An upper level low and tropical moisture created favorable conditions for severe weather with isolated to scattered storms forming during the evening mainly from Tucson eastward. These storms produced blowing dust in Pinal County, significant straight-line wind damage in Tucson and an EF-1 tornado in Willcox.
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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.
An upper level low and tropical moisture created favorable conditions for severe weather with isolated to scattered storms forming during the evening mainly from Tucson eastward. These storms produced blowing dust in Pinal County, significant straight-line wind damage in Tucson and an EF-1 tornado in Willcox.
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 Sep 23, 2:50 PM MST, 50 minutes earlier.
Area Forecast Discussion National Weather Service Tucson AZ 250 PM MST Mon Sep 23 2019 .SYNOPSIS...Showers and scattered thunderstorms will develop across the area overnight and continue through much of Tuesday with local severe storms possible through the evening. Local areas of heavy rain is expected late tonight through Tuesday morning with local flooding possible. After a break in the rain late Tuesday into early Wednesday another round of potentially heavy rain is possible late Wednesday into Wednesday night. Drier weather is then forecast this weekend. && .DISCUSSION...We currently have an air mass over the forecast that is primed and ready for convection with abundant, high levels of moisture, instability and wind shear. Despite this, the convection across our area is rather lazy at the moment. Current mesoanalysis shows the upper level forcing that is needed to make use of this energy remains to our north leaving our area in area of unfavorable vertical motion. However, that area of lift is expected to sag to the south through the evening hours bringing about the threat for thunderstorm development this evening. Will also be watching outflow boundaries moving south from the strong/severe thunderstorms to our north. If we can get the convective initiation going, storm development will be rapid with a potential for storms to quickly evolve into rotating storms due to the shear aloft. That convection would be isolated to scattered through at least midnight with isolated flooding possible until then. Then eyes turn toward late tonight through early to mid afternoon Tuesday. As the upper low continues to sag to the south tonight our area comes into favorable dynamics with plenty of moisture available. All convective allowing models and most larger scale models are pointing to more widespread heavier rains developing after midnight tonight across large parts of southeast Arizona, basically the area covered by our Flash Flood Watch. What it is looking like is repetitive bands of moderate to heavy showers with embedded thunderstorms through this period of time. Confidence is increasing for this to occur for areas east of Sells including the Tucson metro area. There is potential for flash flood warnings to be issued before dawn with impacts during the morning commute and continuing through the remainder of the morning if this potentially significant scenario develops as it looks like it could. An upper low pressure center this deep, at this time of year, with access to tropical moisture is a rare event and will need to be watched carefully as things can develop quickly as was witnessed early this morning east of Phoenix. The showers and thunderstorms will diminish Tuesday evening with a relatively quiet/dry period Tuesday night into Wednesday morning. By Wednesday morning the upper low should have settled down over northern Baja (pretty amazing for September) with southerly flow across southern Arizona and a deep tap into tropical moisture, and our area should be in the favored NE quadrant of the upper low. Wednesday afternoon well into Wednesday night a north-south oriented rain band should develop in this scenario which will set up over a location and linger, which is a set up for a relatively narrow band (less than 100 miles) of heavy rain over an 8-12 hour period. The problem is where will that sets up as under the band flooding is a threat while outside of that band just scattered showers or storms. Models have varied that band from the central portion of the forecast area (eastern Pima/Santa Cruz) to the western portion (western/central Pima county). It all depends on the final position of the upper low so stay tuned to forecast updates over the next day or two. At this time the best bet is for the central part of the forecast area west to central Pima county. The upper low will be slow to leave Thursday into Friday but at that point the convection should be more scattered and less of a threat. It will remain cool through this entire week into the early part of the weekend. For the weekend we should be dry, however we will remain in a "troughy" pattern keeping us a bit on the cooler side. && .AVIATION...Valid through 25/00Z. Isolated to scattered TSRA/SHRA becoming more widespread through the evening/overnight hours and continuing thru Tuesday. Some storms could be strong to severe with hail and strong wind gusts. Ceilings will generally be SCT-BKN 4k-8k ft MSL with MVFR and even occasional IFR ceilings in and around thunderstorms. SFC wind generally less than 12 kts, favoring a SWLY/WLY direction thru 24/03Z and variable in direction at other times. Wind gusts to 40+ kts near TSRA and with any thunderstorm outflow boundaries. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated to scattered showers and thunderstorms becoming widespread tonight into Tuesday ahead of a low pressure system. Locally heavy rainfall and strong thunderstorm outflows will be possible. Scattered showers and thunderstorms will then continue Wednesday into Thursday as the upper low moves east. Dry conditions are then expected Friday through the coming weekend. 20-foot winds will be terrain driven and less than 15 mph, except in the vicinity of thunderstorms where strong, gusty and erratic winds will be possible. && .TWC WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from 6 PM MST this evening through Tuesday evening for Azz501-504-507>509-511>515. Flash Flood Watch through Tuesday evening for Azz501-505-506. && PUBLIC...Cerniglia AVIATION....Zell FIRE WEATHER...Zell Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
The Phoenix radar (KIWA), 52 km away, was scanning. The volume nearest the first event began at 00:11 UTC.
3 thunderstorm wind, 1 dust storm, 1 hail, 1 tornado. Local standard time, as filed.
Thunderstorm winds generated a wall of dust, or haboob, which moved through Eloy and continued south towards Marana reducing visibility to near zero.
Thunderstorm winds damaged power poles in Bylas.
Dozens of trees were downed, there was damage to several residences roofs and fences. At least two vehicles were damaged from falling trees and limbs, and at least one road sign was bent over from the strong winds.
Hail up to 1.5 inches was reported in the Willcox area.
Straight-line wind damage occurred in and around Willcox. Damage to multiple structures along with multiple downed power poles. Many trees were downed as well. A fifth wheel trailer was tipped over with two occupants inside. Both suffered non-life-threatening injuries.
A tornado touched down near Cox and Hamilton Rd, and moved northeast for approximately 1.7 miles causing extensive damage. One mobile home was lifted and moved off its foundation. Five people inside, including three children sustained minor injuries. The roof of another mobile home was ripped off and power poles were snapped. Two other homes were damaged along with a large machine shed-type storage building and several trees were snapped in half or uprooted. The damage survey concluded that peak wind speeds from the tornado were between 90 and 100 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2019Every state in 2019This day in weather historyThe tornado archive for Arizona, 2019Warnings in Arizona, September 2019
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: 857035, 857690, 857042, 857057, 857049, 857061.