At 801 AM EDT, Doppler radar indicated thunderstorms producing heavy rain across the warned area. Between 1 and 2 inches of rain have fallen. The expected rainfall rate is 1 to 2 inches in 1 hour. Additional rainfall amounts of 1 to 2 inches are possible in the warned area. Flash flooding is ongoing or expected to begin shortly. HAZARD...Flash flooding caused by thunderstorms. SOURCE...Radar. IMPACT...Flash flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other poor drainage and low-lying areas. Some locations that will experience flash flooding include... Lowell, Leominster, Fitchburg, Chelmsford, Dracut, Westford, Gardner, Holden, Athol, Pepperell, Tyngsborough, Groton, Winchendon, Lunenburg, Townsend, Littleton, Lancaster, Templeton, Rutland and Sterling.