There are both synoptic and model-input-based reasons to expect that the usual overestimating bias may not apply here, at least across a southwest-to-northeast axis. The synoptic reasons are outlined above; the model input reason boils down to the usual trend we see here, where global models are gung ho on widespread rainfall totals leading into a storm system which are then tempered by CAMs coming in and showing features like dry slots, cold advection regimes, and other details that reduce the forecast. Since model blends like NBM include both global and CAM models, they then end up too high with QPFs when the CAMs verify closer to correct. In this case, though, CAM guidance (particularly the 12Z REFS and HREF) are much wetter than anything that global/medium-range models have shown. The REFS and HREF both show ensemble mean totals of 4-6 inches (and individual members have higher maximums) near/just northwest of the OKC metro through Thursday, which could lead to rather serious flash flooding. This is a rather unusual case for us forecasters, so there's quite a bit of uncertainty regarding just what the higher-end rainfall totals could be. Bottom line: while we do usually see a QPF high bias in our official forecast, there are reasons to consider that this case may be better-calibrated or even biasing low, with a much higher ceiling for flash flood potential.

The rain event will come to an end Thursday as a strong polar trough sweeps east through Canada and pressure rises kick a much colder/drier airmass into our area. Would expect a several-hour window of cold showers/drizzle to continue after the frontal passage as dewpoints rapidly drop, but the lightning risk will come to an end shortly after frontal passage. High temperatures on Thursday will be set early in the day in many spots.

Meister

LONG TERM

(Friday through Monday) Issued at 130 AM CDT Tue Oct 13 2026

The aforementioned cold front will bring a high confidence (60-80%) chance of temperatures remaining below 60F on Friday across areas from northwestern to central Oklahoma. Across southern and southeastern Oklahoma and western north Texas, there is a 20-30% chance of temperatures staying below 60F on Friday.

By Saturday, daytime temperatures will rebound slightly as the cold air advection weakens under clear skies. Mostly clear skies will help overnight lows Friday into Saturday morning to get down into the 40s across most locations, and into the upper 30s in northwestern Oklahoma. There is high confidence in dry conditions through the remainder of the weekend and into next week, with a steady warming trend into early next week. By Monday, highs will likely get back into the 70s across the entire area.

Bunker

AVIATION

(18Z TAFS) Issued at 1221 PM CDT Tue Oct 13 2026

VFR/MVFR ceilings expected this TAF period although a few locations might see IFR ceilings at times. Multiple rounds of showers/storms are expected later today into Wednesday with chances beginning in western parts of the fa late afternoon/evening then spreading east and northeast with highest chances in northern and parts of western OK. Variable, gusty winds will be possible near the stronger storms.

PRELIMINARY POINT TEMPS/POPS

Oklahoma City OK 72 82 68 77 / 40 80 100 90 Hobart OK 70 81 66 75 / 70 90 100 80 Wichita Falls TX 74 89 70 79 / 20 70 80 90 Gage OK 65 76 59 70 / 70 90 80 30 Ponca City OK 69 78 65 76 / 70 100 100 90 Durant OK 75 90 70 86 / 10 30 30 30

OUN WATCHES/WARNINGS/ADVISORIES

OK...Flood Watch from Wednesday morning through Thursday afternoon for OKZ005>029-033>038.

TX...Flood Watch from Wednesday morning through Thursday afternoon for TXZ083>085-087-088.