Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Dec 24 2024 18:51:39 AWUS01 KWNH 241851 FFGMPD LAZ000-ARZ000-TXZ000-OKZ000-250030- Mesoscale Precipitation Discussion 1186 NWS Weather Prediction Center College Park MD 150 PM EST Tue Dec 24 2024 Areas affected...Northeast Texas...Southwest Arkansas...Northwest Louisiana... Concerning...Heavy rainfall...Flash flooding possible Valid 241850Z - 250030Z SUMMARY...A low-end threat of flash flooding continues with slow southeastward drift of frontal zone within favorable training/ back-building regime. DISCUSSION...18z Surface analysis shows a triple point of digging cold front and retrograding sliver of dry line near BBD. A cold front connects up to a surface wave near Denton before flattening further into the Red River Valley just north of Texarkana. GOES-Visible imagery shows the effective warm sector with field of cu across the majority of E TX, becoming more dense closer to the coast given slightly higher Tds in the mid 60s and Temps nearing upper 70s; with the exception of a pocket of low level stratus that impeded filtered solar radiation across the Hill Country generally west of HLR/EDC/T20/BEA. The western Gulf return moisture flow is solid east of this shallow stratus with 20-25kts of flow increasing toward 30-35kt nearing the front. However, there is a bit of veering that has slightly reduced deep layer convergence, likely in continued response to the exiting shortwave across NW AR and an associated diffluence wedge of 3H ascent across north Texas. This continues to support isentropic slantwise ascent across the DFW metro into NE TX in proximity to the frontal boundary and the convergence is maintaining some convective cells into northeast TX, though weaker lapse rates due reduce MUCAPE values below 750 J/kg before reaching SE OK/SW AR where broader moderate shield precipitation continues. Recent RADAR mosaic and GOES-E Visible shows some upstream redevelopment in the core of the peak MLCAPE maxima on the NE side of the stratus where mid-level SWly flow is providing mid-level drying and increased lapse rates; near Hamilton county to Bosque county where values are slowly increasing from 1000 J/kg to 1500 J/kg with further heating. Moisture flux/pooling in/near the boundary will aid low-level convergence to support rainfall production with capability of 1.5"+/hr rates similar to this morning's bout that could occasionally tick up to 2"/hr IF prolonged training deepens moisture profile in depth. As cold pool generation may overcome due to evaporative cooling; it will be a storm scale interaction balance and most likely be widely scattered in nature and limited in duration and therefore coverage. Still, this may result in localized 2-3" totals in less than 2-3 hours. Unlike earlier this morning, the line of convection is less likely to track through larger urban, more hydrophobic ground conditions and rainfall totals are are the lower end of exceeding the slightly higher FFG in the region.=20 Still, an isolated case of FF still remains possible. Downstream into far NE TX/SW AR... Instability is likely to continue to be the limiting factor but stronger isentropic ascent and with increasingly confluent 850-700mb moisture streams may allow for a broader shield precipitation to form with occasional embedded convective cores that ramp up run-off in the short-term. Increasingly deeper cyclogenesis should also enhanced WAA/moisture flux to the region that this activity may increase toward end of daylight hours with rates of 1-1.5"/hr scattered within the deeper unidirectional steering flow. Similar 2-3" totals may exist and while not as flashy in nature given the longer duration; isolated flooding conditions may evolve though 00z across NE TX into SW AR where soil saturation values are more average to slightly above average per NASA SPoRT 0-40cm RSM fields.=20=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9W_4Km_meX7XjyHBudaT4ZRzje7Nt7oiosYUguFSu0i2-PU2qCspQKMl-jCRV2_Ee7vV= RNcKvVR8VUqy5oX31McLl_A$ for graphic product... ATTN...WFO...FWD...SHV... ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC... LAT...LON 34009441 33639344 32849310 32149370 31639564=20 30989700 31119823 31889820 32599750 33519600=20 =20=20=20=20=20=20=20=20=20=20=20=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) .