Flash Flood Prediction Program

Time: 914 AM Sun June 27, 2021 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- ANOTHER COOLER THAN AVERAGE DAY WITH A CHANCE FOR AFTERNOON RAIN/ISOALTED THUNDERSTORMS - Unseasonably cool temperatures once again today with highs 10-15 degrees less than the normal of 87 for DIA. Highs today will reach the low to mid 70's on the plains with mid to upper 60's along the foothills. Slightly less moisture available at the surface this morning and in the mid to upper levels, will result in a lesser chance for heavy rainfall today, although there is still potential for brief heavy rainfall if stronger storms are able to develop this afternoon with a slight chance for rain showers to persist through the overnight and into Monday morning. - Another disturbance will push through the region around midday bringing a chance for rain/isolated thunderstorms across the District this afternoon, with the severity of storms once again hinging on whether or not there is enough daytime heating to get stronger storms to develop. Storm motions will also be fairly brisk between 10-20mph from the N/NW to S/SE, similar to yesterday. Best chance for storms in the District will be between 12-8pm with a slight lull in activity before a second surge moves in late this evening bringing a slight chance for widely scattered rain showers through the overnight and into Monday morning. A few rumbles of thunder cannot be completely ruled out through the overnight, although the threat for heavy rainfall will quickly diminish after 8pm this evening. - Overnight lows will be chilly for this time of year with lows dipping into the low to mid 50's on the plains with upper 40's to around 50 in the foothills. A few areas of fog possible in the early morning hours Monday along with scattered drizzle/light rain through daybreak. STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers/isolated thunderstorms will produce TR-0.3" in 10-30 minutes. a moderate to strong thunderstorm will produce 0.3-0.8" in 10-30 minutes. WORST CASE SCENARIO: An anchored strong thunderstorm or training of strong thunderstorms will have the potential to produce 1.6" in 45-75 minutes. A LOOK AHEAD: Monday looks to be the last day of cool weather for the region with high temperatures remaining in the low to mid 70's across the plains. A decrease in mid to upper-level moisture will limit storm production heading into next week, although the chance remains for scattered rain showers/isolated thunderstorms through Wednesday. Temperatures begin to rise Tuesday into the upper 70's to around 80. Warmer Wednesday with highs in the low 80's. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 1200 PM TO 800 PM Trace (60%) to 0.3" (30%) to 0.6" (15%) LOW Arapahoe 1200 PM TO 800 PM Trace (60%) to 0.3" (30%) to 0.6" (15%) LOW Boulder 1200 PM TO 800 PM Trace (60%) to 0.3" (30%) to 0.6" (15%) LOW Broomfield 1200 PM TO 800 PM Trace (60%) to 0.3" (30%) to 0.6" (15%) LOW Denver 1200 PM TO 800 PM Trace (60%) to 0.3" (30%) to 0.6" (15%) LOW Douglas 1200 PM TO 800 PM Trace (60%) to 0.3" (30%) to 0.6" (15%) LOW Jefferson 1200 PM TO 800 PM Trace (60%) to 0.3" (30%) to 0.6" (15%) LOW Foothills above 6500ft       Boulder 1200 PM TO 800 PM Trace (75%) to 0.3" (50%) to 0.6" (25%) LOW Douglas 1200 PM TO 800 PM Trace (75%) to 0.3" (40%) to 0.6" (20%) LOW Jefferson 1200 PM TO 800 PM Trace (75%) to 0.3" (40%) to 0.6" (20%) LOW MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]