Time: 939 AM Mon August 5, 2024 Forecaster: Tim Tonge ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- Increasing chance of showers/thunderstorms, hot Analysis of satellite imagery this morning shows a large plume of moisture that has draped itself across the entire state of Colorado as the ridge begins to break down. As a result, precipitable water values in the 1.00"-1.10" range are present across the District today. Dewpoints will be in the mid 40s this afternoon, indicating that a large portion of available moisture is already in the upper atmosphere rather than at the surface, and all it needs will be proper forcing to trigger a potential message issuance day. That forcing arrives from a shortwave that is currently over the San Juan mountains. This disturbance will travel northeast over the course of the day, sparking the first round of showers and thunderstorms in the high country west of the District in the early/mid afternoon. These storms will then move east/northeast into the District in the following hours. With abundant moisture to work with, storms today will be capable of producing heavy localized rainfall, hail, and gusty outflow winds up to 50mph. Storm coverage will favor higher elevations as well as the southern portion of the District (mainly Douglas and southern Jefferson counties), and has the potential to linger through the evening and into the early hours of Tuesday. STORM RAINFALL POTENTIAL AND DURATION: Typical showers and thunderstorms will produce 0.10"-0.30" total in 10-30 minutes. Stronger or slower moving thunderstorms will produce 0.30"-0.80" total in 10-30 minutes. WORST CASE SCENARIO: A slow-moving/stationary thunderstorm, or training of thunderstorms along a boundary, may produce 1.50"-1.75" in 30-60 minutes. A LOOK AHEAD: Similar message issuance potential tomorrow as the overall setup of the atmosphere does not change much over the next 36 hours. Slightly warmer and drier Wednesday. Growing confidence in the arrival of a cold front Thursday that will drop temps into the 70s and deliver a large influx in moisture. Likely moderate/high chance of message issuance Thursday and Friday. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 300 PM TO 1200 AM TUE 0.1" (50%) to 0.3" (30%) to 0.8" (10%) LOW Arapahoe 300 PM TO 1200 AM TUE 0.1" (50%) to 0.3" (30%) to 0.8" (10%) LOW Boulder 300 PM TO 1200 AM TUE 0.1" (50%) to 0.3" (30%) to 0.8" (10%) LOW Broomfield 300 PM TO 1200 AM TUE 0.1" (50%) to 0.3" (30%) to 0.8" (10%) LOW Denver 300 PM TO 1200 AM TUE 0.1" (50%) to 0.3" (30%) to 0.8" (10%) LOW Douglas 300 PM TO 1200 AM TUE 0.1" (60%) to 0.4" (40%) to 0.8" (20%) MOD Jefferson 300 PM TO 1200 AM TUE 0.1" (60%) to 0.4" (40%) to 0.8" (20%) MOD Foothills above 6500ft       Boulder 200 PM TO 1200 AM TUE 0.1" (60%) to 0.4" (40%) to 0.8" (20%) MOD Douglas 200 PM TO 1200 AM TUE 0.1" (60%) to 0.4" (40%) to 0.8" (20%) MOD Jefferson 200 PM TO 1200 AM TUE 0.1" (60%) to 0.4" (40%) to 0.8" (20%) MOD MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]