Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Dec 18 2024 03:51:44 AWUS01 KWNH 180351 FFGMPD MOZ000-ARZ000-TXZ000-OKZ000-180920- Mesoscale Precipitation Discussion 1179 NWS Weather Prediction Center College Park MD 1050 PM EST Tue Dec 17 2024 Areas affected...Southeast OK...South-central MO...Far Northeast TX...Arkansas... Concerning...Heavy rainfall...Flash flooding possible Valid 180350Z - 180920Z SUMMARY...Another round of elevated occasionally training showers/thunderstorms with capability of 1.5"/hr and localized totals of 2-3". Intersection with recently saturated increasingly dormant soil conditions may result in increased localized run-off and low-end flash flooding potential overnight. DISCUSSION...03z surface analysis depicts an older polar boundary draped across the Red River Valley, S Arkansas into the TN River Valley. CIRA sfc to 850 LPW shows return moisture from the western Gulf of Mexico streamed northward across central TX, then angling northwest across much of AR while ascending across/above the boundary into the 850-700mb layer. Total PWat values are in the 1.25 range, but sharpening upper-level polar trough across the Central High Plains is increasing flow through the layers into the 30-40kt range through 700mb while sharpening the isentropic boundary as the northern stream cold front presses further south and east over the next few hours. Modest, mid-level drying and lingering steeper lapse rates along with the near surface moisture/heating is providing solid MUCAPE over the boundary with values of 1500-2000 J/kg spreading across SE OK. Additionally to the strengthening low level convergence/isentropic ascent; the right entrance of the 100 kt jet is dropping southeast providing solid divergence and evacuation to developing elevated convection (while also moving into broadly diffluent region across S MO/AR into the MS Valley). Current GOES-E 10.3um and regional RADAR mosaic depict numerous narrow core cells breaking out in two SW to NE orientated bands across E OK and north-central AR. Coverage will increase and updrafts will broaden to support 1.25-1.5"/hr rates occasionally increasing to 2"/hr randomly and widely scattered in nature. Deep layer flow while not ideally unidirectional, will support cross track/repeating particularly over the first 2-4 hours before the stronger flow/height-falls aloft increase forward cell motions and increase southeastward cell propagation. This should allow for a few scattered incidents of 2-3" totals across E OK/W AR and perhaps even further downstream; which is likely to align with areas that missed out on the moderate/heavy rainfall a few days ago; but FFG values of 1.5"/hr and 2-3"/3hrs are well within range. Still there are some overlaps along the edges of south-central MO and eventually SW AR to south-central AR...that may be more susceptible given soil saturation values per NASA SPoRT at or above 65-70% in the 0-40cm layer. Also considered, flash flooding is possible, but given rates and totals are at the thresholds...any flash flooding is likely to be on the lower end and scattered in nature with highest potential in urban locales. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9k0OktekT6-4MAB-s6CmNq1zWrJWc0ukpHtcoOWW2wcxIkYIgfPTxAYzKsNIDQVsEgyO= NeeMQe8udUjNq2_YpnhJcBs$ for graphic product... ATTN...WFO...FWD...LZK...OUN...SGF...SHV...TSA... ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC... LAT...LON 36789162 36309120 35499120 34769177 33929358=20 33409564 33519674 34139694 34849641 36019480=20 36739300=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) .