nov21_03_conditions

PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

Update for November 21, 2003

Region	Precipitation (monthly)¹		Flows (monthly)²
MNR Southern (previously referred to as Southcentral)	To date (Nov 24, 2003), watersheds in 6 Conservation Authorities (CA) are in a confirmed Low Water condition - All CA’s have watersheds in Level I³: (Kettle Creek, Long Point Region, Nottawasaga Valley, Quinte, Grand River, Catfish Creek). Most stations reported greater than 70% of the average precipitation expected for the third week of November¹ (By the end of the third week, 70% of the average precipitation for November would indicate a trend toward the average for the month). As of November 24, the Provincial Response Centre is forecasting 15 to 25mm of water in mixed precipitation over the next 5 days with potential additional amounts of up to 5 mm falling locally. Some stations in the central portion of the region have already received over 100% of normal November precipitation.		Next update November 30 Flood Potential: Immediate flood threat is currently HIGH for the central portion of the region and MODERATE elsewhere. Forecast rainfall in combination with already saturated soil conditions and high streamflows could lead to flooding in some water courses.
	Average Historical Precipitation Overall average November precipitation ranges from 60 mm to 120mm Most stations range from 70mm to 100mm Environment Canada Fall Outlook (September-October-November)⁵ Above normal precipitation for the eastern most portion of S. Ontario, normal elsewhere. Near normal temperatures for all of southern Ontario.
MNR Northeast	Most stations reported greater than 70% of the average precipitation expected for the third week of November¹(By the end of the third week, 70% of the average precipitation for November would indicate a trend toward the average for the month) Northeastern Ontario is forecast to receive 15 to 27 mm of water in mixed precipitation over the next 5 days. Some stations in the southern portion of the region have already received over 100% of normal November precipitation.	Next update November 30 Flood Potential: Immediate flood threat is currently HIGH for the southern portion of the region due to the combined effect of forecast rainfall, saturated soil conditions and high streamflows. Flooding is occurring in some watercourses.
	Average Historical Precipitation Ranges from 60 mm to 100 mm for November for most stations Environment Canada Fall Outlook (September-October-November) ⁵ Above normal precipitation Below normal temperatures
MNR Northwest	One MNR District is in a confirmed Level I low water condition: Dryden All stations reported below 70% of the average precipitation expected for the third week November¹. (By the end of the third week, 70% of the average precipitation for November would indicate a trend toward the average for the month) Northwestern Ontario is forecast to receive 8 to 16 mm of water in mixed precipitation over the next 5 days.	Next update November 30 Flood Potential: Immediate flood threat is currently low. Long term flood threat would be from significant or heavy rainfall.
	Average Historical Precipitation Ranges from 35 mm to 55 mm for November for most stations. Environment Canada Fall Outlook (September-October-November) ⁵ Above normal precipitation Below normal temperatures

^{1Environment Canada’s synoptic stations are equipped to measure snow. Precipitation gauges from dataloggers often are not set up to measure snow adequately. The resulting errors plus the elimination of many of the readings for these gauges means our precipitation coverage is poor during months with snow.

²For each gauge used in the analysis the average flow is calculated for July, and August and September from the historical record. The minimum of these three values is compared to the past month’s average flow. During the winter months most streams are partially filled or covered over with ice. This ice reduces the cross-section of the stream resulting in flow readings that are higher than actual. This error is corrected in the historical record. Thus the observed, relative to the historical minimum, is also higher than the actual in streams with significant ice conditions.

³ Level I conditions initiate the formation of a Water Response Team (WRT) which encourages a voluntary 10% reduction in water use. At Level II the WRT encourages a further 10% reduction by restricting non-essential water use; level III represents the condition where there is insufficient supply of water to meet all needs which July result in regulation of water use.

4Great Lakes summary includes information from Environment Canada, Great Lakes - St. Lawrence Regulation Office and the Detroit District U.S. Army Corps of Engineers.

5Outlook provided by Environment Canada. Environment Canada has assigned very low confidence to this season’s precipitation Outlook across the province and medium confidence to the temperature Outlook.

Val von Zuben
Surface Water Monitoring Officer
November 24, 2003}