Situational Awareness (Monday, 2023-09-18)
River flows have fallen over the past several days as the impact of last week’s rainfall recedes. But the basin received about ¾ of an inch over the weekend, so we expect flows to start rising modestly again. No rain is expected in the basin over the next three days.
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.
Potomac River flows at Little Falls are still elevated due to the recent precipitation. According to the Middle Atlantic River Forecast Center predictions, rainfall averaging about ½ inches is expected in the basin 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)
Situational Awareness (Wednesday, 2023-09-13)
River flows at both the Point of Rocks and Little Falls gages are now above all CO-OP drought monitoring and drought operations thresholds. We are continuing daily drought monitoring because flows are expected to begin falling in the coming week. According to the Middle Atlantic River Forecast Center predictions, only 0.2 inches of rainfall is expected in the basin over the next 7 days.
Recent basin-wide average precipitation (above Little Falls):
Flow at Point of Rocks has reached 2000 cfs. According to the Middle Atlantic River Forecast Center predictions, the next three days may see 0.3 inches of rain.
The Washington Aqueduct suspended voluntary load shift (withdrawal) at Little Falls yesterday. They are currently withdrawing 100% from the Great Falls intake.
CO-OP is suspending drought operations because flow at the US Geological Survey’s gage at Little Falls, Maryland, has risen well above the drought operations threshold and is approaching median flows. We will continue sending daily morning updates on conditions while flow at Point of Rocks remains below 2,000 cfs. According to the Middle Atlantic River Forecast Center predictions, the next 24 hours may see 0.3 inches of rain. Over the next three days, the average basin rainfall may be around 0.6 inches.
River flows at Little Falls continue to respond to local rainfall. According to the Middle Atlantic River Forecast Center predictions, average basin rainfall for the next 3 days is expected to be over 0.5 inches.
Local rainfall has elevated river flow at Little Falls. Flows at Little Falls are now well above the numerical threshold for the Low Flow Allocation Agreement (LFAA) Alert stage.
CO-OP staff will be monitoring flows at upstream gages to better assess the impact of recent rainfall on basin flows.
According to the Middle Atlantic River Forecast Center predictions, the next 24 hours may see 0.4 inches of rain. Over the next 3 days, the average basin rainfall may be around 0.8 inches. The week-long outlook expects a total of approximately 1 inches of rain in the basin.
With the recent rain, river flow at Little Falls has risen to 1550 cfs. According to the Middle Atlantic River Forecast Center predictions, the next 72 hours may see 0.9 inches of rain. The week-long outlook expects a total of approximately 1.5 inches of rain in the basin.
The proactive voluntary load shift from Great Falls to Little Falls by Washington Aqueduct is still ongoing.
Flows at the Little Falls gauge have risen over the past 12 hours, likely in response to the rain that occurred in some parts of the basin yesterday.
Please remember to begin sending a supplemental email each morning by 7:30 am with predicted total and off Potomac withdrawals (in MGD) for today and tomorrow. Thank you for your continued cooperation.
The proactive voluntary load shift from Great Falls to Little Falls by Washington Aqueduct is still ongoing.