Situational Awareness (Saturday, 2023-09-16)
Precipitation is still affecting flows at Point of Rocks and Little Falls. No rain is expected over the next 24 hours. However, the Middle Atlantic River Forecast Center predicts an average basin rainfall of 0.5 inches over the next 3 days.
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: 0 (inches)
Past 3-day cumulative area-weighted average basin precipitation: 0.14 (inches)
Past 7-day cumulative area-weighted average basin precipitation: 1.24 (inches)
Daily flows:
Little Falls gage flow 2023-09-15: 1047 MGD (1620 cfs)
Little Falls gage flow 2023-09-16: 853 MGD (est., based on recently available real-time data) (1320 cfs)
Note: Gage flow at Little Falls is measured after water supply withdrawals.
Point of Rocks flow 2023-09-15: 1002 MGD (1550 cfs)
Point of Rocks flow 2023-09-16: 1073 MGD (est., based on recently available real-time data) (1660 cfs)
Yesterday's Washington metropolitan area Potomac River withdrawals and discharges (2023-09-15):
Fairfax Water Corbalis withdrawal - Potomac: 109 MGD
WSSC Water Potomac withdrawal: 141 MGD
Washington Aqueduct withdrawal - Great Falls: 143 MGD
Washington Aqueduct withdrawal - Little Falls: 0 MGD
Loudoun Water withdrawal: 5 MGD
Loudoun Water Broad Run discharge: 7 MGD
Total Potomac withdrawal: 397 MGD
Total net Potomac withdrawal: 390 MGD
Loudoun Water Potomac River (PR) flow values for drought operations protocol (based on yesterday's flows):
QPR: 1550 cfs
QPR, obs: 1550 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