Flash Flood Prediction Program

Message 1’s have been issued for the entire District and will be valid until 8:30 PM this evening.

Thunderstorms have developed to the N and S of the District and are producing rain cooled outflow boundaries which may collide over the District and produce new storms over the next few hours. Typical weak to moderate thunderstorms will produce light to brief moderate rainfall and gusty winds.

Stronger storms may form along the outflow boundaries or outflow boundary collision and will move more slowly initially before being carried away by upper level steering winds. Strong, slower moving thunderstorms will be capable of producing extended periods of heavy rainfall that may lead to excessive runoff. Thunderstorms will generally move from W to E or WSW to ENE at 20-25mph. 1-2 rounds of thunderstorms is expected into the evening. Strong thunderstorms may also contain large hail.

STORM RAINFALL POTENTIAL AND DURATION: Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.4-0.9” in 10-30 minutes.

WORST CASE SCENARIO: A slower moving strong thunderstorm or training of thunderstorm cells may result in up to 1.4" of rain in 45-75 minutes.

County	Message	Valid Times	Prime Time
Boulder County	1	Current TO 830 PM	300 PM TO 730 PM
Jefferson County	1	Current TO 830 PM	300 PM TO 730 PM
Broomfield County	1	Current TO 830 PM	300 PM TO 730 PM
Douglas County	1	Current TO 830 PM	300 PM TO 730 PM
Adams County	1	Current TO 830 PM	300 PM TO 730 PM
Denver County	1	Current TO 830 PM	300 PM TO 730 PM
DIA	1	Current TO 830 PM	300 PM TO 730 PM
Arapahoe County	1	Current TO 830 PM	300 PM TO 730 PM
the City of Aurora	1	Current TO 830 PM	300 PM TO 730 PM
Arvada	1	Current TO 830 PM	300 PM TO 730 PM
Wheat Ridge	1	Current TO 830 PM	300 PM TO 730 PM
Lakewood	1	Current TO 830 PM	300 PM TO 730 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	Current TO 830 PM WED	0.1" (80%) to 0.4" (50%) to 0.9" (20%)	ISSUED
Arapahoe	Current TO 830 PM WED	0.1" (80%) to 0.4" (50%) to 0.9" (20%)	ISSUED
Boulder	Current TO 830 PM WED	0.1" (80%) to 0.4" (50%) to 0.9" (20%)	ISSUED
Broomfield	Current TO 830 PM WED	0.1" (80%) to 0.4" (50%) to 0.9" (20%)	ISSUED
Denver	Current TO 830 PM WED	0.1" (80%) to 0.4" (50%) to 0.9" (20%)	ISSUED
Douglas	Current TO 830 PM WED	0.1" (80%) to 0.4" (50%) to 0.9" (20%)	ISSUED
Jefferson	Current TO 830 PM WED	0.1" (80%) to 0.4" (50%) to 0.9" (20%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 830 PM WED	0.1" (80%) to 0.4" (50%) to 0.9" (20%)	ISSUED
Douglas	Current TO 830 PM WED	0.1" (80%) to 0.4" (50%) to 0.9" (20%)	ISSUED
Jefferson	Current TO 830 PM WED	0.1" (80%) to 0.4" (50%) to 0.9" (20%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.