Flash Flood Prediction Program

Message 1’s will continue valid until 9pm this evening.

The first round of moderate to strong thunderstorms is currently exiting the District to the east with additional showers and thunderstorms expected to develop over the next few hours. Moderate to strong thunderstorms will still be capable of producing brief heavy rainfall that may lead to excessive runoff. Stronger thunderstorms may also produce hail.

Storm motions are relatively slow from SW to NE at 10-15mph. The slow storm motions will allow for extended periods of moderate to heavy rain under thunderstorms. Best chances for additional storms will be through 8-9pm then drier conditions are expected to develop for the later evening and overnight period.

STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce 0.1-0.3” of rain in 10-30 minutes. Strong thunderstorms will have the potential to produce rainfall rates of 0.3-0.8” in 10-30 minutes.

WORST CASE SCENARIO: A nearly stationary strong thunderstorm may result in up to 1.6” of rain in 45-75 minutes.

County	Message	Valid Times	Prime Time
Boulder County	1	1200 PM TO 900 PM	100 PM TO 830 PM
Jefferson County	1	1200 PM TO 900 PM	100 PM TO 830 PM
Broomfield County	1	1200 PM TO 900 PM	100 PM TO 830 PM
Douglas County	1	1200 PM TO 900 PM	100 PM TO 830 PM
Adams County	1	1200 PM TO 900 PM	100 PM TO 830 PM
Denver County	1	1200 PM TO 900 PM	100 PM TO 830 PM
DIA	1	1200 PM TO 900 PM	100 PM TO 830 PM
Arapahoe County	1	1200 PM TO 900 PM	100 PM TO 830 PM
the City of Aurora	1	1200 PM TO 900 PM	100 PM TO 830 PM
Arvada	1	1200 PM TO 900 PM	100 PM TO 830 PM
Wheat Ridge	1	1200 PM TO 900 PM	100 PM TO 830 PM
Lakewood	1	1200 PM TO 900 PM	100 PM TO 830 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	Current TO 900 PM THU	0.1" (75%) to 0.3" (50%) to 0.8" (15%)	ISSUED
Arapahoe	Current TO 900 PM THU	0.1" (75%) to 0.3" (50%) to 0.8" (15%)	ISSUED
Boulder	Current TO 900 PM THU	0.1" (75%) to 0.3" (50%) to 0.8" (15%)	ISSUED
Broomfield	Current TO 900 PM THU	0.1" (75%) to 0.3" (50%) to 0.8" (15%)	ISSUED
Denver	Current TO 900 PM THU	0.1" (75%) to 0.3" (50%) to 0.8" (15%)	ISSUED
Douglas	Current TO 900 PM THU	0.1" (80%) to 0.3" (60%) to 0.8" (20%)	ISSUED
Jefferson	Current TO 900 PM THU	0.1" (75%) to 0.3" (50%) to 0.8" (15%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 900 PM THU	0.1" (75%) to 0.3" (50%) to 0.8" (15%)	ISSUED
Douglas	Current TO 900 PM THU	0.1" (80%) to 0.3" (60%) to 0.8" (20%)	ISSUED
Jefferson	Current TO 900 PM THU	0.1" (75%) to 0.3" (50%) to 0.8" (15%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.