Time: 1000 AM Sat July 13, 2019 Forecaster: Brad Simmons

Heavy Precipitation Outlook
Flash Flood Prediction Program

CONTINUED HOT WITH WIDELY SCATTERED AFTERNOON THUNDERSTORMS
-High pressure remains centered near the Four Corners area resulting in another hot day in the District with temperatures warming well into the 90's over the plains with 80's in the Front Range foothills.
-Moisture rotating around the ridge will result in widely scattered afternoon thunderstorms some of which may produce pockets of heavy rainfall. Thunderstorms will develop before noon over the foothills but should hold off over the plains until after 1 or 2pm. Upper level steering winds are relatively light from NW to SE at 5-15mph.
-Outflow from initial storms may be the trigger for storms over the plains and could result in erratic or very slow storm motions. Due to the potential for slow storm motions there could be extended periods of heavy rainfall that may lead to excessive runoff. Best chances for thunderstorm activity will be through sunset then dry conditions are expected for the later evening and overnight period.
STORM RAINFALL POTENTIAL AND DURATION: Typical weak to moderate thunderstorms will produce a trace to 0.2". Strong thunderstorms will have the potential to produce 0.3-0.8" in 10-30 minutes.

WORST CASE SCENARIO: An very slow moving or anchored strong thunderstorm may produce up to 1.4" of rainfall in less than 60 minutes.

A LOOK AHEAD: More of the same on Sunday with widely scattered thunderstorms in the afternoon with stronger storms capable of producing heavy rainfall. Temperatures will continue to run in the 90's over the plains.

Location Prime Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 200 PM TO 900 PM
0.1" (75%) to 0.3" (50%) to 0.8" (25%) MOD
Arapahoe 200 PM TO 900 PM
0.1" (75%) to 0.3" (50%) to 0.8" (25%) MOD
Boulder 200 PM TO 900 PM
0.1" (75%) to 0.3" (50%) to 0.8" (25%) MOD
Broomfield 200 PM TO 900 PM
0.1" (75%) to 0.3" (50%) to 0.8" (25%) MOD
Denver 200 PM TO 900 PM
0.1" (75%) to 0.3" (50%) to 0.8" (25%) MOD
Douglas 100 PM TO 900 PM
0.1" (75%) to 0.3" (50%) to 0.8" (25%) MOD
Jefferson 100 PM TO 900 PM
0.1" (75%) to 0.3" (50%) to 0.8" (25%) MOD
Foothills above 6500ft      
Boulder 1200 PM TO 900 PM
0.1" (80%) to 0.3" (60%) to 0.8" (25%) MOD
Douglas 1200 PM TO 900 PM
0.1" (80%) to 0.3" (60%) to 0.8" (25%) MOD
Jefferson 1200 PM TO 900 PM
0.1" (80%) to 0.3" (60%) to 0.8" (25%) MOD
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.