Hydrometeorological Discussion
Issued by NWS
Issued by NWS
983 AGUS74 KWCO 181544 HMDNWC National Hydrologic Discussion - EXPERIMENTAL NWS National Water Center - Tuscaloosa AL 1015 AM CDT THU JUL 18 2025 .Synopsis... Potential for flooding impacts along the Central Gulf Coast and the Ohio Valley through the Mid-Atlantic... Isolated flash flooding possible across the Southwest... .Central Gulf Coast... Additional rainfall bringing the potential for flooding impacts is possible today into day 2 (Sat) as tropical moisture continues to surge into the region, bringing heavy rainfall totals of 2 - 5", with locally higher amounts possible in southern LA. Antecedent conditions are wet (60 - 80%, 0 - 10 cm RSM, NASA SPoRT), suggesting streams may become locally overwhelmed with any high rainfall rates or repeat areas of convection, leading to flooding impacts, most likely of the flash and urban variety. Urban corridors along I-10 remain vulnerable to flash flooding due to impervious surfaces and poor drainage in some areas. .Ohio Valley through the Mid-Atlantic... A wet weather pattern bringing daily rounds of rainfall will maintain the potential for flooding impacts through the weekend. Antecedent conditions are wet to saturated (70 - 90%, 0 - 10 cm, NASA SPoRT) across the southern portions of the Ohio Valley into KY and WV with streamflows running normal to much above normal (USGS). This combination suggests there is limited infiltration and storage capacity available to handle additional rainfall depending on its location, and soils may be overwhelmed and lead to excess runoff, especially where high rainfall rates or repeated storms occur. Overall, the greatest potential for flooding will be where storms train or become slow-moving, especially in urban areas or complex terrain. .Southwest... Isolated flash flooding is possible through today as monsoonal moisture lingers. Localized heavy downpours may lead to flash flooding in sensitive basins, urban areas, and burn scars. The greatest potential will be in east-central NM, where conditions will be most favorable for higher rainfall totals. //TMK $$