MHFD Homepage

 

https://f2p2.udfcd.org/images/f2p2_heading.gif
2021 Flood Season Summary

Meteorological support services provided by Skyview Weather.

Select desired 'Date' to see corresponding 24-hour rainfall map ending at 7AM the following day.

 

 

 

 

 

 

 

 

> 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
1.42"
1.75"
>1.89
Low HPO Issued at 1052. M1 issued for Adams, Arapahoe/Aurora, Denver and Douglas at 1145. The first widespread thrunderstorm day of the season. A north-south line of broken storms peaked between 1200-1400, and exited the District by 1500.
X
X
X
X
X
X
X
X
2
2.05"
2.00"
>2.01"
Moderate HPO issued at 922. M1 issued for all Cities/Counties at 956. A slow-moving low pressure system produced thunderstorms over the District. Storms developed in the foothills around noon producing brief to moderate rainfall, gusty winds and some hail.  The initial round of storms ended in early afternoon,  then widely scattered storms developed about 2000. 
X
X
X
X
X
X
X
X
3
1.42"
0.61"
>1.82
Moderate HPO issued at 935. M1 issued for Arapahoe/Aurora, Douglas County at 1424 and remainder of District at 1618. First storms developed over Jefferson County foothills between 1200 and 1400. These storms weakened as they moved eastward. Storms over NE Douglas County strengthened 1430-1530. New storms developed in Boulder and Jefferson County foothills 1600-1700 and moved through Jefferson County and Denver Metro.

X
X



X

4
1.42"
1.73"
>2.42
Moderate HPO issued at 925. M1 issued for Boulder, Jefferson and Douglas Counties at 1056 and remainder of District at 1156. Showers and storms developed at 1100 in Douglas and Jefferson Counties. Cloud cover slowed storm development but thunderstorms developed over the plains at 1300 and additional storms developed over the District  during the afternoon.
X
X
X
X
X
X
X
X
5
0.94"
0.92"
>1.98
Low HPO issued at 839.  M1 issued for the entire District at 1226. A surface cold front, strong upper-level flow and ample moisture caused development of strong to severe storms in the early afternoon. A line of storms developed and moved S to N from the Palmer Divide into NE Douglas and western Arapahoe and Adams Counties. Storms peaked at 1300-1530 then weakened.
X
X
X
X

X
X
X
6
0.20"
0.16"
>0.61

HPO issued at 839 with no message potential, then updated at 1046 with low/mod message potential. M1 issued for Adams, Arapahoe, Denver and Douglas Counties at 1150. Ample moisture and good wind shear were in place and weak storms developed at 1300 along I25 corridor and 1500 in Arapahoe and Adams Counties. Strongest storms developed E of the District. Dry air spread throughout the District after 1500.  Rainfall measured at station 5740 Trail Creek are  likely erroneous.
X







7
0.83"
0.88"
>2.29
Moderate HPO issed at 912, M1 issued for the entire District at 1156. A slow-moving trough of low pressure and unseasonably cool temperatures were in place as a cold front moved in from E/NE. Storms developed prior to 1200 over Jefferson County and produced a large anvil cloud over the District. Initial cloud cover inhibited strong storm development. Warmer areas S of the District with more sunshine resulted in numerous severe storms.  An outflow gust front triggered late evening storms.

X

X


X
X
8
1.34"
1.61"
>1.68
Low HPO issued at 857, M1 issued at 917. Below normal temperatures and low pressure over Colorado produced storms that transitioned to soaking rain. Widespread rain and embedded thunderstorms impacted the District from late morning until 1500. The large area of rain moved out of the District by 1800.
X
X
X
X
X
X
X
X
9
0.94"
1.89"
>2.05
Low HPO issued at 844, M1 issued for Douglas County at 1916. High pressure, warm temperatures and adequate surface moisture were in place. Daytime heating alone was not enough to initiate storms. Storms in Park, Teller and El Paso counties caused a gust front moving N over Douglas County, causing rapid storm development over Douglas County at 1900. Some weaker storms developed but storms diminished over the District by 2200.



X


X
X
10
0.35"
0.55"
>1.22

Moderate HPO for the foothills of Douglas County, low for remaining counties issued at 832. Warm, moist conditions were in place. Daytime heating initiated storms over the foothills at 1200 producing weak storms but also producing a gust front that moved S to N through the District. Slow moving storms developed over the District 1630-1830 with weaker storms through 2000.
X
X




X
X
11
1.10"
1.47"
>3.94
Low HPO issued for Adams, Arapahoe, Denver, Douglas and Jefferson at 824, upgraded to Moderate for all Counties at 1230. M1 issued for all Counties at 1609. Very warm and moist air was in place but with a warm layer aloft that would have to be overcome for storms to develop. Weak showers developed over the foothills at 1200, but dissipated as they moved to lower terrain. A "pulse type" storm developed at 1600, becoming severe with large hail and remaining nearly stationary. Large hail may have impacted gage data. The strong storm ended by 1900.  Additional moderate storms developed in the evening until ending by 2200.
X
X
X

X
X
X
X
12
0.31"
0.49"
>1.30

Moderate HPO issued at 824, M1 issued for all Counties at 1145. A cold front moved through the previous day causing increased surface moisture and an upper level disturbance moving in during the day. Initial storms formed around noon in central Jefferson County and remained weak. Scattered storms formed through the early afternoon producing some hail. At 1500 a stronger storm formed in Boulder/Broomfield County producing a small area of heavy rainfall weakening by 1600.  Some more weak storm continued over the District until 1900.
X
X

X
X
X
X
X
13
0.47"
0.60"
>1.38

Low HPO issued at 849, M1 issued for all Counties at 1359. A moist upper level disturbance moved in before sunrise. Storms developed around noon on the Palmer Divide producing a gust front to the NW into the District. At 1400-1430 a strong storm developed just NE of the District. As this storm dissipated, other storms developed along the gust front producing heavy but brief rainfall. Storms diminished at 1900.
X


X
X
X
X
X
14
2.91"
3.32"
>2.40
High HPO issued at 824, M1 issued for all Counties at 1116. Two boundaries collided over the District enhancing storm development. Storms formed around 1200 S/SW of the District. Also at 1200 storms began developing over Boulder County until 1530 producing heavy rainfall and large hail. As the boundaries collided, a large storm complex formed over the District around 1400 producing heavy rainfall and hail (at times) until 2200.
X
X
X
X

X
X
X
15
0.59"
0.86"
>0.96

Moderate HPO issued at 852, M1 issued for the entire District at 1026. Cool temperatures and a cold front moving in from the N produced rain and weak storms to develop around 1200. Heating was limited and storms that developed later in the day were weak to moderate and heavy rainfall was isolated ending by 2100.
X
X
X





16
1.26"
1.02"
>0.82
Low HPO issued at 824, M1 issued at 1452 for all Counties. Moisture decreased slightly from previous days but temperatures warmed enough for storm development 1300-1400 over the foothills and 1400-1500 over the plains. Weak to moderate storms continued until 2000.

X
X





17
0.55"
0.49"
>0.53

Low/Moderate HPO issued at 858, M1 issued for Adams, Arapahoe, Denver, Douglas and Jefferson Counties at 1404. Adequate moisture but cool temperatures were in place. Showers and weak storms developed over Foothills of Jefferson and Boulder Counties producing a gust front that traversed the District. Several moderate pulse-like storms developed ending by 1600.








18
2.32"
1.29"
>2.41
Low HPO issued at 934, M1 issued for Boulder, Jefferson and Douglas Counties at 1544. Moisture from Mexico was in place over Colorado but capped by warm air aloft. Isolated, nearly stationary storms developed over the foothills and produced a gust front that would trigger rapid storm development 1500-1600.  Storms were weak, slow-moving thunderstorms but produced moderate rainfall. Storms ended 1800-1900.
X




X

X
19
0.31"
1.11"
>1.06

High HPO issued at 853, M1 issued for the entire District at 1930. Abundant moisture remained in place. A shallow gust front E of the District triggered storms in the District after 1900 with another round 2200-2400.
X
X
X
X
X
X
X
X
20
2.05"
3.71"
>2.90
M2 issued for all Counties at 904. Abundant moisture from the previous day was available. Storms developed in Elbert County and point E and W of the District at 1100 producing an outflow boundary moving W into the District.  Strong storms developed  at 1300 and moved slowly producing several inches of rain and some hail. Storms developed over Boulder and Jefferson Counties 1400-1600 producing heavy rainfall. Storms ended 1800-2000.
X

X


X
X

21
0.16"
1.17"
>1.95

High HPO issued at 849. M1 issued for the entire District at 1207. Significant moisture was still in place, but warmer air aloft slowed storm development. S/SE winds interacting with higher terrain resulted in Denver Convergence Vorticity Zone development.  Storms developed starting at 1830 with large hail and heavy rainfall, diminishing by 2030.
X

X


X
X

22
0.43"
0.48"
>1.57

Low HPO issued at 823. M1 issued for the entire District at 1355.  Moisture decreased in the area. At 1400 daytime heating and a boundary moving in from the N triggered weak to moderate storms that lasted until 1600.

X
X
X


X
X
23
0.79"
2.06"
>2.99
High HPO issued at 914. M1 issued for the entire District at 1154. Storms initially developed over higher terrain. At 1400 a surface wind convergence line set up along the SE side of the District triggering isolated storms with heavy rainfall. More storms developed along the boundary causing more isolated heavy rainfall. Storms ended by 1700.
X
X
X



X
X
24
1.22"
1.15"
>2.06
High HPO issed at 914, M1 issued for the entire District at 1156 valid at 1300. Abundant moisture but a warm layer cap were in place.  Surface heating broke the cap on the S side of the District with storms developing that produced isolated heavy rainfall at 1445. Storms lasted until 1900.
X
X
X

X
X
X
X
25
0.98"
1.03"
>1.44
The last of 13 consecutive message days. Low/Moderate HPO issued at 937. M1 issued for all Counties at 2011. A cold front moved in before sunrise with cooler temperatures reducing storm development until the evening. Storms developed over the foothills at 2000. Multiple rounds of showers and weak to moderate storms moved through the District until 2400.
X
X

X
X
X
X
X
26
0.51"
0.75"
>1.04

High HPO issued at 846, M1 issued for the entire District at 1419. A cold front moved through in the morning, with ample moisture, cool temperatures and thick cloud cover. An upper level disturbance triggered storm development starting at 1530. Weak to moderate storms occurred 1700-1730 with another isolated storm occurring 1800-1830 before dimishing for the day.
X
X
X
X

X

X
27
0.43"
0.51"
>1.52

Low HPO issued at 831, M1 issued for Adams, Arapahoe, Denver, Douglas and Jefferson at 1752. Two gust fronts produced by storms to the N and S collided over the District initiating storms after 1700. Storms peaked at 1900 and diminished by 2000.
X
X
X



X

28
2.52"
0.87"
>3.48
High HPO issued for the entire District at 913, M1 issued for Boulder, Jefferson, Douglas, Adams, Denver and Arapahoe Counties at 1249.  An increase in monsoonal moisture over the region. Storms developed along the continental divide in early afternoon moved to front range foothills at 1600-1700. Additional storms formed along the Palmer divide producing outflow boundaries causing persistent storms in SE Douglas County 1700-1800. Storms ended by 1900.






X
X
29
1.26"
2.68"
>2.62
Moderate HPO issued for the foothills, Low HPO issued for the plains at 838, M1 issued for the entire District at 1654. Monsoon moisture continued to stream into Colorado. With good daytime heating, storms developed by 1700 over Douglas and W Adams Counties diminishing by 1930. Smallers storms continued until 2030.
X
X
X

X
X
X
X
30
0.55"
0.51"
>1.39

High HPO for the foothills, moderate HPO for the plains issued at 825. M1 issued for the entire District at 1400. Abundant moisture was still in place. Storms initiated N of the District in the late morning creating an outflow cold front that moved across the district causing storms to develop over Douglas County 1600-1800. Other storms developed in the N/NW portion of the District 1900-2400.



X


X
X
31
2.01"
2.41"
>1.96
Low HPO issued at 854, M1 issued for the entire District at 1818. A gust front from Kansas moved in during the late afternoon causing stationary storms to form over higher terrain near Morrison at 1800. Another strong storm developed over the Boulder flatirons 1815-1930.



X


X
X
32
0.12"
0.05"
>0.40

Low/No HPO issued at 854, M1 issued for Adams, Boulder, Broomfield and Jefferson Counties at 846. Monsoon moisture was present to the W of the District. A weak surface convergence formed over NW portions of the District. The warm air aloft did not erode enough to produce anything other than rain showers and weak storms.








33
2.01"
3.56"
>5.09
Moderate/High HPO issued at 851. M1 issued for All Counties at 1642. Monsoon moisture overhead and a surface cold front moved through the District.  Storms first developed due to the cold front at 1500 N of the District with storms developing within the District at 1730. A large area of moderate to heavy rainfall occurred 2000-2230 with all rain ending by 0200 overnight. An area just S of Erie, just E of Lafeyette experienced persistent storms resulting in high rainfall over a small area.
X
X
X
X
X
X
X
X
34
1.93"
1.71"
>1.74
M2 continued to be valid from the previous day. Showers and weak thunderstorms developed at 1400 in Boulder County and moved into N Jefferson by 1600. New storms developed in the NW part of the District through 1830 before weakening.
X
X
X
X
X
X
X
X
35
0.87"
1.67"
>1.93
High HPO issued at 0855 for the entire District, M1 low impact flooding issued for Douglas County 1553. A tail end of monsoon moisture plume and an upper level low was present. A surface wind convergence line also set up. Storms initiated at 1300 with outflow from these storms causing other storms by 1500 turning heavy by 1600 and weakening by 1900.



X


X
X
36
0.67"
1.56"
>2.61

HPO issued with NONE message potential at 937, M1 issued for all except Boulder and Broomfield Counties at 2233. Early conditions indicated little sign of thunderstorm development. Storm development SE of the District created an outflow boundary that pushed to the N/NW into the District causing storm development at 2200. A storm over Denver County occurred 2215-2245. A storm over NW Douglas County occurred 2300-2330 before quickly diminishing by 2400.

X



X
X

37
0.75"
0.40"
>1.03
Low HPO issued at 930, M1 issed for the District except Boulder, Broomfield, Adams and DIA at 2034. Dry conditions existed during the day with any foothills storms diminishing before arriving at the District. An upper level disturbance moved through in the afternoon causing rapid storm development around 2000 just S of Denver with an additional cell just N of Castle Rock. Storms diminished by 2300.





X
X
X
38
1.10"
1.95"
>2.78
Low/Moderate HPO issued at 913, M1 issued for all areas of the District except Douglas County at 1057. An upper level disturbance moved into the District during the early afternoon. Storms developed in the Jefferson County foothills at 1200 and in the NW part of the District at 1300. Storms intensified 1430-1600 before dissipating and M1 expired at 1800. Another low HPO for the overnight period was issed at 2006, a second round of M1 issued for Adams, Boulder, Broomfield, Jefferson at 0155. Another disturbance moved across the District in the early morning producing fast-moving storms. Storms developed initially over Boulder County then also developed in Jefferson County then a line of storms moved eastward into the District. Storms over the District 0200-0400 and S  Denver and Arapahoe 0300-0400 before passing through.
X
X
X
X
X
X
X
X
39
0.08"
0.10"
>0.28"

Moderate HPO issued at 1022, M1 issued for all Counties at 1129.  An approaching upper level disturbance and abundant surface moisture were in place. However, a psuedo cold front moved through the District around 1200 and scoured available moisture. Weak storms developed over Jefferson County. With cooler temperatures in place the upper level distrubance produced only minimal storm activity.








40
1.38"
1.64"
>1.83
Moderate/High HPO for the plains, low HPO for the foothills issued at 919, M1 issued for the entire District at 1133. A trough of low pressure moved in overnight and a trailing upper level disturbance produced strong storms. A storm that first developed W of Morrison tracked W to E from 1200-1500 through the District producing heavy rain and hail.
X
X
X
X

X
X
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