Time: 1026 AM Tue September 3, 2019 Forecaster: Alan Smith

Heavy Precipitation Outlook
Flash Flood Prediction Program

COOLER WITH ISOLATED AFTERNOON SHOWERS/THUNDERSTORMS, MAINLY IN THE FOOTHILLS
-A cold front moved through the District earlier this morning, which will provide some welcome relief following yesterday's record heat. Highs today will reach the mid 80s on the plains under scattered cloud cover.
-Shallow low level moisture has increased behind the cold frontal passage, though some of this moisture will mix out this afternoon. Also, a mid-level inversion should largely suppress thunderstorm activity this afternoon.
-Although the atmosphere will largely remain capped over the plains, there is a chance for some isolated shower and thunderstorm development over the foothills and Palmer Divide late this afternoon. A stray shower or weak storm drifting onto the plains can't entirely be ruled out, but any rainfall today will be brief and light. Conditions should quickly dry out after sunset.
STORM RAINFALL POTENTIAL AND DURATION: Showers and weak thunderstorms will produce rainfall amounts of TR-0.1" in 10-30 minutes on the plains, and TR-0.2" in 10-30 minutes in the foothills.

WORST CASE SCENARIO: A slow-moving foothills thunderstorm produces rainfall of up to 0.4" in 30-60 minutes.

A LOOK AHEAD: Hot temperatures will return on Wednesday and Thursday with some subtropical moisture entrained in the flow resulting in a chance of isolated thunderstorms both days. Generally light rainfall is expected both days. A slow-moving trough of low pressure containing subtropical moisture will move across the Central Rockies late this week, resulting in cooler temperatures and better chances for thunderstorms Friday and Saturday, along with some potential for heavy rainfall.

Location Prime Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 400 PM TO 800 PM
Trace (40%) to 0.1" (10%) NONE
Arapahoe 400 PM TO 800 PM
Trace (40%) to 0.1" (10%) NONE
Boulder 400 PM TO 800 PM
Trace (50%) to 0.1" (10%) NONE
Broomfield 400 PM TO 800 PM
Trace (40%) to 0.1" (10%) NONE
Denver 400 PM TO 800 PM
Trace (40%) to 0.1" (10%) NONE
Douglas 400 PM TO 800 PM
Trace (50%) to 0.1" (10%) NONE
Jefferson 400 PM TO 800 PM
Trace (50%) to 0.1" (10%) NONE
Foothills above 6500ft      
Boulder 300 PM TO 800 PM
Trace (65%) to 0.1" (25%) to 0.2" (10%) NONE
Douglas 300 PM TO 800 PM
Trace (65%) to 0.1" (25%) to 0.2" (10%) NONE
Jefferson 300 PM TO 800 PM
Trace (65%) to 0.1" (25%) to 0.2" (10%) NONE
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.