Baltimore residents should prepare for potential flooding and severe thunderstorms today, as the National Weather Service (NWS) has issued a warning for heavy rainfall and hazardous weather conditions. A Flood Watch has been issued across numerous counties in Maryland, Virginia, and West Virginia, with risks of flash flooding in the Shenandoah Valley and the Blue Ridge Mountains. In a statement, the National Weather Service stated, "The tropical airmass will easily support rainfall rates of 1-2+" in 30 minutes, with hourly rainfall rates of 3-4" possible in the heaviest thunderstorms," underscoring the severity of the anticipated downpours.
Today's weather forecast suggests that the stationary front lingering at the PA/MD border is going to play a significant role in the weather activities; it will keep temperatures in the low to mid-80s, while peak heat indices could climb to the mid to upper 90s in Central VA, which is worrying considering the already saturated grounds from the heavy rainfall recently reported. Despite the risk of severe thunderstorms, the National Weather Service anticipates the Baltimore Metro area and NE Maryland will avoid the worst of today's weather. Yet, the same cannot be said for locations south and west of the Potomac River, where there's a "Slight Risk" for severe storms, including damaging wind gusts.
Rising concerns about urban and small stream flooding, exacerbated by the existing wet conditions, have prompted the NWS to coordinate with the Weather Prediction Center (WPC) to issue a Moderate Risk of flash flooding in affected regions. According to the latest National Weather Service forecast, "RRFS ensembles showing up to 40pct chance of seeing 100yr RI rainfall amounts (which equates to roughly 5" or more of rain) in the central Shenandoah Valley," indicating the high-end potential of a serious flash flooding scenario.
Moving into the weekend, weather patterns are expected to shift, but not without first bringing more showers and possible thunderstorms continuing through the weekend. This will lead to an unsettled Saturday, with thunderstorms popping up sporadically due to the weak flow and the absence of strong forcing factors. Sunday might feature a slightly lesser chance of rain, as the forecast suggests 40-60% precipitation chances, compared to Saturday's 50-80%. However, it's still significant; it's not a time to let your guard down, especially for those in open areas such as marines or aviators, where any storm can rapidly upset the balance, significantly worsening conditions in the blink of an eye.
The prolonged drenching will not last indefinitely, however, as a drier weather pattern is expected to take hold next week. A relieving turn of events, with the 500mb ridge building over the Southern U.S. and a surface high pressure system lingering post-Monday, is expected to suppress storm development and lower humidity. The NWS anticipates a welcome change from the rest of the month, with rainfall becoming less likely and temperatures dropping into more comfortable ranges, perhaps even resembling an early autumn rather than the height of summer.
For aviation interests, VFR conditions are forecasted for the majority of the coming week, barring brief disturbances from any thunderstorms that could cause sub-VFR conditions. Mariners will also catch a break, as strong wind gusts and lightning strikes are not expected from midweek onwards. However, certain precautions should be taken until Sunday, as the last of the thunderstorms make their way through the area, as advised by the NWS.
