NOTTINGHAM, MD—A significant lack of recent rain, and unusual late season heat, have led to the development of “flash drought” conditions across a large portion of the area.
The National Weather Service says that the short-term dryness and heat have quickly overcome the long- term record wetness the region experienced between April 2018 and the early summer of 2019, and impacts from this short-term dryness are rapidly increasing.
A United States Drought Monitor (USDM) report released on Thursday, September 26, indicates rapidly-deteriorating conditions. Moderate Drought (D1) is now indicated across portions of the following counties in Maryland: Harford, Baltimore, Howard, Montgomery, Anne Arundel, Prince George’s, Saint Mary’s, Charles, and Calvert.
Many locations throughout the region have seen above normal temperatures in every month this year since April. Most areas have had less than a half inch of rain in the month of September, and in some places that all fell at once.
Impacts are quickly building as a result of the heat and dry conditions. The earliest impact was to lawns and gardens, which have largely browned and growing has ceased. Soil moisture has also taken a substantial hit. Analysis from multiple sensors indicates a severe soil moisture deficit, with rankings below the 10th percentile for this time of year, especially in the DC metro area.
Agricultural interests are reporting drought-related stresses on pastures and hayfields, as well as crop stress to soybeans and other late-planted grains. Other crops such as corn and apples are reported to be faring well.
Streamflows, which had been running seasonably high much of the summer thanks to the long period of heavy rain, are also now responding to the dry conditions. Many locations are now below normal — and normal in September and October is usually the lowest point of the year anyway.
Groundwater — usually the last thing to respond both going into a drought and coming out of a drought — is living up to that reputation. Shallower aquifers are turning below normal quickly over the past few weeks; but deeper groundwater storage is still at or above what is typical for this time of year.
As of Thursday, September 26, 2019, there were no drought declarations by any of the states in the NWS Baltimore/Washington service area.
No water restrictions have yet been reported to the National Weather Service as of the time of this statement. However, the Interstate Commission on the Potomac River Basin (ICPRB) is actively monitoring streamflows on the Potomac River for water supply purposes.
Unfortunately, no relief is in sight, and conditions are likely to worsen. Unseasonably hot conditions are expected into early October, with little or no rainfall expected.
There are some hints at a longer range return to at least more normal precipitation, and the Climate Prediction Center’s outlooks for both October and the rest of the calendar year do favor above normal precipitation. Until and unless this occurs, though, all of the existing conditions will likely continue to deteriorate.