Arizona, 2017Flash Flood in Arizona, January 20 to 21, 2017
January 20 to 21, 2017 · NWS PSR · 1 event in 1 county or zone
A weather system moving into Arizona on Friday January 20th led to the development of widespread locally heavy rains across portions of the central Arizona deserts which affected the northern portion of the greater Phoenix metropolitan area. During the late afternoon and evening hours, trained spotters reported locally heavy rains with up to 2 inches falling within a 6 hour period.
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- Deaths
- 0
- Injuries
- 0
- Property damage
- $10,000
- Crop damage
- None recorded
- Events
- 1
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
A weather system moving into Arizona on Friday January 20th led to the development of widespread locally heavy rains across portions of the central Arizona deserts which affected the northern portion of the greater Phoenix metropolitan area. During the late afternoon and evening hours, trained spotters reported locally heavy rains with up to 2 inches falling within a 6 hour period. Beginning late at night and into the very early morning hours on January 21st, heavy rains caused flooding and flash flooding along Interstate 17 near the towns of Anthem and New River. This resulted in the need for a water rescue in a flooded wash just east of the interstate. Flash flood warnings were not issued, but flood advisories were posted continuing into the morning hours on the 21st.
What forecasters said that day
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Phoenix, AZ wrote its last area forecast discussion before the first event at Jan 20, 9:45 PM MST, 15 minutes earlier.
Area forecast discussion, Jan 20, 9:45 PM MST, 15 minutes before
Area Forecast Discussion
National Weather Service Phoenix AZ
945 PM MST Fri Jan 20 2017
.SYNOPSIS...
A series of Pacific storms will move into the region over the next
few days. The strongest and wettest storm will affect the region
tonight through early Saturday. Snow accumulation will be above 5500
feet. A Winter Storm Warning is posted for the mountains east of
Phoenix through Saturday afternoon. A break in the weather is
expected Saturday night and early Sunday, however another Pacific
storm is expected into the region later Sunday through next Tuesday.
Dry but cool weather will settle over the region for the middle of
next week.
&&
.DISCUSSION...
An expansive area of rainfall has developed across much of western
and central Arizona, in association with a strong Pacific storm
system moving across the Southwest. Observed precipitable water
values both at Tucson and San Diego were above the 90th percentile
for this time of year. Moderate to locally heavy rainfall rates are
expected to peak through early morning across the greater Phoenix
area, while persisting a bit longer over higher terrain areas north
and east of Phoenix. A winter storm warning also remains in effect
for elevations above 5500 feet for southern Gila County. The radar
estimated freezing level is currently near 6000 feet, and should
continue to fall overnight with heavy snow likely at higher elevation
areas.
The potential for strong wind gusts also remains a concern into early
tomorrow morning. Surface winds have veered towards the southwest
ahead of a cold front moving through western Arizona, and should
continue strengthening given 30-40 kt of flow observed in the KIWA
VAD wind profiler above 1 km. Wind gusts of 30 to occasionally near
40 mph, especially south and east of Phoenix, will be possible this
evening, before gradual weakening occurs as a 700-mb speed max
quickly shifts into New Mexico.
Precipitation chances will decrease from west to east overnight,
becoming focused across the higher terrain during the afternoon
through tomorrow afternoon. Otherwise, mostly drier conditions with
breezy west winds appear probable to develop across the lower
deserts.
&&
.PREVIOUS DISCUSSION...
Sunday and Monday Night...
Another Pacific weather system will be approaching the southern CA
coast on Sunday. Considerable clouds will spread into the region
Sunday afternoon through Monday. A slight chance of showers will
develop Sunday, increasing to a chance of showers Sunday night and
Monday. Showers will dissipated from west to east Monday night.
Tuesday through Friday...
A few lingering showers are possible over the mountains east of
Phoenix Tuesday, otherwise dry and rather cool weather is expected
most of next week. Afternoon temperatures should fall to 6 to 8
degrees below normal.
&&
.AVIATION...
South-Central Arizona including KPHX, KIWA,and KSDL:
Periods of moderate to heavy rainfall continue to affect area
terminals this evening, with reductions in visibility down to 1-2
miles and ceilings down to 1000 feet possible at times. Surface winds
have shifted towards a general southerly direction, and will continue
to veer towards the southwest as a cold front moves into central
Arizona, while a few gusts to 30-40 mph are possible through at least
07Z. Improvements in visibilities should occur in the wake of the
cold front as rainfall chances decrease. Ceilings should also
eventually rise as slightly drier air works into the area, currently
expected to improve to above 5k feet by 13Z.
Southeast California/Southwest Arizona including KIPL and KBLH:
Rainfall chances have decreased as a cold front has moved into
western Arizona. Lingering cloud cover with bases of 6-8k ft should
persist through 08Z at KBLH, before becoming more scattered in
nature. Surface winds have been slow to respond to stronger flow
aloft, with only occasional gusts to around 30 kt anticipated. Winds
should remain out of the west through morning with improvements in
ceiling heights and reduced cloud cover anticipated.
Aviation discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Sunday through Thursday: Another Pacific low pressure system will
move into the districts Sunday afternoon, producing additional
rainfall into Monday along with breezy to windy conditions. High
pressure will gradually rebuild across the area Tuesday and
Wednesday, resulting in a drying trend though temperatures will
remain below normal. Fire danger will remain low through the period
due to the persistent and anomalously moist conditions.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter reports of rain and snow will likely be needed later this
week.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Wind Advisory until 8 AM MST Saturday for AZZ022-023-026>028.
Winter Storm Warning until 11 AM MST Saturday for AZZ024.
CA...None.
&&
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DISCUSSION...Rogers
PREVIOUS DISCUSSION...Vasquez
AVIATION...Rogers
FIRE WEATHER...Nolte/HirschFlash Flood, Maricopa
- When
- January 20, 10:00 PM MST to January 21, 2:30 AM MST
- Where
- Maricopa County, 4.49 mi NNW of New River to 1.73 mi NNE of New River
- Cause
- Heavy Rain
- Property damage
- $10,000
- Reported by
- Trained Spotter
- Coordinates
- 33.982, -112.153
Locally heavy rains developed across the northern portion of the greater Phoenix area, along Interstate 17 and near the communities of New River and Anthem, during the evening hours on January 20th. Spotters indicated that up to 2 inches fell within a 6 hours period. The heavy rain led to flash flooding and flooding along Interstate 17 during the very early morning hours on January 21st. According to a trained spotter, as of 0130MST a water rescue was underway from a flooded wash about 1 mile east of Interstate 17 along Table Mesa Road. This was about 4 miles northeast of the town of New River. A Flash Flood Warning was not issued rather a Small Stream Flood Flood Advisory. No injuries were reported to those affected by the water rescue.
- Flash Flood
- Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
- Winter Storm and High Wind in Arizona, January 20 to 21, 2017$177,000 · 58 kt wind · 8 events
- Heavy Snow and Winter Weather in California, January 20 to 24, 201715 events
- Flooding in Illinois, January 20 to 21, 2017$16,000 · 2 events
- Heavy Snow in Arizona, January 20 to 21, 20179 events
- Heavy Snow in New Mexico, January 20 to 21, 20179 events
- Hail and Damaging Wind in Texas, January 20, 20171.75 in hail · 7 events
- Winter Storm in Utah, January 20 to 21, 20176 events
- Flash Flooding and Hail in Texas, January 20, 20171.75 in hail · 5 events
- Heavy Snow and High Wind in New Mexico, January 20 to 21, 201776 kt wind · 5 events
- Flash Flooding and High Wind in California, January 20, 201750 kt wind · 4 events
- Hail and Damaging Wind in Louisiana, January 20, 20171.25 in hail · 3 events
- Cold in Alaska, January 20 to 21, 20171 event
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 687385.