Time: 827 AM Sun May 24, 2020 Forecaster: Brad Simmons

Heavy Precipitation Outlook
Flash Flood Prediction Program

WIDESPREAD SHOWERS AND THUNDERSTORMS WITH THE POTENTIAL FOR HEAVY RAINFALL
-Trough of low pressure moving through the District today will produce widespread rain showers and embedded thunderstorms with the potential to produce moderate and heavy rainfall. Rain showers are already developing over the mountains and foothills and will be filling in over the I-25 corridor through the morning.
-Best chances for precipitation today will be from 10am to 10pm with greatest threat for thunderstorms between noon and 8pm. The cool temperatures in the 50's for highs over the plains may help to keep the thunderstorms weak to moderate in nature with a low risk for strong to severe storms. Even moderate thunderstorms today will have the potential for heavy rainfall that could lead to excessive runoff and flash flooding. Strong thunderstorms (although the threat is low) will have the potential for large hail and gusty winds as well as heavy rain.
-After 10pm rain shower activity is expected to slowly be on the decrease with lingering shower activity possible into the pre-dawn hours Monday. In the foothills the snow line will drop to somewhere between 7,000-8,000ft later this evening with wet snow accumulations expected for the higher terrain.
STORM RAINFALL POTENTIAL AND DURATION: Rain showers and weak thunderstorms will produce 0.1-0.4" in 10-30 minutes. Moderate to strong thunderstorms will have the potential to produce 0.4-1.2" in 10-30 minutes.

WORST CASE SCENARIO: A large slow moving thunderstorm or training of moderate to strong thunderstorm cells may produce up to 2.25" in 60-90 minutes.

A LOOK AHEAD: Conditions most likely dry by daybreak Monday with isolated to widely scattered thunderstorms in the afternoon favoring the foothills and Palmer Divide. Temperatures Monday will remain chilly with 60's for highs over the plains.

Location Prime Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 1000 AM TO 1000 PM
0.1" (95%) to 0.4" (60%) to 1.2" (25%) HIGH
Arapahoe 1000 AM TO 1000 PM
0.1" (95%) to 0.4" (60%) to 1.2" (25%) HIGH
Boulder 1000 AM TO 1000 PM
0.1" (95%) to 0.4" (60%) to 1.2" (25%) HIGH
Broomfield 1000 AM TO 1000 PM
0.1" (95%) to 0.4" (60%) to 1.2" (25%) HIGH
Denver 1000 AM TO 1000 PM
0.1" (95%) to 0.4" (60%) to 1.2" (25%) HIGH
Douglas 1000 AM TO 1000 PM
0.1" (95%) to 0.4" (60%) to 1.2" (25%) HIGH
Jefferson 1000 AM TO 1000 PM
0.1" (95%) to 0.4" (60%) to 1.2" (25%) HIGH
Foothills above 6500ft      
Boulder Current TO 1000 PM SUN
0.1" (95%) to 0.4" (60%) to 1.2" (20%) HIGH
Douglas Current TO 1000 PM SUN
0.1" (95%) to 0.4" (60%) to 1.2" (20%) HIGH
Jefferson Current TO 1000 PM SUN
0.1" (95%) to 0.4" (60%) to 1.2" (20%) HIGH
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.