Flash Flood Prediction Program

Message 1’s have been issued for the entire District effective until 11:59pm as the threat of heavy rainfall has returned.

Gusts fronts from stronger storm development has initiated storms around the Boulder/NW Jeffco area this evening. These storms are very pulse like and have produced brief heavy rainfall just outside of the District between 0.40-0.50” in 10-15 minutes. This has resulted in the reissuance of Message 1s across the District as additional storms have started to fire along norther portions of the District.

Storms that develop will contain moderate to brief heavy rainfall at times, with the largest threat being a quick 0.5” in 10-15 minutes, rather than any long-lasting rainfall. Storms motions have been minimal as most storms have been forming along outflow boundaries. General storm motions will continue to be SE between 10-15mph, with erratic storm movement likley to continue.

By midnight skies should gradually clear as skies stabilize through the overnight. Overnight lows will drop into the mid to upper 50s with some patchy fog possible in the early morning hours.

STORM RAINFALL POTENTIAL AND DURATION: Typical showers and isolated thunderstorms will produce a 0.05-0.25” total in 10-30 minutes. A moderate to strong/severe shower/thunderstorm will produce 0.25-0.75” 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 1.75” total in under 60 minutes.

County	Message	Valid Times	Prime Time
Boulder County	1	Current TO 1159 PM	Current TO 1130 PM
Jefferson County	1	Current TO 1159 PM	Current TO 1130 PM
Broomfield County	1	Current TO 1159 PM	Current TO 1130 PM
Douglas County	1	Current TO 1159 PM	Current TO 1130 PM
Adams County	1	Current TO 1159 PM	Current TO 1130 PM
Denver County	1	Current TO 1159 PM	Current TO 1130 PM
DIA	1	Current TO 1159 PM	Current TO 1130 PM
Arapahoe County	1	Current TO 1159 PM	Current TO 1130 PM
the City of Aurora	1	Current TO 1159 PM	Current TO 1130 PM
Arvada	1	Current TO 1159 PM	Current TO 1130 PM
Wheat Ridge	1	Current TO 1159 PM	Current TO 1130 PM
Lakewood	1	Current TO 1159 PM	Current TO 1130 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	Current TO 1159 PM MON	0.05" (75%) to 0.25" (50%) to 0.75" (25%)	ISSUED
Arapahoe	Current TO 1159 PM MON	0.05" (75%) to 0.25" (50%) to 0.75" (25%)	ISSUED
Boulder	Current TO 1159 PM MON	0.05" (75%) to 0.25" (50%) to 0.75" (25%)	ISSUED
Broomfield	Current TO 1159 PM MON	0.05" (75%) to 0.25" (50%) to 0.75" (25%)	ISSUED
Denver	Current TO 1159 PM MON	0.05" (75%) to 0.25" (50%) to 0.75" (25%)	ISSUED
Douglas	Current TO 1159 PM MON	0.05" (60%) to 0.25" (30%) to 0.75" (20%)	ISSUED
Jefferson	Current TO 1159 PM MON	0.05" (60%) to 0.25" (30%) to 0.75" (20%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 1159 PM MON	0.05" (80%) to 0.25" (40%) to 0.75" (20%)	ISSUED
Douglas	Current TO 1159 PM MON	0.05" (80%) to 0.25" (40%) to 0.75" (20%)	ISSUED
Jefferson	Current TO 1159 PM MON	0.05" (80%) to 0.25" (40%) to 0.75" (20%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.