Flash Flood Prediction Program

Message 1’s have been issued for the entire District and will be valid until 10:00pm this evening.

Thunderstorms have initiated over the foothills and will begin to spread out onto the plains over the next couple hours. Thunderstorm coverage will be widely scattered with typical weak to moderate thunderstorms producing light to moderate rain and gusty winds. Stronger thunderstorms will be capable of producing brief heavy rainfall and may become severe with large hail and winds in excess of 50mph. A nearly stationary thunderstorm that forms along a gust front or wind convergence boundary will produce the greatest threat for an extended period of heavy rain today that may lead to excessive runoff and possibly flash flooding.

1-3 rounds of showers and thunderstorms are expected to move through the District into the evening. Best chances for moderate to strong thunderstorms will be through 9 or 10pm then additional showers and weaker thunderstorms will be possible into the early overnight period.

STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce 0.1-0.3” of rain in 10-30 minutes. Strong thunderstorms will have the potential to produce rainfall rates of 0.3-0.8” in 10-30 minutes.

WORST CASE SCENARIO: A nearly stationary strong thunderstorm may result in up to 1.5” of rain in 45-75 minutes.

County	Message	Valid Times	Prime Time
Boulder County	1	100 PM TO 1000 PM	200 PM TO 900 PM
Jefferson County	1	100 PM TO 1000 PM	200 PM TO 900 PM
Broomfield County	1	100 PM TO 1000 PM	200 PM TO 900 PM
Douglas County	1	100 PM TO 1000 PM	200 PM TO 900 PM
Adams County	1	100 PM TO 1000 PM	200 PM TO 900 PM
Denver County	1	100 PM TO 1000 PM	200 PM TO 900 PM
DIA	1	100 PM TO 1000 PM	200 PM TO 900 PM
Arapahoe County	1	100 PM TO 1000 PM	200 PM TO 900 PM
the City of Aurora	1	100 PM TO 1000 PM	200 PM TO 900 PM
Arvada	1	100 PM TO 1000 PM	200 PM TO 900 PM
Wheat Ridge	1	100 PM TO 1000 PM	200 PM TO 900 PM
Lakewood	1	100 PM TO 1000 PM	200 PM TO 900 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	Current TO 1000 PM WED	0.1" (85%) to 0.3" (55%) to 0.8" (25%)	ISSUED
Arapahoe	Current TO 1000 PM WED	0.1" (85%) to 0.3" (55%) to 0.8" (25%)	ISSUED
Boulder	Current TO 1000 PM WED	0.1" (85%) to 0.3" (55%) to 0.8" (25%)	ISSUED
Broomfield	Current TO 1000 PM WED	0.1" (85%) to 0.3" (55%) to 0.8" (25%)	ISSUED
Denver	Current TO 1000 PM WED	0.1" (85%) to 0.3" (55%) to 0.8" (25%)	ISSUED
Douglas	Current TO 1000 PM WED	0.1" (85%) to 0.3" (55%) to 0.8" (25%)	ISSUED
Jefferson	Current TO 1000 PM WED	0.1" (85%) to 0.3" (55%) to 0.8" (25%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 1000 PM WED	0.1" (95%) to 0.3" (65%) to 0.8" (35%)	ISSUED
Douglas	Current TO 1000 PM WED	0.1" (95%) to 0.3" (65%) to 0.8" (35%)	ISSUED
Jefferson	Current TO 1000 PM WED	0.1" (95%) to 0.3" (65%) to 0.8" (35%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.