Alert archive / Arizona / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 99, NWS Phoenix, AZ
NWS Phoenix, AZ issued this severe thunderstorm warning at Aug 18, 2021, 5:25 PM MST for Maricopa County, Pinal County, Arizona. It was in force for 50 min. 1 report came from inside the area while it was in force.
The area
The outline as issued, with what was reported inside it.
The facts
- Issued
- Aug 18, 2021, 5:25 PM MST (00:25 UTC)
- Expired
- Aug 18, 2021, 6:15 PM MST
- In force
- 50 min
- Issued by
- NWS Phoenix, AZ
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
Counties Maricopa County, AZ, Pinal County, AZ
The radar
The Phoenix radar (KIWA), 30 km from the middle of the area, began a volume at 00:27 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.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Aug 18, 6:00 PM MST | TSTM WND DMG | 4 E Ahwatukee Foothills, AZ | **DELAYED REPORT** REPORTS OF MULTIPLE SNAPPED AND DOWNED TREES IN THE AREA. TIMING MATCHED WITH RADAR. EST WIND GUST SPEEDS 50-60 MPH. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Phoenix, AZ (KPSR), launched 00:00Z, 0.4 hours before the alert went out and 14 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
- 510 J/kg
- Mixed-layer CIN
- -174 J/kg
- Mixed-layer LCL
- 1692 m above ground
- 0-6 km bulk shear
- 24 kt
- 0-1 km storm-relative helicity
- 157 m²/s²
- 0-3 km storm-relative helicity
- 230 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.7
The text
As transmitted.
371 WUUS55 KPSR 190025 SVRPSR AZC013-021-190115- /O.NEW.KPSR.SV.W.0099.210819T0025Z-210819T0115Z/ BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Phoenix AZ 525 PM MST Wed Aug 18 2021 The National Weather Service in Phoenix has issued a * Severe Thunderstorm Warning for... Maricopa County in south central Arizona... Pinal County in southeastern Arizona... * Until 615 PM MST. * At 524 PM MST, a severe thunderstorm was located near South Mountain Park, or 8 miles southwest of Tempe, moving northeast at 15 mph. HAZARD...60 mph wind gusts. SOURCE...Radar indicated. IMPACT...Expect damage to roofs, siding, and trees. * Locations impacted include... Phoenix, Mesa, Chandler, Gilbert, Tempe, Mesa Riverview Mall, Tempe Marketplace, Papago Park, Arizona Mills Mall, Downtown Mesa, South Phoenix, South Mountain Park, Arizona State University, Fiesta Mall and Sky Harbor Airport. This includes the following highways... AZ Interstate 10 between mile markers 147 and 166. AZ Interstate 17 between mile markers 195 and 196. AZ Route 51 between mile markers 1 and 2. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. Large hail and damaging winds and continuous cloud to ground lightning is occurring with this storm. Move indoors immediately. Lightning is one of nature's leading killers. Remember, if you can hear thunder, you are close enough to be struck by lightning. Torrential rainfall is occurring with this storm, and may lead to flash flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 3318 11200 3327 11216 3350 11204 3339 11174 TIME...MOT...LOC 0024Z 214DEG 15KT 3329 11203 HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...<.75 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...60 MPH $$ CK
3 follow-up statements
912 WWUS55 KPSR 190032 SVSPSR Severe Weather Statement National Weather Service Phoenix AZ 532 PM MST Wed Aug 18 2021 AZC013-021-190115- /O.CON.KPSR.SV.W.0099.000000T0000Z-210819T0115Z/ Maricopa AZ-Pinal AZ- 532 PM MST Wed Aug 18 2021 ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM MST FOR MARICOPA AND PINAL COUNTIES... At 532 PM MST, a severe thunderstorm was located near South Mountain Park, or 7 miles southwest of Tempe, moving northeast at 15 mph. HAZARD...60 mph wind gusts and penny size hail. SOURCE...Radar indicated. IMPACT...Expect damage to roofs, siding, and trees. Locations impacted include... Phoenix, Mesa, Chandler, Gilbert, Tempe, Mesa Riverview Mall, Tempe Marketplace, Papago Park, Arizona Mills Mall, Downtown Mesa, South Phoenix, South Mountain Park, Arizona State University, Fiesta Mall and Sky Harbor Airport. This includes the following highways... AZ Interstate 10 between mile markers 147 and 166. AZ Interstate 17 between mile markers 195 and 196. AZ Route 51 between mile markers 1 and 2. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. Continuous cloud to ground lightning is occurring with this storm. Move indoors immediately. Lightning is one of nature's leading killers. Remember, if you can hear thunder, you are close enough to be struck by lightning. Torrential rainfall is occurring with this storm, and may lead to flash flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 3318 11200 3327 11216 3350 11204 3339 11174 TIME...MOT...LOC 0032Z 214DEG 15KT 3331 11201 HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...0.75 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...60 MPH $$ CK
135 WWUS55 KPSR 190050 SVSPSR Severe Weather Statement National Weather Service Phoenix AZ 550 PM MST Wed Aug 18 2021 AZC013-021-190115- /O.CON.KPSR.SV.W.0099.000000T0000Z-210819T0115Z/ Maricopa AZ-Pinal AZ- 550 PM MST Wed Aug 18 2021 ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM MST FOR MARICOPA AND PINAL COUNTIES... At 549 PM MST, a severe thunderstorm was located near South Mountain Park, or near Tempe, moving northeast at 20 mph. HAZARD...60 mph wind gusts and penny size hail. SOURCE...Radar indicated. IMPACT...Expect damage to roofs, siding, and trees. Locations impacted include... Phoenix, Mesa, Chandler, Gilbert, Tempe, South Mountain Park, Arizona Mills Mall, Fiesta Mall, Chandler Fashion Center Mall, Guadalupe and Firebird Lake. This includes the following highways... AZ Interstate 10 between mile markers 151 and 166. US Highway 60 between mile markers 173 and 184. AZ Route 87 between mile markers 167 and 172. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. This storm has a history of rotation and damaging winds. Continuous cloud to ground lightning is occurring with this storm. Move indoors immediately. Lightning is one of nature's leading killers. Remember, if you can hear thunder, you are close enough to be struck by lightning. Torrential rainfall is occurring with this storm, and may lead to flash flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 3318 11200 3327 11216 3343 11201 3339 11174 TIME...MOT...LOC 0049Z 221DEG 18KT 3331 11200 TORNADO...POSSIBLE HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...0.75 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...60 MPH $$ CK
856
WWUS55 KPSR 190112
SVSPSR
Severe Weather Statement
National Weather Service Phoenix AZ
612 PM MST Wed Aug 18 2021
AZC013-021-190122-
/O.EXP.KPSR.SV.W.0099.000000T0000Z-210819T0115Z/
Maricopa AZ-Pinal AZ-
612 PM MST Wed Aug 18 2021
...THE SEVERE THUNDERSTORM WARNING FOR MARICOPA AND PINAL COUNTIES
WILL EXPIRE AT 615 PM MST...
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire. However small hail
and gusty winds are still possible with this thunderstorm.
LAT...LON 3318 11200 3327 11216 3343 11201 3339 11174
TIME...MOT...LOC 0112Z 214DEG 15KT 3338 11195
$$
CKThe office that day
Everything else NWS Phoenix, AZ issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 18, 5:13 PM MST | Flash Flood Warning | PSR | Gila | 4 hr |
| Aug 18, 5:20 PM MST | Special Weather Statement | PSR | Gila | 40 min |
| Aug 18, 5:34 PM MST | Special Weather Statement | PSR | 41 min | |
| Aug 18, 5:39 PM MST | Flash Flood Warning | PSR | Gila | 4 hr |
| Aug 18, 5:40 PM MST | Special Weather Statement | PSR | Maricopa | 50 min |
| Aug 18, 5:43 PM MST | Severe Thunderstorm Warning | PSR | Maricopa | 32 min |
| Aug 18, 5:52 PM MST | Special Weather Statement | PSR | 38 min | |
| Aug 18, 6:09 PM MST | Flash Flood Warning | PSR | Maricopa, Pinal | 3 hr |
| Aug 18, 6:14 PM MST | Flash Flood Warning | PSR | Maricopa | 3 hr |
| Aug 18, 6:20 PM MST | Flash Flood Warning | PSR | Gila | 4 hr |
| Aug 18, 6:36 PM MST | Special Weather Statement | PSR | 39 min | |
| Aug 18, 7:20 PM MST | Areal Flood Warning | PSR | Maricopa | 6 hr |
| Aug 18, 7:33 PM MST | Areal Flood Warning | PSR | Maricopa | 6 hr |
| Aug 18, 7:33 PM MST | Areal Flood Warning | PSR | Maricopa | 6 hr |
| Aug 18, 8:57 PM MST | Areal Flood Warning | PSR | Maricopa | 14 hr |
Nearby
Severe Thunderstorm Warnings in Arizona, 2021Every severe thunderstorm warning in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.