Time: 1021 AM Thu June 22, 2023 Forecaster: Laura Smith

Heavy Precipitation Outlook
Flash Flood Prediction Program

ANOTHER ROUND OF SLOW-MOVING THUNDERSTORMS EXPECTED ACROSS THE DISTRICT TODAY
Another active weather day is expected as multiple ingredients for heavy rainfall come together across the district.

Strong southwesterly upper-level flow across Colorado will support an environment for another active day of showers and thunderstorms in the district. Daytime heating will create an unstable environment favoring widespread clustered thunderstorms by the mid to late afternoon. High temperatures will reach the mid to upper 70s with dew points in the low to mid 50s. Low level moisture remains elevated from widespread heavy rain yesterday. Precipitable water (PWAT) values have decreased some, though look to be in the 0.70-0.80” range today. This combination will result in storms with the potential for locally heavy rainfall. Message 2 will be issued by noon as a flash flood watch has been issued by the NWS for the entire District from noon through midnight.

Storms are expected to exit the Front Range Urban Corridor by the late evening hours.
STORM RAINFALL POTENTIAL AND DURATION: Typical thunderstorms have the potential to produce moderate to heavy rainfall of 0.50” to 1.00” in 10-30 minutes. Strong thunderstorms have the potential to produce very heavy rainfall of 1.00” to 1.50” in 10-30 minutes.

WORST CASE SCENARIO: Anchored or slow-moving thunderstorms have the potential to produce 1.50” to 2.20” in 45 to 60 minutes.

A LOOK AHEAD: Looking ahead, the upper-level pattern will exit the region overnight, followed by a period of high-pressure ridging, sunny skies, and dry conditions. Tomorrow will be mostly sunny with afternoon highs in the mid to upper 80s.

Location Prime Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 200 PM TO 1000 PM
0.5" (90%) to 1" (60%) to 1.5" (30%) HIGH
Arapahoe 200 PM TO 1000 PM
0.5" (90%) to 1" (60%) to 1.5" (30%) HIGH
Boulder 200 PM TO 1000 PM
0.5" (90%) to 1" (60%) to 1.5" (30%) HIGH
Broomfield 200 PM TO 1000 PM
0.5" (90%) to 1" (60%) to 1.5" (30%) HIGH
Denver 200 PM TO 1000 PM
0.5" (90%) to 1" (60%) to 1.5" (30%) HIGH
Douglas 200 PM TO 1000 PM
0.5" (90%) to 1" (60%) to 1.5" (30%) HIGH
Jefferson 200 PM TO 1000 PM
0.5" (90%) to 1" (60%) to 1.5" (30%) HIGH
Foothills above 6500ft      
Boulder 200 PM TO 1000 PM
0.5" (90%) to 1" (60%) to 1.5" (30%) HIGH
Douglas 200 PM TO 1000 PM
0.5" (90%) to 1" (60%) to 1.5" (30%) HIGH
Jefferson 200 PM TO 1000 PM
0.5" (90%) to 1" (60%) to 1.5" (30%) HIGH
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.
https://f2p2.udfcd.org/generator/