Time: 740 PM Sun August 9, 2009 Forecaster: Brad Simmons

QUANTITATIVE PRECIPITATION FORECAST (QPF)
Flash Flood Prediction Program

EVENING THUNDERSTORMS WITH HEAVY RAINFALL POSSIBLE
QPF Map QPF Map
Thunderstorms developing over the higher terrain of Jefferson County currently are expected to become more numerous through the evening bringing possible heavy rainfall and severe weather to the District.
Thunderstorms will move to the east/northeast at around 10-15 mph with the potential of producing 0.50-1.60" of rainfall in 10-30 minutes. Large hail greater than 1.0" in diameter and gusty straight line winds of 60mph will be possible with strong or severe storms.
Thunderstorm training or a very slow moving strong storm may result in up to 2.20" of rain in 45-60 minutes.
STORM STRENGTH vs. PEAK RAINFALL AMOUNTS (inches)
Strength 10 min 30 min 60 min Storm Total
Weak 0.10 0.30 0.60 0.60
Moderate 0.40 0.80 1.40 1.40
Strong 0.70 1.60 2.20 2.20
NOTE: Peak storm rainfalls in >50dBZ radar reflectivity areas only

ZONE/BASIN-SPECIFIC FORECAST PROBABILITIES OF OCCURRENCE
Location Weak Storm Moderate Storm Strong Storm
Foothills
Boulder 80% 50% 30%
Clear Creek 90% 50% 30%
Ralston Creek 80% 50% 30%
Lena Gulch 80% 50% 25%
Bear Creek 80% 50% 25%
Denver
West Denver 75% 40% 20%
East Denver 70% 40% 20%
Cherry Creek 70% 40% 20%
Westerly Creek 70% 40% 20%
Suburbs
Southside - West 70% 40% 20%
Southside - East 70% 40% 20%
Big Dry Creek 70% 40% 20%
Toll Gates 70% 40% 20%
Sand Creek 70% 40% 20%
Plum Creek 60% 30% 10%
No entry means less than a 10% probability
MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.