Time: 909 AM Sat May 1, 2021 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- UNSEASONABLY WARM TODAY AHEAD OF A WET PERIOD SETTING UP SUNDAY THROUGH THE MIDDLE PART OF NEXT WEEK - Ahead of an approaching Pacific storm system SW flow aloft will usher in unseasonably warm air with high temperatures well into the 80's over the plains with 60's and 70's in the Front Range foothills. Normal high for Denver today is 66 degrees. There will be a build up of clouds this afternoon, especially over the higher terrain as high-based showers and possibly a weak thunderstorm develop. - Due to dry lower levels of the atmosphere any showers or weak thunderstorms that develop late this afternoon and evening will generally only produce a few sprinkles and gusty winds. Best chances to see any measurable moisture will be over the foothills between 4pm and midnight with the lower elevations expected to remain on the drier side. STORM RAINFALL POTENTIAL AND DURATION: A high-based rain shower or weak thunderstorm will have the potential to produce a trace to 0.1" of rain. A LOOK AHEAD: Sunday will begin dry with a chance for rain showers and thunderstorms starting by around noon and becoming likely by 3-4pm. Shower and thunderstorm activity increases through the late afternoon with chances for thunderstorms diminishing in the evening as a soaking rain develops overnight into Monday morning with the snow line dropping to around 6,000’. Some storms Sunday afternoon could produce brief heavy rainfall and become strong to severe with hail being the primary severe weather threat. Lingering rain/snow pending elevation into Monday morning looks to be persistent until noon, breaking up in the afternoon and becoming more showery. Significant snow is likely for the Front Range foothills with 1-2" of total precipitation over the District from Sunday afternoon into Monday afternoon. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 400 PM TO 1159 PM Trace (10%) to 0.1" (5%) NONE Arapahoe 400 PM TO 1159 PM Trace (10%) to 0.1" (5%) NONE Boulder 400 PM TO 1159 PM Trace (20%) to 0.1" (10%) NONE Broomfield 400 PM TO 1159 PM Trace (15%) to 0.1" (5%) NONE Denver 400 PM TO 1159 PM Trace (10%) to 0.1" (5%) NONE Douglas 400 PM TO 1159 PM Trace (10%) to 0.1" (5%) NONE Jefferson 400 PM TO 1159 PM Trace (20%) to 0.1" (10%) NONE Foothills above 6500ft       Boulder 300 PM TO 1159 PM Trace (30%) to 0.1" (15%) NONE Douglas 300 PM TO 1159 PM Trace (30%) to 0.1" (15%) NONE Jefferson 300 PM TO 1159 PM Trace (30%) to 0.1" (15%) 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]