textproduct: Norman

KEY MESSAGES

Updated at 315 AM CDT Mon May 18 2026

- There is a risk for strong to severe thunderstorms from this afternoon through Tuesday.

- Critical fire weather conditions are possible for far western Oklahoma into western north Texas this afternoon

- Very warm temperatures are expected today with cooler weather by Tuesday.

NEAR TERM

(Through Monday) Issued at 315 AM CDT Mon May 18 2026

A negatively-tilted trough will lift into the Central Plains this afternoon with a trailing dryline located along the 100th meridian. With the synoptic-scale forcing/ascent lifting to the northeast, thunderstorm development along the dryline remains uncertain as warm mid-level temperatures at the base of the elevated mixed layer (EML) will result in capping inversion at ~750 mb. In addition, low-level convergence along the dryline will be minimal/weak with the surface low and attendant backed winds to the northeast of Oklahoma. The highest chance for development along the dryline is across northwest Oklahoma, which is in closest proximity to the wave. Even so, the chance of development during the late afternoon/early evening is only around 20 to 30%. The chance of development decreases with southward extent along the dryline--but isn't zero.

If thunderstorms develop, instability and vertical wind shear will be sufficient for supercells with CAPE between 3000-3500 J/kg and 0-6 km shear between 30 to 35 knots. By evening, the low- level jet will amplify with 50 to 60 knot winds. The strengthening low-level jet will increase low-level wind shear, resulting in enlarged, clockwise- curved hodographs that will be favorable for tornadoes--including strong tornadoes. As a result, if there are any ongoing supercells in the evening, they will have an increasing tornado potential.

In addition to the dryline, another feature will be a subtle wave embedded in the subtropical jet stream (STJ) that will lift northward into south central/southeast Oklahoma. This wave may result in a few showers and thunderstorms today. While it appears likely this activity will be elevated and associated with isentropic/ascent warm air advection, there is a low chance this activity could become surface-based with a risk of strong to severe thunderstorms.

To the west of the dryline, fire weather conditions will be a concern in the afternoon. Hot temperatures, gusty southerly winds, and low humidity will result in critical fire weather conditions. The worst fire weather conditions will be across the Oklahoma and Texas panhandles. However, far western Oklahoma and adjacent parts of western north Texas will be right on the edge. Depending on the exact location of the dryline, there will likely be a very tight relative humidity gradient near the 100th meridian (Oklahoma/Texas state line). Therefore, the Fire Weather Watch was upgraded to a Red Flag Warning except for Jackson County. It could very well be a situation where the fire weather conditions are worse in the western part of the counties compared to the eastern part of the counties.

In addition to the risk of severe and fire weather, a tight surface pressure gradient will result in breezy southerly winds today.

Mahale

SHORT TERM

(Monday night through Wednesday night) Issued at 315 AM CDT Mon May 18 2026

A cold front will enter northern Oklahoma late this evening, which will likely result in a line of thunderstorms developing along the front. The line of thunderstorms will move to the southeast Monday night into Tuesday morning with the cold front with a threat for strong to severe thunderstorms. Damaging wind gusts and embedded, QLCS tornadoes would be the potential hazards. However, the tendency for the cold front to undercut the line of thunderstorms and unfavorable shear vectors/line orientation should reduce the QLCS tornado risk. Cooler weather and northerly winds are expected in the front's wake Tuesday afternoon.

Another wave is forecast to approach late Tuesday night into Wednesday, which will result in increasing isentropic ascent/warm air advection to the north of the cold front. Widespread elevated showers and thunderstorms are possible with the potential hazards being heavy rainfall/flooding and hail. The location with the highest chance for heavy rainfall is south central/southeast Oklahoma.

Mahale

LONG TERM

(Thursday through Sunday) Issued at 315 AM CDT Mon May 18 2026

An active subtropical jet stream (STJ) with subtle waves lifting into the Southern Plains will result in a daily chance of showers/storms through the end the week into next weekend. At this time, there is no day that has an appreciable risk for severe weather. Temperatures are expected to be seasonable for late May.

Mahale

AVIATION

(06Z TAFS) Issued at 1026 PM CDT Sun May 17 2026

VFR/MVFR ceilings expected this TAF period. Breezy southerly winds will continue overnight into Monday with wind speeds increasing Monday morning. A cold front is expected to be approaching NW OK late Monday evening. There is a chance that a few storms develop near the dryline to the west Monday afternoon/evening. If these storms develop, they could move into parts of western OK but the higher chance for storms is expected to start Monday night as the cold front moves across the area.

PRELIMINARY POINT TEMPS/POPS

Oklahoma City OK 86 61 71 55 / 10 80 40 80 Hobart OK 93 60 75 54 / 10 60 30 60 Wichita Falls TX 92 68 82 58 / 20 50 70 70 Gage OK 96 49 73 46 / 10 20 0 10 Ponca City OK 89 58 70 53 / 10 80 30 30 Durant OK 88 74 84 64 / 30 20 90 70

OUN WATCHES/WARNINGS/ADVISORIES

OK...Wind Advisory until 10 PM CDT this evening for OKZ004>027- 034>038.

Red Flag Warning from 1 PM this afternoon to 9 PM CDT this evening for OKZ004-009-014-021-033-034.

TX...Red Flag Warning from 1 PM this afternoon to 9 PM CDT this evening for TXZ083-084.