Skunk Creek @ I-17, July 23, 2021 4:07 PM MST, Courtesy FCDMC O & M Division

Flood Control District of Maricopa County
Engineering Division, Flood Warning Branch

Storm Report : July 22-25, 2021
Revision 1, Aug. 19, 2021

TABLE OF CONTENTS
Meteorology ............................................................................... 3
Precipitation .............................................................................. 6
Runoff & Impoundments ............................................................... 15
Public Outreach Summary ............................................................. 29
Data Sources ............................................................................. 33

TABLES
Table 1
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Table 8
Table 9

Rainfall Return Periods for Selected ALERT Gages ......................... 12
Summary of Skunk Creek Flows, July 23, 2021 ............................... 16
Summary of Skunk Creek Flows, July 25, 2021 ............................... 20
Summary of New River Flows, July 23, 2021 ................................. 21
Summary of Indian Bend Wash Flows, July 23 & 25, 2021 .................. 23
Hassayampa R. @ US 60 Flows, July 21-25, 2021 ............................ 27
Summary of Peak Impoundments at Wickenburg Structures ............... 28
Summary of Peak Impoundments at White Tank Structures ............... 28
Summary of Peak Impoundments at East Valley Structures ................. 28

FIGURES
Figure 1
Figure 2
Figure 3
Figs. 4-8
Figs. 9-14
Figure 15
Figs. 16-22
Figure 23
Figure 24
Figure 25
Figure 26
Figure 27
Figure 28
Figs. 29-37
Figure 38
Figure 39
Figure 40
Figure 41
Figure 42
Figure 43

4-Panel 12Z (5am MST) Synoptic Setup 07/23/2021 .......................... 5
4-day Rain Totals vs. # of Rain Gages ........................................... 6
Rain Map: 4-day Totals Ending July 25, 2021 at 12pm ........................ 6
Rain Maps: 1-day Totals Ending July 22-26, 2021 at 12pm ............... 7-11
Rain Statistics at Six Selected Gages ...................................... 13-14
Skunk Creek watershed above Adobe Dam ................................... 15
Hydrographs – Skunk Creek ................................................. 16-18
Photo – I-17 at Dixileta Dr. 7/23/2021 ........................................ 19
Photo – I-17 at Dixileta Dr. 7/25/2021 ....................................... 19
New River watershed above New River Dam ................................ 20
Hydrograph – New River Fire Stream Gage, 7/23/2021 .................... 21
Hydrograph – New River Dam, 7/23-25/2021 ................................ 21
Indian Bend Wash watershed above McKellips Rd. Gage ................... 22
Hydrographs – Indian Bend Wash .......................................... 23-26
Hydrograph – Salt River at Priest Dr. ........................................... 26
Twitter Post Impressions ........................................................ 29
Facebook Post Performance Statistics ........................................ 29
ALERT Interactive Data Display Map – Total Pageviews ..................... 30
Instagram Posts ................................................................... 31
Twitter Posts in Spanish ......................................................... 32

2

METEOROLOGY
A high-grade monsoon pattern strongly aided by a slow-moving inverted trough led to widespread heavy
rain across southcentral Arizona during a four-day period ending on July 25th 2021. Maricopa County rain
gages measured event totals anywhere from 1.00”-5.30”. Residents in Phoenix, Scottsdale, New River,
Glendale, Avondale, Surprise, Buckeye, and many other communities experienced significant flash and
urban flooding due to heavy rain from this event.
Synopsis:
In the days leading up to the event, District staff as well as many other Federal agencies kept close tabs
on weather model guidance that depicted an upcoming multi-day active period to the North American
Monsoon. The setup featured a “Four Corners High” pattern (click here for more background
information) and near record moisture values that were already in place across the Desert Southwest.
Additionally, a large upper-level disturbance was forecast to affect the region. These disturbances, also
known as inverted troughs (IT), are historically quite common to the region during the summer months.
They typically form in the Gulf of Mexico and move east to west bringing enhanced/organized t-storm
activity. Please refer to the following page for more background information.
The IT took shape across central Texas during July 20th and 21st before strengthening as it moved into
West TX. The synoptic setup on the morning of July 23rd is shown in Figure 1 (below). The upper-level
images (C and D) depict the aforementioned ridge draped across the Four Corners region of the western
US and the IT along the TX/NM border. Images A and B depict the moisture rich environment in place
across AZ. It’s worth noting that the positioning of the ridge and trough during this period created a
large area of upper-level divergence (rising motion), which proved to be a strong catalyst for t-storm
activity across southcentral AZ (more on this in the next section). Ultimately, the IT slowly traversed
west across NM on the 24th and then across Arizona on the 25th. In fact, the circulation center passed
through Maricopa County during the late morning hours on Sunday July 25th. This system helped spawn
multiple waves of organized thunderstorms that lead to periods of severe weather, heavy rainfall, and
flash flooding across six states encompassing the Desert Southwest. A GOES-16 Water Vapor loop showing
much of the IT’s path can be viewed here.
Mesoscale Analysis and Storm Summary:
Four general waves of storms spanning four days brought widespread rain to most of Maricopa County.
While the IT proved to be the larger scale catalyst for the duration of the event, each wave of storm
activity had unique mesoscale features and drivers worth discussing. Additional information on the heavy
rainfall and flash flooding potential/setup conveyed by the Storm Prediction Center (SPC) and/or
Weather Prediction Center (WPC) was also provided. The National Weather Service Phoenix WFO created
a radar loop covering most of the event which can be viewed here. This loop provides a visual context to
the following summary.

3

The first wave of thunderstorms began during the evening hours of Thursday July 22nd and continued into
the early morning hours Friday. Multiple outflow boundary collisions, generated from late afternoon
higher terrain convection, led to the development of severe t-storms across portions of the central
Phoenix Valley. More details on the near-storm environment provided by SPC can be found here.
Initially, damaging wind gusts were the main impacts from these storms. However, as activity matured a
greater flash flood threat emerged over the Phoenix urban corridor. A large cluster of nearly stationary
storms dropped 1.00”-2.40” in a ninety-minute period over Scottsdale. There were numerous reports of
urban flooding and road closures around Old Town Scottsdale. District gages measured large flows along
Indian Bend Wash (IBW) and its tributaries. Additional heavy rain (0.50”-1.50”) fell across portions of the
southeast Valley including Chandler, Mesa, Queen Creek, and the San Tan Valley. Twelve hour rainfall
totals from the ALERT network can be viewed here.
Round two got underway just after dawn on Friday the 23rd and continued into the evening hours.
Activity from the night before grew upscale into a mesoscale convective system across central AZ. This
feature slowly moved south across Maricopa and Pinal Counties providing a near steady-state environment
for training showers and t-storms. A full description of the heavy rain and flash flooding potential was
conveyed by the Weather Prediction Center through its mesoscale precipitation discussions here and
here. Rainfall totals in the 1.00”-4.00” range were recorded across northern county watersheds.
Notable flows were recorded in New River, Skunk Creek, Cline Creek, and Cave Creek. Additional
flooding was reported along IBW and in the Town of Fountain Hills. District dams including New River,
Adobe, and Cave Buttes ultimately saw small impoundments due to runoff from this bout of rain. Twelve
hour rainfall totals from the ALERT network can be viewed here.
The third wave began just after midnight on Saturday July 24th and continued through the late morning
hours. A decaying tropical wave moved south out of Gila and Yavapai Counties and across the easternhalf of Maricopa County. Showers mixed with embedded t-storms brought longer-duration moderate
rainfall to Scottsdale, Tempe, Chandler, Mesa, Gilbert, Queen Creek, and Apache Junction. More details
on the setup are provided by WPC here. In general, District gages received 0.25”-1.00”. This rain
combined with already soaked watersheds from the previous day was enough to trigger flows in area
washes/channels including Indian Bend Wash, Queen Creek, and the East Maricopa Floodway. District
gages also measured small impoundments behind Vineyard and Rittenhouse dams. Twelve hour rainfall
totals from the ALERT network can be viewed here.
The fourth wave spanned the late evening of July 24th straight through the afternoon of July 25th. A
decaying mesoscale convective vortex with showers and embedded t-storms rolled southwest off the
higher terrain into northern and western portions of Maricopa County Saturday night lasting into the predawn hours on Sunday. The District’s mesonet recorded anywhere from 0.25”-1.00” with this line which
helped soak watersheds. After sunrise, numerous convective t-storms developed across the central and
west Valley lasting into the afternoon hours. The main driver of this activity was forcing from the heart
of the disturbance as it passed through southcentral AZ. More details on the setup from WPC can be
found here. The most notable rain and flooding occurred from the I-17 corridor west through the White

4

Tank Mountains where communities saw anywhere from 1.00”-3.00”. Numerous reports of urbanized
flooding of roads, neighborhoods, channels/basins were recorded in Surprise, Sun City, Avondale and
Buckeye. District stream gages also measured flows on Rainbow Wash, Waterman Wash and Bullard
Wash. Twenty-four hour rainfall totals from the ALERT network can be viewed here. The IT finally
shifted west/northwest out of the region on Sunday evening bringing the event to a close.

4-Panel 12Z (5:00am MST) Synoptic Setup 07/23/2021
FIGURE 1

Figure 1: depicts the synoptic setup at 12Z (5:00 AM MST) on July 23rd, 2021. The images are from the Storm Prediction
Center upper air maps archive. A) is the 850mb map: the black lines are heights, the red dashed lines are isotherms,
the green lines are isodrosotherms, blue barbs are wind speed, and station observations are plotted at each available
location. B) is the 700mb map: variables colored the same as A. C) is the 500mb map: variables colored the same as
in A. D) is the 300mb map: the black lines are stream lines, the yellow lines are divergence, and station observations
are plotted at each available location.

5

PRECIPITATION
Summary Statistics:
FIGURE 2

Figure 2 above presents a plot of rainfall amounts for all FCDMC ALERT rain gages for the period 7/22/2021 0:00 through
7/25/2021 24:00. Thirteen gages, mostly in the west and southwest County, recorded no rain, and one gage failed to operate.
Tabular hourly data for all gages for the 4-day period is available here.

FIGURE 3

Figure 3 above presents an image of rainfall amounts for all FCDMC ALERT rain gages for the period 7/21/2021 12:00 through
7/25/2021 12:00. Click the image for a full-size view in your browser. Use CTRL +/- to zoom in/out.

6

Pre-Storm: Rainfall from 7/21/2021 at Noon through 7/22/2021 at Noon

FIGURE 4

Figure 4 above presents an image of rainfall amounts from gage-adjusted radar rainfall estimates for the period
7/21/2021 12:00 through 7/22/2021 12:00. To see a map of the recorded gage amounts for this period click here.

7

Rainfall from 7/22/2021 at Noon through 7/23/2021 at Noon
FIGURE 5

Figure 5 above presents an image of rainfall amounts from gage-adjusted radar rainfall estimates for the period
7/22/2021 12:00 through 7/23/2021 12:00. To see a map of the recorded gage amounts for this period click here.

8

Rainfall from 7/23/2021 at Noon through 7/24/2021 at Noon
FIGURE 6

Figure 6 above presents an image of rainfall amounts from gage-adjusted radar rainfall estimates for the period
7/23/2021 12:00 through 7/24/2021 12:00. To see a map of the recorded gage amounts for this period click here.

9

Rainfall from 7/24/2021 at Noon through 7/25/2021 at Noon
FIGURE 7

Figure 7 above presents an image of rainfall amounts from gage-adjusted radar rainfall estimates for the period
7/24/2021 12:00 through 7/25/2021 12:00. To see a map of the recorded gage amounts for this period click here.

10

Post Storm: Rainfall from 7/25/2021 at Noon through 7/26/2021 at Noon
FIGURE 8

Figure 8 above presents an image of rainfall amounts from gage-adjusted radar rainfall estimates for the period
7/25/2021 12:00 through 7/26/2021 12:00. To see a map of the recorded gage amounts for this period click here.

11

TABLE 1

Table 1: Return period calculations were performed for all FCD rain gages for the durations shown in the
Table above (1 hour – 4 days). Gages with at least a 10-year return period for any duration are listed in the
Table. The Table is sorted by the column labeled “Located”. Rain gage elevations are conditionally coded
from yellow (955’) to green (4,615’), while return periods are coded from white (1 year) to red (312 years).
Click on the Table to download a PDF for detailed viewing. Data from six individual gages are presented on
the following pages - the figures include a location map, daily rain totals, selected return periods and an
hourly rainfall plot.

12

FIGURE 9

FIGURE 10

FIGURE 11

13

FIGURE 12

FIGURE 13

FIGURE 14

14

Runoff and Impoundment Summary
As discussed in the precipitation section, abundant and excessive rainfall fell across and around
Maricopa County from July 22 – 25, 2021 which in turn caused runoff at many locations in the
county. This section will discuss runoff on a stream/watershed basis for the three watersheds
that were impacted the greatest: Skunk Creek, New River, and Indian Bend Wash. Additional
stream gages receiving runoff are discussed after the watershed summaries.
Skunk Creek Watershed
The Skunk Creek watershed is located in north-central Maricopa County and crosses I-17 near the
Loop 303. It is surrounded by the New River watershed on the north and west and Cave Creek on
the east. Rainfall amounts over 5 inches fell on the upper watershed that caused significant
runoff and amd a minor impoundment at Adobe Dam.

FIGURE 15

Figure 15 – Skunk Creek watershed above Adobe Dam

15

Summary of Skunk Creek Flows, July 23, 2021

Gage

ID

Peak Q
(cfs)

Peak
Stage
(feet,
GH)

Return
Period (yrs)
(1)

Skunk Creek near
New River

66207

395

2.29

3

Cline Creek

66007

2,694

6.90

20

Skunk Creek at
Desert Hills Dr.

64807

6,000 (2)

9.48

Skunk Tank Wash

64707

1,278

7.63

65707

11,278

6.87

64907

3,186

6.78

Sonoran Wash

65907

79

1.83

Skunk Creek at I-17

65807

9,429

5.74

Adobe Dam Pool

65017

499 ac-ft

10.72

Adobe Dam Outlet

65007

460

5.00

Skunk Creek at
Carefree Hwy.
Skunk Creek at
Dixileta Dr.

70

18

TABLE 2
Date/Time of
Peak
7/23/2021
12:49
7/23/2021
12:55
7/23/2021
13:47
7/23/2021
13:34
7/23/2021
14:26
7/23/2021
14:54
7/23/2021
14:16
7/23/2021
15:42
7/23/2021
20:35
7/23/2021
18:40

(1) NOTE: Return Periods are estimated from several sources and are not considered definitive. Sources
include Floodplain Delineation Studies, calculations using USGS Bulletin 17B & C, and the USGS
StreamStats website. (2) Station was washed away at 6,000 cfs.

Select Hydrographs are shown on the following pages, highlighting the July 23 peak flow event.
FIGURE 16

16

FIGURE 17

FIGURE 18

This station was
washed away at a
flow rate of 6,000
cfs.

FIGURE 19

17

FIGURE 20
20

FIGURE 21

FIGURE 22

Significant runoff occurred in the watershed among the gaged locations. One gage failure
occurred at Skunk Creek at Desert Hills Drive (#64807, Fig. 17) The station had been relocated
in May 2021, and unfortunately the gage was washed away in the high-water flows, right after
the peak of about 6,000 cfs was recorded just before 2 pm on July 23, 2021.

18

The flow on Skunk Creek was high enough at Dixileta Drive to overtop the roadway and spill west
out onto I-17.
FIGURE 23

I-17 Freeway looking at the Dixileta Drive bridge. Source: ADOT camera.

FIGURE 24

Skunk Creek at Dixileta Drive, July 24, 2021.
A smaller magnitude runoff event occurred in the Skunk Creek watershed on July 25, 2021, and
its data are included in the hydrographs above (Figs. 16-21) and summarized in the table below.
Nevertheless, rainfall produced a record flow at Sonoran Wash.

19

Summary of Skunk Creek flows, July 25, 2021
Gage Name

TABLE 3

ID

Peak Q

Peak GH

Date/Time of Peak

Skunk Tank Wash

64707

242

5.48

7/25/2021 16:25

Skunk Creek at Carefree Hwy

65707

1,160

3.38

7/25/2021 15:05

Skunk Creek at Dixileta Dr.

64907

752

2.54

7/25/2021 16:05

Sonoran Wash

65907

1,131

5.72

7/25/2021 10:09

Skunk Creek at I-17

65807

1,765

2.63

7/25/2021 11:12

New River Watershed
The New River watershed is located north and west of the Skunk Creek watershed. There are
fewer gages on this watershed than Skunk Creek, but it too ends at an impoundment at New
River Dam. A very large flow was recorded at the upstream gage, New River Fire.
FIGURE 25

Figure 24 – New River Watershed (darker purple) above New River Dam

20

Gage Name
New River Fire
New River at
SR303L
New River Dam
Pool

TABLE 4
Summary of flows on New River, July 23, 2021
Return
Date/Time of
ID
Peak Q
Peak GH
Period
Peak
(years)(1)
62707
15,962
7.88
70
7/23/2021 14:26
7/23/2021 22:00
62213
7,639
5.94
15
(est.)
62017

260 ac-ft

6.63

7/24/2021 02:35

(1) NOTE: Return Periods are estimated from several sources and are not considered definitive.

Fields visits indicated that these flows are reasonable. The gage at New River at SR303L failed
to operate during the event. The peak stage was recovered from the crest-stage gage at the
site. The date and time of peak at that location are estimated and unknown. There were no
flows recorded for the July 25, 2021 event. Below are hydrographs for the event.
FIGURE 26

FIGURE 27

21

Flows downstream of New River Dam flow into New River channel to the Agua Fria River near
Camelback Road. No significant flow occurred downstream, but several recreation trails in
Peoria were likely affected by the runoff below the dam.
Indian Bend Wash below the CAP canal
Indian Bend Wash and the City of Scottsdale experienced significant rainfall and runoff beginning
the late evening of July 22, 2021. A second higher magnitude runoff occurred later in the day on
July 23, 2021.
The Indian Bend Wash watershed has contributing area below the CAP canal and Reach 11 Dikes,
which completely remove the upper watershed from contributing to flows.
FIGURE 28

Figure 28 – Indian Bend Wash watershed above McKellips Rd. Gage

A summary of the flows throughout the period are given on the following page.

22

Summary of flows on Indian Bend Wash, July 23 & 25, 2021
Gage
Name
IBW at
Sweetwater
Ave
IBW at
Shea Blvd
Berneil
Wash
Lake
Margherite
IBW
Interceptor
Channel
IBW below
Indian Bend
Rd
IBW at
McDonald
Dr
IBW at
Indian
School
Road
Granite
Reef Wash
IBW below
McKellips
Rd

ID

Peak
Q

Peak
GH

Date/Time
of Peak

58307

272

1.85

7/23/2021
9:22

59507

117

1.18

7/23/2021
6:05

Peak
Q

Peak
GH

1,226

2.45

59207

250

1.07

59007

58

1.10

Date/Time
of Peak

7/23/2021
11:24
7/23/2021
12:00
7/23/2021
11:49

Peak
Q

Peak
GH

Date/Time
of Peak

281

1.9

7/25/2021
1:37

535

1.8

87

0.49

7/25/2021
5:04
7/25/2021
4:15

56807

230

2.56

7/23/2021
0:00

215

2.49

7/23/2021
13:30

37

1.24

7/25/2021
6:00

56307

294

2.94

7/23/2021
0:13

900

4.11

7/23/2021
13:10

176

2.49

7/25/2021
5:01

57207

1,170

1.67

7/23/2021
0:57

1,833

2.47

7/23/2021
13:36

517

0.73

7/25/2021
6:00

56507

1,738

3.68

7/22/2021
22:00

2,359

4.33

7/23/2021
13:59

700

2.34

7/25/2021
6:00

57507

219

7.68

7/22/2021
22:10

27

3.57

7/25/2021
5:15

55707

248

1.4

7/23/2021
1:11

102

0.92

7/25/2021
12:00

484

1.98

7/23/2021
15:41

TABLE 5
Flows were nowhere near records, but they did cause unbridged crossings within the City of
Scottsdale to be closed for several days. Starting on the next page are hydrographs for each
station for the period. The hydrographs are in stream order starting upstream.
FIGURE 29

23

FIGURE 30

FIGURE 31

FIGURE 32

24

FIGURE 33

FIGURE 34

FIGURE 35

25

FIGURE 36

FIGURE 37

Flows from Indian Bend Wash discharge directly into the Salt River and Tempe Town Lake east of
Scottsdale Road. These in turn affect the Salt River gage at Priest Drive, just below the Tempe
Town Lake dam.
FIGURE 38

26

Other Significant Runoff
As noted at the beginning of this section, aside from the three specifically discussed watersheds
above, there were other runoff and impoundments to note.
The Cave Creek watershed which is east of both Skunk Creek and New River had some runoff,
but it was not of the magnitudes received by the two watersheds to the west.
The Agua Fria River at Buckeye Road (#85307) had a rather large flow that was likely the result
of flow from the ADOT I-10 drain along the north side of I-10. The gage recorded a peak
discharge of 6,176 at a verified peak stage of 1.32 feet on July 25.
Agua Fria at Buckeye Rd.

85307

6,176 cfs

1.32 feet gage
height

7/25/2021 14:37

The Hassayampa River watershed was not largely impacted. The gage on the river at US 60
received some runoff of note.
Gage Name
Hassayampa R at US60
Hassayampa R at US60
Hassayampa R at US60

ID
45707
45707
45707

Peak Q
1,546
220
2,517

Peak GH
1.77
1.02
2.14

Date/Time of Peak
7/21/2021 16:45
7/23/2021 20:48
7/25/2021 13:07
TABLE 6

Another station of note, Blue Tank Wash (#52707, NE of Wickenburg) recorded two small flows,
but it was the first recorded runoff since the station was installed in June 2019.
As far as runoff elsewhere, the East Maricopa Floodway (EMF) had some moderate flows along
the entire reach. All flows were relatively small with the exception of the station at Queen
Creek Road. As of the time of publication, the channel was too wet to perform any type of
reconnaissance to verify the discharge values at that station. A field visit did verify that the
recorded stages were reasonable. However, the rated peak flow was significantly higher than
any upstream or downstream gage and further investigation is warranted.
Impoundments
Several dams received enough runoff to record small impoundments. In the sections above for
both Skunk Creek and New River, impoundments at Adobe Dam and New River Dam have already
been shown. As mentioned, Indian Bend Wash does not flow to a dam, but rather the Salt River
so no impoundment data were part of that discussion.
In the Wickenburg area (Hassayampa River watershed), the three small FCD dams in town all
showed small impoundments.

27

Gage Name

ID

Casandro Dam
Sunset FRS
Sunnycove FRS

53007
46007
46507

Peak
Volume
(acre-feet)
2.0
2.8
0.8

Peak
Stage
(feet GH)
2.63
5.13
3.93

Date/Time of Peak
7/25/2021 9:13
7/25/2021 9:19
7/25/2021 10:20
TABLE 7

Along the White Tank Mountains, the two largest structures, White Tank FRS #3 and #4, both had
small impoundments.
Gage Name

ID

White Tank FRS #3
White Tank FRS #4

87307
87807

Peak
Volume
(acre-feet)
111
29

Peak
Stage
(feet GH)
1.7
4.2

Date/Time of Peak
7/25/2021 10:28
7/25/2021 18:00
TABLE 8

Finally, in the southeast valley, several structures in Pinal County recorded impoundments, with
Magma FRS (#42307, operated by Magma FCD) having the second largest impoundment since
2008 when the structure was re-built.
ID

Peak
Volume
(acre-feet)

Magma FRS

42307

650.8

Rittenhouse FRS

37207

171.7

7.22

7/24/2021 17:21

Vineyard FRS

37007

802.5

3.83

7/25/2021 10:17

Gage Name

Peak Stage
(feet GH/feet
NAVD88)
12.51 /
1,613.91

Date/Time of Peak
7/25/2021 16:02

TABLE 9
Summary
The weather event of July 22 – 25, 2021 dropped significant precipitation over a wide area, but
caused major runoff on two specific watersheds, Skunk Creek and New River, with the upper
parts of both watersheds besieged by high runoff. Much of that runoff attenuated before
entering their respective impoundment dams. Indian Bend Wash also received significant runoff,
enough to close roads and golf courses for several days.
The remainder of the stream gages had flows that were typical of summer monsoon rain and
runoff and were not of great magnitude with the noted exception of Magma FRS having its
second highest impoundment of record since dam reconstruction in 2008.

28

Public Outreach Summary
The District has a total of 410 ALERT stations located throughout Maricopa and adjoining
Counties. All of the information for these stations is available in real-time on our webpage.
During this event (July 22-25) we used social media to help inform the media and the public of
current weather and rainfall information.
Our best platform continues to be Twitter @FCDFloodInfo. We are up to 2,560 followers which
consist of different agencies, news media and the public. We had a total of 156,524 impressions
and 8,050 engagements over this 4-day period. Our top post had over 21,628 impressions.

FIGURE 39

Our Facebook page “Flood Control District of Maricopa County” had 4,506 impressions and 740
engagements over this 4-day period. Our top post has a total of 1,024 impressions.

FIGURE 40

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Our ALERT Interactive Data Display Map is the primary tool for access to our ALERT data. During
this event there were a total of 73,091 sessions for both the desktop, mobile and Flood Response
Plan Online Map versions combined. The highest impact day was July 23rd with 30,390
pageviews. That is the highest daily pageviews since we started tracking in June 2013. The
second highest was July 25th with 20,662.

FIGURE 41

Additionally, the Flood Warning Branch and the Information, Outreach and Support Division (IOS)
at the Flood Control District contributed to media interviews and stories. These included
AZCentral, ABC15, KJZZ, Arizona Radio Company, FOX10 Live, Telemundo and Wittmann
Emergency Alerts (online outlet).

30

IOS made three posts on Instagram, making 281 impressions...
FIGURE 42a

FIGURE 42b

FIGURE 42c

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... and six Twitter posts in Spanish that earned 1.1 thousand impressions.

FIGURE 43

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DATA SOURCES
1.

NOAA National Severe Storms Laboratory; Multi-Radar Multi-Sensor System, Norman, OK
http://nmq.ou.edu/

2.

National Weather Sevice, Storm Predicition Center, Norman, OK:
http://www.spc.noaa.gov/obswx/maps/

3.

Flood Control District of Maricopa County, Phoenix, AZ
http://www.maricopa.gov/floodcontrol and http://www.reportaflood.org

4.

National Weather Service, National Hurricane Center, Miami, FL:
http://www.nhc.noaa.gov/?epac

5.

NOAA Atlas 14 Point Precipitation Frequency Data Server,
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html

6.

National Weather Service, Weather Prediction Center, College Park, MD:
http://www.wpc.ncep.noaa.gov/

7.

National Weather Service, Tucson WFO, Monsoon Tracker, Tucson, AZ:
https://www.wrh.noaa.gov/twc/monsoon/monsoon_patterns.php

8.

National Weather Service, Weather Prediction Center, College Park, MY:
http://www.wpc.ncep.noaa.gov/

9.

National Weather Service, Tucson WFO, Monsoon Tracker, Tucson, AZ:
https://www.wrh.noaa.gov/twc/monsoon/monsoon_patterns.php

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