Flash Flood Prediction Program

A gust front from the northeast has moved into the District this afternoon resulting in a few strong storms to develop over portions of the District. Some of these storms contain large hail and moderate to brief heavy rain. The biggest threat from these storms will be a quick 0.5” in 10-20 minutes, rather than any long-lasting rainfall.

Storms are generally moving west to east with erratic storm motions likely along gust fronts. These erratic storms will have the best chance for Low Impact Flooding as heavy rainfall likely to stall over some areas. Storms will likely be off and on through the rest of the afternoon and into the evening hours.

Skies will gradually clear after 10pm with clearing skies overnight. A few areas of fog in the morning will be possible as overnight temperatures drop into the low 60s on the plains with mid 50s along the foothills.

STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce rainfall rates of 0.1-0.4” total in 10-30 minutes. Strong to severe thunderstorms will have the potential to produce rainfall rates of 0.4-0.8” total of rain in 10-30 minutes.

WORST CASE SCENARIO: A slow-moving strong thunderstorm or a large thunderstorm complex may result in up to 1.5” of rain in 45-60 minutes.

County	Message	Valid Times	Prime Time
Lakewood	1	Current TO 1000 PM	Current TO 900 PM
Wheat Ridge	1	Current TO 1000 PM	Current TO 900 PM
the City of Aurora	1	Current TO 1000 PM	Current TO 900 PM
Arvada	1	Current TO 1000 PM	Current TO 900 PM
Arapahoe County	1	Current TO 1000 PM	Current TO 900 PM
DIA	1	Current TO 1000 PM	Current TO 900 PM
Adams County	1	Current TO 1000 PM	Current TO 900 PM
Denver County	1	Current TO 1000 PM	Current TO 900 PM
Douglas County	1	Current TO 1000 PM	Current TO 900 PM
Broomfield County	1	Current TO 1000 PM	Current TO 900 PM
Jefferson County	1	Current TO 1000 PM	Current TO 900 PM
Boulder County	1	Current TO 1000 PM	Current TO 900 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	Current TO 1000 PM WED	0.1" (60%) to 0.4" (40%) to 0.8" (20%)	ISSUED
Arapahoe	Current TO 1000 PM WED	0.1" (60%) to 0.4" (40%) to 0.8" (20%)	ISSUED
Boulder	Current TO 1000 PM WED	0.1" (60%) to 0.4" (40%) to 0.8" (20%)	ISSUED
Broomfield	Current TO 1000 PM WED	0.1" (60%) to 0.4" (40%) to 0.8" (20%)	ISSUED
Denver	Current TO 1000 PM WED	0.1" (60%) to 0.4" (40%) to 0.8" (20%)	ISSUED
Douglas	Current TO 1000 PM WED	0.1" (60%) to 0.4" (40%) to 0.8" (20%)	ISSUED
Jefferson	Current TO 1000 PM WED	0.1" (60%) to 0.4" (40%) to 0.8" (20%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 1000 PM WED	0.1" (40%) to 0.4" (30%) to 0.8" (10%)	ISSUED
Douglas	Current TO 1000 PM WED	0.1" (50%) to 0.4" (40%) to 0.8" (20%)	ISSUED
Jefferson	Current TO 1000 PM WED	0.1" (40%) to 0.4" (30%) to 0.8" (10%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.