Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jun 25 2023 08:13:06 FOUS30 KWBC 250812 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 412 AM EDT Sun Jun 25 2023 Day 1 Valid 12Z Sun Jun 25 2023 - 12Z Mon Jun 26 2023 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE GREAT LAKES...OHIO AND TENNESSEE VALLEYS...AND NORTHEAST... ....Previous Excessive Rainfall Discussion... ....Northeast... Deep southerly flow will remain in place across the Northeast today, ahead of the approaching deeper closed low tracking into the Great Lakes, and with the anomalous moisture in place (upwards of +2.5 standard deviations) and expected daytime heating/instability, scattered to widespread thunderstorms are expected across mainly the interior Northeast. Mean flow will be relatively weak (under 10-15 kts) and warm cloud depths will continue to be relatively high, supporting efficient rainfall producing thunderstorms and a localized/isolated threat of flash flooding. ....Great Lakes to Tennessee Valley... The deep closed mid/upper low will move from Minnesota this morning toward the Great Lakes by early Monday morning. Ahead of that, ongoing convection will slide eastward into portions of Wisconsin and Michigan, where greater forcing will align with an axis of higher moisture that has lifted northward. The latest guidance indicates upwards of 1.0-1.25" of PW present and with daytime heating today providing sufficient instability, some higher rain rates are likely with deeper convection just ahead of the surface low tracking through Wisconsin into Michigan. The 00Z HREF indicates some hourly totals up to 1-2" possible and storm motions may be slow or allow for repeating rounds, so a few instances of flash flooding will be possible. Further south into portions of the Ohio Valley, Tennessee Valley and into Arkansas, the environment will much more conducive for deeper convection with a better setup for one or more complexes of strong/severe storms. With higher dewpoints in the mid 60s to near 70F and precipitable water values up to 1.5" and plenty of instability, storms should quickly develop this afternoon into the evening and progress quickly east/southeast. Storm motions are likely to be quite progressive, limiting the duration of the intense rain rates, but a few colliding clusters or cell mergers may pose an isolated flash flood risk with isolated rainfall amounts up to 2". ....Central Washington... Isolated thunderstorms are once again expected to develop this afternoon across portions of north-central Washington and will have the potential to produce isolated rain rates up to 1"/hr per the latest guidance including the 00Z HREF neighborhood probabilities. Given some of the more sensitivity/vulnerable burn scars in the outlook area, particularly across western Okanogan County (Cedar Creek, Cub Creek, and Muckamuck), a Marginal Risk was introduced in coordination with WFO OTX. Taylor Day 2 The Day 2 outlook will be updated by 0830Z. Day 3 The Day 3 outlook will be updated by 0830Z. Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9Bd6Zf_3xfBBj3oRg7uhPeoRKHQaQWdXxAFah5BofhG2= 5g5BUXV2UQsYf2ZZKUJYAvfvo9cNuu-sWf-i0VTXUr-0cyg$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9Bd6Zf_3xfBBj3oRg7uhPeoRKHQaQWdXxAFah5BofhG2= 5g5BUXV2UQsYf2ZZKUJYAvfvo9cNuu-sWf-i0VTXS4FOKE8$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9Bd6Zf_3xfBBj3oRg7uhPeoRKHQaQWdXxAFah5BofhG2= 5g5BUXV2UQsYf2ZZKUJYAvfvo9cNuu-sWf-i0VTXd0hdNfI$=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) .