CO-OP is suspending daily drought monitoring emails because flow at the US Geological Survey’s gage at Point of Rocks, Maryland, has risen above the 2000 cfs monitoring threshold. Yesterday, a tornado watch lasted until 9 p.m., but there were no confirmed tornadoes in the region. Some parts of the basin observed up to 1.75 to 2 inches of precipitation during this time. The Middle Atlantic River Forecast Center predicts an additional 0.1 to 1.25 inches of rainfall over the next 72 hours, possibly arriving by this Thursday.
Recent basin-wide average precipitation (above Little Falls):
(based on CO-OP's Low Flow Forecast System analysis of Middle Atlantic River Forecast Center (MARFC) gridded multisensor precipitation estimates)
Yesterday's area-weighted average basin precipitation: 1.11 (inches)
Past 3-day cumulative area-weighted average basin precipitation: 1.44 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 1.51 (inches)
Daily flows:
Little Falls gage flow 2023-08-07: 1493 MGD (2310 cfs)
Little Falls gage flow 2023-08-08: 2857 MGD (est., based on recently available real-time data) (4420 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2023-08-07: 1131 MGD (1750 cfs)
Point of Rocks flow 2023-08-08: 1474 MGD (est., based on recently available real-time data) (2280 cfs)
Yesterday's Washington metropolitan area Potomac River withdrawals and discharges (2023-08-07):
Fairfax Water Corbalis withdrawal (Potomac): 94 MGD
WSSC Water Potomac withdrawal: 109 MGD
Washington Aqueduct withdrawal: 142 MGD
Loudoun Water withdrawal: 13 MGD
Loudoun Water Broad Run discharge: 6 MGD
Total Potomac withdrawal: 358 MGD
Total net Potomac withdrawal: 352 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1750 cfs
QPR, obs: 1750 cfs
QPR, WS: 0 cfs
Note to Loudoun Water: See NWS ensemble flow forecasts (HEFS, GEFS, NAEFS) for Point of Rocks flow for the next 7 days – see https://www.weather.gov/erh/mmefs_marfc?id=PORM2&model=NAEFS.