Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Oct 24 2024 08:16:09 FOUS30 KWBC 240815 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 415 AM EDT Thu Oct 24 2024 Day 1 Valid 12Z Thu Oct 24 2024 - 12Z Fri Oct 25 2024 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS=20 OF THE MIDDLE MISSISSIPPI VALLEY... Introduced a Marginal Risk for portions of the Middle MS Valley, from northwest IL and southeast IA into northern MO (and adjacent=20 portions of far northeast KS). Strengthening southwesterly low- level flow (850 mb) to 40-50 kts this evening will usher in PWATs=20 to near 1.25" (well above the 90th percentile, per SPC sounding=20 climatology), along with sufficient instability (ML CAPE 1000+ J/kg) and forcing (potent shortwave trough crossing the Central Plains) for convective development. Strong vertical shear (~50=20 kts) with idealized curving hodographs will likely favor discrete=20 convection (with both the mean flow and bunkers right vectors=20 favoring storm motions of 20-30 kts), and despite relatively low=20 PWs (particularly compared to warm season convection) any supercells will likely be capable of 1-2"/hr rainfall rates (per=20 40-km neighborhood HREF probabilities for 1"/1-hr exceedance of=20 40-50%). While 1-2" totals should be well tolerated by soils (and=20 largely beneficial, given dry antecedent conditions), localized=20 training could result in too much rainfall (2"+) too quickly (in a=20 matter of 2-3 hours). Given this threat, an isolated instance or=20 two of flash flooding is possible.=20 Churchill Day 2 Valid 12Z Fri Oct 25 2024 - 12Z Sat Oct 26 2024 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Churchill Day 3 Valid 12Z Sat Oct 26 2024 - 12Z Sun Oct 27 2024 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Churchill Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6CeD7NrPF0Sn5y0Oo45azqn821JBx8H-pTqTnaTsMelQ= 7fMErAlxIapHNJg9dZen9I3xjAxRjWtJ9wGNlAPlZKLewIo$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6CeD7NrPF0Sn5y0Oo45azqn821JBx8H-pTqTnaTsMelQ= 7fMErAlxIapHNJg9dZen9I3xjAxRjWtJ9wGNlAPlxTc_RM0$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6CeD7NrPF0Sn5y0Oo45azqn821JBx8H-pTqTnaTsMelQ= 7fMErAlxIapHNJg9dZen9I3xjAxRjWtJ9wGNlAPluNH43xs$=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) .