Flash Flood Prediction Program

Time: 1054 PM Sun August 27, 2023 Forecaster: Justin Brooks ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1’S HAVE BEEN EXTENDED UNTIL 11:59 PM FOR PORTIONS OF THE DISTRICT AS THE THREAT FOR HEAVY RAIN CONTINUES Message 1’s will be extended until 11:59pm for Arapahoe and Douglas County as the threat of heavy rainfall continues. Message 1's will be allowed to expire at 11:00pm for ALL other areas of the District. The late evening round of showers/thunderstorms slowed over the Denver metro this evening which has resulted in the extension of Message 1’s for southeastern portions of the District. Storms producing heavy rainfall have moved through Denver with some areas receiving up to 0.91” of rainfall in under 1 hour in western Arapahoe County. This line of storms has entered both Douglas and Arapahoe Counties and will impact the area over the next hour or so. Storms will likely bring 0.30-0.80” of rainfall for portions of Dougals and Arapahoe Counties. A chance for off and on showers will persist through the overnight with any shower activity coming to an end between 2-3am. Skies will gradually clear through the rest of the overnight as lows decrease into the low to mid 60s. Very little overall chance for tomorrow with another chance for storms by midday, with similar NW to SE storm motions. STORM RAINFALL POTENTIAL AND DURATION: Typical showers/isolated thunderstorms will produce a 0.10-0.30” total in 10-30 minutes. A moderate to strong shower/thunderstorm will produce 0.30-0.80” total in 10-30 minutes. WORST CASE SCENARIO: A strong thunderstorm, or training of thunderstorm cells has the potential to produce 0.80-1.40” in under 60 minutes. COUNTY MESSAGE VALID TIMES PRIME TIME Boulder County 1 Current TO 1100 PM Current TO 1100 PM Jefferson County 1 Current TO 1100 PM Current TO 1100 PM Broomfield County 1 Current TO 1100 PM Current TO 1100 PM Douglas County 1 Current TO 1159 PM Current TO 1130 PM Adams County 1 Current TO 1100 PM Current TO 1100 PM Denver County 1 Current TO 1100 PM Current TO 1100 PM DIA 1 Current TO 1100 PM Current TO 1100 PM Arapahoe County 1 Current TO 1159 PM Current TO 1130 PM the City of Aurora 1 Current TO 1100 PM Current TO 1100 PM Arvada 1 Current TO 1100 PM Current TO 1100 PM Wheat Ridge 1 Current TO 1100 PM Current TO 1100 PM Lakewood 1 Current TO 1100 PM Current TO 1100 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams Current TO 1159 PM SUN 0.1" (20%) to 0.3" (10%) to 0.8" (5%) NONE Arapahoe Current TO 1159 PM SUN 0.1" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Boulder Current TO 1159 PM SUN 0.1" (10%) to 0.3" (5%) to 0.8" (0%) NONE Broomfield Current TO 1159 PM SUN 0.1" (10%) to 0.3" (5%) to 0.8" (0%) NONE Denver Current TO 1159 PM SUN 0.1" (30%) to 0.3" (15%) to 0.8" (5%) NONE Douglas Current TO 1159 PM SUN 0.1" (60%) to 0.3" (30%) to 0.8" (15%) ISSUED Jefferson Current TO 1159 PM SUN 0.1" (10%) to 0.3" (5%) to 0.8" (0%) NONE Foothills above 6500ft       Boulder Current TO 1159 PM SUN 0.1" (10%) to 0.3" (5%) to 0.8" (0%) NONE Douglas Current TO 1159 PM SUN 0.1" (50%) to 0.3" (25%) to 0.8" (10%) ISSUED Jefferson Current TO 1159 PM SUN 0.1" (10%) to 0.3" (5%) to 0.8" (0%) NONE MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]