The cold front associated with the lumbering upper level low near Chicago moves little over the next day. Out ahead of it a stream of moisture from the south keeps flowing, meaning more clouds, tropical humidity, and periodic showers and storms.
Through Tonight: Scattered (i.e., not everywhere) showers and storms are around and about. They’re most numerous through around 7 and 8 p.m. (60% chance), and a few may be severe with damaging winds and small hail. Another possible risk from these storms is isolated flash flooding given recent heavy rains and the saturated ground. A Flash Flood Watch has been extended into our northern suburbs (Frederick, Carroll and Baltimore counties) thru Wednesday morning. After 7 or 8 p.m., odds of experiencing storms drop to about 40-50%. It’s cloudy and mild overnight, with lows 65-70.
Wednesday: Take today and hit repeat. It’s cloudy and muggy and showers and thunderstorms are once again likely - perhaps even a bit more widespread than today during the afternoon and evening (60-70% chance, slightly less during the morning and early afternoon, 30-40% chance). Highs are again from the upper 70s to low 80s
Pollen update from Walter Reed: Trees, grasses, and weeds are LOW. Mold spores are HIGH.