Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Apr 29 2025 19:39:46 AWUS01 KWNH 291937 FFGMPD TXZ000-OKZ000-300135- Mesoscale Precipitation Discussion 0196 NWS Weather Prediction Center College Park MD 336 PM EDT Tue Apr 29 2025 Areas affected...West-Central to Northwest TX...Southwest to Central OK Concerning...Heavy rainfall...Flash flooding likely Valid 291935Z - 300135Z SUMMARY...Considerable development and expansion of heavy showers and thunderstorms can be expected over the next several hours going into the evening time frame. Areas of flash flooding will become likely in time due to heavy rainfall rates and storm totals along with locally sensitive soil/streamflow conditions. DISCUSSION...The mid-afternoon GOES-E visible satellite imagery shows convection beginning to initiate across areas of western TX in close proximity to the dryline, with additional agitated CU/TCU development noted off to the northeast near a stationary front situated over northwest TX and into southwest and central OK. In fact, there is a cluster of stronger convection evolving over central OK to the south of the Oklahoma City metro area which is near the intersection of the front and a nearby long-lived outflow boundary. The warm sector airmass across the southern Plains near these boundaries is quite unstable with MLCAPE values of 2000 to 2500+ J/kg in place with the aid of strong diurnal heating and a moisture-laden boundary layer with surface dewpoints in the mid to upper 60s. A substantial amount of shear is already in place with effective bulk shear values of 50 to 60+ kts noted, and this coupled with the favorable thermodynamic environment will set the stage for developing and expanding clusters of heavy showers and thunderstorms over the next few hours. Given the arrival of subtle height falls from the west in association with a deep upper trough over the Southwest, and with some additional strengthening of the low to mid-level wind field, the convection should grow upscale heading into the evening hours with well-organized convection focusing near the dryline and especially the front/outflow boundary locations. This will include supercell thunderstorm activity with potential for cell-mergers and potentially some smaller scale QLCS evolution in time. The environment will be rather moist by this evening across the region and especially over northern TX and into southern OK where PWs should increase to near or above 1.5 inches and this will be running a solid 2 standard deviations above normal. This coupled with the kinematic and thermodynamic environment should help support rainfall rates as high as 1.5 to 2.5"/hour with the stronger convective cores, and especially any supercells. In time, the upscale growth along with concerns for cell-mergers and localized cell-training will favor some storm totals by early this evening of 3 to 5 inches. The heaviest rainfall totals are expected to be over areas of northwest TX into southwest and south-central OK and this closely aligns with the current WPC D1 ERO depiction of a Moderate Risk of excessive rainfall. Areas of flash flooding are expected to gradually become likely across these areas, and especially given elevated soil/streamflow sensitivities. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_c1eevdiFtS-0Cwz6NjADVsbGIGzBbVl9q2QZNdUHRDAADw_Sufx18Piy8FaE1z9zc1H= M29cIQgMWgk5RcT8C7jD3j4$ for graphic product... ATTN...WFO...FWD...LUB...MAF...OUN...SJT...TSA... ATTN...RFC...ABRFC...WGRFC...NWC... LAT...LON 36489622 36179484 35469462 34559520 33889625=20 33269753 32199944 31610038 30810235 30700312=20 30960329 31850260 32510223 33110226 33680167=20 34340032 35129907 36029763=20 =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .