Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Apr 19 2023 15:59:48 FOUS30 KWBC 191559 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1159 AM EDT Wed Apr 19 2023 Day 1 Valid 16Z Wed Apr 19 2023 - 12Z Thu Apr 20 2023 ....THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR AN EASTERN PORTION OF THE CENTRAL PLAINS... Round 1 of activity continues over WI this afternoon ahead of an impulse over MN/IA with locally heavy rain generally moving out of the areas with snowpack. A stronger impulse currently over CO shifts over the central Plains this evening, riding a cold front currently pushing south over western KS that will stall this afternoon. Round 2 of activity is ahead this cold front over the eastern portions of the Central Plains (southeast Neb/northeast KS) this evening with initiation after 00Z. One or two rounds of activity occurs over this area spreading into southwest IA/northwest MO before expanding southwest to northeast through the night from eastern Kansas through Wisconsin. PW of 1.25" is 2 sigma above normal. A Slight Risk area has been raised for far southeast Neb/northeast KS/southwest IA and far northwest MO. The new 12Z HREF still depicts a risk for rainfall rates over 1"/hr. While KS/Neb/IA/MO will have the most instability this evening, antecedent conditions are also favorable for flash flooding in Wisconsin due to added snowmelt from the recent winter storm over the western half of the state. Thus if FFG is able to be exceeded, we could realize some lower end flood impacts, especially over any more susceptible areas. The Marginal Risk area was expanded west a bit for activity over southeast Neb and trimmed on the eastern end per 12Z CAM trends. Jackson Day 2 Valid 12Z Thu Apr 20 2023 - 12Z Fri Apr 21 2023 ....THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FROM NORTHEAST TEXAS TO THE MID-SOUTH... A steady stream of deep-layered moisture will be advecting northward as a cold front progresses southeast form the Central plains. PW values of 1 to 1.75 inches (1.5 to 2 sigma) will in place ahead of the frontal boundary as it approaches the Mid-South and eastern Texas Thursday afternoon. Continued southwesterly deep layer flow, which will be nearly parallel to the front will be conducive for storms repeating with some backbuilding of convection. General consensus depicts areal averages of 1 to 3 inches from eastern Texas to the Mid-Mississippi Valley with amounts closer to the 1 inch mark for the Upper Mississippi Valley and Great Lakes. FFG will remain lower due to recent rains (and snowmelt in the Upper Midwest), thus keeping an elevated threat for flooding concerns. The Slight Risk area was expanded further southwest into eastern Texas and southward into northern Louisiana. The southern bounds of the Marginal Risk ares was also expanded south and eastward to reflect the latest WPC forecast and QPF trends. Campbell Day 3 Valid 12Z Fri Apr 21 2023 - 12Z Sat Apr 22 2023 ....THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FROM THE CENTRAL GULF COAST TO THE MID-SOUTH... The cold front mentioned in the day 2 period will continue to advance into the Deep South and into the Tennessee/Ohio Valley during this period. Meanwhile the deep layered Gulf moisture will continue to fuel showers and thunderstorms ahead of and along the frontal boundary. The strongest moisture convergences will align from southern Louisiana to western Tennessee. Model guidance does show some spread in exactly where the highest QPF will be and of what values. However, most are indicating 2 to 3 inches along the Lower Mississippi Valley with embedded higher amounts along the Gulf Coast. A Slight Risk for excessive rainfall spans for the extreme eastern Texas/Louisiana to western Tennessee/Kentucky border. A broader Marginal Risk spans from Texas to Alabama and then northward to Ohio. Campbell Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-HzimI8uca2JpOG27pPxmr_5UtM-9wlMfUa4GagW2J-V= 5KO-Qy0_NRQkUfPbfk_fJNY9k9dCQS4uXhefo5BSb5l1RWE$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-HzimI8uca2JpOG27pPxmr_5UtM-9wlMfUa4GagW2J-V= 5KO-Qy0_NRQkUfPbfk_fJNY9k9dCQS4uXhefo5BS8rLZUpI$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-HzimI8uca2JpOG27pPxmr_5UtM-9wlMfUa4GagW2J-V= 5KO-Qy0_NRQkUfPbfk_fJNY9k9dCQS4uXhefo5BSFigi_J8$=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) .