Thursday’s light rainfall did little to improve the drought conditions that have plagued the northern Shenandoah Valley for most of the summer. Simply stated, Thursday’s less than quarter of an inch of rain was much too little much too late to offset crop losses by area farmers or to infuse life into grass fields struggling to produce hay for winter livestock feed. As Clarke Countians enjoy clear and cool Autumn days, farmers and livestock look to the horizon for signs of moisture that will break summer’s dry grip before it extends into the fall.
So far there is no relief in sight.
During the first 7 days of September, weak cold fronts traversing the northern tier of the U.S. and tropical activity associated with Hurricane Ivan contributed the most to drought improvement along the East Coast. As weather fronts progressed eastward and Hurricane Earl moved northeastward and weakened, rains spread along the East Coast and into coastal New England. By early September, moisture from Tropical Storm Hermine spread northward over the western Gulf Coast and southern Great Plains while storm systems intensified across the central Great Plains. Significant rains accompanied each of these systems but ultimately dried up prior to reaching Clarke County.
Rainfall associated with Hurricane Earl (0.5 to 4.5 inches) prompted improvements in the drought conditions from Long Island to Maine but away from the path of the hurricane, little to no precipitation fell across our region. North American Land Data Assimilation System (NLDAS) soil moisture values and 3-month standardized precipitation index (SPI) values both indicate extreme drought in Clarke County but so far the depiction has been kept to severe drought due to the short duration of the drought so far.
Clarke Drought Conditions “Extreme”
According to NLDAS Clarke County’s most recent 30 days have been much drier than the most recent 90 days; 40% of normal precipitation for the most recent 30 days versus about 70% of normal on a statewide basis for the most recent 90 days.
Unofficial rainfall measurements for Clarke County near Mount Weather recorded 1.4” of rain in June, 2.5” in July, 3.25” in August and less than a quarter of an inch so far in September. During a normal rainfall year our area receives approximately 11 – 12 inches of rain during the same period.
Similarly, Martinsburg West Virginia through September 9th has received less than half of its normal rainfall, reporting only 5.65 inches since June 1st. Normal rainfall there during that period is 11.64 inches. So far, it has been the third driest period of June 1st through September 9th since 1997. The current dry period has only been eclipsed only by drier periods in 1966 and 1991.
Charlottesville, Virginia has had a little more rainfall than our area but still recording only 6.09 inches since June 1st. Hagerstown, Maryland has fared the worst in the region with only 3.13 inches of rain since June 1st.
Across northern Virginia, abnormal dryness has expanded from the west toward the District of Columbia to reflect the field reports of deciduous trees dropping leaves and fruit earlier than normal due to lack of recent rainfall. Dropping lake levels and scorched lawns are becoming more common across this region.
According to the National Weather Service, the 8 to 14 day outlook calls for below normal rainfall. Both the 30 day and 90 day outlooks for precipitation show no strong indications of drier or wetter conditions than normal.
Although the most significant impacts of this summer’s drought are the affect on agriculture with crops and pasture conditions suffering due to the dry soil moisture, many US Geological Survey average stream flow levels across the drought area are running very low, in many cases below the 20th percentile.
With little precipitation expected during the next week drought conditions will maintain or worsen during September. However temperatures are expected to be cooler so evaporation of ground moisture will be less.