Flash Flood Prediction Program - 2016 Summary
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2016 Season Summary

Meteorological support services are provided by Skyview Weather.

Click on desired 'Date' below to see a regional map with gauge and radar-estimated 24-hour rainfall totals.

 

 

 

 

 

 

 

 

> 0.6" RADAR ESTIMATE OR 0.5" GAUGED IN FORECAST AREA

Event

Date

Max ALERT

Max CoCoRaHS

QPE STP

ALERT

Alarms

ALERT

Rain

Alarms

Note

ADAM

ARAP

AURA

BLDR

BROM

DENV

DOUG

JEFF

1
0.87"
0.88"
>1.11"

Message 1 issued for Adams, Boulder inc FMBA and City of Boulder, Jefferson, Broomfield at 1305.

Initially storms were very fast moving from SSE to NNW but would slow as the afternoon progressed. Strong thunderstorms would impact mainly W and NW areas of the District producing moderate and brief heavy rainfall. Some of the stronger thunderstorms produced accumulating hail. Thunderstorm activity diminished by mid to late afternoon. No rainfall alarms were reported.

 
X
 
X
X
X
X
X
2
0.59"
0.83"
>2.42"

Message 1 issued for Adams, Arapahoe/Aurora, Denver, Douglas and Jefferson Counties at 1516.

Slow moving heavy storms around central areas of the District. Denver Zoo reported 0.43" in around 9 minutes. Most areas experienced light to moderate rain with some hail accumulation. Thunderstorms diminshed by 4:30PM - 5:00PM with less intense showers in the late afternoon. A rainfall alarm was reported in Brighton.

X
X
X
X
X
X
X
 
3
1.30"
0.87"
>1.46"
 

Message 1 issued for all areas at 1259.

Few light rain showers in the morning with a steady rain filling in between noon and 1pm from S to N. Widespread light to moderate rain fell over the District from 1pm to 4pm. Scattered showers continued past 4pm into the evening diminishing overnight. Most of the precipitation fell within the 3 hour period from 1-4pm with 0.25"-0.75” of rain most areas during that time.There was a threat for rainfall rates
reaching or exceeding 1”/hr had thunderstorms become embedded in the showers but that did not occur. No rainfall alarms were reported.

X
X
X
X
X
X
X
X
4
0.39"
0.58"
>1.21"
 

Message 1 issued for the entire District at 1251.

Storm cells initially began to develop over the Jefferson County foothills around 12:45pm. Two main storm cells impacted the District, both of which became severe-warned and produced large hail. The northern cell was the stronger of the two and impacted the Arvada, Westminster, and Thornton
areas, resulting in hail up to 1.25” in diameter and rainfall of 0.05-0.40”. The southern cell was smaller and size and impacted southern and eastern Denver, resulting in similar rainfall amounts, but large hail with reports of 1.75” in diameter. The heaviest rainfall rates were 0.28” in 15 minutes. No rainfall reports greater than 0.5” from UDFCD gages but a CoCoRaHS report of 0.83” was reported in Adams County. No rainfall alarms were reported.

X
 
X
 
X
X
 
X
5
1.81"
2.62"
>3.61"
 

Message 1 issued for the entire District at 1129.

storms developed over the foothills west of the District with widely scattered coverage by 11am. A lineof strong and severe thunderstorms were formed along and east of the I-25 corridor from Adams County through Douglas County. Storms moved slowly to the NE producing areas of heavy rain and hail Light to moderate rain would continue to fall into the evening, mainly over eastern and southern portions of the District. No rainfall alarms were reported.

X
X
X
X
 
X
X
X
6
0.94"
1.38"
>1.83"
 

Message 1 issued for Boulder, Jefferson, and Douglas county District at 1426.

Message 1 issued for Arapahoe and Aurora county at 1844.

A line of thunderstorm cells moved over northern, central and eastern Douglas County during the late afternoon producing moderate to heavy rainfall. A second line of thunderstorm cells moved over southeast Aurora and northern and eastern Douglas County during the early evening. No rainfall alarms were reported.

X
   
X
   
X
 
7
2.44"
2.81"
>3.19"

Message 1 issued for the entire District at 1429.

Multiple strong and severe thunderstorms would develop over northern and southern areas of the District shortly after 3pm in the afternoon merging into a strong thunderstorm cluster over a large portion of the District through around 6pm.  Thunderstorms produced heavy rainfall and accumulating hail resulting in 9 severe thunderstorm warnings issued by the NWS and 2 aerial flood advisories.  Multiple rain alarms were triggered with 1” to nearly 3” of rain reported in the District, heaviest over Douglas County in the Highlands Ranch area.

X
X
X
X
 
X
X
X
8
0.59"
0.83"
>1.00"
 

Message 1 issued for the entire District at 1339.

A line of thunderstorm cells developed over southwest Arapahoe county, extending into central Douglas County during the early evening.  Line moved to east/southeast through Douglas county and into Elbert County.Moderate to heavy rainfall was observed in Southglenn and Centennial in Arapahoe County and northern, eastern and central Douglas County.

 
X
       
X
 
9
0.75"
0.76"
>0.85"

Message 1’s issued for Boco, including FMBA at 1948.

Message 1’s issued for Adco, Denco, Arapco and Aurora at 2040.

Message 1’s issued for Dougco at 2112.

A thunderstorm cell developed over north central Boulder County in the late evening. A second thunderstorm cell formed over southwest Adams and northern Denver County.  Cell moved to the southeast into the City of Aurora. Moderate to heavy rainfall was observed in central Boulder County, eastern Denver County and northwest Aurora.

X
       
X
   
10
0.87"
1.08"
>092"

Message 1 issued for the entire District at 1713.

Storms developed over the foothills between 4-5pm and began to encroach upon the District. A strong thunderstorm developed over Eastern Boulder County at about 5:45pm, resulting in locally heavy rainfall.  The heaviest rain fell across a region with little UDFCD gauge coverage, so no rainfall alarms were triggered.

X
   
X
 
X
 
X
11
2.44"
2.41"
>2.97"

Message 1 issued for the entire District at 1035.

By 3pm, a line of storms had developed over the foothills and approached western portions of the District shortly thereafter, resulting in heavy rainfall across Jefferson County, Lakewood, and Denver by 4pm. Thunderstorm cells also developed over Southwest Douglas County around 4pm, and these cells would track across Northeast Douglas County and portions of Arapahoe and Adams County during the ensuing hours, producing very heavy rainfall along with hail and gusty winds as training of cells occurred in this area through 6pm. As these cells were weakening, a new line of storms developed across the Jefferson County foothills by 6:30pm and would slowly move across the District between 7:00-8:30pm. Thunderstorm activity began to wind down across the District between 8:30-9:00pm. Rainfall alarms were triggered at Lakewood Country Club, Bingham Lake Park, Tallman Gulch, and Bayou Gulch, Bear Creek at Morrison, Jeffco Fairgrounds.

X
X
X
   
X
X
X
12
1.02"
1.03"
>1.94"

Message 1 issued for Dougco at 2007.

Line of thunderstorm cells developed over northeast
Douglas County in the late evening. Cells moved slowly to the south/southeast into Elbert County. Moderate to heavy rainfall was observed in east central Douglas County (south of the District). A rainfall alarm was triggered at East Cherry Creek in Dougco

           
X
 
13
1.22"
1.11"
>2.97"

Message 1 issued for Jeffco and Dougco at 1634.

Thunderstorm cells developed over southwestern Jefferson County and moved slowly to the east into central Douglas County. Outflow from cells in central Douglas County initiated new cells in northern Douglas County. Moderate to heavy rainfall was observed in southwest Jefferson County and central and northern Douglas County. A rainfall alarm was triggered at East Plum Creek in Dougco.

           
X
X
14
0.55"
0.78"
>1.48"

Message 1 issued for the entire District at 1215.

The first storms initially developed over the foothills as early as 11:15am, with additional development occurring over Douglas County by 12:30pm.The heaviest rainfall occurred with this round of storms south of the District in southwestern Douglas County. Locally heavy rainfall did occur across south Denver and Arapahoe County with several gauges receiving greater than 0.5". A rainfall alarm was triggered at the Stump Bump gauge with 0.79” in less than 1 hour.

 
X
X
   
X
X
X
15
0.55"
0.56"
>0.96"
 

Message 1 issued for Jeffco, Dougco, Arapco, and Aurora at 1326 valid until 2100.

Thunderstorm cells developed over central Jefferson County/northwest Douglas County and moved slowly to the east into northern Douglas County. Outflow from cells in northern Douglas County initiated new cells in northern central Douglas County. New cells moved slowly to the east/southeast into Elbert County. Moderate to heavy rainfall was observed in east central Jefferson County, northwest, central and northern Douglas County and extreme southwest Arapahoe County.

           
X
X
16
0.47"
0.49"
>0.93"

Message 1 issued for Dougco and Jeffco at 1652.

A thunderstorm cell developed over west central Jefferson
County in the late afternoon. Cell moved quickly to the east/southeast over the lower elevations of central Jefferson
County. Light to Moderate rainfall was observed in west central Jefferson County. A rainfall alarm was triggered at Horse Creek in Dougco.

           
X
X
17
1.69"
1.89"
>1.91"

Message 1 issued for the entire District at 1718

A single thunderstorm developed over northern Boulder County around 5pm. This storm would strengthen over Boulder County and move SE/SSE becoming a large and intense thunderstorm as it progressed into the Denver Metro area. This storm entered northern Jefferson County at around 545pm and into the downtown Denver area by around 6-615pm. This storm produced very heavy rainfall of 0.5-1.5” in 10-30 minutes as well as large hail over a fairly large area. This storm would weaken as it moved south into Arapahoe and Douglas Counties but heavy rainfall would continue to accompany the storm. The storm exited the District shortly after 8pm with additional weaker showers and thunderstorms continuing through roughly 10pm. There was significant street flooding in Denver and parts of Jefferson County due to this intense thunderstorm.

X
X
X
X
X
X
X
X
18
0.24"
0.20"
>1.18"

Message 1 issued for Douglas, Denver, and Arapahoe Counties, including the City of Aurora at 1723.

Abundant moisture remained in place over the District. A few weak storms initially formed over the foothills by 1pm but would dissipate before reaching the lower elevations of the District. Around 5pm a line of storms in the southern and southeastern portions of the District developed. These storms briefly became strong, producing hail and gusty winds, but ultimately fell apart before any heavy rainfall occurred. Thunderstorm activity tapered off after 6pm, although a few weak storms did occur during the late evening hours over
northern portions of the District.

 
X
       
X
X
19
0.51"
0.76"
>0.84"
 

Message 1 issued for the entire District at 1258 valid until 2300. Message 2 issued for the entire District at 1442 valid until 0200 (7/1).

Two waves of rain showers and isolated weak thunderstorms moved over portions of the District. Potential for heavy rainfall existed. However, the low level atmosphere remained to cool to support strong convection over the District. Light to moderate rainfall was observed across the southern and central potion of the District.

X
           
X
20
1.54"
1.20"
>2.13"

Message 2 issued for the entire District at 1016 effective 1200-2200.

High moisture levels were in place but strong storms failed to develop over the District. One strong storm developed over central Douglas County between 1:30-3pm producing a severe thunderstorm warning that did include a small portion of the District. Due to cloud cover, temperatures did not warm sufficiently over the District to generate storm development. Storms to the N of the District did not trigger anything more than showers and weak thunderstorms. Additional rain showers and thunderstorms developed in the evening along the east District boundary producing moderate to brief heavy rain. Heavy rainfall and large damaging hail would accompany the Douglas County storm that remained just south of the District.

X
X
X
   
X
X
X
21
0.51"
0.38"
>1.04"
 

Message 1 issued entire District at 1344.

Unseasonably high moisture levels were in place. Widely scattered morning shower activity thunderstorms developed and moved from NW to SE into the District, but did not strengthen. One stronger storm did form along a convergence line east of DIA around 6pm that produced a brief tornado warning near the east District boundary. No meaningful storm activity was observed after 8pm. Tornado Warning issued for Adams And Arapahoe Counties at 1833 until 1900 at 1846 this warning was cancelled.

X
X
           
22
0.39"
0.40"
>1.87"
 

Message 1 issued for Dougco, Jeffco, Denver, Arapahoe, DIA, Adams and Aurora at 1251.

Thunderstorm cells developed over northwest Douglas County and south central Jefferson County. Cells moved slowly to the southeast and weakened due to a stable air mass in place. Moderate to heavy rainfall was observed across northwest Douglas County and south central Jefferson County.

           
X
X
23
0.72"
0.86"
>1.21"

Message 1 issued for the entire District at 1510.

A cluster of strong thunderstorms developed across the Boulder County foothills around 3:00pm and would move into the lower elevations of Boulder and Broomfield Counties over the next two hours. The cluster only skirted the Four Mile Burn Area, but rainfall alarms were triggered in foothills locations north of the burn area. Around 5:00pm, a severe thunderstorm developed over the City of Denver and would move southeast into Arapahoe and Douglas Counties through 6:30pm.

X
X
X
X
X
 
X
 
24
0.75"
1.30"
>1.78"

Message 1 issued for the entire District at 1251.

The first heavy-rainfall producing storms over the District developed over Douglas County around 1:30pm, with additional storm development across eastern portions of the District, especially Adams County and DIA, around 3:00pm. Additional storms developed across the District between 5:00-6:30pm to the northeast. Rainfall of up to 1.97” fell south of the District at the Stump Bump gauge along the Douglas/El Paso County border. Numerous rainfall alarms were triggered in the higher elevations of Boulder and Douglas Counties.

X
X
X
X
 
X
X
 
25
1.54"
1.57"
>2.51"

Message 1 issued all areas at 1329.

Message 3 issued for Adams, Denver/DIA, Arapahoe/Aurora at 1914 until 2045.

A few isolated thunderstorms developed over the foothills early in the afternoon but it was not until around 5pm when strong thunderstorms began to develop. One storm moved through Boulder County but was rather small and weakened as it moved onto the plains. A more significant storm developed over Jefferson County and would begin to impact the SW part of the District between 5-6pm. This storm would continue to grow over the Denver Metro area. Heavy rainfall would occur over a rather large area as this storm moved towards Adams County. Rain rates were around 1” in 15-20minutes under the heaviest downpours. This storm prompted many rainfall alarms as well as an NWS Flash Flood Warning.

X
X
X
X
 
X
X
X
26
0.63"
0.35"
>0.47"
 

Message 1 issued for the entire District at 1332.

Thunderstorms began to develop over the western foothills between 1-2pm. These storms would weaken and fall apart over the plains by around 3pm producing only light rain/sprinkles. Additional storms fired SW of the District by around 4pm with a single small moderate cell that developed over NE Douglas County. No rainfall alarms were triggered.

           
X
 
27
0.91"
0.68"
>1.02"

Message 1 issued for Jefferson, Douglas, Denver, and Arapahoe Counties, including the City of Aurora at 1338.

Thunderstorms began to develop over the foothills shortly after noon, with a strong storm cell moving into western edge of the District west of Morrison between 1:30-2:00pm, resulting in locally heavy rainfall. Shortly before 3:00pm, another strong storm cell developed over Douglas County near the southern boundary of the District. Few light thunderstorms developed over Jefferson and Boulder counties. Rainfall alarms were triggered in Douglas County.

     
X
   
X
X
28
0.20"
0.57"
>0.59"
 

Message 1 issued ALL areas at 1618.

Strong and severe storms developed between 2-5pm over Weld County and over El Paso County and over eastern Arapahoe and eastern Adams Counties outside the District. Heavy rainfall was not observed within the District with only weak to briefly moderate storms developing. No rainfall alarms were triggered.

               
29
0.47"
0.30"
>0.70"
 

Message 1 issued for ALL Counties except Boulder and Broomfield at 2036.

During the evening a thunderstorm developed over NW Jefferson County between 810-840pm. This storm would strengthen becoming severe as it moved to the SE. Large hail was observed including reports up to 1.5". Another storm would initiate over N Douglas County around midnight moving out of the District by around 1am Friday the 29th. No rainfall alarms were reported.

             
X
30
0.59"
0.67"
>0.63"
 

Message 1 issued for Adco, Brmco, DIA, Denco at 1743 valid until 2100.  0.40-1.10” rainfall in 10-30 min.

Thunderstorm cells developed over portions of the District from a thunderstorm generated outflow boundary.  Cells moved slowly to the northeast where they weakened.

X
           
X
31
0.59"
0.67"
>0.63"
 

Message 1 issued at 1857 for Arapahoe/Aurora, Adams, Denver/DIA, Douglas until 2100.

Message 1 issued for Boulder, Broomfield and Jefferson Counties and extend ALL other M1’s at 2009 until 2300.

Thunderstorms developed along the east of I25 after 730pm slowly strengthening.  These initial storms would split with one moving east and the stronger one moving southward along the I-25 corridor weakening as it entered Douglas County. Storms diminished between 9-10PM. No rainfall alarms were reported.

X
X
     
X
 
X
32
0.83"
0.56"
>1.31"

Message 1 issued for Boco, FMBA, Dougco and Jeffco at 1412 valid until 2100.

Message 1 issued for Arapco and Aurora at 2013 valid until 2100.

Thunderstorm cells developed over the District and moved slowly to the southeast during the evening hours. Moderate to heavy rainfall was observed across southern Boulder County, northern and southwest Jefferson County, eastern Douglas County and southeast Aurora.

           
X
X
33
0.16"
0.38"
>0.91"
 

Message 1 issued for Boco, FMBA, Dougco and Jeffco at 1437 valid until 2100.

Message 1 issued for Brmco, Adco, Denco and DIA at 1838 valid until 2100.

Northward moving thunderstorm outflow boundary initiated
thunderstorms over Adams County during the early evening. Moderate to brief heavy rainfall was observed across northwest Adams County.

X
       
X
   
34
0.59"
0.69"
>0.84"
 

Message 1 issued for the entire District at 1136.

Message 4 issued at 1722.

A strong storm cell developed over the Central Jefferson County resulting in heavy rain. Kinney Peak gauge just outside the district reported levels with 0.51” falling in 12 minutes, but no rainfall alarms were reported. Aditional cells developed over Douglas county producing very light rainfall.

           
X
 
35
0.83"
0.73"
>0.90"
 

Message 1 issued for Jeffco and suburbs at 1918

Message 1 issued for Boulder/FMBA, Broomfield at 1926

Stationary storms developed over Jefferson county producing light to moderate rain. Since these storms moved very little they would rain the whole time in one location, creating extended periods of rainfall. No rainfall alarms were reported.

             
X
36
0.28"
0.43"
>0.74"
 

Message 1 issued ALL areas at 1425

Scattered thunderstorms appeared between 2pm to 5pm over the District. Storms remained weak to moderate and produced rainfall amounts just shy of 0.5” per CoCoRaHS reports and up to 0.28” per UDFCD gauges under the more moderate storms over Denver County. Strong storms with heavy rainfall were not observed. No rainfall alarms were reported.

       
X
   
X
37
1.10"
1.79"
>2.38"

Message 1 issued for the entire District at 1221

Thunderstorm cell developed over Weld county and moved south/southeast into Adams County North of DIA. Thunderstorm cell developed over northwest Jefferson County and moved to the south/southeast through central Jefferson County and into northwest Arapahoe county and northwest Douglas county. Moderate to heavy rainfall was observed across east central Jefferson County, northwest Arapahoe County, northwest Douglas County and northern Adams County.

 
X
 
X
   
X
X
38
0.91"
1.23"
>2.06"
 

Message 1 issued for Boco, Jeffco and Dougco at 1501

Message 1 issued for Adco at 1532

A line of thunderstorm cells moved through Boulder and Jefferson Counties and weakened as they moved. Cells later developed in Adams County. Heavy rainfall was reported in Douglas and Adams County. No rainfall alarms were reported.

 
X
       
X
X
39
0.79"
0.63"
>1.57"

Message 1 issued for the entire District at 1317

Thunderstorms developed over the eastern portion of the
District and moved slowly to the west during the early afternoon. Moderate to heavy rainfall was observed across Boulder County, central Jefferson County, southwest Arapahoe County, southern Denver County and western Douglas County. A rainfall alarm was reported at Cal-Wood Ranch in Boulder County for 0.5" in 10 minutes.

 
X
X
X
X
 
X
X
40
3.15"
1.53"
>2.81"

Message 1 issued for the entire District at 1741

Favorable conditions for thunderstorm development occurred late in the afternoon. Slow moving storms produced prolonged periods of moderate and heavy rainfall. Heaviest rainfall was observed over Jefferson, Boulder, Adams, Denver and Arapahoe Counties with some totals of 1-2” or more with an isolated area west of Boulder where over 3” was measured by the UDFCD Filter Plant station 4100. The stronger cells produced Flash Flood Warnings for small portions of Adams and Boulder Counties. Numerous Flood Advisories were also issued by the NWS for other counties.

X
X
X
X
X
X
X
X
41
0.35"
0.65"
>1.15"
 

Message 1 issued for Boulder, Jefferson, Broomfield, and Adams Counties at 1921

Around 6pm scattered thunderstorms began to develop across the Jefferson County foothills, some of which were on the stronger side, with storm motions to the NNE. The strongest cells developed over the Northern Jefferson County foothills around 7pm, prompting messages to be issued for the Boulder and Jefferson Counties, as well as Broomfield and Adams Counties. Storms quickly weakened by 8pm as the moved onto the lower foothills, with the plains remaining dry. Light showers quickly dissipated over the mountains and foothills over the remainder of the evening.

             
X
42
0.79"
0.60"
>0.84"
 

Message 1 issued for Boulder County at 1402

Storms developed over the foothills of Jefferson and Boulder County between 1-2pm. One stronger cell approached the FMBA resulting in the M1 being issued for Boulder County. This storm would weaken and move rather quickly through the burn area with mainly light to moderate rain. Stronger storms remained outside the District and away from the FMBA near Allenspark.

     
X
       

 

 

Maximum 24-hour value

Maximum 24-hour value

Maximum

Radar

estimated

24-hour

precip

Alarm Log

Rainfall

Rate Alarm

 

ADAM

ARAP

AURA

BLDR

BROM

DENV

DOUG

JEFF