Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jan 22 2023 08:50:14 FOUS30 KWBC 220850 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 349 AM EST Sun Jan 22 2023 Day 1 Valid 12Z Sun Jan 22 2023 - 12Z Mon Jan 23 2023 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHEAST... An upper trough will rotate from the Great Plains up to the Ohio/Tennessee Valleys today, while it's associated surface low strengthens. A line of convection is expected to develop over the far western panhandle of Florida and continue eastward into northern Florida Georgia and the Carolina coast. All of this will be happening within the warm sector of a strengthening surface wave lifting up from the Gulf. MUCAPE between 500-1000J/Kg, an axis of heightened frontogenesis, strong low-mid level sheering, PWATs around 1.5in and rain rates around a half inch may cause isolated instances of flash flooding in the Panhandle. Yesterday's Marginal risk area was revised quite a bit in collaboration with RAH/Raleigh, AKQ/Wakefield and MHX/Moorehead City to keep the risk area confined to the Carolina coasts. This is consistent with coastal trends in the latest guidance with respect to the axis of greatest QPF, as well as high FFGs, low soil moisture, lack of favorable instability and dynamics. Rain rates will be below a quarter of an inch and PWAT's will be below 1.5in. through tonight, when a line of showers forced by a cold front pushes through. Kebede Day 2 Valid 12Z Mon Jan 23 2023 - 12Z Tue Jan 24 2023 The probability of rainfall exceeding flash flood guidance is less than 5 percent Day 3 Valid 12Z Tue Jan 24 2023 - 12Z Wed Jan 25 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY... The inherited Slight risk area was expanded a bit to incorporate more portions of eastern Texas and the Lower Mississippi Valley. A closed upper level low will lift into the Southern Plains and Mississippi Valley on Tuesday. Meanwhile, the associated southern stream surface low pressures system will strengthen as it glides across the Texas/Louisian Gulf Coast. Showers and thunderstorms are likely to develop on the leading edge of the attendant warm front lifting up from the Gulf of Mexico beginning Tuesday morning. The general QPF trend has been wetter, due, in part, to a slower evolution of the 500 mb pattern across the southern tier as depicted by the 00z suite of global deterministic models. The ensembles struggle to pin down the timing of the upper trough's progression. The GFS has remained consistent with its diffuse QPF footprint to the north of the other guidance, while the UKMET and CMC are in the best agreemnt regarding the axis of greatest QPF. Ensemble probabilities of exceeding 2 inches within the slight risk area is currently between 15-35%. PWATs will be between 1.25-1.75in as Gulf moisture surges into the aforementioned areas. Mid-level winds in excess of 50kts and out of the south will help to transport the moist and unstable airmass northward. Rainfall rates are likely to exceed 1in/hr from eastern Texas through Louisiana Tuesday evening. Kebede Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5qrC2dS_MuXbs2r-bEZwv8l9Vv_zKv8MKspN12Y2eTeI= 3IDLq4B9NmKKZiT-6I8cRXQ6OQ1b3p4HHGqucDaau05zAq8$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5qrC2dS_MuXbs2r-bEZwv8l9Vv_zKv8MKspN12Y2eTeI= 3IDLq4B9NmKKZiT-6I8cRXQ6OQ1b3p4HHGqucDaaQ-wA9C4$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5qrC2dS_MuXbs2r-bEZwv8l9Vv_zKv8MKspN12Y2eTeI= 3IDLq4B9NmKKZiT-6I8cRXQ6OQ1b3p4HHGqucDaasw38Udk$=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) .