Monitoring Reports

Up to 2 inches of rain fell in some areas of the basin in the past 24 hours. 1 to 2.5 inches of rain is expected in the next 72 hours.

CO-OP is suspending daily drought monitoring because flow at the US Geological Survey’s gage at Point of Rocks, Maryland has risen above the 2000 cfs monitoring threshold. Thank you for your daily submission of withdrawal and reservoir storage data. Although active monitoring has been discontinued, it is still helpful if you submit data on a daily basis to help us maintain, update, and verify our forecast tools.

Up to half an inch of precipitation fell in some areas of the basin in the past 24 hours. Over the next three days, one to four inches of rain is expected in the basin depending on location. Daily flows: Little Falls gage flow 2021-08-15: 1480 MGD (2290 cfs) Little Falls gage flow 2021-08-16: 1409 MGD (est., based on recently available real time data) (2180 cfs) Note: Gage flow at Little Falls is measured after water supply withdrawals.

Over the past 24 hours, the Potomac Basin received 0.1 to 0.5 inches of rain. Depending on location, some isolated areas saw as much as 2 inches. In the next 72 hours, an additional 0.25 to 1.25 inches of rain is possible.

Over the past 24 hours, the Potomac Basin received 0.1 to 2 inches of rain, depending on location. 0.5 to 2 inches of rain are expected in the next 72 hours.

Zero precipitation occurred in the basin over the past 24 hours. The Potomac basin has been experiencing a heat advisory that is expected to continue into today.

Scattered precipitation across the basin over the past 24 hours resulted in varied totals, up to 1.75 inches. Up to an inch of rain is expected over the next three days.

Note a correction to the Broad Run discharge for August 10th: the correct value is 6 MGD.

River flows have responded to yesterday’s storm events. Precipitation in the basin over the past 24 hours was scattered, with trace amounts in most areas but up to an inch and a half in some locations. The National Weather Service forecast calls for accumulations of 0.10 to 0.50 inches in the basin during the next three days.

Scattered locations across the upper Potomac Basin received between 0.1 and 0.5 inches of rain over the past 24 hours. Small portions of the basin near Washington D.C received up to 2 inches of rain. 0.1 to 1.5 inches of rain are expected over the next 3 days.
Adjustments made yesterday to the Little Falls gage’s rating curve resulted in discharge values lower than previously reported.

Flows continued to fall over the weekend. Yesterday there were scattered amounts of precipitation in the North Branch of the Potomac basin. In the next 3 days, the basin may receive between a tenth of an inch to one inch of precipitation depending on location.Thank you for participating in weekend data submissions.

Widely scattered locations across the upper basin received trace amounts of rain (up to 0.1 inches) over the past 24 hours. Precipitation totaling 0.01 to 0.25 inches is expected in the upper basin over the next three days. Higher amounts of half an inch are also possible in scattered locations in Pennsylvania and along the Virginia-West Virginia border. Flow at Point of Rocks is holding steady above 1500 cfs.