textproduct: Norman

KEY MESSAGES

Updated at 600 PM CDT Wed May 20 2026

- Heavy rainfall possible across southern/southeastern Oklahoma on Thursday afternoon.

- Scattered thunderstorms expected Friday afternoon into Saturday with some severe risk.

- Cool through Thursday, then near 80 for the next several days.

NEAR TERM

(Rest of today and tonight) Issued at 114 PM CDT Wed May 20 2026

Widespread cloud cover continues across much of the area in a postfrontal regime. This will bring a complex and fragmentary high temperature forecast across the region this afternoon:

-Central/northern Oklahoma - widespread stratus remains, highs in the mid-60s -Southeast Oklahoma - some mixing already ongoing with greater dewpoints advecting from the east, highs in the mid-70s -Northwest and southwest Oklahoma and western north Texas - at least some breaks in the cloud cover are expected late, with temperatures reaching about 70

Storms have begun developing in far west Texas ahead of a slow- moving MCV this afternoon. This will begin translating northeastward this evening. We should end up with a narrow zone of about 1,000 MUCAPE just west of the stratus deck by sunset, which could permit elevated showers or storms to move into far western Oklahoma/western north Texas. With that said, the greater and more widespread storm chances will hold until after midnight as the MCV approaches, a convectively-enhanced 25 kt LLJ develops, and tropospheric water vapor content increases. Severe weather is not expected but heavy rainfall is possible with any slow-moving/repeat storms.

Meister

SHORT TERM

(Thursday through Friday night) Issued at 114 PM CDT Wed May 20 2026

Main story tomorrow will be the potential for very heavy rainfall with slow-moving showers and storms. Storm chances will exist across the entire area, but the most likely spot for problematic rain/flooding will be along and southeast of I-44 where PWATs will sit in the 95th-98th percentile for this time of year. Severe thunderstorms are unlikely due to mushy "skinny-CAPE" profiles with only about 1,000 J/kg of MLCAPe and extremely weak deep-layer shear. In fact, it wouldn't be a surprise to see that convection tomorrow is on the more modest side in overall lightning production, as well. Still, very heavy rain is likely in spots. Widespread rain totals of 0.75-1.5 inches are expected southeast of I-44, but localized spots that see multiple storms could receive as much as 3-4 inches of rain.

The pattern turns over a bit on Friday as the modified warm sector makes a northward run closer to the 100th meridian. Most models show a pseudo-triple-point environment developing by late Friday afternoon. The caveat here is that forcing will be minimal with the midlatitude jet remaining off to our north. In addition to nebulous forcing, this will also limit the amount of deep-layer shear available to any storms that develop. For that reason, a mix of supercell and multicell modes is expected with however many storms develop. Apart from the convective potential, Friday will see a rather considerable warmup across much of the area.

Meister

LONG TERM

(Saturday through Tuesday) Issued at 206 AM CDT Wed May 20 2026

The upcoming holiday weekend is forecast to be on the cool-side for Oklahoma standards, with highs in the upper 70's to mid-80's. Shower/storm chances increase Saturday afternoon with precipitation likely by Saturday evening in association with a weak upper trough. Moderate to strong instability could lead to strong to severe storm chances late Saturday. However, organized severe storms could be tough to come by given weak shear.

Rain chances generally decrease Sunday through Tuesday, with the higher probabilities over southeastern Oklahoma and the return of seasonable temperatures.

Thompson

AVIATION

(00Z TAFS) Issued at 600 PM CDT Wed May 20 2026

Mainly MVFR ceilings this evening, but dropping into the IFR category late this evening and overnight as showers and thunderstorms become more widespread late tonight and through much of the day Thursday. Expect to see mainly IFR conditions both with regards to ceilings and visibility. Winds will remain light from the east and northeast.

PRELIMINARY POINT TEMPS/POPS

Oklahoma City OK 56 68 58 78 / 50 100 70 10 Hobart OK 55 70 56 81 / 50 70 50 10 Wichita Falls TX 58 73 58 83 / 50 90 40 10 Gage OK 50 68 53 78 / 50 60 30 40 Ponca City OK 53 69 57 77 / 50 70 90 10 Durant OK 63 74 63 82 / 40 100 90 10

OUN WATCHES/WARNINGS/ADVISORIES

OK...None. TX...None.