Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Sep 07 2025 00:55:52 FOUS30 KWBC 070055 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 855 PM EDT Sat Sep 6 2025 Day 1 Valid 01Z Sun Sep 07 2025 - 12Z Sun Sep 07 2025 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF NEW MEXICO... 01Z Update... Surface observations indicate that the cold front moving across=20 the eastern U.S. this evening was beginning to move off of the=20 northern New England Coast at 00Z while extending back through the Mid-Atlantic States into the Southeast.=20 With those areas now behind the cold front and with drier, more=20 stable air moving into place, the Slight Risk was removed from the Northeast and the Marginal Risk trimmed out of northern New=20 England and the Tennessee Valley. Storms continue to track from=20 southwest to northeast ahead of the front, with MRMS continuing to=20 indicate 1+ in/hr rainfall rates within some of the stronger cells. Therefore a Marginal Risk was maintained from parts of southern=20 New England back through the Mid-Atlantic into the Southeast. Across the West and southern Texas, the previous outlook areas=20 were maintained and adjusted based on recent observation trends and hi- res guidance. This includes the Slight Risk over portions of=20 New Mexico, where isolated to scatted storms continue to fire and=20 where the 18Z HREF shows notable probabilities (greater than 40=20 percent in most areas) for additional accumulations greater than=20 0.5 inch this evening. Pereira=20 Day 2 Valid 12Z Sun Sep 07 2025 - 12Z Mon Sep 08 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR SOUTHERN TEXAS AND COASTAL PORTIONS OF THE SOUTHEAST... ....Texas... Gulf moisture in place across Texas will interact with some of the remnant moisture from former Hurricane Lorena on Sunday. PWATs rising to between 1.75 and 2 inches will be enough moisture to support widely scattered convection across much of the southern half of the state. There's still some disagreement on the guidance as to where the most convection will organize, but the majority of the guidance agrees that the heaviest QPF should reside closer to the Rio Grande and well south of Interstate 10. Since the overall forecast is little changed from the inherited forecast, the Marginal Risk remains largely in place with few changes needed for this update. ....Florida to North Carolina... The stalled out front that remains across Florida will extend northeastward near the coast of the Carolinas on Sunday. Thus, expect multiple rounds of afternoon and evening convection over much of the Florida Peninsula. There remains some indication that the convection will favor the eastern side of the state, but since the area remains in a pattern where much of the Peninsula sees numerous showers and thunderstorms developing each afternoon, the inherited Marginal remains, depicting all of the southern half of the state in an isolated risk for flash flooding. This is most likely should any storms develop and sit over urban areas, or in an area that has seen particularly heavy rain in recent days. For the updated ERO, the Marginal Risk area was extended northward to include coastal portions of the Carolinas up to the Albemarle Sound, with the cold front a little slower to exit the Coast with some heavy rainfall lingering near the coast on Sunday, although most of the heaviest rainfall should be offshore by that time. Wegman/Hamrick Day 3 Valid 12Z Mon Sep 08 2025 - 12Z Tue Sep 09 2025 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE FLORIDA PENINSULA AND PORTIONS OF THE CENTRAL PLAINS... ....Southeast... As on previous days, much of the Florida Peninsula will remain under the influence of a stalled out front that has been sitting over the state for much of the past week. This will result in yet another afternoon of widespread convection, which will take advantage of abundant tropical moisture in the area to support additional convective development from prior storms' cold pools. Meanwhile, the front as a whole will very slowly drift northwestward with time, which will increase the rain chances along the beaches from Georgia through the Carolinas. There's high uncertainty as to whether the heavier rainfall will even make it to the coast, so this will continue to be closely monitored in the days ahead. Otherwise, as in previous days, there will be little to support organized convective growth across Florida, with no particularly strong signals for heavy rain anywhere in Florida. Therefore, once again, the Marginal Risk remains in place. ....Central Plains... There is a modestly growing signal in the 12Z guidance for potential heavy rain into portions of the Central Plains in conjunction with a potential MCS that develops. There is now enough model support to add a Marginal Risk area from north-central Kansas to eastern Nebraska and western Iowa during this time period, where some convective training will be possible in association with the MCS. Wegman/Hamrick Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9VfHsGpCauKE-yUrNlfnQvyjbJEBw89d1Han4-PlOrL0= S_6SWY7EykxtSkw-lnHQ49iV4mFJRdiIZKKYjIoJyFzjeqI$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9VfHsGpCauKE-yUrNlfnQvyjbJEBw89d1Han4-PlOrL0= S_6SWY7EykxtSkw-lnHQ49iV4mFJRdiIZKKYjIoJ_T6c--w$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9VfHsGpCauKE-yUrNlfnQvyjbJEBw89d1Han4-PlOrL0= S_6SWY7EykxtSkw-lnHQ49iV4mFJRdiIZKKYjIoJUdg0nsY$=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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .