Upper level moisture which sheared off from former Pacific Hurricane Jova fueled isolated thunderstorms in far northwest Arizona. One produced flash flooding.
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The episode as NWS VEF wrote it up.
Upper level moisture which sheared off from former Pacific Hurricane Jova fueled isolated thunderstorms in far northwest Arizona. One produced flash flooding.
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 Las Vegas, NV wrote its last area forecast discussion before the first event at Sep 13, 12:13 PM MST, 4 hours 47 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 1213 PM PDT Wed Sep 13 2023 .SYNOPSIS...Scattered showers and storms today across southern Nevada and northwest Arizona. Activity expands into Inyo and San Bernardino Counties tomorrow. Dry conditions return Friday and persist into early next week as temperatures remain near normal. && .SHORT TERM...through Thursday. Low-amplitude troughing persists over the western US today, leaving our area under quasi-zonal flow ahead of an approaching shortwave. Latest RAP shows very few (if any) vort maxima passing through this afternoon, so convection is likely going to be terrain-driven. Additionally, we'll be in the left entrance region of a 250mb jet streak, inducing subsidence and producing an inversion around 500mb. However, temperatures above the inversion have cooled slightly, resulting in CAPE values similar to what we saw yesterday, even despite the slight decrease in moisture. 12z HREF mean shows 500-750 J/kg of SBCAPE this afternoon, primarily across Lincoln, Clark, and Mohave Counties. This lines up well with modeled convection being largely limited to southern NV and northwestern AZ this afternoon. Dry low levels are expected to limit heavy rain potential, but up on the high terrain where sub-cloud evaporation is mitigated, heavy downpours will be possible. The HREF depicts this well, highlighting the high terrain of Clark County and the AZ Strip with a 30% chance of seeing 1" of rain. Gusty winds and lightning will be the main concerns for the lower elevations. Later this evening and tonight, another round of convection is possible across our northern areas as the base of the aforementioned shortwave moves in. Given the limited moisture and instability after sunset, impacts are expected to be minimal at best. Tomorrow, the shortwave moves through the area, sparking scattered convection across much of the area, generally north of I-40. With moisture continuing to decrease, so too will instability. Ensemble mean SCAPE values are forecast to be less than 500 J/kg except for Mohave County where they get up to 750 J/kg. In terms of potential storm impacts, tomorrow looks fairly similar to today. Heavy rain possible on the high terrain, gusty winds and lightning the main concerns for the lower elevations. Temperatures both today and tomorrow expected to remain slightly below normal. .LONG TERM...Friday through Tuesday. After the shortwave passes through on Thursday, drier air will begin to filter into the region. As a result, PoPs drop below 10% for pretty much the entire CWA and remain that way into early next week. The only exceptions to this may be the Spring Mountains on Friday, and the Sierra crest this weekend. As ridging develops over the western US, temperatures creep up to slightly above-normal values over the weekend. By next week, the ridge axis is forecast to shift eastward, with troughing developing upstream. This will result in decreasing temperatures and possibly increasing winds. How well the northern and southern branches of the jet stream can phase will determine how cool/windy we get. && .AVIATION...For Harry Reid...Another day with mountain showers and storms is expected from 18z through around 02z. Some of this activity may drift off the higher terrain to the west and into the Las Vegas Valley, but confidence is quite low. Still, gusty outflow winds could affect KLAS in the late afternoon/early evening. Otherwise light winds 10 knots or less are expected, first from the northeast, turning slightly southeast after 20z. Winds to turn back to the northeast tonight, becoming variable after 07z. Similar conditions are expected again tomorrow. For the rest of southern Nevada, northwest Arizona and southeast California...Mountain showers and thunderstorms may bring impacts, namely gusty outflow winds, to KVGT/KHND between 22z and 02z. Otherwise generally light diurnal winds 10 to 15 knots or less can be expected most terminals. The one exception will be KDAG, where a few gusts to 20 knots can be expected late this afternoon into this evening. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && DISCUSSION...Woods AVIATION...Austin For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter
The Cedar City radar (KICX), 67 km away, was scanning. The volume nearest the first event began at 00:05 UTC.
1 flash flood. Local standard time, as filed.
Flash flooding of Short Creek closed all of the Colorado City roads which cross the creek. The Hildale Street crossing was heavily damaged and will likely be closed for some time.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2023Every state in 2023This day in weather historyWarnings in Arizona, September 2023
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: 1141945.