Time: 110 PM Wed May 10, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S ISSUED FOR THE ENTIRE DISTRICT Message 1's have been issued for the entire District and will be valid until 11:59 PM, with a chance Messages will have to be extended through the overnight if the heavy rainfall threat persists after midnight tonight. Temperatures have been suppressed this morning, which could help limit the potential for severe thunderstorm activity this afternoon and evening. However, good upper-level dynamics heading into the afternoon and evening will likely result in widespread rain showers and thunderstorms with a good chance for isolated heavy rainfall, leading to some localized flash flooding. Storm motions today will be generally fast from south to north, between 10-15mph which should help limit point rainfall amounts. Additional storms formed along outflow boundaries will have the largest potential to produce longer lasting heavy rainfall. The best chance for heavy rainfall producing storms will be from 1pm this afternoon through midnight tonight. Off and on rain shower chances will likely continue overnight and into daybreak Thursday. The threat for heavy rainfall should diminish after midnight, however, with significant moisture in place both at the surface and upper levels, there will be a chance for rain showers that could produce rainfall rates exceeding 1" per hour through the overnight and into Thursday. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers/isolated thunderstorms will produce 0.1-0.5" in 10-30 minutes. A Moderate to strong thunderstorm will produce 0.5-1.0" in 10-30 minutes. WORST CASE SCENARIO: A slow moving/stationary thunderstorm formed off an outflow boundary, or training of thunderstorm cells has the potential to produce up to 2.0" in under 60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 100 PM TO 1159 PM 200 PM TO 1100 PM Jefferson County 1 100 PM TO 1159 PM 200 PM TO 1100 PM Broomfield County 1 100 PM TO 1159 PM 200 PM TO 1100 PM Douglas County 1 100 PM TO 1159 PM 200 PM TO 1100 PM Adams County 1 100 PM TO 1159 PM 200 PM TO 1100 PM Denver County 1 100 PM TO 1159 PM 200 PM TO 1100 PM DIA 1 100 PM TO 1159 PM 200 PM TO 1100 PM Arapahoe County 1 100 PM TO 1159 PM 200 PM TO 1100 PM the City of Aurora 1 100 PM TO 1159 PM 200 PM TO 1100 PM Arvada 1 100 PM TO 1159 PM 200 PM TO 1100 PM Wheat Ridge 1 100 PM TO 1159 PM 200 PM TO 1100 PM Lakewood 1 100 PM TO 1159 PM 200 PM TO 1100 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 100 PM TO 1159 PM 0.1" (90%) to 0.5" (60%) to 1" (30%) ISSUED Arapahoe 100 PM TO 1159 PM 0.1" (90%) to 0.5" (60%) to 1" (30%) ISSUED Boulder 100 PM TO 1159 PM 0.1" (90%) to 0.5" (60%) to 1" (30%) ISSUED Broomfield 100 PM TO 1159 PM 0.1" (90%) to 0.5" (60%) to 1" (30%) ISSUED Denver 100 PM TO 1159 PM 0.1" (90%) to 0.5" (60%) to 1" (30%) ISSUED Douglas 100 PM TO 1159 PM 0.1" (90%) to 0.5" (60%) to 1" (30%) ISSUED Jefferson 100 PM TO 1159 PM 0.1" (90%) to 0.5" (60%) to 1" (30%) ISSUED Foothills above 6500ft       Boulder 100 PM TO 1159 PM 0.1" (80%) to 0.5" (40%) to 1" (20%) ISSUED Douglas 100 PM TO 1159 PM 0.1" (80%) to 0.5" (40%) to 1" (20%) ISSUED Jefferson 100 PM TO 1159 PM 0.1" (80%) to 0.5" (40%) to 1" (20%) 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]