Flash Flood Prediction Program

Message 1’s have been issued for the entire District effective until 1159pm.

A few isolated storms are starting to initiate along the foothills currently and will continue to build over the next hour or two before moving into the District. Multiple rounds of strong to severe storms will be possible today with a good chance for heavy rainfall leading to localized flooding through the afternoon and evening.

Typical storm movements will be from W/SW to E/NE between 5-10mph. Some erratic storm movements will be possible as storms form and stall out along outflow boundaries. These storms will likely have the highest chance of producing longer lasting heavy rainfall. Storms today will have the potential to produce both a quick 0.5” in 10 minutes as well as over 1” per hour rainfall if a storm stalls out for an extended time, or training of thunderstorms cells.

Storm intensities should diminish after midnight tonight. However, if the heavy rainfall threat persists past midnight, Message 1’s may need to be extended.

STORM RAINFALL POTENTIAL AND DURATION: Typical thunderstorms have the potential to produce moderate to heavy rainfall of 0.25-0.50" total, in 10-30 minutes. Strong thunderstorms have the potential to produce moderate to heavy rainfall of 0.5-1.5" total, in 10-30 minutes.

WORST CASE SCENARIO: Stationary or training of slow-moving thunderstorms have the potential
to produce up to 2.4” total, in 45-60 minutes.

County	Message	Valid Times	Prime Time
Denver County	1	100 PM TO 1159 PM	100 PM TO 1159 PM
Adams County	1	100 PM TO 1159 PM	100 PM TO 1159 PM
Douglas County	1	100 PM TO 1159 PM	100 PM TO 1159 PM
Broomfield County	1	100 PM TO 1159 PM	100 PM TO 1159 PM
Jefferson County	1	100 PM TO 1159 PM	100 PM TO 1159 PM
Boulder County	1	100 PM TO 1159 PM	100 PM TO 1159 PM
DIA	1	100 PM TO 1159 PM	100 PM TO 1159 PM
Arapahoe County	1	100 PM TO 1159 PM	100 PM TO 1159 PM
the City of Aurora	1	100 PM TO 1159 PM	100 PM TO 1159 PM
Arvada	1	100 PM TO 1159 PM	100 PM TO 1159 PM
Wheat Ridge	1	100 PM TO 1159 PM	100 PM TO 1159 PM
Lakewood	1	100 PM TO 1159 PM	100 PM TO 1159 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	100 PM TO 1159 PM	0.25" (90%) to 0.5" (60%) to 1.5" (30%)	ISSUED
Arapahoe	100 PM TO 1159 PM	0.25" (90%) to 0.5" (60%) to 1.5" (30%)	ISSUED
Boulder	100 PM TO 1159 PM	0.25" (90%) to 0.5" (60%) to 1.5" (30%)	ISSUED
Broomfield	100 PM TO 1159 PM	0.25" (90%) to 0.5" (60%) to 1.5" (30%)	ISSUED
Denver	100 PM TO 1159 PM	0.25" (90%) to 0.5" (60%) to 1.5" (30%)	ISSUED
Douglas	100 PM TO 1159 PM	0.25" (90%) to 0.5" (60%) to 1.5" (30%)	ISSUED
Jefferson	100 PM TO 1159 PM	0.25" (90%) to 0.5" (60%) to 1.5" (30%)	ISSUED
Foothills above 6500ft
Boulder	100 PM TO 1159 PM	0.25" (90%) to 0.5" (60%) to 1.5" (30%)	ISSUED
Douglas	100 PM TO 1159 PM	0.25" (90%) to 0.5" (60%) to 1.5" (30%)	ISSUED
Jefferson	100 PM TO 1159 PM	0.25" (90%) to 0.5" (60%) to 1.5" (30%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.