Flash Flood Prediction Program

Message 1’s will be allowed to expire as the threat for heavy rainfall has ended at least temporarily.

Conditions are expected to be generally dry this evening but if an outflow boundary from storms to the E or S of the District pushes through new storm development may occur and Message 1’s could be re-issued. Rain showers are expected to build in overnight after midnight and likely linger into Saturday morning with possibly an isolated thunderstorm. Precipitation overnight will remain light as long as thunderstorms do not develop.

Rain showers and isolated to widely scattered thunderstorms are expected to increase in coverage Saturday morning 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 that may lead to excessive runoff and possibly flash flooding. If temperatures remain too cool precipitation may favor general light to moderate rain showers versus thunderstorms. Either way a wet day is in store for Saturday and Message 1’s will likely be issued by noon or before.

STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce a trace to 0.3” of rain in 10-30 minutes.

WORST CASE SCENARIO: Should a moderate to strong thunderstorm develop rainfall rates of 0.3-0.8” in 10-30 minutes is possible and up to 1.5” in 45-75 minutes.

County	Message	Valid Times	Prime Time
Boulder County	1	Current TO 800 PM	Current TO 730 PM
Jefferson County	1	Current TO 800 PM	Current TO 730 PM
Broomfield County	1	Current TO 800 PM	Current TO 730 PM
Douglas County	1	Current TO 800 PM	Current TO 730 PM
Adams County	1	Current TO 800 PM	Current TO 730 PM
Denver County	1	Current TO 800 PM	Current TO 730 PM
DIA	1	Current TO 800 PM	Current TO 730 PM
Arapahoe County	1	Current TO 800 PM	Current TO 730 PM
the City of Aurora	1	Current TO 800 PM	Current TO 730 PM
Arvada	1	Current TO 800 PM	Current TO 730 PM
Wheat Ridge	1	Current TO 800 PM	Current TO 730 PM
Lakewood	1	Current TO 800 PM	Current TO 730 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	Current TO 900 AM SAT	Trace (90%) to 0.1" (60%) to 0.3" (20%)	LOW
Arapahoe	Current TO 900 AM SAT	Trace (90%) to 0.1" (60%) to 0.3" (20%)	LOW
Boulder	Current TO 900 AM SAT	Trace (90%) to 0.1" (60%) to 0.3" (20%)	LOW
Broomfield	Current TO 900 AM SAT	Trace (90%) to 0.1" (60%) to 0.3" (20%)	LOW
Denver	Current TO 900 AM SAT	Trace (90%) to 0.1" (60%) to 0.3" (20%)	LOW
Douglas	Current TO 900 AM SAT	Trace (90%) to 0.1" (60%) to 0.3" (20%)	LOW
Jefferson	Current TO 900 AM SAT	Trace (90%) to 0.1" (60%) to 0.3" (20%)	LOW
Foothills above 6500ft
Boulder	Current TO 900 AM SAT	Trace (90%) to 0.1" (60%) to 0.3" (20%)	LOW
Douglas	Current TO 900 AM SAT	Trace (90%) to 0.1" (60%) to 0.3" (20%)	LOW
Jefferson	Current TO 900 AM SAT	Trace (90%) to 0.1" (60%) to 0.3" (20%)	LOW

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.