Time: 1117 AM Sat June 17, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 2’s HAVE BEEN ISSUED FOR DOUGLAS COUNTY, MESSAGE 1’S FOR THE REMAINDER OF THE DISTRICT Message 1’s have been issued for the entire District, NOT including Douglas County, effective now until 6pm. Message 2’s have been issued for Douglas County, effective now until 6pm. This coincides with the NWS Flood Watch for northeastern Douglas County effective from noon until 6pm. Storms have started to initiate along the foothills at this time and will progress eastward and into the District this afternoon and early evening. Temperatures have not warmed up significantly so far, which should help limit the strength of storms today, however, due to the excessive rain this season, even a moderate shower with rainfall between 0.35-0.45” in 10-20 minutes will produce some LOW IMPACT FLOODING today. The best chance for storms will be from now, through 6pm with skies quickly clearing this evening as drier air races in behind this disturbance from the NW into the evening. Storm motions should be relatively fast today, between 10-15 from NW to SE, hopefully helping limit point rainfall amounts. The biggest threat today will be any storm with moderate to brief rainfall stalling out, or erratic storm movements from storms formed along outflow boundaries. Any persistent moderate to heavy rainfall over 10-20 minutes will likely result in an issuance of LOW IMPACT FLOODING today. STORM RAINFALL POTENTIAL AND DURATION: Typical showers and weak thunderstorms will produce a 0.10-0.0” total, in 10-30 minutes. A moderate to strong thunderstorm will produce 0.40-1.2” total, in 10-30 minutes. WORST CASE SCENARIO: A stalled strong thunderstorm, or training of moderate to heavy showers/thunderstorms will have the potential to produce 1.8” total in under 60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Denver County 1 Current TO 600 PM Current TO 600 PM Adams County 1 Current TO 600 PM Current TO 600 PM Douglas County 2 Current TO 600 PM Current TO 600 PM Broomfield County 1 Current TO 600 PM Current TO 600 PM Jefferson County 1 Current TO 600 PM Current TO 600 PM Boulder County 1 Current TO 600 PM Current TO 600 PM DIA 1 Current TO 600 PM Current TO 600 PM Arapahoe County 1 Current TO 600 PM Current TO 600 PM the City of Aurora 1 Current TO 600 PM Current TO 600 PM Arvada 1 Current TO 600 PM Current TO 600 PM Wheat Ridge 1 Current TO 600 PM Current TO 600 PM Lakewood 1 Current TO 600 PM Current TO 600 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 600 PM SAT 0.1" (75%) to 0.4" (50%) to 1.2" (25%) ISSUED Arapahoe Current TO 600 PM SAT 0.1" (75%) to 0.4" (50%) to 1.2" (25%) ISSUED Boulder Current TO 600 PM SAT 0.1" (75%) to 0.4" (50%) to 1.2" (25%) ISSUED Broomfield Current TO 600 PM SAT 0.1" (75%) to 0.4" (50%) to 1.2" (25%) ISSUED Denver Current TO 600 PM SAT 0.1" (75%) to 0.4" (50%) to 1.2" (25%) ISSUED Douglas Current TO 600 PM SAT 0.1" (90%) to 0.4" (60%) to 1.2" (30%) ISSUED Jefferson Current TO 600 PM SAT 0.1" (90%) to 0.4" (60%) to 1.2" (30%) ISSUED Foothills above 6500ft       Boulder Current TO 600 PM SAT 0.1" (80%) to 0.4" (60%) to 1.2" (30%) ISSUED Douglas Current TO 600 PM SAT 0.1" (90%) to 0.4" (60%) to 1.2" (30%) ISSUED Jefferson Current TO 600 PM SAT 0.1" (90%) to 0.4" (60%) to 1.2" (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]