Updated

Updated · CBS New York · Jun 21

Pittsburgh Braces for 1-Inch Overnight Rain as Showers Snarl Monday Morning Commute

Updated

Updated · CBS New York · Jun 21

Pittsburgh Braces for 1-Inch Overnight Rain as Showers Snarl Monday Morning Commute

Q: How did a Texas tropical storm's remnants travel over a thousand miles to bring rain to Pittsburgh?

The rain reaching Pittsburgh was likely carried by the remnants of Tropical Storm Arthur after the storm weakened but kept moving northeast with a large plume of tropical moisture. Arthur formed near the Texas Gulf Coast, made landfall near Galveston, and then quickly lost its tropical structure. But storms do not need to remain fully tropical to keep producing rain. Once Arthur became a post-tropical system, its leftover moisture and energy were picked up by the broader steering winds in the atmosphere and drawn into a frontal boundary moving across the eastern United States. That interaction is the key reason a Texas storm could affect western Pennsylvania more than 1,000 miles away. Upper-level winds and the attached front helped transport deep Gulf moisture from the South through the Southeast and into the Appalachians and Mid-Atlantic. Meteorologists often see this when tropical remnants merge with a front: the storm itself weakens, but its moisture field expands and shifts far from where it came ashore. In Pittsburgh’s case, the forecast for overnight heavy rain into Monday fits that pattern. The city is not expected to see a tropical storm directly, but rather rain generated by the moisture-rich remnants embedded in a larger weather system. That is why the heaviest rain can arrive long after landfall and far inland, even in places like western Pennsylvania.

3 articles · Updated · CBS New York · Jun 21

Heavy rain is set to reach Pittsburgh overnight, continue through the Monday morning commute and linger until about noon, with areas north of the city likely to see 1 inch or slightly more.
Forecasters expect only a few rumbles of thunder and no severe storms, but say the downpours could still create a low flash-flood risk during the busiest travel hours.
Pittsburgh is about 1.50 inches below normal rainfall for the month, making the soaking rain broadly beneficial despite the commute disruption.
Cooler air follows Monday, with highs in the low to mid-70s and scattered showers fading by evening before mostly sunny, upper-70s weather returns Tuesday and Wednesday.