Flash Flood Prediction Program

Message 1’s have been issued effective until 9pm as there is a threat of heavy rainfall this afternoon and evening. A few storms have formed along the foothills at this time and are slowly moving onto the plains. Generally, storms have mixed out as they move off the foothills, however, a better chance for storms to remain moderate to strong as we move into the late afternoon and evening. Storm motions should be west to east between 5-10mph, with some erratic storm motions possible. Especially due to gusts fronts that will likely move into the District over the next couple of hours. The largest threat for storms today will be a quick 0.30-0.75” in 10-30 minutes, with a very low threat for any rainfall over an inch as most storms pulse up and down relatively quickly. Showers and thunderstorm chances will last through sunset, with a few lingering showers/isolated thunderstorms possible through the overnight, although the threat for heavy rainfall should diminish between 8-9pm.

STORM RAINFALL POTENTIAL AND DURATION: Typical thunderstorms will produce rainfall of 0.10 to 0.30” total in 10-30 minutes. Strong storms have the potential to produce heavy rainfall of 0.30 to 0.75” total in 10-30 minutes.

WORST CASE SCENARIO: Strong stationery, or training of thunderstorms has the potential to produce 0.75” to 1.25” in under 60 minutes.

County	Message	Valid Times	Prime Time
Boulder County	1	Current TO 900 PM	Current TO 800 PM
Jefferson County	1	Current TO 900 PM	Current TO 800 PM
Broomfield County	1	Current TO 900 PM	Current TO 800 PM
Douglas County	1	Current TO 900 PM	Current TO 800 PM
Adams County	1	Current TO 900 PM	Current TO 800 PM
Denver County	1	Current TO 900 PM	Current TO 800 PM
DIA	1	Current TO 900 PM	Current TO 800 PM
Arapahoe County	1	Current TO 900 PM	Current TO 800 PM
the City of Aurora	1	Current TO 900 PM	Current TO 800 PM
Arvada	1	Current TO 900 PM	Current TO 800 PM
Wheat Ridge	1	Current TO 900 PM	Current TO 800 PM
Lakewood	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 SUN	0.05" (80%) to 0.3" (40%) to 0.75" (20%)	ISSUED
Arapahoe	Current TO 900 PM SUN	0.05" (80%) to 0.3" (40%) to 0.75" (20%)	ISSUED
Boulder	Current TO 900 PM SUN	0.05" (80%) to 0.3" (40%) to 0.75" (20%)	ISSUED
Broomfield	Current TO 900 PM SUN	0.05" (80%) to 0.3" (40%) to 0.75" (20%)	ISSUED
Denver	Current TO 900 PM SUN	0.05" (80%) to 0.3" (40%) to 0.75" (20%)	ISSUED
Douglas	Current TO 900 PM SUN	0.05" (80%) to 0.3" (40%) to 0.75" (20%)	ISSUED
Jefferson	Current TO 900 PM SUN	0.05" (80%) to 0.3" (40%) to 0.75" (20%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 900 PM SUN	0.05" (80%) to 0.3" (40%) to 0.75" (20%)	ISSUED
Douglas	Current TO 900 PM SUN	0.05" (80%) to 0.3" (40%) to 0.75" (20%)	ISSUED
Jefferson	Current TO 900 PM SUN	0.05" (80%) to 0.3" (40%) to 0.75" (20%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.