Time: 956 AM Tue June 18, 2024 Forecaster: Laura Smith

Heavy Precipitation Outlook
Flash Flood Prediction Program

Cooler temperatures and isolated thunderstorms today
The heat wave has finally shifted east this morning, thanks to the arrival of an upper-level trough and its associated cold front. Temperatures will reach the mid to upper 70s with slight chances for isolated showers and thunderstorms developing by the afternoon. Dewpoints will be in the mid 30s, with precipitable water (PWAT) values between 0.50”-0.60”. Storms will be capable of producing light rainfall, with better chances across the foothills. Storm motions will be from southwest to northeast between 15-20 mph. Thunderstorms are expected to dissipate by mid evening with skies remaining partly cloudy overnight.
STORM RAINFALL POTENTIAL AND DURATION: Typical storms will produce a trace to 0.10” in 10-30 minutes.

WORST CASE SCENARIO: Slow moving or training thunderstorms may be capable of producing up to 0.50” in 45-60 minutes.

A LOOK AHEAD: A more active pattern emerges tomorrow as elevated moisture levels and favorable upper-level winds support chances for scattered thunderstorms. Storms are expected to continue into the evening, with a few isolated showers possible overnight. An expanding and near-stationary heat dome over the east coast will force the upper-level trough to reposition over the Great Basin on Thursday. As a result, a warmer airmass and moisture from the Gulf of Mexico will advect (transport) into the four-corners region. Elevated moisture levels and favorable upper-level winds from the southwest will support afternoon and evening scattered thunderstorms across the High Plains on Thursday, with a few storms capable of producing brief heavy rain. There is still some uncertainty about the exact timing and precipitation amounts, which will depend on the behavior of the heat wave over the eastern US.

Location Prime Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Adams 300 PM TO 1000 PM
Trace (35%) to 0.05" (25%) to 0.1" (15%) NONE
Arapahoe 300 PM TO 1000 PM
Trace (35%) to 0.05" (25%) to 0.1" (15%) NONE
Boulder 300 PM TO 1000 PM
Trace (35%) to 0.05" (25%) to 0.1" (15%) NONE
Broomfield 300 PM TO 1000 PM
Trace (35%) to 0.05" (25%) to 0.1" (15%) NONE
Denver 300 PM TO 1000 PM
Trace (35%) to 0.05" (25%) to 0.1" (15%) NONE
Douglas 300 PM TO 1000 PM
Trace (35%) to 0.05" (25%) to 0.1" (15%) NONE
Jefferson 300 PM TO 1000 PM
Trace (35%) to 0.05" (25%) to 0.1" (15%) NONE
Foothills above 6500ft      
Boulder 200 PM TO 1100 PM
Trace (45%) to 0.05" (35%) to 0.1" (25%) NONE
Douglas 200 PM TO 1100 PM
Trace (45%) to 0.05" (35%) to 0.1" (25%) NONE
Jefferson 200 PM TO 1100 PM
Trace (45%) to 0.05" (35%) to 0.1" (25%) NONE
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.
https://f2p2.udfcd.org/generator/