Time: 946 AM Fri May 17, 2019 Forecaster: Brad Simmons

Heavy Precipitation Outlook
Flash Flood Prediction Program

SCATTERED AFTERNOON THUNDERSTORMS WITH BRIEF HEAVY RAIN POSSIBLE
-An upper level disturbance over western Colorado this morning will move through the District this afternoon and produce scattered showers and thunderstorms some of which may be capable of producing brief heavy rainfall, gusty winds and hail. Temperatures will reach the 70's over the plains before cloud cover increases this afternoon.
-Thunderstorms will initiate over the foothills before noon and then spread eastward onto the plains. Storms will be relatively fast moving from SSW to NNE at 25-35mph helping to reduce point rainfall amounts. One to three rounds of storms are likely through the early evening.
-Surface moisture has increased from previous days with dew points expected to be in the mid 40's to around 50. The modest surface moisture will allow for some storms to produce brief heavy rainfall which may lead to excessive runoff.
STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers and weak to moderate thunderstorms will produce a trace to 0.3". Strong thunderstorms will have the potential to produce up to 0.6" in 10-30 minutes.

WORST CASE SCENARIO: A slower moving strong thunderstorm or training of strong thunderstorm cells may result in up to 1.3" in 45-75 minutes.

A LOOK AHEAD: Drier air aloft will move into Colorado on Saturday lowering the threat for thunderstorms activity but there will still likely be isolated afternoon thunderstorms favoring the foothills. Temperatures will continue to lower with highs on the plains in the 60's.

Location Prime Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 1200 PM TO 900 PM
Trace (90%) to 0.3" (60%) to 0.6" (20%) LOW
Arapahoe 1200 PM TO 900 PM
Trace (90%) to 0.3" (60%) to 0.6" (20%) LOW
Boulder 1200 PM TO 900 PM
Trace (95%) to 0.3" (65%) to 0.6" (25%) LOW
Broomfield 1200 PM TO 900 PM
Trace (90%) to 0.3" (60%) to 0.6" (20%) LOW
Denver 1200 PM TO 900 PM
Trace (90%) to 0.3" (60%) to 0.6" (20%) LOW
Douglas 1200 PM TO 900 PM
Trace (90%) to 0.3" (60%) to 0.6" (20%) LOW
Jefferson 1200 PM TO 900 PM
Trace (90%) to 0.3" (60%) to 0.6" (20%) LOW
Foothills above 6500ft      
Boulder 1100 AM TO 900 PM
Trace (100%) to 0.3" (70%) to 0.6" (25%) LOW
Douglas 1100 AM TO 900 PM
Trace (90%) to 0.3" (60%) to 0.6" (20%) LOW
Jefferson 1100 AM TO 900 PM
Trace (90%) to 0.3" (60%) to 0.6" (20%) LOW
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.