Time: 955 AM Wed July 3, 2019 Forecaster: Alan Smith

Heavy Precipitation Outlook
Flash Flood Prediction Program

HEATING UP WITH ISOLATED AFTERNOON THUNDERTORMS
-Drier air is moving into the District from the southwest today as high pressure builds over Eastern Colorado. This will result in warmer temperatures today with highs getting into the low 90s on the plains.
-Enough lingering moisture remains for isolated thunderstorms to develop across the District this afternoon. Storms will initially develop over the foothills by midday, before spreading onto the plains during the mid to late afternoon hours. Storm activity should quickly taper off this evening with the loss of daytime heating.
-Moisture will be on the decrease today with dewpoints projected to fall into the low 40s this afternoon. However, storm movement is expected to be slow and erratic again today. Typical storm motions will be from west to east at 7-12mph, but some storms could stall over an area for a period of time. If a stronger thunderstorm manages to develop, then the potential will exist for moderate to heavy rainfall due to slow movement.
STORM RAINFALL POTENTIAL AND DURATION: Typical weak to moderate thunderstorms will produce rainfall amounts of 0.05-0.3" in 10-30 minutes. A strong thunderstorm will be capable of producing heavy rainfall of 0.3-0.6" in 10-30 minutes.

WORST CASE SCENARIO: A strong thunderstorm stalls over an area, resulting in heavy rainfall of up to 1.3" in 45-75 minutes.

A LOOK AHEAD: Similar conditions are expected across the District on Thursday with highs in the low 90s along with isolated afternoon thunderstorms. The heavy rainfall threat will likely hinge upon whether or not a moisture boundary across NE Colorado backs its way into the District or if it stays out east. A cold front will arrive Friday morning, leading to cooler temperatures and increasing moisture with a good chance of afternoon/evening thunderstorms with heavy rainfall possible. Elevated thunderstorm potential can be expected on Saturday as well with heavy rainfall possible as deep moisture remains in place. Highs Friday and Saturday will be cooler in the low 80s on the plains.

Location Prime Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 200 PM TO 800 PM
Trace (80%) to 0.3" (40%) to 0.6" (20%) LOW
Arapahoe 200 PM TO 800 PM
Trace (85%) to 0.3" (45%) to 0.6" (20%) LOW
Boulder 200 PM TO 800 PM
Trace (80%) to 0.3" (40%) to 0.6" (20%) LOW
Broomfield 200 PM TO 800 PM
Trace (80%) to 0.3" (40%) to 0.6" (20%) LOW
Denver 200 PM TO 800 PM
Trace (80%) to 0.3" (40%) to 0.6" (20%) LOW
Douglas 200 PM TO 800 PM
Trace (90%) to 0.3" (50%) to 0.6" (25%) LOW
Jefferson 200 PM TO 800 PM
Trace (85%) to 0.3" (45%) to 0.6" (20%) LOW
Foothills above 6500ft      
Boulder 1230 PM TO 800 PM
Trace (90%) to 0.3" (45%) to 0.6" (20%) LOW
Douglas 1230 PM TO 800 PM
Trace (95%) to 0.3" (55%) to 0.6" (25%) LOW
Jefferson 1230 PM TO 800 PM
Trace (95%) to 0.3" (55%) to 0.6" (25%) LOW
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.