Time: 920 AM Fri July 3, 2020 Forecaster: Brad Simmons

Heavy Precipitation Outlook
Flash Flood Prediction Program

THUNDERSTORMS RETURN TO THE DISTRICT WITH THE THREAT FOR HEAVY RAINFALL
-Thunderstorms are expected to return to the District today as moisture has increased both at the surface and aloft. Temperatures will continue to run above normal with highs reaching the lower 90's over the plains before cloud cover and rain showers cool temperatures down later this afternoon.
-Daytime heating in tandem with ample surface moisture will begin to initiate storms over the foothills by around noon or before. Weak steering winds aloft from the SW at around 10mph will push the storms onto the plains between 1-2pm. Prime time for thunderstorms is 2-6pm. Stronger storms may move erratically or could potentially anchor along a gust front. Generally 1 round of scattered storms is expected but there could be a weaker additional round for some locations.
-Due to slow storm motions the strong thunderstorms that develop today will have the potential to produce extended periods of heavy rainfall that may lead to excessive runoff and possibly flash flooding. Roadways, smaller creeks and streams would be the most likely impacted areas today. Strong thunderstorms may also contain large hail, frequent cloud-to-ground lightning and damaging winds.
STORM RAINFALL POTENTIAL AND DURATION: Typical weak to moderate thunderstorms will produce 0.1-0.4" in 10-30 minutes. Strong thunderstorms will have the potential to produce 0.5-1.3" in 10-30 minutes.

WORST CASE SCENARIO: A large thunderstorm complex or a nearly stationary strong thunderstorm may produce up to 2.5" in 60 minutes or less.

A LOOK AHEAD: Mother Nature looks to provide some of her own fireworks on Saturday as there will be a high risk for thunderstorms with the potential for heavy rainfall in the afternoon and early evening. Hopefully many areas are able to experience wetting rains over the next couple days to help lower the fire risk.

Location Prime Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 200 PM TO 600 PM
0.1" (75%) to 0.4" (40%) to 1.3" (15%) MOD
Arapahoe 200 PM TO 600 PM
0.1" (75%) to 0.4" (40%) to 1.3" (15%) MOD
Broomfield 200 PM TO 600 PM
0.1" (75%) to 0.4" (40%) to 1.3" (15%) MOD
Denver 200 PM TO 600 PM
0.1" (75%) to 0.4" (40%) to 1.3" (15%) MOD
Boulder 100 PM TO 600 PM
0.1" (75%) to 0.4" (40%) to 1.3" (15%) MOD
Douglas 100 PM TO 600 PM
0.1" (75%) to 0.4" (40%) to 1.3" (15%) MOD
Jefferson 100 PM TO 600 PM
0.1" (75%) to 0.4" (40%) to 1.3" (15%) MOD
Foothills above 6500ft      
Boulder 1200 PM TO 600 PM
0.1" (80%) to 0.4" (40%) to 1.3" (10%) MOD
Douglas 1200 PM TO 600 PM
0.1" (80%) to 0.4" (40%) to 1.3" (10%) MOD
Jefferson 1200 PM TO 600 PM
0.1" (80%) to 0.4" (40%) to 1.3" (10%) MOD
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.