Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue May 06 2025 19:00:32 AWUS01 KWNH 061900 FFGMPD MSZ000-LAZ000-ARZ000-TXZ000-070059- Mesoscale Precipitation Discussion 0235 NWS Weather Prediction Center College Park MD 259 PM EDT Tue May 06 2025 Areas affected...Eastern Texas and Louisiana Concerning...Heavy rainfall...Flash flooding likely Valid 061859Z - 070059Z SUMMARY...Organized line of thunderstorms with hourly rates up to 3 inches expected to continue sliding eastward while additional merging cells along a warm front increase the potential for 5 inch totals, likely resulting in areas of flash flooding. DISCUSSION...GOES-E CH9 WV loop this afternoon depicts a picturesque upper low churning over the southern High Plains with an expansive area of increased ascent extending to the east and north, with a well-organized line of thunderstorms entering eastern TX along a cold front. Additionally, a surface warm front extends eastward from the squall line across southern LA, with low-to-mid 70s dew points south of the front and 60s north. PWATs continue to creep upward and are generally 1.7-2.0" in the highlighted area, but will continue to rise above 2.0" across a larger region of the central Gulf Coast per the RAP. The 06z ECWMF highlights these values as exceeding the 99th percentile when compared to climatology. Rainfall totals up to 3 inches have been observed from this line near Round Rock, TX and are expected to maintain or increase in intensity through this evening given the increasing moisture and daytime instability being advected northward. Helping this northward advection is a potent 40-50kt 850mb jet extending into eastern TX as of 18z. Recent HRRR runs support the potential for hourly rates up to 3 inches and 5 inch totals, with the 12z HREF highlighting widespread 20-50% chances for 3-hrly totals greater than 3 inches in the MPD area. Although, the HRRR has been developing too much leading convection compared to current radar data. Outside of the eastern extent of the Texas Triangle, where 3-hrly FFGs are under 3 inches, much of LA does have elevated FFG that could inhibit the initial impacts of heavy rainfall. However, for southern sections of LA along the warm front, thunderstorms are anticipated to remain less progressive and oriented more west-east (similar to the mean wind) by this evening. Current convection near Baton Rouge shows this potential for slow-moving warm frontal storms that may continue and congeal with the approaching line. Scattered flash flooding is likely within this area, with greatest potential for significant impacts where convection is slower to progress on the southern flank from east-central TX through central LA. Snell ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-We7JFvC5PFF4_SXBouUY-5YNdCX72TI3auSt4vVsjxP_mBdDrWVhnm6KBf_JWkZnUsw= FXB_NfnIRJ93335YRP7QMxw$ for graphic product... ATTN...WFO...EWX...FWD...HGX...JAN...LCH...LIX...SHV... ATTN...RFC...LMRFC...WGRFC...NWC... LAT...LON 33209438 33169319 32189208 31309121 30619057=20 30039088 29969184 29989302 29949431 29799642=20 30279701 31309620 32449527=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) .