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Storm Impacting the Northwest U.S.; Fire Weather Conditions in Southern California; Severe Weather in the South

A Pacific storm is bringing areas of low elevation rain, moderate to heavy mountain snow, and high winds to the Northwest. Strong Santa Ana winds and very dry conditions are producing elevated to critical fire weather conditions in southern California. Isolated strong to severe thunderstorms are possible through early Wednesday morning across parts of northeast Texas into western Tennessee. Read More >

Overview

Fast Facts:

  • An area of 3 to 6 inches of rain fell in about a 3-hour period over southeastern and east central LaSalle County into western Grundy County on Monday evening, July 12. The maximum estimated point rainfall amount was nearly 7 inches.
  • The result was significant flash flooding in this area along numerous creeks, including impacts to multiple structures, multiple roadways, and channel erosion. Damage to roadways occurred in at least 4 locations, with one injury reported when the approach to a bridge on River Road washed out.
  • A Flash Flood Warning was issued at 8:42 p.m. Monday evening, and upgraded to a "considerable" threat at 10:07 p.m.
  • The meteorology responsible for this event was on several scales:
    • High atmospheric moisture, particularly in the lowest 10,000 ft of the troposphere
    • ​An atypical-for-summer, slow-moving low pressure system over western Illinois inching its way northeast throughout Monday
    • A near-stationary warm front that had lifted northward during the day was parked in the area of the heavy rain on Monday evening
    • A semi-organized, small scale complex of heavy showers and some storms remained nearly stationary along these focus areas, resulting in convergence of the rich moisture and replenishment for re-firing heavy rain showers and storms

For detailed information about this event, see Analysis of the July 12-13, 2021, Flash flood near Seneca, IL, a NWS Technical Paper detailing the rainfall, flooding, and impacts.

 

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Event Summary

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Radar Loop (8 - 11 PM CDT)

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