Flash Flood Prediction Program

Message 1’s have been issued for the entire District effective until 9:00pm as the threat of heavy rainfall has increased into the late afternoon and evening. A few weak showers and thunderstorms moved across the District this afternoon. A stronger line of showers and thunderstorms is currently moving in from the SW and will progress through the District over the next few hours. This line of storms will have the potential to produce localized heavy rainfall leading to isolated LOW IMPACT FLOODING for portions of the District. The main threat will likely be a quick 0.4-0.6” in 10-15 minutes, rather than long lasting heavy rainfall. Storms will generally move from the SW to NE between 10-15mph, which should help limit point rainfall amounts, although a gust front from a stronger storm will have the potential to produce erratic storm movements from storms initiating off these outflow boundaries. Storm chances will decrease after sunset with a few lingering showers possible through 10pm.

STORM RAINFALL POTENTIAL AND DURATION: Typical showers/weak thunderstorms will produce a 0.05-0.30” total, in 10-30 minutes. A moderate to strong shower/thunderstorm will produce 0.30-0.60” total in 10-30 minutes.

WORST CASE SCENARIO: A strong, stationary thunderstorm, or training of thunderstorm cells will have the potential to produce 0.60-1.20” total in under 60 minutes.

County	Message	Valid Times	Prime Time
Lakewood	1	Current TO 900 PM	Current TO 800 PM
Wheat Ridge	1	Current TO 900 PM	Current TO 800 PM
Arvada	1	Current TO 900 PM	Current TO 800 PM
the City of Aurora	1	Current TO 900 PM	Current TO 800 PM
Arapahoe County	1	Current TO 900 PM	Current TO 800 PM
DIA	1	Current TO 900 PM	Current TO 800 PM
Denver County	1	Current TO 900 PM	Current TO 800 PM
Adams County	1	Current TO 900 PM	Current TO 800 PM
Douglas County	1	Current TO 900 PM	Current TO 800 PM
Broomfield County	1	Current TO 900 PM	Current TO 800 PM
Jefferson County	1	Current TO 900 PM	Current TO 800 PM
Boulder County	1	Current TO 900 PM	Current TO 800 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	Current TO 900 PM FRI	0.05" (75%) to 0.3" (50%) to 0.6" (25%)	ISSUED
Arapahoe	Current TO 900 PM FRI	0.05" (75%) to 0.3" (50%) to 0.6" (25%)	ISSUED
Boulder	Current TO 900 PM FRI	0.05" (75%) to 0.3" (50%) to 0.6" (25%)	ISSUED
Broomfield	Current TO 900 PM FRI	0.05" (75%) to 0.3" (50%) to 0.6" (25%)	ISSUED
Denver	Current TO 900 PM FRI	0.05" (75%) to 0.3" (50%) to 0.6" (25%)	ISSUED
Douglas	Current TO 900 PM FRI	0.05" (75%) to 0.3" (50%) to 0.6" (25%)	ISSUED
Jefferson	Current TO 900 PM FRI	0.05" (75%) to 0.3" (50%) to 0.6" (25%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 900 PM FRI	0.05" (80%) to 0.3" (40%) to 0.6" (30%)	ISSUED
Douglas	Current TO 900 PM FRI	0.05" (80%) to 0.3" (40%) to 0.6" (30%)	ISSUED
Jefferson	Current TO 900 PM FRI	0.05" (80%) to 0.3" (40%) to 0.6" (30%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.