Time: 257 PM Sat May 15, 2021 Forecaster: Brad Simmons

Internal Message Status
Flash Flood Prediction Program

MESSAGE 1'S ISSUED FOR SOUTHEAST AREAS OF THE DISTRICT
-Message 1's have been issued for Arapahoe and Douglas Counties and will be valid until 9:00pm this evening. Additional Message 1's may be issued for the remainder of the District later this afternoon.
-Thunderstorms have developed over south/southeast areas of the District where there was more sunshine which allowed for better surface heating this morning. These storms have the potential to produce heavy rainfall that may lead to excessive runoff. Strongest storms are currently in and around Aurora Reservoir and will be tracking E/NE out of the District over the next 60-90 minutes. Hail may also accompany the stronger thunderstorm cells.
-Storm motions will generally be from west to east at 15-20mph. Stronger thunderstorms may anchor briefly or have erratic storm movements at times due to outflow boundaries/gust fronts.
STORM RAINFALL POTENTIAL AND DURATION: Typical rain showers and weak thunderstorms will produce a 0.1-0.3" of rain. Moderate to strong thunderstorms will have the potential to produce 0.3-0.8" in 10-30 minutes.

WORST CASE SCENARIO: A stalled out thunderstorm along an outflow boundary may result in up to 1.6" of rain in 60 minutes or less.

County Message Valid Times Prime Time
the City of Aurora 1 Current TO 900 PM Current TO 800 PM
Arapahoe County 1 Current TO 900 PM Current TO 800 PM
Douglas County 1 Current TO 900 PM Current TO 800 PM

County-specific Quantitative
Precipitation Outlook
Precipitation Time 30-Minute Rainfall
and % Probability
Message
Potential
Plains      
Boulder 400 PM TO 900 PM
0.1" (80%) to 0.3" (60%) to 0.8" (20%) MOD
Broomfield 400 PM TO 900 PM
0.1" (80%) to 0.3" (60%) to 0.8" (20%) MOD
Jefferson 400 PM TO 900 PM
0.1" (80%) to 0.3" (60%) to 0.8" (20%) MOD
Adams 300 PM TO 900 PM
0.1" (90%) to 0.3" (60%) to 0.8" (20%) MOD
Denver 300 PM TO 900 PM
0.1" (80%) to 0.3" (60%) to 0.8" (20%) MOD
Arapahoe Current TO 900 PM SAT
0.1" (100%) to 0.3" (80%) to 0.8" (40%) ISSUED
Douglas Current TO 900 PM SAT
0.1" (100%) to 0.3" (75%) to 0.8" (30%) ISSUED
Foothills above 6500ft      
Douglas 400 PM TO 900 PM
0.1" (100%) to 0.3" (75%) to 0.8" (25%) ISSUED
Jefferson 400 PM TO 900 PM
0.1" (80%) to 0.3" (60%) to 0.8" (20%) MOD
Boulder Current TO 900 PM SAT
0.1" (80%) to 0.3" (60%) to 0.8" (20%) MOD
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.