Flash Flood Prediction Program

Message 1’s have been issued effective until 7pm as there is a threat of heavy rainfall.

Storms have initiated along western portions of the District today and will be moving eastward through the afternoon and early evening. Dew points at this time are well in the 50’s with around 60 by DIA. Strong upper-level support sits just east of the District, out on the eastern plains where strong to severe storms are likely.

A chance for moderate to brief heavy rainfall within the District this afternoon and early evening. The best chance will be from now until 6pm with storms quickly moving east this evening and out of the District. A slight chance a storm could become severe inside the District, mainly for gusty winds and hail up to 1”. Storm motions will generally be from west to east between 15-25mph with some erratic storm movements possible along gust fronts. These storms will have the best chance of producing longer lasting heavy rainfall.

STORM RAINFALL POTENTIAL AND DURATION: Typical showers/thunderstorms will produce a 0.05-0.25” total in 10 to 30 minutes. A moderate thunderstorm will produce 0.25” to 0.50” total in 10 to 30 minutes. A strong thunderstorm will produce 0.50” to 1.00” total in 10 to 30 minutes.

WORST CASE SCENARIO: An anchored strong thunderstorm or training of thunderstorm cells has the potential to produce up to 1.5” in under 60 minutes.

County	Message	Valid Times	Prime Time
Boulder County	1	Current TO 700 PM	200 PM TO 600 PM
Jefferson County	1	Current TO 700 PM	200 PM TO 600 PM
Broomfield County	1	Current TO 700 PM	200 PM TO 600 PM
Douglas County	1	Current TO 700 PM	200 PM TO 600 PM
Adams County	1	Current TO 700 PM	200 PM TO 600 PM
Denver County	1	Current TO 700 PM	200 PM TO 600 PM
DIA	1	Current TO 700 PM	200 PM TO 600 PM
Arapahoe County	1	Current TO 700 PM	200 PM TO 600 PM
the City of Aurora	1	Current TO 700 PM	200 PM TO 600 PM
Arvada	1	Current TO 700 PM	200 PM TO 600 PM
Wheat Ridge	1	Current TO 700 PM	200 PM TO 600 PM
Lakewood	1	Current TO 700 PM	200 PM TO 600 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	Current TO 700 PM THU	0.25" (75%) to 0.5" (40%) to 1" (20%)	ISSUED
Arapahoe	Current TO 700 PM THU	0.25" (75%) to 0.5" (40%) to 1" (20%)	ISSUED
Boulder	Current TO 700 PM THU	0.25" (60%) to 0.5" (30%) to 1" (15%)	ISSUED
Broomfield	Current TO 700 PM THU	0.25" (60%) to 0.5" (30%) to 1" (15%)	ISSUED
Denver	Current TO 700 PM THU	0.25" (60%) to 0.5" (30%) to 1" (15%)	ISSUED
Douglas	Current TO 700 PM THU	0.25" (60%) to 0.5" (30%) to 1" (15%)	ISSUED
Jefferson	Current TO 700 PM THU	0.25" (60%) to 0.5" (30%) to 1" (15%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 700 PM THU	0.25" (60%) to 0.5" (30%) to 1" (15%)	ISSUED
Douglas	Current TO 700 PM THU	0.25" (60%) to 0.5" (30%) to 1" (15%)	ISSUED
Jefferson	Current TO 700 PM THU	0.25" (60%) to 0.5" (30%) to 1" (15%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.