FXUS64 KTSA 210539 AFDTSA Area Forecast Discussion National Weather Service Tulsa OK 1239 AM CDT Sun Jun 21 2026 ...New AVIATION... .KEY MESSAGES... Updated at 1238 AM CDT Sun Jun 21 2026 - Advisory level heat and humidity is forecast this afternoon for portions of northeast Oklahoma and west central Arkansas. - Unsettled weather is expected to begin today/tonight and persist through much of the upcoming work week. There will be multiple opportunities for heavy rainfall and some severe weather during this time frame. - Below average temperatures are forecast this upcoming work week. && .SHORT TERM... (Through Sunday Night) Issued at 1146 PM CDT Sat Jun 20 2026 Imagery from GOES-19 shows a well defined, southeastward- advancing MCS beginning to push in south-central KS. Latest model guidance shows the mean mid-level flow becoming more zonal after midnight, helping propagate the MCS to more of a west-to-east motion. With that said, much of the moderate to heavy rainfall is anticipated to stay just north of the CWA, through a few isolated to scattered showers and thunderstorms may affect the northern- tier OK counties through the morning. Healthy storms that are able to cross the OK/KS border will be capable of producing marginally severe wind gusts up to 60 mph, though the overall severe potential is low at this time. The MCS should be in the process of weakening and/or exiting the area to the northeast by midday. Will need to monitor for remnant outflow boundaries caused by the MCS, where convection can re- initiate as diurnal heating gets going. Additionally, guidance continues to hold onto diurnally-driven convection forming off of a theta-e gradient that will setup across southeast OK and into northwest AR. Convection is expected to be isolated in nature and any activity should quickly dissipate with the loss of daytime heating late in the afternoon or early in the evening. Overall, Sunday looks mostly dry, hot, humid, and very breezy for much of the area. The surface pressure gradient will tighten as a cold front slowly work its way southeast across KS through the daytime, in addition to area of low pressure setting up across northwest OK. As a result, breezy and gust southerly winds will develop, with frequent gusts between 20 and 30 mph through the day. The strong winds and compression ahead of the front will draw up moisture and heat temperatures up, causing some dangerous heat index values across the district. Highest heat indices are forecast to occur across northeast OK and in the Arkansas River Valley, with values as high as 108 degrees. A Heat Advisory remains in effect for portions of northeast OK and west-central AR between 1 PM and 7 PM Sunday. The slow-moving cold front will be on the doorstep of the CWA, or near the OK/KS border, around sunset Sunday evening. High resolution models are in good agreement that storms will fire off the frontal boundary in southeast KS late in the afternoon, with storms pushing ahead of the frontal boundary as it shifts south. Guidance shows another MCS developing in far southeast KS or northeast OK from this activity, with movement towards the east- southeast, generally from late evening through sunrise Monday morning as the MCS pushes across far northeast OK and northwest AR. Though there are still a few questions regarding coverage and exact intensity of the storms, strong to severe thunderstorms appear likely with the storm complex, with mostly damaging wind gusts as the primary hazard with storms. However, a brief window for large and/or very large hail and a limited risk for a couple of tornadoes will exist early to mid evening, initially with storm development, before storms cluster and the MCS fully develops. On top of the severe potential, very heavy rainfall is anticipated with the MCS. Rainfall amounts through sunrise Monday of one to two inches will be common, with higher amounts possible, underneath the heaviest storms and where training occurs. Minor flooding is likely, with isolated flash flooding possible through daybreak Monday morning. Will hold off on a Flood Watch due to low confidence of widespread rainfall amounts reaching flash flood guidance. However, a Watch may be needed by the next forecast package for at least portions of the forecast area, especially for far northeast OK and northwest AR, through the next few days if QPF guidance trends higher. Mejia && .LONG TERM... (Monday through Saturday) Issued at 1146 PM CDT Sat Jun 20 2026 Storms should be ongoing at the start of the long-term period as a cold front continues to slowly advance south through the CWA on Monday. The main concern with the ongoing storms Monday morning will be the heavy rain/flooding threat, but instability, shear, and lift will all be sufficient enough for strong and marginally severe storms through the morning and perhaps early on into the afternoon. Storms should shift east and south of the area in the afternoon and things should stay mostly dry as the atmosphere becomes worked over. By Monday evening/night and into Tuesday morning, another mid-level shortwave trough becomes better defined and will move across the area. Heavy rain, flooding, and some severe potential will exist with this shortwave trough. The frontal boundary from Monday will remain in the region through at least midweek, perhaps even into late in the week. With a favorable upper-level pattern for storms remaining in place, chances for showers and thunderstorms will continue daily as the frontal boundary hangs out in the area, though chances and coverage may differ slightly each day. Mejia && .AVIATION... (06Z TAFS) Issued at 1238 AM CDT Sun Jun 21 2026 Mid and high clouds spreading across ern OK and nwrn AR ahead of severe MCS currently over south central KS. This convection has turned more east past hour or so, and most guidance keeps it north of the OK/KS border as it heads toward MO overnight. Maintained PROB30 group for BVO for a few hours into mid morning. Moderate confidence in low clouds/MVFR CIGs developing around sunrise and continuing through late morning, most likely across wrn AR sites. Additional strong/severe convection expected to develop across sern KS this evening along the cold front. At this time, carried PROB30 groups nern OK and nwrn AR sites 22/01-06z to account for this. Gusty southerly wind expected at all sites from mid morning until around sunset this evening. && .PRELIMINARY POINT TEMPS/POPS... TUL 93 71 82 68 / 20 60 30 80 FSM 93 75 88 72 / 10 70 60 80 MLC 92 76 88 72 / 0 60 60 90 BVO 93 66 80 65 / 30 60 20 70 FYV 89 71 83 68 / 10 80 50 80 BYV 88 69 81 65 / 20 90 60 70 MKO 91 72 84 69 / 10 70 50 80 MIO 90 67 80 65 / 30 90 20 60 F10 91 72 84 69 / 10 70 50 80 HHW 91 76 89 74 / 10 40 60 60 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...Heat Advisory from 1 PM this afternoon to 7 PM CDT this evening for OKZ055-056-059>061-064>067-070-071-074-154-176-254-272- 354. AR...Heat Advisory from 1 PM this afternoon to 7 PM CDT this evening for ARZ129-219-220. && $$ SHORT TERM...67 LONG TERM....67 AVIATION...69