The National Weather Service issued a flash flood warning at 3:46 p.m. on Sunday in effect until 6:45 p.m. for Allegheny and Westmoreland counties.

Sunday morning recovering efforts were suspended in Kerr County due to heavy rainfall and a new flash flood warning issued for the Hill Country.

Steamy summer conditions for your Sunday with highs in the upper 80s but feeling like the 90s. Skies will be mostly cloudy with isolated storms this afternoon. Any storm could produce heavy rain and localized flooding. Monday is a NEXT Weather Alert Day for tropical downpours and an elevated flash flood risk.

Scholars and designers of early warning systems say that there are still huge gaps in our ability to predict flash floods and warn those at risk.

KHOU 11 Meteorologist Pat Cavlin says it's impossible to determine exactly where the heaviest of rain will fall, but everyone in risky areas should stay aware.

Here's what to know about the deadly flooding, the colossal weather system that drove it and ongoing efforts to identify victims.

In the Midwest, quarter-sized hail and an isolated tornado cannot be ruled out, while in the South, flood alerts are in effect for areas that were devastated by flash floods last week.