Drought in Maryland, May 1 to 31, 1999

High pressure was the dominant weather feature across Maryland during the month. This weather pattern directed rain producing low pressure systems north of the region and continued the climatological drought that has gripped the area since last summer. The Maryland Department of the Environment issued a drought warning in December and it remained in effect through May. By the last week of the month the Palmer Drought Index, a measure of long term drought conditions, indicated North Central and Northeast Maryland were in a moderate drought, and South Central Maryland was in a severe drought. May was the 7th month in the past 12 months that precipitation was below normal. From June 1998 through May 1999 precipitation was a staggering 14 inches below average, the 2nd driest 12 months on record. Only 1.72 inches of rain fell at Baltimore/Washington International Airport in Anne Arundel County during the month of May, 2.00 inches below normal. The Maryland Science Center at Inner Harbour Baltimore reported a total of only 1.40 inches, and rain only fell on 6 days during the month. Andrews Air Force Base in Prince Georges County reported a monthly total of only 0.95 inches. Additional rainfall totals included Allegany County at 2.6 inches, Washington County at1.5 inches, Frederick and Northern Prince Georges County at 1.8 inches, Carroll County at 2.2 inches, Northern Baltimore County at 1.7 inches, Howard and Southern Anne Arundel County at 1.3 inches, Montgomery County at 2.0 inches, Charles County at 0.9 inches, and St. Mary's County at 0.7 inches. The lack of rainfall affected water levels along the Potomac River and the Chesapeake Bay. In the Potomac watershed where below normal water levels have been recorded for the past 9 months stream flow averaged around 38% of normal and several record low daily flows were recorded. The flow of water past the Washington D.C. gage was only 23% of the long term monthly average. The total water flow into the Chesapeake Bay which has been below average for the past 10 months was only 46% of average during May, an all time record low. The deficit of fresh water flowing into the Chesapeake resulted in an increase of salinity levels in the bay and had an impact on animal and plant life. Contents of the Baltimore reservoir system decreased to 85% of average by month's end. The University of Maryland Agricultural Facility in Upper Marlboro recorded a pan evaporation of 24.56 inches in May. Western Maryland ground water levels fell from above normal to below normal during the month, and remained below normal elsewhere. Carroll County banned outdoor water use by the end of the month in Eldersburg and Sykesville. A popular swimming beach at Greenbriar State Park near Hagerstown had to be closed for the summer after spring rains never came to fill up the 50 acre reservoir. Closing the beach for the summer led to $120,000 in lost revenue. The lack of precipitation also played havoc with spring planting and livestock maintenance. Corn stalks normally knee high were only 2 to 6 inches tall. Hay and pasture land wilted, soybean planting slowed or was halted, and watering holes and irrigation systems slowly dried up. Tobacco, normally a drought-tolerant crop suffered in the fields after being recently transplanted. 34% of pasture land, 35% of corn, and 40% of soybeans across the state were reported in poor or very poor condition. 96% of topsoil was reported as short or very short of moisture by the end of the month.