Time: 1120 AM Fri July 15, 2022 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 2 ISSUED FOR BOULDER COUNTY/MESSAGE 1'S ISSUED FOR ALL OTHER COUNTIES - The National Weather Service in Boulder has issued a Flash Flood Watch for the higher terrain of Boulder County above 6,000ft from 11am until 9pm this evening. The Flash Flood Watch is primarily issued for the Calwood burn area of Boulder County. Although the flood threat is lower outside the Calwood burn area the Message 2 will cover areas within the MHFD as a portion of the District is included in the NWS zone. Message 1's will go into effect at noon for all other Counties within the District. - Thunderstorms will begin to initiate over the higher terrain between noon and 2pm. Upper level steering winds from SW to NE at 10-15mph will push the storm activity onto the plains during the early afternoon. Prime time for thunderstorms is between 1-8pm. Relatively slow storm motions and ample moisture to fuel thunderstorms will result in stronger storms capable of producing heavy rainfall that may lead to excessive runoff and possibly flash flooding. - The main culprit for extended periods of heavy rainfall today will be storms that are able to anchor or move more slowly. Training of thunderstorm cells is less likely but cannot be ruled out over the foothills. East of I-25 stronger storms may become severe with large hail and gusty winds being the primary threats as well as heavy rainfall. STORM RAINFALL POTENTIAL AND DURATION: Moderate to strong thunderstorms will have the potential to produce rainfall rates of 0.5-1.5" in 10-30 minutes. WORST CASE SCENARIO: A large thunderstorm complex or a nearly stationary strong thunderstorm cell may result in up to 2.5" of rain in 60-90 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 2 1100 AM TO 900 PM 100 PM TO 800 PM Jefferson County 1 1200 PM TO 900 PM 100 PM TO 800 PM Broomfield County 1 1200 PM TO 900 PM 100 PM TO 800 PM Douglas County 1 1200 PM TO 900 PM 100 PM TO 800 PM Adams County 1 1200 PM TO 900 PM 200 PM TO 800 PM Denver County 1 1200 PM TO 900 PM 200 PM TO 800 PM DIA 1 1200 PM TO 900 PM 200 PM TO 800 PM Arapahoe County 1 1200 PM TO 900 PM 200 PM TO 800 PM the City of Aurora 1 1200 PM TO 900 PM 200 PM TO 800 PM Arvada 1 1200 PM TO 900 PM 100 PM TO 800 PM Wheat Ridge 1 1200 PM TO 900 PM 100 PM TO 800 PM Lakewood 1 1200 PM TO 900 PM 100 PM TO 800 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 900 PM 0.1" (90%) to 0.5" (60%) to 1.5" (25%) ISSUED Arapahoe 200 PM TO 900 PM 0.1" (90%) to 0.5" (60%) to 1.5" (25%) ISSUED Broomfield 200 PM TO 900 PM 0.1" (90%) to 0.5" (60%) to 1.5" (20%) ISSUED Denver 200 PM TO 900 PM 0.1" (90%) to 0.5" (60%) to 1.5" (20%) ISSUED Boulder 100 PM TO 900 PM 0.1" (90%) to 0.5" (60%) to 1.5" (20%) ISSUED Douglas 100 PM TO 900 PM 0.1" (90%) to 0.5" (60%) to 1.5" (20%) ISSUED Jefferson 100 PM TO 900 PM 0.1" (90%) to 0.5" (60%) to 1.5" (20%) ISSUED Foothills above 6500ft       Boulder 1200 PM TO 900 PM 0.1" (95%) to 0.5" (65%) to 1.5" (20%) ISSUED Douglas 1200 PM TO 900 PM 0.1" (95%) to 0.5" (65%) to 1.5" (20%) ISSUED Jefferson 1200 PM TO 900 PM 0.1" (95%) to 0.5" (65%) to 1.5" (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]