Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Mar 08 2024 06:41:20 AWUS01 KWNH 080641 FFGMPD MSZ000-LAZ000-ARZ000-TXZ000-081245- Mesoscale Precipitation Discussion 0086 NWS Weather Prediction Center College Park MD 140 AM EST Fri Mar 08 2024 Areas affected...Northeast TX....Northern LA...Southern AR...Central Western MS... Concerning...Heavy rainfall...Flash flooding possible Valid 080645Z - 081245Z SUMMARY...Increasing breadth of isentropic ascent across the area of concern within fairly unidirectional cell motions suggest prolonged duration of moderate to occasionally heavy elevated thunderstorms capable of 1-1.5"/hr rates and possible localized 2-3.5" totals and isolated possible incidents of flash flooding. DISCUSSION...06z surface analysis denotes a weak boundary defined mainly as a convergence axis extending from NW AL across central MS, northern LA into northeast TX. Here, the boundary is reinforced by strengthening low level ridging behind older outflow boundary from dying convective clusters/linear that crossed northern Texas and S Oklahoma. GOES-E and RAP analysis suggest the catalyst for the earlier convection continues across along/north of the Red River as a weak inflection/shortwave along the 500-300 mb jet streak. Weak diffluence and DPVA has increased LLJ off the northwest Gulf of Mexico with southeasterly return flow across E TX/W LA. Surface obs and Sfc-850mb CIRA LPW denote the eastern edge of enhanced moisture through the Sabine River Valley generally intersecting across northeast TX. CIRA LPW in the 850-700 layer also notes an enhanced slug of moisture along solid veering through the layer intersecting across the area of best DPVA/vertical ascent in proximity to the surface boundary. As such a recent uptick in convective activity has started to occur in across NE TX into northern LA and far southern AR, ascending to elevated LFC. VWP in the region has been steadily increasing to over 40 to 45kts through the layer further supporting moisture flux for efficient rainfall production. Lapse rate and profiles are very weak and so instability has been limited for updraft vigor, but the sheer magnitude of convergence will likely continue given the strength of the LLJ and convergence along the veering profile. Currently, this is supporting .75"/hr rates that will steadily increase to over 1-1.5"/hr. Combine this with the length of the ascent across the boundary and unidirectional flow for steering generally parallel to the boundary should support training profiles through the early morning. As such, spots of 2-3.5" totals can be expected. While the area has remained dry recently (with 14-day anomalies less than 25% of normal; with exception of far NE LA into central Western MS); NASA SPoRT LIS suggests relative soil moisture values are near 50% and at or just above normal (70th percentile) suggesting perhaps an isolated incident or two of flash flooding will be possible through early morning. Later in the time period (10-12z), there is some model uncertainty...but appears to becoming into focus that enhanced theta-E air will emerge from the western Gulf and reach the boundary toward this time period increasing overall moisture depth to 1.5-1.7 still within a highly confluent 850mb isentropic ascent channel across northeast LA into west-central MS increasing rainfall efficiency from 1.5" to 2"/hr.=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5l_Qa9sf1ZQw5CPY2LkwUwLkvDXMwUf8VK0cZao0q07g4IRrIdUMAc7aqZCxol4OGx-u= brLmpspVZ8--D6chQU6t1eo$ for graphic product... ATTN...WFO...JAN...LZK...SHV... ATTN...RFC...LMRFC...WGRFC...NWC... LAT...LON 33449141 33249053 32689004 32079031 31909164=20 31899251 31839495 32529539 32979493 33269389=20 33399256=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) .