Isolated thunderstorms developed over and moved northeast across Greenlee and far eastern Cochise counties during the afternoon. One storm produced damaging winds near Duncan.
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The episode as NWS TWC wrote it up.
Isolated thunderstorms developed over and moved northeast across Greenlee and far eastern Cochise counties during the afternoon. One storm produced damaging winds near Duncan.
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 Oct 4, 9:50 AM MST, 5 hours 55 minutes earlier.
Area Forecast Discussion National Weather Service Tucson AZ 950 AM MST Wed Oct 4 2017 .SYNOPSIS...Isolated to scattered showers and thunderstorms east of Tucson into Thursday evening. Dry conditions will then prevail Friday into next Tuesday. Unseasonably warm daytime temperatures will continue through the weekend, cooling closer to seasonal normals early next week. && .DISCUSSION...Clear skies prevail across much of southeast Arizona at this time. The exceptions were over the White Mountains and near the International border adjacent Cochise County where mostly clear skies to partly cloudy skies were noted. Dew points at lower elevations valid 9 am MST ranged from the upper 30s-40s, and lower 60s dew points were observed just east of this forecast area in southwest New Mexico. The 04/12Z Univ of AZ WRF-NAM is quite similar to the 04/06Z WRF-NAM and WRF-GFS as well as several HRRR solutions with the development of showers/tstms early this afternoon mainly near the New Mexico border. Appears that showers and thunderstorms, some of which may be strong, will generally remain east of a Safford to Douglas line into this evening. The bulk of showers/tstms should dissipate or move east of this forecast area later this evening, though some may continue especially from Safford northeastward overnight into early Thursday morning. Appears that showers/tstms will develop further westward Thursday, perhaps as far west as near the Rincon Mountains just east of Tucson. At any rate, based on these solutions as well as the 04/12Z NAM12/ GFS, will likely increase PoPs across far eastern areas this afternoon and evening. May also include the mention/depiction of large hail/gusty winds as well. Otherwise, high temperatures this afternoon will be a degree-or-two warmer versus Tuesday, and will average about 5-8 degrees above normal. Please refer to the additional sections in this product for further detail. && .AVIATION...Valid thru 05/18Z. Isolated to scattered -TSRA/-SHRA mainly east of a KSAD-KDUG line especially this afternoon and evening, and again late Thursday morning. Otherwise, VFR conditions into Thursday morning. Surface wind variable in direction less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated to scattered showers and thunderstorms east of Tucson through Thursday evening. A slight chance of showers and thunderstorms continues across the White Mountains late Thursday night, then dry conditions return area-wide Friday into next Tuesday. 20-foot winds will generally be terrain driven at less than 15 mph into early next week. However, occasional afternoon gusts to 25 mph are possible. && .PREV DISCUSSION /230 AM MST/...Mid/upper level flow regime features an upper low currently over northern Nevada resulting with a large scale ridge extending from Texas into the Mid-Atlantic. This puts southeast Arizona under southwesterly flow aloft between these features. Lower level easterly to southeasterly flow is currently pushing west across southern New Mexico towards the Arizona border. Latest surface observations depict dewpoints in the upper 50's to lower 60's just to our east with satellite derived PWAT values in excess of 1 inch. This moisture will continue to move westward into Graham, Greenlee and Cochise counties today. While there is no large scale synoptic feature that will help with convection, the deeper moisture in eastern areas with MLCAPE values in excess of 1000 j/kg combined with steep low to mid lapse rates and 0-6 km bulk shear of around 30 kts will aid in isolated to scattered thunderstorm development. A strong storm or two can't be ruled out this afternoon. The best chance for storms will be east of a Safford to Douglas line with isolated to scattered showers and thunderstorms persisting across eastern areas this evening and tonight. A fairly similar setup on Thursday continues with the chance of showers and thunderstorms once again for locales to the east of Tucson. Thereafter, as the aforementioned upper low shifts into Montana and eastward, the flow will become more westerly to northwesterly aloft shunting the deeper moisture to our east by Friday. This flow regime will continue through the weekend and into early next week. Some differences are seen as early as Monday with the 00Z ECMWF more robust with troughing to our north and east which would knock our temperatures lower a few more degrees compared to the 00Z GFS and GEFS ensembles. Thereafter, we'll have to watch tropics a bit closer but confidence remains very low on any development and subsequent moisture impacts to our area later next week. Daytime temperatures will remain well above normal into this weekend with gradual cooling to around seasonal normals by early next week. Low temperatures will remain well through Friday, then return to near normal starting this weekend as much drier air moves in. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && Francis PREV DISCUSSION...GL Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
The Tucson radar (KEMX), 170 km away, was scanning. The volume nearest the first event began at 22:43 UTC.
1 thunderstorm wind. Local standard time, as filed.
Thunderstorms winds downed two power poles just south of Duncan. Power was lost in Duncan for several hours as a result.
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, October 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 2026-10-01. Each event’s entry at NCEI: 725418.