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2020 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
0.31"
0.59"
>1.14"


Low HPO issued at 953. M1 issued for the entire District at 1439. A cold front moved through overnight, an upper level disturbance was in place over N Colorado. Weak storm activity began at noon over the foothills causing development of storms over the District by 1300. A slow moving storm developed along the Jeff/Boulder County line and increased in size before moving out of the District at 1700.  Isolated storms continued until 2100.
X
X
X
X
X
X

X
2
0.87"
0.98"
>1.44"

Moderate HPO issued at 934. M1 issued for the entire District at 1217. An upper level disturbance produced scattered afternoon and evening storms over the District. Storms developed in the foothills by noon and moved itno NE Douglas and SE Aurora producing small areas of heavy rainfall.  Isolated storms continued throughout the afternoon before weakening by 2300.
X
X
X
X

X
X
X
3
2.17"
1.65"
>3.29"

High HPO issued at 0827. M1 issued for the entire District at 0957. A strong and cold trough of low pressure moved in overnight. Rain showers began 0900-1100 and continued all day as temperatures fell. Thunderstorms did not produce any heavy rainfall in the District. Moderate showers persisted until 2200-2300 producing 1.5" + over the District.
X
X
X
X
X
X
X
X
4
0.67"
0.41"
>1.62"

Low HPO issued at 937. M1 issued for the entire District (not including Boulder, FMBA and Broomfield) at 1719. High pressure was in place over the region, but with abundant low-level moisture in the morning. Temperatures warmed quickly resulting in early storm development over the foothills. Cloud cover limited daytime heating and storm development. Less cloud cover existed in El Paso County to the south and storms developed in the early afternoon, producing a gust front and cluster of storms south of Denver at 1700. These storms extended eastward and became severe before dissipating quickly.
X
X
X
X

X
X
X
5
0.55"
0.68"
>1.04"

High HPO issued at 1035 via ST pathway. NO IMS issued/attempted at 1100. Mid and upper level moisture increased during the day. Storms developed over the mountains and foothills 1000-1200 producing some cloud cover over the District.  Initial storms diminished but additional storms developed 1300-1500 SW of the District.  Showers and storms eventually built in the District at 1800 with moderate activity in the NW  portion of the District.


X


X
X
6
0.35"
0.57"
>0.74"

Low HPO issued at 0842. M1 issued for the entire District at 1455. A strong low pressure system moved across the district. Light to moderate storms developed along the foothills at 1100. A strong line of storms moved very rapidly across the District between 1600-1700. Very high straight line winds (up to 80mph) occurred.  These winds and hail may have caused reductions in ground measured rainfall totals. Storms ended in early evening.
X
X
X
X
X
X
X
X
7
0.31"
0.55"
>0.87"

HPO issued at 0842 as Moderate for Foothills and High for the plains. M1 issued for the entire District at 1136. An upper level low pressure system produced a 2 day period of cool wet weather. Overnight showers continued in the NW part of the District and storm activity increased throughout the day. Two rounds of storms occurred 1400-1700 producing moderate rain over Boulder County before ending at 1700.



X




8
1.69"
1.20"
>2.97"
Moderate/High HPO was issued at 0918. M1 issued at 1129. M3 issued for Arapahoe/Aurora, Denver, Jefferson including Arvada, Lakewood, Wheat Ridge at 1731. An overnight cold front brought moisture and cooler temperatures. Storms developed at 1300 in the Jefferson County foothills. At 1400 strong thunderstorms started tracking across the S portion of the District turning severe. At 1500 storms began developing in Boulder County turning severe as they tracked E. As these storms moved east more storms developed on the southern side, causing strong storm development in the central portion of the District. NWS flash flood warning was issued for east-central Jefferson County, Denver County and Arapahoe County. Storms diminished by 1800.
X
X
X
X
X
X
X
X
9
0.63"
0.77"
>1.97"

Moderate HPO issued at 0920. M1 issued for all counties and cities at 1357. Moisture increased from previous days and storms developed by 1300 at the Palmer Divide. Storms strengthened by 1400 S of the District entering the District at 1500 moving NE producing quick rain and some hail. Another small storm developed in NE portions of the District at 1700.  Storm activity decreased after 1800.
X
X


X



10
1.77"
1.78"
>3.41"
High HPO issued at 0900. M1 issued at 1210. M3 issued for Arapahoe County/Aurora at 1622. Moisture remained elevated and a weak line of storms formed from Dougas County into Arapahoe and Adams counties at 1400. At 1500 a storm storm developed over Aurora holding there for nearly 2 hours.  Multiple urban and small stream flood advisories were issued and a flash flood warning issued for north central Arapahoe including Aurora. Storms moved E out of the District after 1700.
X
X
X

X
X


11
0.39"
1.35"
>1.84"

HPO issued at 0856 with NO message potential. M1 issued for Adams County and DIA at 2027. M1 issued for Arapahoe County and Aurora at 2120. After a dry day, a surge of moisture moved into the District from the E at 1700. At 2000 storms developed over W Adams County moving E/SE and strengthened becoming severe with wind, hail and heavy rainfall. Heavy rainfall was not captured by ALERT gages due to hail with hail 1-2" in diameter spotted. This was the only storm of the day.
X
X
X


X


12
0.59"
1.12"
>1.35"

Low HPO issued at 0824. M1 issued for the entire District at 1229. A cold front moved through overnight. Initial storm development occurred by midday over the foothills. Multiple rounds of storms moved through the District producing light rainfall. At 1800 a line of moderate storms developed over Boulder and Jefferson Counties. This line of stormed moved over the District producing isolated heavy rain over 1-2 hours. Storms ended by midnight.

X



X
X
X
13
0.24"
0.27"
>0.78"

Low HPO issued at 0818. M1 issued for all Counties and Cities at 1714. Significant increase in moisture occurred during the morning. Storms developed S of the District producing a gust front 1600-1700. Isolated weak storms developed along the front over Jefferson County. Storms did not develop as expected over the District as the front moved N. Lack of heating due to cloud cover kept storms from developing dispite high moisture levels and the gust front.






X

14
0.43"
0.44"
>1.31"

Moderate HPO issued at 0900. M1 issued for the entire District at 1053. A potential heavy rain threat day was forecast. Moisture, heating and upslope flow caused rapid storm initiaton in the Jefferson County foothills between 1000 - 1100. These initial storms dissipated but produced a gust front producing new storms over Douglas County in the afternoon ending at 1600.






X
X
15
0.83"
0.52"
>1.96"
Low/moderate HPO was issued at 0824, M1 issued for all counties at 1103. A cold front moved through overnight. Storms first developed over the Palmer Divide before 1200. These initial storms produced an outflow boundary that moved N into the District initiating new storms at 1300. Strong storms impacted S and SE portions of the District until 1530. Additional storms developed outside of the District boundary ending by 1800.

X
X
X

X
X
X
16
0.28"
0.28"
>0.87"
Mod/High HPO was issued at 0801. M1 issued for all Counties at 1217. A cold front moved through overnight.  Storms developed over the central Jefferson County foothills by 1200 but weakened as they moved to lower elevations. Additional storms developed over the Southern Jefferson County foothills at 1300 and strengthened as they moved into the Hayman burn area and S Douglas County at 1600 producing heavy rainfall. Storms did not develop over the District but stayed to the S and SW.

X




X
X
17
1.06"
1.23"
>1.15"
High HPO issued at 0856. M1 issued for all Counties at 1137.  The first plume of monsoon moisture moved over the District resulting in storms developing by 1200 over the foothills and Palmer Divide. Storms strengthened at 1300 over Douglas County. At 1400 a small but strong storm developed over SE Aurora tracking N producing high rainfall rates. Weaker storms moved through the District until 1800, then another round 2000-2300.
X
X
X
X

X
X
X
18
0.83"
0.60"
>1.60"

High HPO issued at 0854. M1 issued for all Counties at 1102. The monsoon moisture remained in place over the District. Storms developed at 1200 over S Jefferson and the Palmer Divide. A strong storm developed along the Douglas/El Paso County line tracking NE and missing the District. Cooler temperatures remained in place caused by cloud cover from earlier storms. Additional showers occurred over the District 1430-1800 and 1900-2200 impacting the S and W District boundaries.



X


X
X
19
0.28"
0.82"
>0.71"

High HPO was issued at 0854. M1 was issued for Arapahoe, Douglas and Jefferson Counties. Ample moistured remained in place and a cold front would push through NW to SE in the early afternoon keeping temperatures in the low 80s. Storms developed in S Jefferson County at 1200 with light rain spreading out onto the plains by 1400. Stronger storms developed outside of District boundaries. Light rain only occurred over the District due to cooler temperatures.







X
20
1.18"
0.85"
>1.55"
High HPO issued at 0901. M1 issued for the entire District at 1256. A strong low pressure system moved in from Wyoming. Initial storms developed over higher terrain at 1000-1200. As storms increased in strength, clouds over the District limited heating. A storm N of the District produced heavy rain along N Boulder County. At 1400 storms began to approach the District from the W and developed over the I-25 corridor at 1500 bringing heavy rainfall from Thornton to N-central Arapahoe County before moving quickly out eastward. Rainfall after 1700 was light.
X
X
X
X
X
X
X
X
21
0.35"
0.43"
>0.96"

Moderate HPO issued at 0854.  M1 issued at 1542 for the entire District. A cold front provided moisture and upslope conditions along the front range. A few fast storms moved across N Colorado causing development of additional storms in N Boulder County to Greeley. Heavy rains anchored over the foothills just W of the District. The District received only light rain.



X



X
22
0.28"
0.41"
>1.29"

HPO with NO message potential issued at 814, updated to low at 2019. M1 issued 2105 for Boulder, Broomfield, Adams and Arapahoe including DIA and Aurora. Storms developed over the N mountains in the afternoon and evening. Fast storms kept heavy rainfall brief, but heavy rains fell just N of the District. Storms fell apart on the District boundaries with no heavy rains in the District.
X


X



X
23
0.08"
0.11"
>0.31"

Low to Moderate HPO issued at 0856. M1 issued at 1358 for the entire District. A low-pressure system provided wrap-around moisture in NE Colorado and clear morning skies with forecast high temperatures signaled an elevated risk of heavy rainfall. Initial storms were fast NW to SE but dissipated quickly once off the foothills. Clouds and cooler temperatures prevailed over the District, although storms developed E of the District.








24
0.20"
0.14"
>0.70"

Low HPO issued at 0806. M1 issued at 1615 for all Counties. Persistent NW flow aloft, ample moisture and good surface heating were in place. Storms first developed over Larimer and Weld counties in early afternoon. These storms produced a rain/hail outflow boundary/gust front that moved into the District at 1700. A strong storm developed in Weld County. Storms weakened as they entered the District with no additional storms developing over the District.
X


X

X


25
0.59"
1.16"
>1.76"
Low HPO was issued at 0759. M1 issued for all Counties at 1520. Persistent NW flow aloft continued. Storms developed over S Jefferson County, the Palmer Divide and Elbert County. A gust front was sent N into the District triggering additional storms over E Denver at 1500. As these storms weakened another boundary moved in from the N intensifying storms in NW areas of the District with strong winds and hail. Another storm developed at 1700 over Douglas County producing moderate rain and some hail.
X
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