Flash Flood Prediction Program

Message 1’s continue valid until 8:00pm but the threat for heavy rainfall is rapidly diminishing as drier air is working its way into the District.

An outflow boundary from storms outside the District may push back into the District and increase moisture and supply a trigger for new storms but the threat for this situation to play out is quite low. Isolated light rain showers will be the most likely outcome for the rest of the afternoon and evening resulting in Message 4’s (All Clear) possibly being issued over the next 1-2 hours.

Rain showers and isolated to widely scattered thunderstorms are expected to increase in coverage on Saturday as the low pressure system will be to our east and “upslope” flow will be in place along the I-25 corridor. Moisture will increase and thunderstorms will be capable of producing heavy rainfall. If temperatures remain too cool precipitation may favor general rain showers versus thunderstorms.

STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak to moderate thunderstorms will produce a trace to 0.2" of rain. Moderate thunderstorms will have the potential to produce rainfall rates of 0.2-0.5” in 10-30 minutes.

WORST CASE SCENARIO: A strong thunderstorm is able to develop with the potential to produce brief heavy rainfall of 0.3-0.8" in 10-30 minutes.

County	Message	Valid Times	Prime Time
Boulder County	1	Current TO 800 PM	Current TO 700 PM
Jefferson County	1	Current TO 800 PM	Current TO 700 PM
Broomfield County	1	Current TO 800 PM	Current TO 700 PM
Douglas County	1	Current TO 800 PM	Current TO 700 PM
Adams County	1	Current TO 800 PM	Current TO 700 PM
Denver County	1	Current TO 800 PM	Current TO 700 PM
DIA	1	Current TO 800 PM	Current TO 700 PM
Arapahoe County	1	Current TO 800 PM	Current TO 700 PM
the City of Aurora	1	Current TO 800 PM	Current TO 700 PM
Arvada	1	Current TO 800 PM	Current TO 700 PM
Wheat Ridge	1	Current TO 800 PM	Current TO 700 PM
Lakewood	1	Current TO 800 PM	Current TO 700 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	Current TO 800 PM FRI	Trace (50%) to 0.2" (20%) to 0.5" (10%)	ISSUED
Arapahoe	Current TO 800 PM FRI	Trace (50%) to 0.2" (20%) to 0.5" (10%)	ISSUED
Boulder	Current TO 800 PM FRI	Trace (50%) to 0.2" (20%) to 0.5" (10%)	ISSUED
Broomfield	Current TO 800 PM FRI	Trace (50%) to 0.2" (20%) to 0.5" (10%)	ISSUED
Denver	Current TO 800 PM FRI	Trace (50%) to 0.2" (20%) to 0.5" (10%)	ISSUED
Douglas	Current TO 800 PM FRI	Trace (65%) to 0.2" (30%) to 0.5" (10%)	ISSUED
Jefferson	Current TO 800 PM FRI	Trace (60%) to 0.2" (30%) to 0.5" (10%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 800 PM FRI	Trace (75%) to 0.2" (40%) to 0.5" (10%)	ISSUED
Douglas	Current TO 800 PM FRI	Trace (75%) to 0.2" (40%) to 0.5" (10%)	ISSUED
Jefferson	Current TO 800 PM FRI	Trace (75%) to 0.2" (40%) to 0.5" (10%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.