Potomac River flows have been steadily decreasing. Current flows at Point of Rocks are at 1890 cfs. National Weather Service (NWS) quantitative precipitation forecasts (qpf) indicate that an accumulation of approximately 0.5 inch of rain is likely for most of the basin over the next 5 days. Some areas have slightly higher or lower qpf totals.
The basin received no rain over the past 24-hour period and is not expected to receive rain over the next 5-day period. However, given the higher flows, lower demands, and lower temperatures, we are discontinuing daily reporting on conditions. A summary of the weekend demands are included below.
The basin received between 0.25 and 1 inch of rain over the past 24-hour period. The heavier rainfall was seen in the central and
eastern portions of the basin. Zero to trace amounts of precipitation are forecasted to accumulate over the next 5 days.
Given the recent precipitation and low demands, we will not report on conditions over the weekend. A summary of the weekends flows and
demands, along with an assessment of conditions will be sent on Monday with the daily report.
Over the past 24 hours locations in the basin have seen between 0.25 and 1.5 inches of rain. An isolated area near Paw Paw received 2 inches. The 48-hour forecast predicts 0.5 inches of rain in the western portion of the basin and up to 0.75 inches in the metro area. The 5-day forecast shows a chance of up to 1 inch of accumulated rainfall across the basin.
Trace amounts of rain fell upstream of the metro area yesterday. Otherwise, the basin received no precipitation over the last 24 hours. The 48-hour forecast indicates a chance of up to 1 inch of rain in the southern Shenandoah area and between 1/2 and 3/4 of an inch across the rest of the basin. The 5-day forecast predicts accumulations of 1/2 an inch across the basin.
Point of Rocks flow has fallen below 2,000 cfs again. Over the last 24 hours, approximately 0.1 to 0.25 inches of rain fell over portions of the basin. The 48-hour forecast predicts up to a 0.25 inch of rain over the basin. The 5-day forecast predicts total accumulations of 0.25 to 0.9 inches of rain over the basin.
As you may have noticed, for several days the flow at Point of Rocks dropped below the threshold of 2,000 cfs (1293 MGD). When this occurs, daily monitoring and reporting of Potomac River flows and withdrawals are conducted by CO-OP per the Drought Operations Manual of the Water Supply Coordination Agreement. Last Friday we asked that CO-OP utilities begin sending us reports of yesterday's demand, and we will be sending out a daily summary of demands and flows.
Daily monitoring is discontinued because Point of Rocks flow has well exceeded the low flow monitoring threshold. Also, the observed precipitation over the past 48-hours has equaled 1 to 6 inches across most locations in the basin, and the forecast includes additional precipitation in the near future. Thank you all for your contributions to the monitoring effort.
The October Water Supply Outlook, which reports on water conditions in the basin, will be published sometime next week when the available data reflects the recent precipitation in the basin.
Over the past 24 hours between 0.5 and 4.0 inches of rain has accumulated across the basin, with the heavier rainfall occurring in the downstream area. The 48-hour forecast indicates a chance of another 2.0 to 8.0 inches of rain. Flow at the Point of Rocks gage remains below the 2,000 cfs threshold for now, but we expect it to continue to rise throughout the day. If the anticipated rain arrives in the upstream portions of the basin we expect to discontinue daily monitoring tomorrow.
The 24-hour observed precipitation shows that a 1/10 to a 1/4 inch of rain fell on some locations in the basin. The weather forecasts gives a chance of showers for this afternoon and a higher chance of rain for Thursday. The 48-hour and 5-day quantitative precipitation forecasts show 1/2 to 3.8 inches of rain possible across the basin.