Flash Flood Prediction Program

Time: 928 AM Thu June 16, 2022 Forecaster: Brad Simmons ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- HOT WITH SMOKE/HAZE ON THE INCREASE AND POSSIBLY AN ISOLATED EVENING THUNDERSTORM - Temperatures will continue to warm today over the District with afternoon highs topping out in the 90's over the plains with 80's in the Front Range foothills under sunny to mostly sunny skies through much of the day. Surface winds will become breezy at times varying from SW to SE at 5-15mph and gusts to 20mph or more. - SW flow aloft will begin to import smoke from wildfires over AZ/NM northward into Colorado as the day progresses with haze on the increase and air quality deteriorating. Hazy conditions are expected to persist over the coming days. Moisture will be increasing at the surface and aloft as the day wears on and an isolated evening thunderstorm or two may develop over southern and eastern areas of the District if all the ingredients come together just right. The most likely outcome is that the District squeaks out one more dry day before thunderstorms become more active over NE Colorado tomorrow and over the weekend. - The chances are relatively low but if thunderstorms were to develop today they would favor the plains over the foothills, initiating sometime between 5-7pm. Storms would then quickly lift to the NE with chances ending before midnight. The one fly in the ointment is that although the chances for storms to develop are quite low, if a storm does manage to develop it would likely become strong with the potential for brief moderate/heavy rainfall and gusty winds resulting in a low Message potential for eastern areas of the District. STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms if able to develop will have the potential to produce a trace to 0.2" or rain in 10-30 minutes. WORST CASE SCENARIO: Moisture levels increase sufficiently at the surface to support strong thunderstorms with the potential to produce heavy rainfall rates of 0.3-0.9" in 10-30 minutes. A LOOK AHEAD: Temperatures will tack on a few more degrees on Friday with readings in the 90's to near 100 degrees over the plains. There will be a little relief from the heat for some as thunderstorm activity is expected to increase with isolated to widely scattered afternoon thunderstorms, more numerous over the foothills. Stronger storms will have the potential to produce gusty winds and moderate to briefly heavy rain. Chances for thunderstorms increases further over the weekend with stronger storms capable of producing heavy rainfall that may lead to excessive runoff. The first Message 1's of the season will be likely over the coming days! LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 500 PM TO 1000 PM Trace (30%) to 0.2" (15%) to 0.6" (5%) LOW Arapahoe 500 PM TO 1000 PM Trace (30%) to 0.2" (15%) to 0.6" (5%) LOW Boulder 500 PM TO 1000 PM Trace (20%) to 0.2" (10%) to 0.6" (5%) NONE Broomfield 500 PM TO 1000 PM Trace (20%) to 0.2" (10%) to 0.6" (5%) NONE Denver 500 PM TO 1000 PM Trace (30%) to 0.2" (15%) to 0.6" (5%) LOW Douglas 500 PM TO 1000 PM Trace (25%) to 0.2" (10%) to 0.6" (5%) NONE Jefferson 500 PM TO 1000 PM Trace (20%) to 0.2" (10%) to 0.6" (5%) NONE Foothills above 6500ft       Boulder 400 PM TO 1000 PM Trace (25%) to 0.1" (10%) to 0.3" (5%) NONE Douglas 400 PM TO 1000 PM Trace (25%) to 0.1" (10%) to 0.3" (5%) NONE Jefferson 400 PM TO 1000 PM Trace (25%) to 0.1" (10%) to 0.3" (5%) 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]