Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Apr 06 2024 22:36:39 FOUS30 KWBC 062236 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 636 PM EDT Sat Apr 6 2024 Day 1 Valid 01Z Sun Apr 07 2024 - 12Z Sun Apr 07 2024 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Roth Day 2 Valid 12Z Sun Apr 07 2024 - 12Z Mon Apr 08 2024 The probability of rainfall exceeding flash flood guidance is less than 5 percent. Roth Day 3 Valid 12Z Mon Apr 08 2024 - 12Z Tue Apr 09 2024 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE SOUTHERN STATES... 21Z update... The environment continues to look conducive for thunderstorms to break out over portions of the Southern Plains and Lower Mississippi Valley that have the potential to reach or exceed hourly rainfall rates of 0.50 inch/hour. Model consensus suggest 2 to 4 inches in accumulations with locally higher amounts certainly possible. Given the latest guidance had small shifts in the placement and axis of orientation of the QPF the Slight Risk area was broadened a little to the north in north-central Arkansas and to the south in northern Louisiana. The Marginal Risk area was expanded to the north and northeast further across northern Arkansas, Missouri Bootheel and western Tennessee. Campbell Convection capable of producing heavy to excessive rainfall will develop later in the day on Monday and persist into the early morning hours on Tuesday. The flow of moisture from the Gulf of Mexico will increase as low level flow increases in response to the approach of an upper level low from the Desert Southwest...and moisture flux convergence will be maximized as the deepening Gulf moisture encounters the southern end of a cold front extending from the Tennessee Valley southwestward towards the upper Texas coast. Increasing coverage of storms and increasingly intense rainfall rates are expected due to the upper level divergence ahead of the approaching upper low atop of an airmass with climbing precipitable water values. At the same time, precipitable water values in excess of 1.50 inches start advecting northward in southeast Texas and southwest Louisiana Monday night/early Tuesday as moisture transport continues off of the Gulf. There is a decent amount of north/south placement differences...with the ECMWF being well south and the GFS continuing its idea from earlier runs about being too far to scoot the system northward/eastward. Focused a Slight Risk area where there was best overlap and where there was at least a modest consensus for 2 to 4 inch rainfall amounts through 12Z Tuesday. With the risk of excessive rainfall persisting beyond the end of the Day 3 period, refer to the Excessive Rainfall Outlooks for Days 4 and 5 from the WPC Medium Range desk. Bann Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_LKTwGg9SsweMow_j0XcGNMOZSuPaQu-UoEndX55t_vo= Ijk9wMhQmJHrlPNxXCFMYH_vVeBXO8PG5u6TkhXMGF1tug4$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_LKTwGg9SsweMow_j0XcGNMOZSuPaQu-UoEndX55t_vo= Ijk9wMhQmJHrlPNxXCFMYH_vVeBXO8PG5u6TkhXMmTuIYMM$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_LKTwGg9SsweMow_j0XcGNMOZSuPaQu-UoEndX55t_vo= Ijk9wMhQmJHrlPNxXCFMYH_vVeBXO8PG5u6TkhXMwG2mf4s$=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) .