Flash Flood Prediction Program

A blocking pattern is in place over the continental US, positioning southwesterly upper-level flow across Colorado while mid-level anti cyclonic flow continues to transport moisture into eastern Colorado.

This morning will be mostly cloudy across the District followed by afternoon temperatures in the upper 60s to low 70s and dew points in the low 50s. Forecast soundings reveal bulk shear around 30 kt, and PWAT values between 0.75” to 0.85”.

These conditions will support an unstable environment favoring persistent clustered thunderstorms by the mid to late afternoon. Storms are expected to exit the District by the late evening hours.

STORM RAINFALL POTENTIAL AND DURATION: Typical thunderstorms have the potential to produce moderate to heavy rainfall of 0.4” to 0.75” in 10 to 30 minutes. Strong thunderstorms have the potential to produce moderate to heavy rainfall of 0.75” to 1.50” in 10 to 30 minutes.

WORST CASE SCENARIO: Anchored or slow-moving thunderstorms have the potential to produce 1.50” to 2.25” in 30 to 60 minutes.

A LOOK AHEAD: Tomorrow will be similar with temperatures in the upper 60s to low 70s and scattered to widespread clustered severe thunderstorms and heavy rain across the Front Range Urban Corridor. Looking ahead, the upper-level pattern will finally exit the region mid-week, followed by a more seasonal pattern of isolated afternoon showers and thunderstorms.

Location	Prime Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	300 PM TO 1000 PM	0.4" (90%) to 0.75" (50%) to 1.5" (25%)	HIGH
Arapahoe	300 PM TO 1000 PM	0.4" (90%) to 0.75" (50%) to 1.5" (25%)	HIGH
Boulder	300 PM TO 1000 PM	0.4" (90%) to 0.75" (50%) to 1.5" (25%)	HIGH
Broomfield	300 PM TO 1000 PM	0.4" (90%) to 0.75" (50%) to 1.5" (25%)	HIGH
Denver	300 PM TO 1000 PM	0.4" (90%) to 0.75" (50%) to 1.5" (25%)	HIGH
Douglas	300 PM TO 1000 PM	0.4" (90%) to 0.75" (50%) to 1.5" (25%)	HIGH
Jefferson	300 PM TO 1000 PM	0.4" (90%) to 0.75" (50%) to 1.5" (25%)	HIGH
Foothills above 6500ft
Boulder	100 PM TO 800 PM	0.4" (90%) to 0.75" (50%) to 1.5" (25%)	HIGH
Douglas	100 PM TO 800 PM	0.4" (90%) to 0.75" (50%) to 1.5" (25%)	HIGH
Jefferson	100 PM TO 800 PM	0.4" (90%) to 0.75" (50%) to 1.5" (25%)	HIGH

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.