####018003392#### AGUS74 KWCO 131512 HMDNWC National Hydrologic Discussion - EXPERIMENTAL NWS National Water Center - Tuscaloosa AL 1015 AM CDT WED MAR 13 2024 .Synopsis... Flooding impacts possible in ArkLaTex across East Texas into the Southeast...Recessions continue in the Northeast... .Discussion... .ArkLaTex... Widespread moderate to locally heavy rainfall will bring the possibility of flooding impacts to portions of AR starting on day 2 (Thu). Top soils (0 - 10 cm) are wet but not saturated according to NASA SPoRT with a relative soil moisture between 55 - 60%. While this indicates that some storage capacity is present, any heavy rainfall rates may quickly overwhelm soils thus leading to some flash flooding. The National Water Model (NWM) GFS-forced Medium Range Forecast (MRF) continues to highlight high-end annual exceedance probabilities (AEPs) (as low as 2%) on smaller streams north of Little Rock, AR suggesting locally considerable flooding impacts are possible. .East Texas into the Southeast... Multiple rounds of moderate to heavy rainfall are forecast across east TX into the Southeast on days 3 - 5 (Fri - Sun). Starting on day 3 (Fri), a low pressure system will stretch across east TX and the Southeast. This system will continue to expand further into portions of southern TX on day 4 (Sat) until pushing eastward to southern LA and the Florida Panhandle. Top soils across the area of concern varies with portions of LA, MS, and AL being the wettest, having a relative soil moisture between 55 - 75% (NASA SPoRT). Streamflows are much above normal for much of the southeast (USGS). Elevated streamflows and wet soils will have another day or two to recover ahead of this rainfall, and the amounts and locations of the rainfall remain somewhat uncertain due to the extended nature of the forecast. However, the potential for at least isolated flooding impacts is present, especially in portions of east TX where rainfall appears more likely to occur over multiple days. Additionally, river ensemble forecasts are suggesting the potential for minor to isolated moderate river flooding throughout the area of concern. The NWM MRF is signaling the potential for rapid-onset flooding (ROF) in areas of LA, MS, AL and GA with probabilities less than 25%. Associated AEPs in these areas are around 50% with local probabilities as low as 2%. While widespread flooding impacts are not expected with this system, localized flash flooding may become possible and out-of-bank rises on small streams are not unlikely however, uncertainty still remains high with this system. Minor to moderate river flooding is ongoing across MS, AL, GA, and SC due to recent rainfall, and will likely continue through this week for many locations. Most locations have already crested however, many of the forecast locations on larger rivers closer to the coasts will continue to rise through the week. .Northeast... Widespread elevated flows continue, including scattered minor river flooding, following recent rainfall and snowmelt. Most locations have crested and with very little precipitation expected over the next 7 days, recessions should continue unimpeded. //Kirkpatrick $$