Flash Flood Prediction Program

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

Cool temperatures have suppressed thunderstorm activity over the District so far today but stronger storms have developed to the W/SW of the District and with abundant moisture in place should these storms survive they will be capable of producing brief heavy rainfall. With the ground at or near saturation for many areas of the District due to rainfall yesterday it may not take as much rain today to produce excessive runoff and possibly flash flooding.

Typical thunderstorms will move from W to E at around 20mph with stronger storms potentially moving more slowly or erratically along outflow boundaries. A large thunderstorm or training of thunderstorm cells will be the likely culprit for extended periods of heavy rainfall. Strong thunderstorms may also contain large hail. Best chances for thunderstorms will be through 10:00 PM. Should thunderstorm activity linger past 10:00 PM Message 1’s may need to be extended.

STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce 0.1-0.5” of rain. Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.5-1.5” in 10-30 minutes.

WORST CASE SCENARIO: A large thunderstorm or training of thunderstorm cells may result in up to 2.3” of rain in 45-75 minutes.

County	Message	Valid Times	Prime Time
Boulder County	1	Current TO 1000 PM	Current TO 900 PM
Jefferson County	1	Current TO 1000 PM	Current TO 900 PM
Broomfield County	1	Current TO 1000 PM	Current TO 900 PM
Douglas County	1	Current TO 1000 PM	Current TO 900 PM
Adams County	1	Current TO 1000 PM	Current TO 900 PM
Denver County	1	Current TO 1000 PM	Current TO 900 PM
DIA	1	Current TO 1000 PM	Current TO 900 PM
Arapahoe County	1	Current TO 1000 PM	Current TO 900 PM
the City of Aurora	1	Current TO 1000 PM	Current TO 900 PM
Arvada	1	Current TO 1000 PM	Current TO 900 PM
Wheat Ridge	1	Current TO 1000 PM	Current TO 900 PM
Lakewood	1	Current TO 1000 PM	Current 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" (80%) to 0.5" (40%) to 1.5" (10%)	ISSUED
Arapahoe	Current TO 1000 PM WED	0.1" (80%) to 0.5" (40%) to 1.5" (10%)	ISSUED
Boulder	Current TO 1000 PM WED	0.1" (80%) to 0.5" (40%) to 1.5" (10%)	ISSUED
Broomfield	Current TO 1000 PM WED	0.1" (80%) to 0.5" (40%) to 1.5" (10%)	ISSUED
Denver	Current TO 1000 PM WED	0.1" (80%) to 0.5" (40%) to 1.5" (10%)	ISSUED
Douglas	Current TO 1000 PM WED	0.1" (80%) to 0.5" (40%) to 1.5" (10%)	ISSUED
Jefferson	Current TO 1000 PM WED	0.1" (80%) to 0.5" (40%) to 1.5" (10%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 1000 PM WED	0.1" (90%) to 0.5" (50%) to 1.5" (20%)	ISSUED
Douglas	Current TO 1000 PM WED	0.1" (90%) to 0.5" (50%) to 1.5" (20%)	ISSUED
Jefferson	Current TO 1000 PM WED	0.1" (90%) to 0.5" (50%) to 1.5" (20%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.