textproduct: Norman

KEY MESSAGES

Updated at 629 AM CDT Thu May 21 2026

- Showers and thunderstorms and cool temperatures are expected today; locally heavy rainfall is possible.

- Strong to severe thunderstorms are possible on Friday afternoon and Friday night across western Oklahoma and adjacent north Texas.

- Rainy pattern and unseasonably cool temperatures continue through middle of next week.

NEAR TERM

(Through Thursday) Issued at 247 AM CDT Thu May 21 2026

Today will be cool and wet with highs in the mid-60's to mid-70's. Widespread rainfall amounts of 1 to 2 inches are expected for areas along/east of I-44 by this evening, with locally higher amounts (3 to 4 inches) possible for south/southeastern Oklahoma.

Radar echoes are beginning to appear as low-level WAA increases ahead of a southern-stream shortwave approaching from west Texas. As the wave continues to advance, we expect showers to become more widespread over the next several hours with thunderstorm chances increasing after dawn. Hourly rainfall rates of 1 to 1.5 inches/hour are possible this morning and could increase to perhaps 2-3 inches per hour this this afternoon over south/southeastern Oklahoma.

The axis of greatest rain chances through noon (80-95%) reside along the I-44 corridor and shift a bit along/east of the I-35 corridor by afternoon and evening. We will have to monitor for flash flooding potential, especially for areas that have received heavy rainfall over the past two days - namely parts of south-central and southeastern portions of the CWA (e.g., Stuart, Centrahoma and Madill). Even the OKC metro, which has received upwards of 1 inch of rainfall, may be prone to flash flooding due to urban runoff. Thunderstorm activity is expected to remain sub-severe.

Thompson

SHORT TERM

(Thursday night through Saturday night) Issued at 247 AM CDT Thu May 21 2026

The majority of rainfall exits this evening with isolated activity possible tonight. Our attention then turns to the severe thunderstorm potential on Friday across western Oklahoma and adjacent north Texas. This is not the most promising synoptic setup for severe weather as our area resides on the back side of the departing shortwave with mid-level height rises. The dryline will become more defined - but west of the 100th meridian - and a warm front may begin to lift northward across our area. For now, shower and storm chances remain low and hazards from any severe activity would be large hail up to golfballs and damaging wind gusts before shifting to a wind threat as storms grow into a complex on Friday night over west-central or southwest Oklahoma.

Below average temperatures continue on Saturday with highs near 80 deg. While there is a medium chance (30-50%) of showers/storms during the day on Saturday, probabilities increase substantially on Saturday night with the passage of another wave. Strong to marginally severe storms appear possible on Saturday night.

Thompson

LONG TERM

(Sunday through Wednesday) Issued at 247 AM CDT Thu May 21 2026

A weak closed upper low is forecast to develop over north Texas and bring continued shower and thunderstorm chances Sunday through possibly Wednesday. While temperatures could rise to near seasonable, it appears it will be relatively cool as we go into middle of next week with highs in the low 80's.

Thompson

AVIATION

(12Z TAFS) Issued at 630 AM CDT Thu May 21 2026

IFR to LIFR flight conditions are ongoing this morning and will likely persist at most terminals through the TAF period with low ceilings. KSPS and KWWR are the most likely terminals to briefly see MVFR flight conditions before conditions deteriorate again tonight.

Rain with some embedded thunderstorms will continue to move to the northeast through the day with chances gradually ending from west to east. Drizzle and mist is still possible even when the rain exists.

Mahale

PRELIMINARY POINT TEMPS/POPS

Oklahoma City OK 67 59 79 60 / 90 60 10 80 Hobart OK 70 57 82 58 / 70 20 20 80 Wichita Falls TX 71 59 84 61 / 90 30 10 80 Gage OK 70 54 79 53 / 50 30 40 70 Ponca City OK 68 58 78 58 / 80 60 30 60 Durant OK 75 64 83 65 / 80 80 20 70

OUN WATCHES/WARNINGS/ADVISORIES

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