Flash Flood Prediction Program

Message 1’s have been issued for the entire District effective until 10:00pm for the threat for heavy rainfall with the potential for severe storms across the District this afternoon and evening.

The best chance for any shower/thunderstorm activity withing the District will be between 3pm-9pm with a few lingering showers possible through 2am. The best chance for heavy rainfall will be throughout the entire message period. Storm motions will be southwest to northeast between 15-20 mph. Outflow boundaries will likely produce erratic storm movement and clustering thunderstorms which will increase chances for heavy rainfall.

Due to updated current conditions, values will be increased from the current message 1. Severe storms will also contain isolated heavy rainfall with the largest threat being stationary heavy rainfall creating a quick 0.50-1.00" in 10-15 minutes.

STORM RAINFALL POTENTIAL AND DURATION: Typical showers and thunderstorms will produce a 0.25-0.75” total in 10-30 minutes. A moderate to strong shower/thunderstorm will produce 0.75-1.25" total in 10-30 minutes.

WORST CASE SCENARIO: A strong, stationary thunderstorm, or training of thunderstorm cells will have the potential to produce up to 1.50-2.00” total in 30-60 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 900 PM THU	0.5" (75%) to 0.75" (50%) to 1.25" (25%)	ISSUED
Arapahoe	Current TO 900 PM THU	0.5" (75%) to 0.75" (50%) to 1.25" (25%)	ISSUED
Boulder	Current TO 900 PM THU	0.5" (75%) to 0.75" (50%) to 1.25" (25%)	ISSUED
Broomfield	Current TO 900 PM THU	0.5" (75%) to 0.75" (50%) to 1.25" (25%)	ISSUED
Denver	Current TO 900 PM THU	0.5" (75%) to 0.75" (50%) to 1.25" (25%)	ISSUED
Douglas	Current TO 900 PM THU	0.5" (75%) to 0.75" (50%) to 1.25" (25%)	ISSUED
Jefferson	Current TO 900 PM THU	0.5" (75%) to 0.75" (50%) to 1.25" (25%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 900 PM THU	0.5" (75%) to 0.75" (50%) to 1.25" (25%)	ISSUED
Douglas	Current TO 900 PM THU	0.5" (75%) to 0.75" (50%) to 1.25" (25%)	ISSUED
Jefferson	Current TO 900 PM THU	0.5" (75%) to 0.75" (50%) to 1.25" (25%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.