Flash Flood Prediction Program

The National Weather Service in Boulder has issued a Flood Watch for the entire District effective from 1000 AM Today, June 12th, 2023, until 1159 PM June 12th, 2023. The MHFD Message 2 will start prior to the NWS Flood Watch due to the potential for storms with heavy rainfall to enter the District before to 1000 AM.

These storms have already initiated along the higher terrain foothills and will slowly progress eastward and onto the I-25 corridor today. Good upper-level support and an abundance of moisture is in place and has resulted in a good chance for widespread thunderstorms with heavy rainfall leading to localized flooding. The best time for storms to enter the western portions of the District will be between 1000AM and noon with storms likely throughout the District between 800PM - midnight. Multiple rounds of storms are likely today, leading to a Flood Watch through the evening.

A chance some of these storms become severe, with large hail up to 1.5”, gusty winds 60+ mph throughout the District. The best chance for severe weather will likely be during the initial round of storms, with additional storms decreasing in intensity, however, with elevated moisture and good dynamics, even moderate rain showers will produce heavy rainfall well into the late evening hours.

STORM RAINFALL POTENTIAL AND DURATION: Typical thunderstorms have the potential to produce moderate to heavy rainfall of 0.5” to 0.75” total, in 10 to 30 minutes. Strong thunderstorms have the potential to produce moderate to heavy rainfall of 0.75” to 1.75” total, in 10 to 30 minutes.

WORST CASE SCENARIO: Anchored or slow-moving thunderstorms have the potential to produce up to 2.50” total in 45-60 minutes.

County	Message	Valid Times	Prime Time
Boulder County	2	1000 AM TO 1159 PM	1200 PM TO 800 PM
Jefferson County	2	1000 AM TO 1159 PM	1200 PM TO 800 PM
Broomfield County	2	1000 AM TO 1159 PM	1200 PM TO 800 PM
Douglas County	2	1000 AM TO 1159 PM	1200 PM TO 800 PM
Adams County	2	1000 AM TO 1159 PM	1200 PM TO 800 PM
Denver County	2	1000 AM TO 1159 PM	1200 PM TO 800 PM
DIA	2	1000 AM TO 1159 PM	1200 PM TO 800 PM
Arapahoe County	2	1000 AM TO 1159 PM	1200 PM TO 800 PM
the City of Aurora	2	1000 AM TO 1159 PM	1200 PM TO 800 PM
Arvada	2	1000 AM TO 1159 PM	1200 PM TO 800 PM
Wheat Ridge	2	1000 AM TO 1159 PM	1200 PM TO 800 PM
Lakewood	2	1000 AM TO 1159 PM	1200 PM TO 800 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	1000 AM TO 1159 PM	0.5" (90%) to 0.75" (50%) to 1.75" (25%)	ISSUED
Arapahoe	1000 AM TO 1159 PM	0.5" (90%) to 0.75" (50%) to 1.75" (25%)	ISSUED
Boulder	1000 AM TO 1159 PM	0.5" (90%) to 0.75" (50%) to 1.75" (25%)	ISSUED
Broomfield	1000 AM TO 1159 PM	0.5" (90%) to 0.75" (50%) to 1.75" (25%)	ISSUED
Denver	1000 AM TO 1159 PM	0.5" (90%) to 0.75" (50%) to 1.75" (25%)	ISSUED
Douglas	1000 AM TO 1159 PM	0.5" (90%) to 0.75" (50%) to 1.75" (25%)	ISSUED
Jefferson	1000 AM TO 1159 PM	0.5" (90%) to 0.75" (50%) to 1.75" (25%)	ISSUED
Foothills above 6500ft
Boulder	1000 AM TO 1159 PM	0.5" (90%) to 0.75" (50%) to 1.75" (25%)	ISSUED
Douglas	1000 AM TO 1159 PM	0.5" (90%) to 0.75" (50%) to 1.75" (25%)	ISSUED
Jefferson	1000 AM TO 1159 PM	0.5" (90%) to 0.75" (50%) to 1.75" (25%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.