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KEY MESSAGES

Updated at 1152 AM CDT Mon Aug 17 2026

- Thunderstorm chances this morning west and north, and again this afternoon/evening near and north of the cold front.

- Some temporary relief to the heat in the north today... but only temporary.

- Dangerous heat continues in the south today, and throughout the area through the week.

NEAR TERM

(Through Monday) Issued at 222 AM CDT Mon Aug 17 2026

The cold front has settled to the south and the wind shift is located from near McAlester to Ada to Lawton to Hollis. It is not expected to move significantly today. Cooler weather is expected across the north today, although from a heat index perspective it will be somewhat offset by an increase in dewpoints and humidity in the easterly/northeasterly surface winds. But the cooling is enough to keep expected heat index values below 100 across northern Oklahoma, and the below heat advisory criteria of 105 for most of central and west central Oklahoma. But there is no relief in the south where afternoon maximum heat index values will again reach 105 to 110, and a heat advisory has been issued for these areas of southern Oklahoma and north Texas.

Convection has increased this morning across northwestern Oklahoma. These showers and thunderstorms will persist early this morning before moving northeast out of the area. There are two camps of models for redevelopment this afternoon with many of the CAMs only developing very isolated convection, while the synoptic models and the WRF-FV3 are more aggressive. So while there is still some question, believe that the probability of precipitation is likely greater than the NBM initialization, and have included higher POPs than the NBM again for today, especially across central Oklahoma.

As was the case yesterday, forecast model soundings show an inverted-V configuration and downdraft CAPE in the 1200-1500 J/kg range again. This (relatively) dry low-level environment will be conducive to acceleration of thunderstorm downdrafts with the potential of damaging downbursts. And as was the case yesterday, there may not be too many strong thunderstorms develop, but those that do get taller and stronger will be capable of producing these damaging winds.

SHORT TERM

(Monday night through Wednesday night) Issued at 222 AM CDT Mon Aug 17 2026

The thunderstorms that develop this afternoon will persist into at least the early evening. Some of the synoptic models hold on to QPF development through the late evening, but the signal for that is more uncertain.

The pattern begins to shift through this period with the ridge beginning to shift to the west and northwest flow aloft developing across the central and northern Plains as a trough moves toward the Great Lake region. Behind this northern trough, a front pushes down into Kansas, but likely not far enough to bring us any relief through Wednesday. But with the surface pressure pattern adjusting to the front to the north, southwest surface winds will develop allowing a warming downslope component to the winds, so the heat returns areawide for Tuesday and Wednesday. Heat Advisories will be needed again on these days.

Models show a slight potential of thunderstorms in northern Oklahoma on Wednesday night with the potential of the front being close to the Kansas-Oklahoma state line, but expect the bulk of the precipitation to remain to the north in Kansas.

LONG TERM

(Thursday through Sunday) Issued at 222 AM CDT Mon Aug 17 2026

The pattern shift we have been seeing in the model forecasts continues to show some consistency in the latest model runs with the upper ridge establishing itself more in the intermountain west and northwest flow developing over the Central Plains between the ridge and troughing expected in the Great Lakes/Mid-Mississippi Valley. With this pattern, the potential increases of getting a cold front to slide down from the Central Plains into the forecast area. But the question will be, how much cooler will it be north of the front given that the surface ridge and the best cold air advection will be to the northeast of here pushing more toward the Ohio Valley. NBM suggests highs may be in the mid-upper 90s in northern Oklahoma on Thursday and Friday, which granted will be some relief from the 104-110 highs we expect in the north on Tuesday and Wednesday, but will still be warmer than average for this time of year. Farther south the forecast reduction in high temperatures will likely not be as significant.

Then, the ridge starts building back over the Southern Plains this weekend and we are back to the areawide triple digit heat.

AVIATION

(18Z TAFS) Issued at 1152 AM CDT Mon Aug 17 2026

VFR conditions with mid/high clouds. Isolated to scattered showers/storms are possible (20-30%) this afternoon/evening although chances are too low at some locations for mention in TAF. Variable, strong winds possible near any storms. Winds will generally be from the E or NE or variable this afternoon. Winds are then expected to shift towards the S and SW by Tuesday morning.

PRELIMINARY POINT TEMPS/POPS

Oklahoma City OK 96 74 104 79 / 30 30 0 0 Hobart OK 102 74 107 78 / 20 20 0 0 Wichita Falls TX 106 77 107 80 / 10 10 0 0 Gage OK 95 69 105 75 / 20 10 0 0 Ponca City OK 93 72 104 78 / 30 10 10 0 Durant OK 105 77 106 80 / 20 20 10 0

OUN WATCHES/WARNINGS/ADVISORIES

OK...Heat Advisory from 11 AM to 8 PM CDT Tuesday for OKZ004>006- 009>011-014>017-021>023-033>038-044.

Extreme Heat Warning from 11 AM to 8 PM CDT Tuesday for OKZ007- 008-012-013-018>020-024>032-039>043-045>048-050>052.

Heat Advisory until 8 PM CDT this evening for OKZ032-036>048- 050>052.

TX...Heat Advisory from 11 AM to 8 PM CDT Tuesday for TXZ083>090.

Heat Advisory until 8 PM CDT this evening for TXZ085-086-088>090.