Area Forecast Discussion
Issued by NWS Oklahoma City, OK
Issued by NWS Oklahoma City, OK
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683 FXUS64 KOUN 220328 AFDOUN Area Forecast Discussion National Weather Service Norman OK 1028 PM CDT Tue May 21 2024 ...New AVIATION... .SHORT TERM... (This evening through Wednesday) Issued at 241 PM CDT Tue May 21 2024 Within the short term period alone, three distinct regimes of active convection are expected, each carrying a risk of severe weather. This active forecast will largely be centered along and southeast of I-44, with an attendant risk for flooding especially by tomorrow afternoon and evening. The first round will occur this evening. The dryline has been mixing eastward rapidly throughout the day with winds veering out ahead of it. Some radar echoes have been noted across south central Oklahoma as of the time of this writing, though there is some uncertainty about whether they mature and become surface-based. If they do, the environment is characterized by moderate-to-strong instability (2,000-3,000 J/kg of MLCAPE) and rather impressive deep-layer shear. Therefore, the concern will be for large to very large hail with any storms that can mature into supercells. Additional development is possible late this evening from south central to southeast Oklahoma as a weak cold front impinges on the dryline, with a similar concern mostly for hail. To the west of the dryline, expect a hot one with highs jumping into the 90s. A much stronger frontal push is expect to reach the area after midnight, impinging on the original washed-out boundary near I-40 sometime after midnight. Warm advection aloft associated with the NLLJ will lead to the development of strong to extreme (2,000-4,000 J/kg) of instability atop a stable surface layer. Initial storm development in central to north central Oklahoma near the 850 frontal surface is expected, with storms propagating southward along the crashing/outflow-reinforced surface boundary. Initial development may be cellular or supercellular with sufficient speed shear above the base of the warm nose for a large hail threat. Given the crashing nature of the front, upscale growth into a squall line is probable, with the potential for damaging wind gusts with an MCS along and south of I-40 in south central/southeast Oklahoma. The existence, strength, and duration of this MCS will determine the geographic scope of tomorrow afternoon`s severe threat. A stronger and progressive MCS might help wash the front entirely south of our area with an attendant reduction in the severe threat. A nonexistent or weaker MCS would stall the boundary closer to the Red River, which would most likely prime our environment for redevelopment of storms in south central and southern Oklahoma by early afternoon. The risk for severe weather here will be primarily damaging-wind- driven along and south of the front, with a chance for marginally severe hail north of the front. North of the front there may be a chance for repeated rounds of thunderstorms in the afternoon and evening, which will start to increase the risk for excess runoff and local flooding issues. HREF 75h percentile 24-hour QPF values in southeast Oklahoma will reach about 2.50 inches tomorrow evening. Therefore, a flood watch has been issued for that area. Highs tomorrow will be much cooler than today thanks to the cold front and associated widespread cloud cover. Most places will struggle to reach 80 degrees. Meister && .LONG TERM... (Wednesday night through next Monday) Issued at 241 PM CDT Tue May 21 2024 Continuing chances for storms and severe weather will occur through the weekend, so bear with us. The first, and potentially one of the more impactful rounds of severe weather will occur Thursday afternoon and evening. Most guidance indicates impressive mass response to return most or all of our area into the warm sector (no doubt aided by evapotranspiration). Subtle height falls along an eastern-mixing dryline should favor an environment favorable for all types of severe weather. Hydrologic issues will continue in areas that have received pre-conditioning in the short term timeframe. The risk will continue on Friday in what might look like a very similar day to today - a cold front looks like it will impinge on the northwestern half of our area and might act as a focusing mechanism for severe weather. Highs will rise into the low 90s south of the front but will remain in the "cooler" low 80s north of the front. If you`re looking for a sign that summer is coming, the temperatures this week will be it. Another potentially high-impact environment is being shown by global models on Saturday, although uncertainty continues to rise each day. Severe weather will be possible particularly along and east of I-35 (per SPC/machine learning guidance). Meanwhile, highs will begin to heat up even further out to the west of the dryline, with upper 90s possible in western north Texas. Sunday might be one last day with a dryline near I-35 with severe chances to the east of it and building heat to the west. After that, there is a strong signal beginning Monday for ridging to build in across the Plains. This might reduce the chance for severe weather (and/or shift it to north of I-40 in more of a northwest flow regime), and it would seem to mean that heat will start to build in next week (although interestingly some global guidance is keeping highs cooler within the northwest flow regime). Meister && .AVIATION... (06Z TAFS) Issued at 1025 PM CDT Tue May 21 2024 VFR/MVFR ceilings this TAF period. Winds will continue to shift as a frontal boundary continues to slowly move across the area overnight into Wednesday. Showers/storms are expected to develop early Wednesday and move across the area with additional storm development possible late Wednesday afternoon/evening although the later activity will be somewhat dependent on what occurrs Wednesday morning. The highest chances will be across portions of central and southern OK and north TX although chances are currently too low in some places for mention in TAF. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 62 75 62 83 / 30 40 30 50 Hobart OK 61 79 62 89 / 20 20 20 30 Wichita Falls TX 70 81 66 88 / 10 50 30 40 Gage OK 54 78 56 91 / 10 10 10 10 Ponca City OK 59 75 59 83 / 20 30 20 50 Durant OK 73 82 67 84 / 20 80 70 60 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...Flood Watch from 4 AM CDT Wednesday through late Thursday night for OKZ032-041>043-046>048-050>052. TX...None. && $$ SHORT TERM...04 LONG TERM....04 AVIATION...25