Flash Flood Prediction Program

The Denver metro was able to miss stronger storms so far today and this could continue, however, a gust front approaches from the east with an uptick in surface moisture. This uptick combined with good upper-level support in and and around the area will bring a chance for rapid storm development leading to localized heavy rainfall. Stronger storms will favor eastern portions of the District at this time. Showers and weak thunderstorms that have developed are currently moving fairly quick, between 25-30mph, although strong storms that form along outflow boundaries could stall out and produce a quick 0.5-1.0” in 10-30 minutes. The best chance for storms will be between now and 9pm, with a few off and on showers through the late evening.

Note: if stronger storms are able to develop, there is potential for large hail 1+”, gusty winds 60mph, and frequent cloud-to-ground.

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 1.75” in under 60 minutes.

County	Message	Valid Times	Prime Time
Boulder County	1	Current TO 900 PM	Current TO 800 PM
Jefferson County	1	Current TO 900 PM	Current TO 800 PM
Broomfield County	1	Current TO 900 PM	Current TO 800 PM
Douglas County	1	Current TO 900 PM	Current TO 800 PM
Adams County	1	Current TO 900 PM	Current TO 800 PM
Denver County	1	Current TO 900 PM	Current TO 800 PM
DIA	1	Current TO 900 PM	Current TO 800 PM
Arapahoe County	1	Current TO 900 PM	Current TO 800 PM
the City of Aurora	1	Current TO 900 PM	Current TO 800 PM
Arvada	1	Current TO 900 PM	Current TO 800 PM
Wheat Ridge	1	Current TO 900 PM	Current TO 800 PM
Lakewood	1	Current TO 900 PM	Current TO 800 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	Current TO 900 PM SAT	0.25" (50%) to 0.5" (25%) to 1" (15%)	ISSUED
Arapahoe	Current TO 900 PM SAT	0.25" (50%) to 0.5" (25%) to 1" (15%)	ISSUED
Boulder	Current TO 900 PM SAT	0.25" (50%) to 0.5" (25%) to 1" (15%)	ISSUED
Broomfield	Current TO 900 PM SAT	0.25" (50%) to 0.5" (25%) to 1" (15%)	ISSUED
Denver	Current TO 900 PM SAT	0.25" (50%) to 0.5" (25%) to 1" (15%)	ISSUED
Douglas	Current TO 900 PM SAT	0.25" (50%) to 0.5" (25%) to 1" (15%)	ISSUED
Jefferson	Current TO 900 PM SAT	0.25" (50%) to 0.5" (25%) to 1" (15%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 900 PM SAT	0.25" (50%) to 0.5" (25%) to 1" (15%)	ISSUED
Douglas	Current TO 900 PM SAT	0.25" (50%) to 0.5" (25%) to 1" (15%)	ISSUED
Jefferson	Current TO 900 PM SAT	0.25" (50%) to 0.5" (25%) to 1" (15%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.