Flash Flood Prediction Program

Storms have started to initiate along the foothills and will start moving into the District over the next hour. Temperatures today reached the mid to upper 80s, combined with dew points in the low to mid 50s, storms today could potentially produce moderate to brief heavy rainfall.

Storm motions will be from west to east, generally between 10-15mph with some erratic storm movement possibly along outflow boundaries. These outflow storms will likely have the most potential for heavy rainfall with a quick 0.5” in 10-20 minutes rather than any long-lasting rainfall. Storms may also contain hail up to 1.0”, frequent cloud-to-ground lightning and gusty winds up to 60mph.

One round of showers and thunderstorms with moderate to heavy rainfall is expected today, with skies likely clearing out by sundown. A slight chance for a few overnight showers as temperatures drop into the low 60s on the plains with mid to upper 50s along the foothills.

STORM RAINFALL POTENTIAL AND DURATION: Typical showers/thunderstorms will produce a 0.05-0.30" total in 10-30 minutes. A moderate to strong thunderstorm will produce rainfall rates of 0.30”-0.70” total in 10-30 minutes.

WORST CASE SCENARIO: A slow-moving stationary thunderstorm, training of thunderstorms cells or a large thunderstorm complex may result in up to 1.40” total rain in under 60 minutes.

County	Message	Valid Times	Prime Time
Broomfield County	1	Current TO 700 PM	230 PM TO 630 PM
Jefferson County	1	Current TO 700 PM	230 PM TO 630 PM
Boulder County	1	Current TO 700 PM	230 PM TO 630 PM
Douglas County	1	Current TO 700 PM	230 PM TO 630 PM
Adams County	1	Current TO 700 PM	230 PM TO 630 PM
Denver County	1	Current TO 700 PM	230 PM TO 630 PM
DIA	1	Current TO 700 PM	230 PM TO 630 PM
Arapahoe County	1	Current TO 700 PM	230 PM TO 630 PM
the City of Aurora	1	Current TO 700 PM	230 PM TO 630 PM
Arvada	1	Current TO 700 PM	230 PM TO 630 PM
Wheat Ridge	1	Current TO 700 PM	230 PM TO 630 PM
Lakewood	1	Current TO 700 PM	230 PM TO 630 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	Current TO 700 PM FRI	0.05" (75%) to 0.3" (50%) to 0.7" (25%)	ISSUED
Arapahoe	Current TO 700 PM FRI	0.05" (75%) to 0.3" (50%) to 0.7" (25%)	ISSUED
Boulder	Current TO 700 PM FRI	0.05" (75%) to 0.3" (50%) to 0.7" (25%)	ISSUED
Broomfield	Current TO 700 PM FRI	0.05" (75%) to 0.3" (50%) to 0.7" (25%)	ISSUED
Denver	Current TO 700 PM FRI	0.05" (75%) to 0.3" (50%) to 0.7" (25%)	ISSUED
Douglas	Current TO 700 PM FRI	0.05" (80%) to 0.3" (60%) to 0.7" (30%)	ISSUED
Jefferson	Current TO 700 PM FRI	0.05" (80%) to 0.3" (60%) to 0.7" (30%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 700 PM FRI	0.05" (80%) to 0.3" (60%) to 0.7" (30%)	ISSUED
Douglas	Current TO 700 PM FRI	0.05" (80%) to 0.3" (60%) to 0.7" (30%)	ISSUED
Jefferson	Current TO 700 PM FRI	0.05" (80%) to 0.3" (60%) to 0.7" (30%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.