Flash Flood Prediction Program

-	The first real surge of Monsoon moisture this season has moved into CO and will pass over the District today resulting in scattered to widespread showers and thunderstorms this afternoon and evening. Showers and thunderstorms are expected to develop over the higher terrain to the W of the District by around noon and then spread onto the I-25 corridor by 1-2pm.
-	With abundant moisture in place at the surface and aloft the storms that develop today will be very capable of producing heavy rainfall. However, the heavy rainfall is expected to be fairly brief from most storms as upper level steering winds from the SW at 20-25mph will help to keep storms moving and reduce point rainfall amounts from a single storm.
-	Training of thunderstorm cells or large thunderstorms will have the potential to produce extended periods of heavy rainfall that may lead to excessive runoff and possibly flash flooding. Best chances for shower and thunderstorm activity will be through 10pm this evening with lingering rain showers possible overnight. Message 1's will likely be issued by Noon or before.

STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers and weak to moderate thunderstorms will produce 0.1-0.5" in 10-30 minutes. Strong thunderstorms will have the potential to produce 0.5-1.5" in 10-30 minutes. Supplemental QPF is available at https://qpf.udfcd.org

WORST CASE SCENARIO: Training of thunderstorm cells or a very large slower moving thunderstorm may produce up to 2.8" of rain in 45-60 minutes.

A LOOK AHEAD: Monsoon moisture will continue to impact the District through early next week with daily chances for thunderstorms with the potential for heavy rainfall. Thunderstorm activity will likely decrease a bit on Saturday only to uptick again on Sunday and Monday with Tuesday potentially being the peak of activity before drier air moves into NE CO on Wednesday of next week.

Location	Prime Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	100 PM TO 1000 PM	0.1" (90%) to 0.5" (60%) to 1.5" (20%)	HIGH
Arapahoe	100 PM TO 1000 PM	0.1" (90%) to 0.5" (60%) to 1.5" (20%)	HIGH
Boulder	100 PM TO 1000 PM	0.1" (90%) to 0.5" (60%) to 1.5" (20%)	HIGH
Broomfield	100 PM TO 1000 PM	0.1" (90%) to 0.5" (60%) to 1.5" (20%)	HIGH
Denver	100 PM TO 1000 PM	0.1" (90%) to 0.5" (60%) to 1.5" (20%)	HIGH
Douglas	100 PM TO 1000 PM	0.1" (90%) to 0.5" (60%) to 1.5" (20%)	HIGH
Jefferson	100 PM TO 1000 PM	0.1" (90%) to 0.5" (60%) to 1.5" (20%)	HIGH
Foothills above 6500ft
Boulder	1200 PM TO 1000 PM	0.1" (95%) to 0.5" (60%) to 1.5" (20%)	HIGH
Douglas	1200 PM TO 1000 PM	0.1" (95%) to 0.5" (60%) to 1.5" (20%)	HIGH
Jefferson	1200 PM TO 1000 PM	0.1" (95%) to 0.5" (60%) to 1.5" (20%)	HIGH

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.