Time: 1232 PM Sun June 11, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 2'S HAVE BEEN ISSUED FOR THE ENTIRE DISTRICT The National Weather Service in Boulder has issued a Flood Watch for the entire District effective from 3:00 PM Today, June 11th, 2023, until 3:00 AM Monday, 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 3pm. These storms have already initiated along the higher terrain foothills and will slowly progress eastward and onto the I-25 corridor this afternoon. Very week steering flow aloft, good upper-level support and an abundance of moisture in place has resulted in a good chance for widespread thunderstorms with heavy rainfall leading to localized flooding. The best chance for storms to enter the western portions of the District will be between 1-2pm with storms likely throughout the District between 2-4pm. Multiple rounds of storms will be likely today, leading to a Flood Watch through the evening and into the overnight. 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 likely 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 0.4” to 0.75” total, in 10 to 30 minutes. Strong thunderstorms have the potential to produce moderate to heavy rainfall of 0.75” to 1.50” 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 2 100 PM TO 300 AM MONDAY 200 PM TO 200 AM MONDAY Jefferson County 2 100 PM TO 300 AM MONDAY 200 PM TO 200 AM MONDAY Broomfield County 2 100 PM TO 300 AM MONDAY 200 PM TO 200 AM MONDAY Douglas County 2 100 PM TO 300 AM MONDAY 200 PM TO 200 AM MONDAY Adams County 2 100 PM TO 300 AM MONDAY 200 PM TO 200 AM MONDAY Denver County 2 100 PM TO 300 AM MONDAY 200 PM TO 200 AM MONDAY DIA 2 100 PM TO 300 AM MONDAY 200 PM TO 200 AM MONDAY Arapahoe County 2 100 PM TO 300 AM MONDAY 200 PM TO 200 AM MONDAY the City of Aurora 2 100 PM TO 300 AM MONDAY 200 PM TO 200 AM MONDAY Arvada 2 100 PM TO 300 AM MONDAY 200 PM TO 200 AM MONDAY Wheat Ridge 2 100 PM TO 300 AM MONDAY 200 PM TO 200 AM MONDAY Lakewood 2 100 PM TO 300 AM MONDAY 200 PM TO 200 AM MONDAY County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 100 PM TO 300 AM MON 0.4" (90%) to 0.75" (60%) to 1.5" (30%) ISSUED Arapahoe 100 PM TO 300 AM MON 0.4" (90%) to 0.75" (60%) to 1.5" (30%) ISSUED Boulder 100 PM TO 300 AM MON 0.4" (90%) to 0.75" (60%) to 1.5" (30%) ISSUED Broomfield 100 PM TO 300 AM MON 0.4" (90%) to 0.75" (60%) to 1.5" (30%) ISSUED Denver 100 PM TO 300 AM MON 0.4" (90%) to 0.75" (60%) to 1.5" (30%) ISSUED Douglas 100 PM TO 300 AM MON 0.4" (95%) to 0.75" (70%) to 1.5" (40%) ISSUED Jefferson 100 PM TO 300 AM MON 0.4" (95%) to 0.75" (70%) to 1.5" (40%) ISSUED Foothills above 6500ft       Boulder 100 PM TO 300 AM MON 0.4" (100%) to 0.75" (75%) to 1.5" (50%) ISSUED Douglas 100 PM TO 300 AM MON 0.4" (100%) to 0.75" (75%) to 1.5" (50%) ISSUED Jefferson 100 PM TO 300 AM MON 0.4" (100%) to 0.75" (75%) to 1.5" (50%) ISSUED MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]