Flash Flood Prediction Program

Storms have initiated along the foothills this afternoon and will likely move into the District over the next hour or so. Temperatures today have been cooler, however, dew points are elevated at the surface currently in the upper 40s to low 50s. Combined with model driven PWAT values between 1.00-1.25” will result in efficient rainfall producing storms this afternoon and evening. Storms will also be slow moving from west to east around 5mph, with anchored storms likely forming along outflow boundaries. These slow-moving storms will result in the potential for both 0.50” in 10-20 minutes and due to PWAT values above an inch, could result in an isolated 1.00-1.25” in under 60 minutes. A couple of rounds of storms will be possible this afternoon and evening, the first round, moving in between 4-6pm likely having more impact than the later round moving in between 7-9pm. Once these rounds move out, skies will gradually clear through the overnight with temperatures dropping into the mid 60s for the plains with around 60 degrees along the foothills.

STORM RAINFALL POTENTIAL AND DURATION: Typical showers will produce 0.05-0.30" total in 10-30 minutes. A moderate to strong thunderstorm will produce rainfall rates of 0.30”-0.80” total in 10- 30 minutes.

WORST CASE SCENARIO: A slow-moving thunderstorm, training of thunderstorms cells or a large thunderstorm complex may result in up to 1.25” of rain in 30-60 minutes.

County	Message	Valid Times	Prime Time
Boulder County	1	Current TO 1000 PM	Current TO 900 PM
Jefferson County	1	Current TO 1000 PM	Current TO 900 PM
Broomfield County	1	Current TO 1000 PM	Current TO 900 PM
Douglas County	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
DIA	1	Current TO 1000 PM	Current TO 900 PM
Arapahoe County	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
Wheat Ridge	1	Current TO 1000 PM	Current TO 900 PM
Lakewood	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 MON	0.05" (60%) to 0.3" (30%) to 0.8" (15%)	ISSUED
Arapahoe	Current TO 1000 PM MON	0.05" (60%) to 0.3" (30%) to 0.8" (15%)	ISSUED
Boulder	Current TO 1000 PM MON	0.05" (60%) to 0.3" (30%) to 0.8" (15%)	ISSUED
Broomfield	Current TO 1000 PM MON	0.05" (60%) to 0.3" (30%) to 0.8" (15%)	ISSUED
Denver	Current TO 1000 PM MON	0.05" (60%) to 0.3" (30%) to 0.8" (15%)	ISSUED
Douglas	Current TO 1000 PM MON	0.05" (60%) to 0.3" (30%) to 0.8" (15%)	ISSUED
Jefferson	Current TO 1000 PM MON	0.05" (60%) to 0.3" (30%) to 0.8" (15%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 1000 PM MON	0.05" (75%) to 0.3" (50%) to 0.8" (25%)	ISSUED
Douglas	Current TO 1000 PM MON	0.05" (75%) to 0.3" (50%) to 0.8" (25%)	ISSUED
Jefferson	Current TO 1000 PM MON	0.05" (75%) to 0.3" (50%) to 0.8" (25%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.