Time: 342 PM Mon July 31, 2023 Forecaster: Brad Simmons ------------------------- MESSAGE 2 Flash Flood Prediction Program ------------------------- FLOOD WATCH The National Weather Service has issued a FLOOD WATCH for: the following counties: BOULDER (CITY OF BOULDER AFFECTED, FOUR MILE BURN AREA AFFECTED), JEFFERSON, BROOMFIELD, DOUGLAS, ADAMS, DENVER, ARAPAHOE including: DIA, THE CITY OF AURORA, ARVADA, WHEAT RIDGE, LAKEWOOD ------------------------------------------------------------------------------ from: 400 PM to 1159 PM . THE NATIONAL WEATHER SERVICE IN BOULDER HAS ISSUED A FLOOD WATCH FOR THE ENTIRE DISTRICT WHICH INCLUDES THE THREAT OF FLASH FLOODING FROM 4:00 PM TODAY UNTIL MIDNIGHT TONIGHT. THE MESSAGE 2'S MAY BE EXTENDED BEYOND MIDNIGHT SHOULD CONDITIONS WARRANT. Prime time for flooding: 500 PM to 1130 PM . ------------------------------------------------------------------------------ Forecast rainfall: Weak to moderate thunderstorms will produce rainfall rates of 0.2-0.8” in 10-30 minutes. Strong thunderstorms will have the potential to produce rainfall rates of 0.8-2.0” of rain in 10-30 minutes. A slow moving strong thunderstorm or a large thunderstorm complex may result in up to 3.5” of rain in 60-90 minutes. ------------------------------------------------------------------------------ The most likely areas to be impacted by flooding are: X Mountain streams & floodplains; road crossings; canyon roads & highways; recreational trails; adjacent open space areas/campgrounds/parks; fishing access points & stream reaches; buildings near streams; utilities X Urban streams/gulches; road crossings; recreational trails; adjacent open space areas/campgrounds/parks; floodplain properties; utilities X Urban streets, intersections, low lying areas, known trouble spots X Mountain locations subject to mud/rock/debris slide ------------------------------------------------------------------------------ Additional information: Heavy rainfall may result in excessive runoff and possibly flash flooding over the District this afternoon into the late evening. Strong thunderstorms may also contain large hail, gusty winds, and frequent cloud-to-ground lightning. A Flood Watch means that flooding is possible within the watch area. This message is not intended for public dissemination. Please pass this information along to affected emergency response organizations (police, fire, public works, etc.) within your area. Also, please take appropriate actions to prepare for possible flooding. Further information will be provided to you as it becomes available. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]