Hydrometeorological Discussion
Issued by NWS Tuscaloosa, AL
Issued by NWS Tuscaloosa, AL
140 AGUS74 KWCO 191517 HMDNWC National Hydrologic Discussion - EXPERIMENTAL NWS National Water Center - Tuscaloosa AL 1015 AM CDT THU SEP 19 2024 .Synopsis... Urban flooding possible in Southern Florida... Isolated flash flooding and ongoing river flooding and coastal flooding across the Carolinas... Coastal flooding across the Mid-Atlantic... Rainfall for the Central Plains this weekend... Receding flows across Central Montana... .Discussion... .Southern Florida... Heavy rainfall is forecast in southern Florida today and tomorrow, and associated urban flooding is possible. The extensive urban nature of this region will be at highest risk of flash flooding, with flooding of roads and ponding of water possible. Additionally, with already saturated grounds, slow moving storms may generate flash flooding. Impacts will largely be dependent on storm motion and rainfall rates. .Carolinas... There is potential for isolated flash flooding impacts through the day today associated with scattered convection. The NWM SRF is signaling potential for rapid-onset flooding, particularly across eastern North Carolina, though associated Annual Exceedance Probabilities, forced by the NWM 18-Hour Maximum High Flow Magnitude Forecast, are generally not less than 50%, decreasing confidence that flows will be impactful. Isolated river flooding will continue across the Coastal Plain of the Carolinas (Pee Dee, Cape Fear/NE Cape Fear, Neuse, Contentnea) into this weekend in response to the recent tropical rainfall. Additionally, minor-to-moderate coastal flooding at high tide is possible through day 3 (Sat) from Savannah, GA to Duck, NC. .Mid-Atlantic... Minor-to-moderate coastal flooding at high tide continues to be possible through tomorrow from the Chesapeake Bay to Long Island Sound. This could continue into the weekend. Check with your local NWS office for more information related to coastal flooding impacts. .Central Plains... Potentially heavy rainfall (totals up to 3") this weekend may bring an isolated flash flooding threat to the region. Dry antecedent conditions will likely mitigate the majority of flooding impacts, with abnormally dry to moderate drought conditions in place (USDM) throughout the region. The NASA GRACE-Based Root Zone Soil Moisture Drought Indicator is signaling a wetness percentile of less than 10 throughout much of the area adding to confidence that much of this rainfall will likely be beneficial. However, isolated areas of lowland flooding or urban flash flooding cannot be ruled out in areas of heavier rainfall. .Central Montana... Over the past 48 hours, much of Central Montana received 2 - 4", locally 5" (48 hr, MRMS) and water will continue to route downstream unimpeded resulting in elevated flows. Small stream flooding in low lying areas remains possible through the morning today. //Ayala $$