Two rounds of scattered thunderstorms moved northwest across southeast Arizona. The first round moved through in the early morning hours producing flash flooding in Nogales.
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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.
The episode as NWS TWC wrote it up.
Two rounds of scattered thunderstorms moved northwest across southeast Arizona. The first round moved through in the early morning hours producing flash flooding in Nogales. The second round in the afternoon produced gusty winds in Safford and additional flash flooding in the Tucson Metro area.
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 Tucson, AZ wrote its last area forecast discussion before the first event at Jul 17, 3:30 AM MST, 2 hours earlier.
Area Forecast Discussion
National Weather Service Tucson AZ
330 AM MST Mon Jul 17 2017
.SYNOPSIS...Expect widespread showers and thunderstorms into
Tuesday. Heavy rainfall will occur with the stronger thunderstorms.
Isolated to scattered mainly afternoon and evening thunderstorms
will then prevail Wednesday into next weekend. The greatest daily
thunderstorm coverage will generally be east to south of Tucson.
&&
.DISCUSSION...IR satellite imagery depicted warming cloud tops
associated with a decaying MCS over central/southern Arizona at this
time. Scattered showers were ongoing from southern Pinal County
southward across the Tucson metro area, then a line of showers and
thunderstorms extended from just south of Tucson westward to near
Organ Pipe National Monument. Other showers and thunderstorms have
developed during the past 30-60 minutes near the international
border adjacent Santa Cruz/southwest Cochise Counties.
KEMX WSR-88D radar imagery also depicted a cyclonic twist
representing an MCV just south of Florence. Given the warming cloud
tops, showers/tstms should gradually dissipate during the next few
hours. The 17/06Z Univ of AZ WRF-NAM suggests the bulk of this
activity should end around 8 a.m. MST this morning.
Several HRRR solutions as well as the Univ of AZ WRF-NAM and WRF-GFS
were in good agreement that showers/tstms will redevelop late this
morning or by early this afternoon mainly south-to-southeast of
Tucson. A veering mid-level steering flow more toward the east and
southeast should translate into west-to-northwest moving/propagating
precip echoes into tonight. Have noted that the high-res models keep
northeastern sections generally dry this afternoon, but showers/
tstms are depicted to occur from near Tucson northeastward into the
White Mountains this evening. The favored area for showers/tstms late
tonight appears to be northwest of Tucson.
Per coordination with the Weather Prediction Center (WPC) and
neighboring WFO's, the Flash Flood Watch for all of southeast
Arizona remains in effect through this evening. Although ample
moisture will be available, various NWP model solutions suggest
fairly robust storm motions will occur. This may mitigate the threat
for widespread flash flooding.
At any rate, there were some model depictions from 24 hours or
longer ago that Tuesday may have been a relative "down" day
regarding coverage of showers/tstms. The 17/00Z GFS/ECMWF/CMC
suggest that Wednesday may now be the relative "down" day regarding
coverage of showers/tstms. Given the progged available moisture, the
presence of inverted upper troughs, and a more southeasterly mid-
level steering flow, forecast confidence of "down" days depicted via
the models is somewhat to considerably low at this time.
Thus, have made only very minor changes to the inherited PoPs into
next weekend. The scenario Wednesday into next Sunday continues with
isolated to scattered mainly afternon and evening showers/tstms. The
generally southeasterly mid-level flow regime and model generated
liquid rainfall amounts favors locales east-to-south of Tucson with
the greatest daily coverage, and lesser coverage of showers/tstms
west of Tucson.
Below normal daytime temperatures will prevail for much of southeast
Arizona into next weekend, with today and Tuesday forecast to be the
relatively coolest days.
&&
.AVIATION...Valid thru 18/12Z.
Scattered -TSRA/-SHRA KTUS vicinity westward ending around 15Z this
morning. Scattered -TSRA/-SHRA developing mainly south-to-southeast
of KTUS by early this afternoon, then widespread -TSRA/-SHRA later
this afternoon into tonight. Otherwise, VFR conditions with cloud
decks generally 6k-12k ft AGL, and surface wind variable in
direction mainly less than 12 kts. Aviation discussion not updated
for TAF amendments.
&&
.FIRE WEATHER...Widespread showers and thunderstorms will prevail
through Tuesday. Thereafter, the greatest daily coverage of
thunderstorms Wednesday into next weekend is expected to generally
occur east to south of Tucson. Enough moisture will remain for
isolated coverage of thunderstorms west of Tucson. Below normal
daytime temperatures will also dominate much of this week.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through this evening for AZZ501>515.
&&
Francis
Visit us on Facebook...Twitter...YouTube...and at weather.gov/TucsonThe Tucson radar (KEMX), 68 km away, was scanning. The volume nearest the first event began at 12:30 UTC.
2 flash flood, 1 thunderstorm wind. Local standard time, as filed.
Ephriam Wash overflowed its banks at Western Avenue bridge. Nearby rain gauge recorded 2.17 inches of rain in about an hour.
Thunderstorm produced a gust of 58 mph at Safford Airport. Outflow winds continued toward the northwest to the north of Safford.
Heavy rain caused flash flooding of the Camino de Oeste Wash. This caused Silverbell Road to be closed between Sweetwater and Goret roads. Swift water rescue occurred where Camino de Oeste Wash crossed Lloyd Bush Drive. Stone Avenue underpass south of 6th Street flooded 7 feet deep.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2017Every state in 2017This day in weather historyWarnings in Arizona, July 2017
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: 711016, 711015, 711369.