Issued to inform the public that flash flooding is imminent or occurring, generally within 6 hours after the causative event, when there is a rapid rise in water levels in urban areas, small drainages, or arroyos. Issued from areas as small as portions of cities to multiple counties.
In general, a Flash Flood is defined as the following in Deep South Texas:
≥3 feet of standing water;
High water entering multiple structures sufficient to cause property damage;
≥6 inches of fast flowing water across roads;
Arroyos/streams overtopping banks sufficient to produce ≥6 inches of fast flowing water
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