Flash Flood Prediction Program

Time: 257 PM Sat May 15, 2021 Forecaster: Brad Simmons ------------------------- Internal Message Status Flash Flood Prediction Program ------------------------- MESSAGE 1'S ISSUED FOR SOUTHEAST AREAS OF THE DISTRICT - Message 1's have been issued for Arapahoe and Douglas Counties and will be valid until 9:00pm this evening. Additional Message 1's may be issued for the remainder of the District later this afternoon. - Thunderstorms have developed over south/southeast areas of the District where there was more sunshine which allowed for better surface heating this morning. These storms have the potential to produce heavy rainfall that may lead to excessive runoff. Strongest storms are currently in and around Aurora Reservoir and will be tracking E/NE out of the District over the next 60-90 minutes. Hail may also accompany the stronger thunderstorm cells. - Storm motions will generally be from west to east at 15-20mph. Stronger thunderstorms may anchor briefly or have erratic storm movements at times due to outflow boundaries/gust fronts. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers and weak thunderstorms will produce a 0.1-0.3" of rain. Moderate to strong thunderstorms will have the potential to produce 0.3-0.8" in 10-30 minutes. WORST CASE SCENARIO: A stalled out thunderstorm along an outflow boundary may result in up to 1.6" of rain in 60 minutes or less. COUNTY MESSAGE VALID TIMES PRIME TIME the City of Aurora 1 Current TO 900 PM Current TO 800 PM Arapahoe County 1 Current TO 900 PM Current TO 800 PM Douglas County 1 Current TO 900 PM Current TO 800 PM County-specific Quantitative Precipitation Outlook PRECIPITATION TIME 30-Minute Rainfall and % Probability Message Potential Plains       Boulder 400 PM TO 900 PM 0.1" (80%) to 0.3" (60%) to 0.8" (20%) MOD Broomfield 400 PM TO 900 PM 0.1" (80%) to 0.3" (60%) to 0.8" (20%) MOD Jefferson 400 PM TO 900 PM 0.1" (80%) to 0.3" (60%) to 0.8" (20%) MOD Adams 300 PM TO 900 PM 0.1" (90%) to 0.3" (60%) to 0.8" (20%) MOD Denver 300 PM TO 900 PM 0.1" (80%) to 0.3" (60%) to 0.8" (20%) MOD Arapahoe Current TO 900 PM SAT 0.1" (100%) to 0.3" (80%) to 0.8" (40%) ISSUED Douglas Current TO 900 PM SAT 0.1" (100%) to 0.3" (75%) to 0.8" (30%) ISSUED Foothills above 6500ft       Douglas 400 PM TO 900 PM 0.1" (100%) to 0.3" (75%) to 0.8" (25%) ISSUED Jefferson 400 PM TO 900 PM 0.1" (80%) to 0.3" (60%) to 0.8" (20%) MOD Boulder Current TO 900 PM SAT 0.1" (80%) to 0.3" (60%) to 0.8" (20%) MOD MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]