Time: 1105 AM Thu June 22, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 2’S HAVE BEEN ISSUED FOR THE ENTIRE DISTRICT Message 2’s have been issued for the entire District effective from noon until 1159pm this evening. Strong southwesterly upper-level flow across Colorado will support an environment for another active day of showers and thunderstorms in the district. Daytime heating will create an unstable environment favoring widespread clustered thunderstorms by the mid to late afternoon. High temperatures will reach the mid to upper 70s with dew points in the low to mid 50s. Low level moisture remains elevated from widespread heavy rain yesterday. Precipitable water (PWAT) values have decreased some, though look to be in the 0.70-0.80” range today. This combination will result in storms with the potential for locally heavy rainfall. The best chance for storm activity will be from noon through 11:00pm, with weaker rainfall/thunderstorms likely after 11am and into the overnight. Storms will have their typical West to east motions. However, some erratic storm movement will be likely from outflow boundaries resulting in the possibility of a few stationary storms. These stationary storms will produce the largest threat for heavy rainfall today with both threats 0.5” in 10-15 minutes and the possibility of rainfall to exceed 1” per hour on longer lasting storms. Storms today may also become severe, with large hail, up to 2”, gusty winds 60+ mph and heavy localized rainfall. STORM RAINFALL POTENTIAL AND DURATION: Typical thunderstorms have the potential to produce moderate to heavy rainfall of 0.50” to 1.00” in 10-30 minutes. Strong thunderstorms have the potential to produce very heavy rainfall of 1.00” to 1.50” in 10-30 minutes. WORST CASE SCENARIO: Anchored or slow-moving thunderstorms have the potential to produce 1.50” to 2.20” in 45 to 60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 2 1200 PM TO 1159 PM 1200 PM TO 1100 PM Jefferson County 2 1200 PM TO 1159 PM 1200 PM TO 1100 PM Broomfield County 2 1200 PM TO 1159 PM 1200 PM TO 1100 PM Douglas County 2 1200 PM TO 1159 PM 1200 PM TO 1100 PM Adams County 2 1200 PM TO 1159 PM 1200 PM TO 1100 PM Denver County 2 1200 PM TO 1159 PM 1200 PM TO 1100 PM DIA 2 1200 PM TO 1159 PM 1200 PM TO 1100 PM Arapahoe County 2 1200 PM TO 1159 PM 1200 PM TO 1100 PM the City of Aurora 2 1200 PM TO 1159 PM 1200 PM TO 1100 PM Arvada 2 1200 PM TO 1159 PM 1200 PM TO 1100 PM Wheat Ridge 2 1200 PM TO 1159 PM 1200 PM TO 1100 PM Lakewood 2 1200 PM TO 1159 PM 1200 PM TO 1100 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 1200 PM TO 1159 PM 0.5" (90%) to 1" (60%) to 1.5" (30%) ISSUED Arapahoe 1200 PM TO 1159 PM 0.5" (90%) to 1" (60%) to 1.5" (30%) ISSUED Boulder 1200 PM TO 1159 PM 0.5" (90%) to 1" (60%) to 1.5" (30%) ISSUED Broomfield 1200 PM TO 1159 PM 0.5" (90%) to 1" (60%) to 1.5" (30%) ISSUED Denver 1200 PM TO 1159 PM 0.5" (90%) to 1" (60%) to 1.5" (30%) ISSUED Douglas 1200 PM TO 1159 PM 0.5" (90%) to 1" (60%) to 1.5" (30%) ISSUED Jefferson 1200 PM TO 1159 PM 0.5" (90%) to 1" (60%) to 1.5" (30%) ISSUED Foothills above 6500ft       Boulder 1200 PM TO 1159 PM 0.5" (90%) to 1" (60%) to 1.5" (30%) ISSUED Douglas 1200 PM TO 1159 PM 0.5" (90%) to 1" (60%) to 1.5" (30%) ISSUED Jefferson 1200 PM TO 1159 PM 0.5" (90%) to 1" (60%) to 1.5" (30%) 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]