Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu May 11 2023 04:11:59 AWUS01 KWNH 110411 FFGMPD LAZ000-ARZ000-TXZ000-111010- Mesoscale Precipitation Discussion 0258 NWS Weather Prediction Center College Park MD 1210 AM EDT Thu May 11 2023 Areas affected...Portions of Eastern TX...Northwest LA...Central/Southern AR Concerning...Heavy rainfall...Flash flooding likely Valid 110410Z - 111010Z SUMMARY...Locally training bands of heavy showers and thunderstorms are expected to set up overnight and into the pre-dawn hours. Areas of flash flooding are likely, and some of it may be locally significant. DISCUSSION...The latest satellite imagery shows a well-defined and slow-moving mid-level vort center/shortwave trough over the Arklatex region. This energy is expected to generally produce an expanding focus for bands of heavy showers and thunderstorms overnight across areas of central to southern AR, northwest LA, and into areas of far eastern TX. Already radar imagery shows a couple of broken bands of convection with one axis situated near and to the north of Arkadelphia, AR and another that stretches from near Lufkin, TX northeastward to near Shreveport, LA. Increasingly convergent flow in the 925/700 mb layer around the southern and eastern flanks of the vort center and associated shortwave trough will work in tandem with a very moist airmass and a return of favorable instability for these bands of convection. In fact, the latest RAP guidance shows a southerly to southwesterly low-level jet increasing to 30 to 40+ kts and nosing itself up across northwest LA and into southern AR in the 06Z to 09Z time frame, and some of the convection across this region is already aligning itself along a north/south instability axis with MUCAPE values of as much as 1000 to 2000 J/kg. The convective environment overnight will be conducive for back-building and training cells given favorable Corfidi vectors and alignment of the convection with the deeper layer mean flow. This will favor a strong concern for some very heavy rainfall totals at least locally. The PWs are on the order of 1.75 inches, and the 00Z RAOB from KSHV shows a notably deep warm/moist layer (noting WBZ levels over 12,000 feet) that is highly conducive for enhanced warm-rain processes and extreme rainfall rate potential when coupled with the instability. Expect convection to be capable of producing 2 to 3+ inch/hour rainfall rates. The 00Z HREF guidance shows the heaviest rainfall potential setting up over far eastern TX and into northwest LA where a consensus of the hires models suggest rainfall totals of as much as 4 to 6+ inches going through dawn. However, the backbuilding/training convection potential suggest a threat for even higher totals which is what the HRRR has been advertising. All areas around the southern and eastern flanks of this aforementioned vort center inclusive of far eastern TX, northwest LA and into adjacent areas of central/southern AR will need to be closely watched for the potential of seeing high-impact rainfall overnight and heading into the dawn time frame. Areas of flash flooding are likely and some of it may be locally significant. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9xth3oAo9FJfX4o8J4B-yGWz3WpAj2RDjSTMwDieaH0lj8ujkLanr-ZSKOPLKVBhsVC0= W7jT05Q1X5QQlPwKUU77nD4$ for graphic product... ATTN...WFO...FWD...HGX...LCH...LZK...SHV... ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC... LAT...LON 35509274 35199199 33879199 31949265 31049363=20 30949500 31509549 32779452 34709417 35339366=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .