Time: 959 AM Sat August 3, 2019 Forecaster: Alan Smith

Heavy Precipitation Outlook
Flash Flood Prediction Program

HOT WITH ISOLATED THUNDERSTORMS OVER THE FOOTHILLS AND PALMER DIVIDE
-High pressure remains centered over Western Colorado, with a more stable airmass spreading over the plains today that should largely suppress thunderstorm activity. It will be a hot day across the lower elevations of the District with highs in the low 90s.
-Low level moisture remains elevated this morning, but drier and more stable air is arriving at the mid-levels. Low level moisture should mix out this afternoon with dewpoints projected to fall into the low 40s. Isolated thunderstorms will develop over the foothills and Palmer Divide this afternoon, while the plains should remain mostly dry with only a minor threat for a late day weak thunderstorm.
-Storms that develop could remain anchored to the higher terrain at times, with general movement to the S/SE at 7-12mph. Typical storms will be on the weaker side and produce light rainfall amounts, though some brief moderate rains will be possible over the foothills if a stronger storm manages to develop. Thunderstorm activity should quickly diminish after sunset.
STORM RAINFALL POTENTIAL AND DURATION: Typical showers and weak thunderstorms will produce rainfall amounts of TR-0.2" over the foothills and plains. A stronger thunderstorm over the foothills could produce rainfall of up to 0.4" in 10-30 minutes.

WORST CASE SCENARIO: A strong thunderstorm anchored to the foothills produces rainfall of up to 0.65" in 30-60 minutes across the higher terrain above 6,500'.

A LOOK AHEAD: A shortwave disturbance will arrive from the northwest on Sunday, resulting in a good chance of afternoon and evening thunderstorms across the District with heavy rainfall possible. The active northwest flow pattern will continue through the first half of next week with daily afternoon thunderstorm chances, some of which could produce heavy rainfall. A further uptick in heavy rainfall potential is likely on Thursday and Friday as a surge of monsoonal moisture arrives from the west.

Location Prime Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 300 PM TO 800 PM
Trace (40%) to 0.1" (20%) to 0.2" (10%) NONE
Arapahoe 300 PM TO 800 PM
Trace (40%) to 0.1" (20%) to 0.2" (10%) NONE
Boulder 300 PM TO 800 PM
Trace (45%) to 0.1" (20%) to 0.2" (10%) NONE
Broomfield 300 PM TO 800 PM
Trace (40%) to 0.1" (20%) to 0.2" (10%) NONE
Denver 300 PM TO 800 PM
Trace (40%) to 0.1" (20%) to 0.2" (10%) NONE
Douglas 300 PM TO 800 PM
Trace (45%) to 0.1" (20%) to 0.2" (10%) NONE
Jefferson 300 PM TO 800 PM
Trace (45%) to 0.1" (20%) to 0.2" (10%) NONE
Foothills above 6500ft      
Boulder 100 PM TO 800 PM
Trace (70%) to 0.2" (35%) to 0.4" (10%) NONE
Douglas 100 PM TO 800 PM
Trace (80%) to 0.2" (40%) to 0.4" (15%) NONE
Jefferson 100 PM TO 800 PM
Trace (80%) to 0.2" (40%) to 0.4" (15%) NONE
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.