Flash Flood Prediction Program

-	Message 1's have been issued for Adams, Arapahoe, Broomfield and Denver Counties and will be valid until midnight tonight. Message 2's (NWS Flood/Flash Flood Watch) have been issued for Boulder, Douglas and Jefferson Counties and will also be valid until midnight. Although Message 1's and 2's are issued for differing Counties the threat level for heavy rainfall is elevated all areas within the District.
-	Thunderstorms are beginning to develop over the higher terrain to the W and upper level steering winds will push these storms eastward as the afternoon progresses. Numerous showers and thunderstorms or multiple rounds of showers and thunderstorms are expected into the evening. Moderate to strong thunderstorms will be very capable of producing heavy rainfall.
-	The greatest threats for extended periods of heavy rainfall today will be from training of thunderstorm cells or a large, slower moving thunderstorm. The first or second round of storms will most likely be the strongest of the day but subsequent storms will be very efficient rainfall producers and even weak thunderstorms will be capable of producing heavy rain into the evening.

STORM RAINFALL POTENTIAL AND DURATION: Weak to moderate thunderstorms will produce rainfall rates of 0.3-0.8" in 10-30 minutes. Strong thunderstorms will have the potential to produce heavy rainfall rates of 0.8-2.2" in 10-30 minutes.

WORST CASE SCENARIO: Training of thunderstorm cells or a large/slower moving thunderstorm may produce up to 3.5" of rain in 45-60 minutes.

County	Message	Valid Times	Prime Time
Lakewood	2	100 PM TO 1159 PM	200 PM TO 1000 PM
Wheat Ridge	2	100 PM TO 1159 PM	200 PM TO 1000 PM
the City of Aurora	1	100 PM TO 1159 PM	200 PM TO 1000 PM
Arapahoe County	1	100 PM TO 1159 PM	200 PM TO 1000 PM
Denver County	1	100 PM TO 1159 PM	200 PM TO 1000 PM
DIA	1	100 PM TO 1159 PM	200 PM TO 1000 PM
Douglas County	2	100 PM TO 1159 PM	200 PM TO 1000 PM
Adams County	1	100 PM TO 1159 PM	200 PM TO 1000 PM
Broomfield County	1	100 PM TO 1159 PM	200 PM TO 1000 PM
Boulder County	2	100 PM TO 1159 PM	200 PM TO 1000 PM
Jefferson County	2	100 PM TO 1159 PM	200 PM TO 1000 PM
Arvada	2	100 PM TO 1159 PM	200 PM TO 1000 PM

County-specific Quantitative Precipitation Outlook	Precipitation Time	30-Minute Rainfall and % Probability	Message Potential
Plains
Adams	200 PM TO 1159 PM	0.5" (75%) to 1.3" (50%) to 2.0" (25%)	ISSUED
Arapahoe	200 PM TO 1159 PM	0.5" (90%) to 1.3" (60%) to 2.0" (30%)	ISSUED
Boulder	200 PM TO 1159 PM	0.5" (80%) to 1.3" (60%) to 2.0" (30%)	ISSUED
Broomfield	200 PM TO 1159 PM	0.5" (75%) to 1.3" (50%) to 2.0" (25%)	ISSUED
Denver	200 PM TO 1159 PM	0.5" (80%) to 1.3" (60%) to 2.0" (30%)	ISSUED
Douglas	200 PM TO 1159 PM	0.5" (90%) to 1.3" (60%) to 2.0" (30%)	ISSUED
Jefferson	200 PM TO 1159 PM	0.5" (90%) to 1.3" (60%) to 2.0" (30%)	ISSUED
Foothills above 6500ft
Boulder	Current TO 1159 PM MON	0.5" (95%) to 1.3" (65%) to 2.0" (30%)	ISSUED
Douglas	Current TO 1159 PM MON	0.5" (95%) to 1.3" (65%) to 2.0" (30%)	ISSUED
Jefferson	Current TO 1159 PM MON	0.5" (95%) to 1.3" (65%) to 2.0" (30%)	ISSUED

MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS.