Alert archive / Arizona / Severe Thunderstorm Warnings in 2018
Severe Thunderstorm Warning 129, NWS Flagstaff, AZ
NWS Flagstaff, AZ issued this severe thunderstorm warning at Aug 12, 2018, 6:42 PM MST for Coconino County, Gila County, Navajo County, Arizona. It was in force for 33 min. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Aug 12, 2018, 6:42 PM MST (01:42 UTC)
- Expired
- Aug 12, 2018, 7:15 PM MST
- In force
- 33 min
- Issued by
- NWS Flagstaff, AZ
- Area
- Storm-based polygon
- Hail
- 1.0 in
- Wind
- 60.0 mph
Counties Coconino County, AZ, Gila County, AZ, Navajo County, AZ
The radar
The Flagstaff radar (KFSX), 53 km from the middle of the area, began a volume at 01:42 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Aug 12, 3:40 PM MST | Severe Thunderstorm Watch | SPC | 7 hr |
The nearest sounding before it
Phoenix, AZ (KPSR), launched 00:00Z, 1.7 hours before the alert went out and 199 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 492 J/kg
- Mixed-layer CIN
- -151 J/kg
- Mixed-layer LCL
- 2378 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- -12 m²/s²
- 0-3 km storm-relative helicity
- 59 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
What forecasters said that day
The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Flagstaff, AZ wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 12, 2:40 PM MST, 4 hours 2 minutes earlier.
Area forecast discussion, Aug 12, 2:40 PM MST, 4 hours 2 minutes before
Area Forecast Discussion National Weather Service Flagstaff AZ 240 PM MST Sun Aug 12 2018 .SYNOPSIS...Typical monsoon conditions will continue across Arizona this week, bringing scattered afternoon and early evening thunderstorms to much of the area. The highest chances will remain along and south of the Mogollon Rim. Some storms will produce heavy rainfall, hail, and strong winds. && .DISCUSSION...Scattered convection has fired along the Mogollon Rim and southwest of the Black Mesa and Chuska Mountains this afternoon. The environment south and west of the Mogollon Rim is conducive for severe thunderstorm development with SPC's mesoanalysis painting MUCAPEs around 2000 J/kg and effective bulk shear around 20 knots. Thunderstorms and the severe threat (1" hail, 60 mph winds) should continue through the late afternoon into the early evening hours. The latest HRRR progs convection ending across all of northern Arizona after 9pm MST. Mainly dry conditions are then forecast overnight. For Monday through Tuesday, high pressure will slowly meander southeastward into Arizona and become centered over the White Mountains Tuesday. This could result in a slight downward trend in afternoon convective activity. However, scattered storms along the higher terrain (Mogollon Rim, Black Mesa, and Chuskas) are still forecast each afternoon. Storm motions will be primarily instability driven with weak steering flow expected. For Wednesday through Saturday, the aforementioned high pressure then slides east into New Mexico and is progged to open up Gulf of California moisture into Arizona. A little more active monsoonal thunderstorm pattern is forecast during the latter half of the week. The medium range models around now a day slower with high pressure rolling into the Great Basin with Sunday now looking to show a drying trend. Will hold off on making any significant changes in the precip forecast given the model to model and run to run inconsistencies. Stay tuned. && .AVIATION...For the 00Z package...VFR conditions will continue across northern Arizona for the next 24 hrs with southwest and west winds at 5-10 kts and possible gusts of 10-20 kts. Showers and thunderstorms near KGCN, KFLG, KSEZ are beginning to move to the southwest near KPRC. Near thunderstorms, expect gusty and erratic winds along with possible localized local MVFR/IFR conditions. Storms will weaken after sunset. Thunderstorms near KFLG, KSOW and other high terrain areas Monday after 19Z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Scattered thunderstorms will develop both Monday and Tuesday afternoons along and south of the Mogollon Rim, Black Mesa, and Chuska Mountains. Storm motions will be erratic due to weak winds aloft. Wednesday through Friday...Afternoon monsoonal thunderstorm chances will continue each day primarily along and south of the Mogollon Rim, with a gradual uptick in activity forecast each day through Friday. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC...TM AVIATION...NL FIRE WEATHER...TM For Northern Arizona weather information visit weather.gov/flagstaff
In the hours before
Special weather statement, Aug 12, 3:37 PM MST, 3 hours 5 minutes before
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</html>Local storm report, Aug 12, 4:59 PM MST, 1 hour 43 minutes before
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</html>Special weather statement, Aug 12, 6:07 PM MST, 35 minutes before
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</html>Special weather statement, Aug 12, 6:39 PM MST, 3 minutes before
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</html>The office that day
Everything else NWS Flagstaff, AZ issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 12, 5:42 PM MST | Severe Thunderstorm Warning | FGZ | Gila | 48 min |
| Aug 12, 6:07 PM MST | Special Weather Statement | FGZ | 38 min | |
| Aug 12, 6:14 PM MST | Severe Thunderstorm Warning | FGZ | Apache | 46 min |
| Aug 12, 6:27 PM MST | Severe Thunderstorm Warning | FGZ | Gila, Yavapai | 48 min |
| Aug 12, 6:39 PM MST | Special Weather Statement | FGZ | 51 min | |
| Aug 12, 6:59 PM MST | Severe Thunderstorm Warning | FGZ | Coconino, Gila, Navajo | 46 min |
| Aug 12, 7:02 PM MST | Severe Thunderstorm Warning | FGZ | Apache, Navajo | 17 min |
| Aug 12, 7:08 PM MST | Severe Thunderstorm Warning | FGZ | Gila, Yavapai | 21 min |
| Aug 12, 7:46 PM MST | Severe Thunderstorm Warning | FGZ | Coconino, Gila, Yavapai | 44 min |
| Aug 12, 8:25 PM MST | Severe Thunderstorm Warning | FGZ | Gila, Yavapai | 50 min |
| Aug 12, 9:02 PM MST | Areal Flood Advisory | FGZ | Gila, Navajo | 3 hr |
| Aug 12, 9:11 PM MST | Special Weather Statement | FGZ | 49 min | |
| Aug 13, 2:36 PM MST | Special Weather Statement | FGZ | Apache | 39 min |
| Aug 13, 2:44 PM MST | Special Weather Statement | FGZ | 46 min | |
| Aug 13, 3:06 PM MST | Flash Flood Warning | FGZ | Coconino, Yavapai | 3 hr |
| Aug 13, 3:23 PM MST | Severe Thunderstorm Warning | FGZ | Coconino, Yavapai | 22 min |
| Aug 13, 3:34 PM MST | Special Weather Statement | FGZ | 26 min | |
| Aug 13, 3:52 PM MST | Special Weather Statement | FGZ | 23 min | |
| Aug 13, 4:13 PM MST | Special Weather Statement | FGZ | 47 min | |
| Aug 13, 4:29 PM MST | Severe Thunderstorm Warning | FGZ | Yavapai | 31 min |
Nearby
Severe Thunderstorm Warnings in Arizona, 2018Every severe thunderstorm warning in 2018
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.