Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 155, NWS Tucson, AZ

August 28, 2021Pima County, Arizona

NWS Tucson, AZ issued this flash flood warning at Aug 28, 2021, 4:31 PM MST for Pima County, Arizona. It was in force for 119 min. 2 reports 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 28, 2021, 4:31 PM MST (23:31 UTC)
Expired: Aug 28, 2021, 6:30 PM MST
In force: 119 min
Issued by: NWS Tucson, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Pima County, AZ

The radar

The Tucson radar (KEMX), 49 km from the middle of the area, began a volume at 23:31 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 28, 4:50 PM MST	FLOOD	5 Nw Tucson, AZ	ROADS FLOODED NEAR EUCLID AND GRANT FLOODED OVER 6 INCHES DEEP.
Aug 28, 5:15 PM MST	FLOOD	3 N Tucson, AZ	ROAD FLOODED ABOUT 8 INCHES DEEP.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Tuscon, AZ (KTUS), launched 12:00Z, 11.5 hours before the alert went out and 13 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 21 J/kg
Mixed-layer CIN: -393 J/kg
Mixed-layer LCL: 2964 m above ground
0-6 km bulk shear: 9 kt
0-1 km storm-relative helicity: -35 m²/s²
0-3 km storm-relative helicity: 65 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.7

Open this sounding in Storm Lab

The text

As transmitted.

488 
WGUS55 KTWC 282331
FFWTWC
AZC019-290130-
/O.NEW.KTWC.FF.W.0155.210828T2331Z-210829T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Tucson AZ
431 PM MST Sat Aug 28 2021

The National Weather Service in Tucson has issued a

* Flash Flood Warning for...
  Eastern Pima County in southeastern Arizona...

* Until 630 PM MST.

* At 431 PM MST, Doppler radar and automated rain gauges indicated 
  thunderstorms producing heavy rain across the warned area. Between 
  0.5 and 1 inch of rain has fallen in 30 minutes. Flash flooding is 
  ongoing or expected to begin shortly.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Radar and automated gauges.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Tucson, Marana, Davis-Monthan Air Force Base, Casas Adobes, 
  Flowing Wells, Tanque Verde, South Tucson, Catalina Foothills, 
  Sabino Canyon Recreation Area and Seven Falls.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Be aware of your surroundings and do not drive on flooded roads.

Remain alert for flooding even in locations not receiving rain. 
Washes, streams, and rivers can become raging killer currents in a 
matter of minutes, even from distant rainfall.

&&

LAT...LON 3235 11073 3219 11081 3218 11101 3234 11109

FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

GZ

2 follow-up statements

648 
WGUS75 KTWC 290012
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
512 PM MST Sat Aug 28 2021

AZC019-290130-
/O.CON.KTWC.FF.W.0155.000000T0000Z-210829T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pima AZ-
512 PM MST Sat Aug 28 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 630 PM MST THIS 
EVENING FOR EASTERN PIMA COUNTY...

At 512 PM MST, Doppler radar and automated rain gauges indicated 
that thunderstorms earlier had produced heavy rainfall, with between 
0.5 and 1.3 inches of rain occurring in the warning area.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Radar and automated gauges.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Tucson, Marana, Davis-Monthan Air Force Base, Casas Adobes, 
  Flowing Wells, Tanque Verde, South Tucson, Catalina Foothills, 
  Sabino Canyon Recreation Area and Seven Falls.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Be aware of your surroundings and do not drive on flooded roads.

Remain alert for flooding even in locations not receiving rain. 
Washes, streams, and rivers can become raging killer currents in a 
matter of minutes, even from distant rainfall.

&&

LAT...LON 3235 11073 3219 11081 3218 11101 3234 11109

FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

GZ

061 
WGUS75 KTWC 290127
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
627 PM MST Sat Aug 28 2021

AZC019-290137-
/O.EXP.KTWC.FF.W.0155.000000T0000Z-210829T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pima AZ-
627 PM MST Sat Aug 28 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 630 PM MST THIS EVENING FOR 
EASTERN PIMA COUNTY...

Flood waters have receded. The heavy rain has ended. Flooding is no 
longer expected to pose a threat. Please continue to heed remaining 
road closures.

LAT...LON 3235 11073 3219 11081 3218 11101 3234 11109

$$

GL

The office that day

Everything else NWS Tucson, AZ issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 27, 5:01 PM MST	Special Weather Statement	TWC		44 min
Aug 27, 5:04 PM MST	Areal Flood Advisory	TWC	Pima	2 hr
Aug 27, 5:27 PM MST	Special Weather Statement	TWC		33 min
Aug 28, 3:54 AM MST	Areal Flood Advisory	TWC	Pima	3 hr
Aug 28, 2:34 PM MST	Special Weather Statement	TWC	Santa Cruz	41 min
Aug 28, 2:42 PM MST	Special Weather Statement	TWC	Santa Cruz	48 min
Aug 28, 3:13 PM MST	Severe Thunderstorm Warning	TWC	Pima	47 min
Aug 28, 3:32 PM MST	Areal Flood Advisory	TWC	Pima	118 min
Aug 28, 3:49 PM MST	Special Weather Statement	TWC	Santa Cruz	41 min
Aug 28, 3:53 PM MST	Dust Storm Warning	TWC	Pima	52 min
Aug 28, 3:57 PM MST	Flash Flood Warning	TWC	Santa Cruz	108 min
Aug 28, 3:58 PM MST	Severe Thunderstorm Warning	TWC	Pima	62 min
Aug 28, 4:03 PM MST	Flash Flood Warning Considerable damage threat	TWC	Pima	117 min
Aug 28, 4:06 PM MST	Special Weather Statement	TWC		39 min
Aug 28, 4:14 PM MST	Areal Flood Advisory	TWC	Pima	2 hr
Aug 28, 4:24 PM MST	Severe Thunderstorm Warning	TWC	Pima	51 min
Aug 28, 4:26 PM MST	Flash Flood Warning Considerable damage threat	TWC	Pima	2 hr
Aug 28, 4:26 PM MST	Severe Thunderstorm Warning	TWC	Pima	34 min
Aug 28, 4:34 PM MST	Areal Flood Advisory	TWC	Graham, Pinal	116 min
Aug 28, 4:37 PM MST	Severe Thunderstorm Warning	TWC	Pinal	38 min
Aug 28, 4:47 PM MST	Dust Storm Warning	TWC	Pima, Pinal	118 min
Aug 28, 4:58 PM MST	Severe Thunderstorm Warning	TWC	Pima, Pinal	62 min

Nearby

Flash Flood Warnings in Arizona, 2021 Every flash flood 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.