Flash Flood Prediction Program

-	Message 1's have been issued for Boulder, Jefferson and Douglas Counties and will be valid until 10:00pm this evening. Additional Message 1's will likely be issued for the remainder of the District in the coming hours.
-	Thunderstorms are just beginning to initiate over the foothills, a little earlier than expected and will become more numerous into the afternoon. Thunderstorms that develop today will be very capable of producing heavy rainfall that may lead to excessive runoff and possibly flash flooding. Storm motions will be slow, at 10mph or less and thunderstorms may have a tendency to anchor along the foothill/plains interface potentially producing moderate to heavy rainfall for an extended period of time.
-	Thunderstorms are expected to remain over the higher terrain until early to mid afternoon then become widespread into the evening. Best chances for thunderstorm activity will be until around 10:00pm with scattered showers until midnight. After midnight a drying trend is expected but there will continue to be a modest chance for light rain into Tuesday morning.

STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce 0.1-0.4" in 10-30 minutes. Moderate to strong thunderstorms. Moderate to strong thunderstorms will have the potential to produce 0.4-1.0" in 10-30 minutes.

WORST CASE SCENARIO: A strong thunderstorm becomes stationary producing an extended period of heavy rainfall with up to 2.0" in 60 minutes or less.

County	Message	Valid Times	Prime Time
Jefferson County	1	Current TO 1000 PM	100 PM TO 900 PM
Boulder County	1	Current TO 1000 PM	100 PM TO 900 PM
Douglas County	1	Current TO 1000 PM	100 PM TO 900 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	200 PM TO 1159 PM	0.1" (90%) to 0.4" (50%) to 1.0" (15%)	MOD
Arapahoe	200 PM TO 1159 PM	0.1" (90%) to 0.4" (50%) to 1.0" (15%)	MOD
Broomfield	200 PM TO 1159 PM	0.1" (90%) to 0.4" (50%) to 1.0" (15%)	MOD
Denver	200 PM TO 1159 PM	0.1" (90%) to 0.4" (50%) to 1.0" (15%)	MOD
Boulder	100 PM TO 1159 PM	0.1" (95%) to 0.4" (60%) to 1.0" (20%)	ISSUED
Jefferson	100 PM TO 1159 PM	0.1" (95%) to 0.4" (60%) to 1.0" (20%)	ISSUED
Douglas	Current TO 1159 PM MON	0.1" (95%) to 0.4" (60%) to 1.0" (20%)	ISSUED
Foothills above 6500ft
Boulder	100 PM TO 1159 PM	0.1" (100%) to 0.4" (75%) to 1.0" (25%)	ISSUED
Douglas	Current TO 1159 PM MON	0.1" (100%) to 0.4" (75%) to 1.0" (25%)	ISSUED
Jefferson	Current TO 1159 PM MON	0.1" (100%) to 0.4" (75%) to 1.0" (25%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.