Time: 940 AM Mon September 16, 2019 Forecaster: Alan Smith

Heavy Precipitation Outlook
Flash Flood Prediction Program

WARM WITH ISOLATED HIGH-BASED SHOWERS AND THUNDERSTORMS
-A trough of low pressure deepening to the west will send a shortwave disturbance across Colorado today, resulting in scattered cloud cover throughout the day. Temperatures will remain above average with highs in the mid to upper 80s on the plains.
-There will be enough mid to upper level moisture associated with this shortwave for isolated high-based showers and thunderstorms to develop over the foothills and Palmer Divide by early to mid afternoon. A few showers and storms may drift onto the plains late this afternoon, but any storms will be on the weaker side due to marginal instability.
-Low level moisture will be lacking today, so any showers/thunderstorms that develop will produce light rainfall and gusty winds. Storm motions will be to the NE at 12-17mph. Storm activity should quickly shut down after sunset with dry conditions expected overnight.
STORM RAINFALL POTENTIAL AND DURATION: Showers and thunderstorms will produce rainfall amounts of TR-0.2" in 10-30 minutes.

WORST CASE SCENARIO: A foothills thunderstorm produces rainfall of up to 0.3" in 30-45 minutes.

A LOOK AHEAD: A trough of low pressure will move north of Colorado on Tuesday with most of the associated moisture remaining north of the District. Some isolated high-based shower or thunderstorm activity can't entirely be ruled out over the District Tuesday afternoon, but any rainfall will be minimal. Generally dry conditions are expected on Wednesday though a stray shower or weak thunderstorm can't entirely be ruled out over the foothills. Thursday and Friday will continue to see marginal shower/thunderstorm chances with minimal if any rainfall. Temperatures will remain above average for most of the week before cooling to near average on Friday.

Location Prime Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 300 PM TO 700 PM
Trace (50%) to 0.1" (15%) to 0.2" (5%) NONE
Arapahoe 300 PM TO 700 PM
Trace (50%) to 0.1" (15%) to 0.2" (5%) NONE
Boulder 300 PM TO 700 PM
Trace (60%) to 0.1" (20%) to 0.2" (5%) NONE
Broomfield 300 PM TO 700 PM
Trace (50%) to 0.1" (15%) to 0.2" (5%) NONE
Denver 300 PM TO 700 PM
Trace (50%) to 0.1" (15%) to 0.2" (5%) NONE
Douglas 300 PM TO 700 PM
Trace (60%) to 0.1" (25%) to 0.2" (10%) NONE
Jefferson 300 PM TO 700 PM
Trace (60%) to 0.1" (20%) to 0.2" (5%) NONE
Foothills above 6500ft      
Boulder 130 PM TO 700 PM
Trace (80%) to 0.1" (30%) to 0.2" (10%) NONE
Douglas 130 PM TO 700 PM
Trace (80%) to 0.1" (30%) to 0.2" (10%) NONE
Jefferson 130 PM TO 700 PM
Trace (80%) to 0.1" (30%) to 0.2" (10%) NONE
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.