ZCZC NFDTCPAT4 ALL TTAA00 KWNH DDHHMM BULLETIN Tropical Depression Ida Advisory Number 23 NWS Weather Prediction Center College Park MD AL092021 400 PM CDT Tue Aug 31 2021 ...TROPICAL DEPRESSION IDA IS MOVING ACROSS THE TENNESSEE VALLEY... ...WIDESPREAD HEAVY RAIN AND AREAS OF POTENTIALLY LIFE THREATENING FLASH FLOODING ARE POSSIBLE BEGINNING WEDNESDAY ACROSS PORTIONS OF THE MID ATLANTIC AND SOUTHERN NEW ENGLAND... SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...35.5N 86.2W ABOUT 65 MI...105 KM NNE OF HUNTSVILLE ALABAMA ABOUT 125 MI...200 KM W OF KNOXVILLE TENNESSEE MAXIMUM SUSTAINED WINDS...25 MPH...35 KM/H PRESENT MOVEMENT...NE OR 55 DEGREES AT 17 MPH...28 KM/H MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES WATCHES AND WARNINGS -------------------- Flood and Flash Flood Watches extend from the Tennessee and Ohio Valleys across the central and southern Appalachians, into the Mid-Atlantic and southern New England. DISCUSSION AND OUTLOOK ---------------------- At 400 PM CDT (2100 UTC), the center of Tropical Depression Ida was located near latitude 35.5 North, longitude 86.2 West. The depression is moving toward the northeast near 17 mph (28 km/h) and this motion is expected to gradually accelerate through Wednesday. Maximum sustained winds are near 25 mph (35 km/h) with higher gusts. Some strengthening is forecast during the next 48 hours as Ida becomes extratropical and moves offshore by early Thursday. The estimated minimum central pressure is 999 mb (29.50 inches). HAZARDS AFFECTING LAND ---------------------- RAINFALL: Tropical Depression Ida will produce the following rainfall totals: Portions of the Southeast, including the western Florida panhandle, eastern and northern Alabama, and northern Georgia: An additional 1 to 3 inches through Wednesday morning. Middle Tennessee Valley, Ohio Valley, Central and Southern Appalachians: 3 to 6 inches with isolated higher amounts through Wednesday morning. Mid Atlantic to Southern New England: 3 to 8 inches with isolated higher amounts, Wednesday into Thursday. Considerable flash flooding is possible from the Middle Tennessee Valley, Ohio Valley, Central and Southern Appalachians. Significant and life-threatening flash flooding is possible from the Mid-Atlantic into southern New England, especially across highly urbanized metropolitan areas and areas of steep terrain. Widespread moderate and major river flooding impacts are forecast from northern West Virginia and western Maryland into southern Pennsylvania and New Jersey, particularly in the Monongahela, Potomac, Susquehanna, Delaware, and lower Hudson river basins. Widespread minor to isolated major river flooding is occurring or forecast from the Lower Mississippi Valley into far western Alabama. Rivers will remain elevated into next week. For the latest rainfall reports and wind gusts associated with Tropical Depression Ida, see the companion storm summary at WBCSCCNS4 with the WMO header of ACUS44 KWBC or at the following link: www.wpc.ncep.noaa.gov/discussions/nfdscc4.html TORNADOES: The threat for an isolated tornado will continue this evening across portions of the Southeast, shifting towards portions of the Mid Atlantic overnight. On Wednesday, several tornadoes are probable across portions of the Mid Atlantic, mainly during the afternoon and evening hours. NEXT ADVISORY ------------- Next complete advisory at 1000 PM CDT. $$ Forecaster Churchill FORECAST POSITIONS AND MAX WINDS INIT 31/2100Z 35.5N 86.2W 20 KT 25 MPH...INLAND 12H 01/0600Z 37.0N 83.5W 20 KT 25 MPH...INLAND 24H 01/1800Z 39.0N 79.0W 25 KT 30 MPH...INLAND 36H 02/0600Z 40.4N 73.6W 35 KT 40 MPH...POST-TROP/EXTRATROP 48H 02/1800Z 43.8N 67.4W 35 KT 40 MPH...POST-TROP/EXTRATROP NNNN