Time: 1016 AM Sun May 2, 2021 Forecaster: Brad Simmons

Internal Message Status
Flash Flood Prediction Program

MESSAGE 1'S ISSUED FOR THE ENTIRE DISTRICT
-Message 1's have been issued for the entire District and are currently valid until 8:00pm this evening.
-Shower and thunderstorm activity is already blossoming over W/NW Boulder County and will fill in over the District through noon. 2-3 rounds of showers and thunderstorms are likely into the evening with stronger storms capable of producing brief heavy rainfall that may lead to excessive runoff. Relatively fast storm motions from SW to NE at 20-25mph will help to keep heavier rainfall brief with training of thunderstorm cells having the greatest threat for a prolonged period of heavy rainfall.
-Strong thunderstorms may also become severe, producing large hail/accumulating hail, gusty winds and frequent cloud-to-ground lightning. Thunderstorm activity is expected to diminish as temperatures cool this evening with a widespread rain forecast to fill in with lighter rainfall rates overnight into Monday morning.
STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce 0.1-0.3" in 10-30 minutes. Moderate to strong thunderstorms will have the potential to produce 0.3-0.9" in 10-30 minutes.

WORST CASE SCENARIO: Training of moderate/strong thunderstorm cells may result in up to 1.6" of rain in 60-90 minutes.

County Message Valid Times Prime Time
Broomfield County 1 Current TO 800 PM 1100 AM TO 700 PM
Jefferson County 1 Current TO 800 PM 1100 AM TO 700 PM
Boulder County 1 Current TO 800 PM 1100 AM TO 700 PM
Douglas County 1 Current TO 800 PM 1100 AM TO 700 PM
Adams County 1 Current TO 800 PM 1100 AM TO 700 PM
Denver County 1 Current TO 800 PM 1100 AM TO 700 PM
DIA 1 Current TO 800 PM 1100 AM TO 700 PM
Arapahoe County 1 Current TO 800 PM 1100 AM TO 700 PM
the City of Aurora 1 Current TO 800 PM 1100 AM TO 700 PM
Arvada 1 Current TO 800 PM 1100 AM TO 700 PM
Wheat Ridge 1 Current TO 800 PM 1100 AM TO 700 PM
Lakewood 1 Current TO 800 PM 1100 AM TO 700 PM

County-specific Quantitative
Precipitation Outlook
Precipitation Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 1100 AM TO 800 PM
0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED
Arapahoe 1100 AM TO 800 PM
0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED
Broomfield 1100 AM TO 800 PM
0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED
Denver 1100 AM TO 800 PM
0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED
Douglas 1100 AM TO 800 PM
0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED
Jefferson 1100 AM TO 800 PM
0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED
Boulder Current TO 800 PM SUN
0.1" (100%) to 0.3" (80%) to 0.9" (30%) ISSUED
Foothills above 6500ft      
Douglas 1100 AM TO 800 PM
0.1" (100%) to 0.3" (80%) to 0.9" (20%) ISSUED
Jefferson 1100 AM TO 800 PM
0.1" (100%) to 0.3" (80%) to 0.9" (20%) ISSUED
Boulder Current TO 800 PM SUN
0.1" (100%) to 0.3" (80%) to 0.9" (20%) ISSUED
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.