Flash Flood Prediction Program

Message 1’s have been issued for the entire District effective until 8:30pm as the threat of heavy rainfall with a slight chance for severe storms, favoring eastern portions of the District. Sever storms may contain large hail up to 1.0” and gusty winds 60+ mph.

The best chance for any shower/thunderstorm activity within the District will be between NOW-8:30pm with a few lingering showers possible through 9:00-10:00pm. The best chance for heavy rainfall will be during this initial round of storms, with storm intensities decreasing into the evening hours. Storm motions will be northwest to southeast between 10-20mph which could limit point rainfall amounts. However, outflow boundaries will likely produce some erratic storm movement which will increase chances for brief heavy rainfall.

Skies will clear this evening with dry conditions expected through the overnight as temperatures drop into the mid to upper 50s on the plains with upper 40s to around 50 degrees along the foothills.

STORM RAINFALL POTENTIAL AND DURATION: Typical showers and isolated thunderstorms will produce a 0.05-0.40” total in 10-30 minutes. A moderate to strong/severe shower/thunderstorm will produce 0.40-1.20” total in 10-30 minutes.

WORST CASE SCENARIO: A strong, stationary thunderstorm, or training of thunderstorm cells will have the potential to produce up to 2.25” total in under 60 minutes.

County	Message	Valid Times	Prime Time
Boulder County	1	Current TO 830 PM	Current TO 800 PM
Jefferson County	1	Current TO 830 PM	Current TO 800 PM
Broomfield County	1	Current TO 830 PM	Current TO 800 PM
Douglas County	1	Current TO 830 PM	Current TO 800 PM
Adams County	1	Current TO 830 PM	Current TO 800 PM
Denver County	1	Current TO 830 PM	Current TO 800 PM
DIA	1	Current TO 830 PM	Current TO 800 PM
Arapahoe County	1	Current TO 830 PM	Current TO 800 PM
the City of Aurora	1	Current TO 830 PM	Current TO 800 PM
Arvada	1	Current TO 830 PM	Current TO 800 PM
Wheat Ridge	1	Current TO 830 PM	Current TO 800 PM
Lakewood	1	Current TO 830 PM	Current TO 800 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	Current TO 830 PM MON	0.05" (60%) to 0.4" (30%) to 1.2" (15%)	ISSUED
Arapahoe	Current TO 830 PM MON	0.05" (60%) to 0.4" (30%) to 1.2" (15%)	ISSUED
Boulder	Current TO 830 PM MON	0.05" (60%) to 0.4" (30%) to 1.2" (15%)	ISSUED
Broomfield	Current TO 830 PM MON	0.05" (60%) to 0.4" (30%) to 1.2" (15%)	ISSUED
Denver	Current TO 830 PM MON	0.05" (60%) to 0.4" (30%) to 1.2" (15%)	ISSUED
Douglas	Current TO 830 PM MON	0.05" (60%) to 0.4" (30%) to 1.2" (15%)	ISSUED
Jefferson	Current TO 830 PM MON	0.05" (60%) to 0.4" (30%) to 1.2" (15%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 830 PM MON	0.05" (75%) to 0.4" (50%) to 1.2" (25%)	ISSUED
Douglas	Current TO 830 PM MON	0.05" (75%) to 0.4" (50%) to 1.2" (25%)	ISSUED
Jefferson	Current TO 830 PM MON	0.05" (75%) to 0.4" (50%) to 1.2" (25%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.