Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jun 30 2023 23:05:16 AWUS01 KWNH 302305 FFGMPD KYZ000-INZ000-ILZ000-MOZ000-010430- Mesoscale Precipitation Discussion 0607 NWS Weather Prediction Center College Park MD 704 PM EDT Fri Jun 30 2023 Areas affected...Southern IL...Western KY...Southwest IND...Ext. Eastern MO... Concerning...Heavy rainfall...Flash flooding possible Valid 302305Z - 010430Z SUMMARY...Very strong updrafts with potential for slow movement or training likely to induce flash flooding across saturated soils from yesterday's heavy rainfall event. Drier areas may also see possible localized flash flooding, particularly near urban centers. DISCUSSION...Scattered thunderstorms are starting to fill in along a well defined stationary front extending across central MO to near STL before bending south across southern IL into Western KY.=20 As noted by SPC MCD and Severe Watch boxes, very unstable air mass with 4500 to 5500 J/kg MLCAPE exists along the boundary, enhanced moisture with Tds in the upper 70s into the low 80s exists further east across W KY where total PWat values are near or slightly above 2". Though mid-level RH values suggest enough dry air that may reduce rainfall efficiency initially (with some loss to hail production); however, rainfall rates will be intense accompanying the hail with 1.5-2"/hr probable with localized higher short-duration intensity. This alone crossing the area from Richland county IL, to Daviess, IND to Ohio/Bulter in KY is likely to result in flash flooding given the nearly fully saturated upper soil conditions.=20 Further possible flash flooding conditions upstream and east of the wet ground will become increasingly possible given the potential for increased duration due to slow cell motions and potential for training. Deep layer flow is generally weak (10-15kts) and parallel to the boundary. Thickness analysis also suggest propagation vectors becoming increasingly weaker and divergent across W KY the eastern edge of a 500-1000mb thickness ridge. As such, spots of 2-4" are possible across W KY. Further west, there is less deeper moisture but values of 1.75-2" exist along the frontal zone, but the deeper layer steering is at least favorable for short-term training over the next 1-3 hours across metro STL into S IL. Strengthening broad LLJ with 15-20kts at 850 will support isentropic ascent across the front(reinforced by outflow), suggesting further upstream development along the front across S IL, though the early overnight period.=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-gVu6TQxj6NbKuI2DY3ATanjfWeEDj6nmmv7fuy50_t9lAjrcpuE8m6iVzk3FZeA69PW= Khb2mqcaerpW8Lh0XuK0jWQ$ for graphic product... ATTN...WFO...ILX...IND...LMK...LSX...PAH... ATTN...RFC...LMRFC...MBRFC...NCRFC...OHRFC...NWC... LAT...LON 39039045 38828749 37798516 36738542 36818807=20 37979055=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) .