Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Mar 16 2023 19:17:11 AWUS01 KWNH 161917 FFGMPD LAZ000-ARZ000-TXZ000-OKZ000-170100- Mesoscale Precipitation Discussion 0112 NWS Weather Prediction Center College Park MD 316 PM EDT Thu Mar 16 2023 Areas affected...Southern & Southeast OK...Northeast TX...Western AR...Ext Northwest LA... Concerning...Heavy rainfall...Flash flooding possible Valid 161915Z - 170100Z SUMMARY...Quick moving but increasingly efficient rainfall production with sub-hourly totals of 1-1.5" ahead of the cold front. Isolated incidents of flash flooding are possible as these cells intersect wetter soil conditions near the Red River as well as areas affected by warm advection thunderstorms into the OK/TX/AR region by late evening. DISCUSSION...GOES-E IR/WV suite depicts two convective regimes across the Southern Plains this afternoon as anomalous deep layer broad trough emerges across the High Plains attm. A lead smaller scale shortwave is lifting quickly out of north-central OK, while the main core of vorticity energy is pressing east across the TX Panhandle. This is providing solid height-falls while maintaining a strong LLJ across E TX pumping near record moisture values for the date across a narrow warm sector. CIRA LPW sfc-850mb layer shows this well with .75"+ values into central TX generally aligned with mid-60s Tds, though .5-.6" values extend into central and eastern OK along the front. While there a weak dry slot across northwest TX, the LPW values depict the solid connection back to the subtropical East Pacific, bringing total PWat values of 1.25" across much of the warm sector, with a narrow axis of 1.5" building from Milam to Hunt to Lamar county, which is expected to expand with time as layers align better this evening.=20 This moisture and weak confluence on the eastern edge of th 50kt LLJ has sparked slow moving warm advection thunderstorms.=20 Back-building and highly isolated training may allow for some localized 1-2" totals, but not likely rising to flash flooding conditions just yet. Upstream...initially elevated convection across central OK has enhanced cold front as it is starting to shift eastward with the better height-falls aloft, the increased forward motion should intersect LLJ a bit better though still at an oblique angle for the next few hours. Stronger instability and that weak dry slot denoted in the 850-700mb layer in the LPW, have allowed for increased instability for stronger updrafts...please see SPC MCD 291 for further details wrt severe weather. Cells along the tail of the cold front near a triple-point with the dry line in NW TX, may allow for more discrete stronger supercells and as such, will enhance isallobaric increased convergent sfc to boundary layer flow and strengthen moisture flux convergence into broadening updraft cores. This will allow for higher rainfall efficiency with time with HRRR 15 minute rain totals of 1-1.25" even with faster eastward progression. Duration may only be up to an hour, but 1.25-1.75" totals in sub-hourly ranges may allow for localized flash flooding conditions...especially after 22z as the cells move into the deeper low level moisture axis (east of I-35).=20 Additionally, soil conditions are a bit more susceptible to higher runoff given 200-300% of normal precip across the Red River Valley from Young to Cooke to Choctaw, OK counties...where NASA SPoRT LIS 0-40cm soil ratios remain above normal at 65-70%. After 00z, depending on the cells forward speed, these intense short-term rates may intersect those areas affected by the aforementioned 1-2" spots from the warm advection development of Northeast TX into Western AR, sparking a slightly higher probability of flash flooding situations.=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9BxaIpAG6SV-MKKXpsA9AGtyCDzTirDsr0og1oMObjvCdOFUuHMcajaghgelt-6GBwWA= uIRSOz0qkNRMhiTjI05XvFE$ for graphic product... ATTN...WFO...FWD...LZK...OUN...SHV...TSA... ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC... LAT...LON 35709463 35639377 35099329 33879330 32689372=20 32059503 32609645 32809730 32999805 33549829=20 34659775 35309658 35649557=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .