Flash Flood Prediction Program

Time: 854 AM Wed May 19, 2021 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- SUNNY AND WARM WITH ISOLATED AFTERNOON THUNDERSTORMS - Finally a sunny and mild start to the day as high temperatures reach the low to mid 70's on the plains this afternoon with mid to upper 60's along the foothills. A slight chance for isolated thunderstorms this afternoon with skies gradually clearing into the evening. - Rain showers and thunderstorms will initially develop along the higher terrain to the west around midday with some isolated thunderstorms making their way into the District this afternoon and early evening. Storms that do make it onto the plains will move between 5-10mph from west to east. Best chance for storms in the District will be from 2-8pm. Typical storms will produce between a TR-0.2" with isolated higher amounts possible if a stronger storm is able to develop. Storms will also contain some small hail, gusty winds and lightning. - Overnight lows will drop into the upper 40's to around 50 on the plains with low to mid 40's along the foothills. Even warmer tomorrow as high temperatures move back into the low 80's with a very slight chance for some scattered high-based showers in the afternoon favoring northern portions of the District. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will have the potential to produce TR-0.2" in 10-30 minutes. Strong thunderstorms will have the potential to produce 0.2-0.3" in 10-30 minutes. WORST CASE SCENARIO: An anchored strong thunderstorm or training of thunderstorm cells may result in up to 1.0" of rain in 60 minutes or less. A LOOK AHEAD: a weak high-pressure settles over the region tomorrow bringing a very slight chance for a high-based thunderstorm. Similar conditions to start the day Friday as high temperatures reach the low 80's. Another slow moving disturbance starts to move in Friday bringing a chance for rain showers/isolated thunderstorms in the afternoon and evening. This trend continued into the weekend with rain/thunderstorm chances Saturday and Sunday with some storms having the potential for heavy rainfall. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 800 PM Trace (40%) to 0.2" (20%) to 0.3" (5%) NONE Arapahoe 200 PM TO 800 PM Trace (40%) to 0.2" (20%) to 0.3" (5%) NONE Boulder 200 PM TO 800 PM Trace (40%) to 0.2" (20%) to 0.3" (5%) NONE Broomfield 200 PM TO 800 PM Trace (40%) to 0.2" (20%) to 0.3" (5%) NONE Denver 200 PM TO 800 PM Trace (40%) to 0.2" (20%) to 0.3" (5%) NONE Douglas 200 PM TO 800 PM Trace (60%) to 0.2" (40%) to 0.3" (20%) NONE Jefferson 200 PM TO 800 PM Trace (50%) to 0.2" (30%) to 0.3" (10%) NONE Foothills above 6500ft       Boulder 100 PM TO 700 PM Trace (75%) to 0.2" (50%) to 0.3" (25%) NONE Douglas 100 PM TO 700 PM Trace (75%) to 0.2" (50%) to 0.3" (25%) NONE Jefferson 100 PM TO 700 PM Trace (75%) to 0.2" (50%) to 0.3" (25%) 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]