Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 162, NWS Tucson, AZ

August 31, 2021Pima County, Arizona

NWS Tucson, AZ issued this flash flood warning at Aug 31, 2021, 10:06 PM MST for Pima County, Arizona. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 31, 2021, 10:06 PM MST (05:06 UTC)
Expired: Sep 1, 2021, 1:00 AM MST
In force: 3 hr
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), 71 km from the middle of the area, began a volume at 05:09 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 nearest sounding before it

Tuscon, AZ (KTUS), launched 00:00Z, 5.1 hours before the alert went out and 35 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: 238 J/kg
Mixed-layer CIN: -58 J/kg
Mixed-layer LCL: 905 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: -36 m²/s²
0-3 km storm-relative helicity: 161 m²/s²
Significant tornado parameter: -0.1
Supercell composite: -1.2

Open this sounding in Storm Lab

The text

As transmitted.

038 
WGUS55 KTWC 010506
FFWTWC
AZC019-010800-
/O.NEW.KTWC.FF.W.0162.210901T0506Z-210901T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Tucson AZ
1006 PM MST Tue Aug 31 2021

The National Weather Service in Tucson has issued a

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

* Until 100 AM MST.

* At 1006 PM MST, Heavy rainfall in the Canada Del Oro watershed 
  over the last several hours has caused elevated flows at the 
  Rancho Solano stream gauge. This runoff is expected to cause 
  flooding along the CDO from the Pima/Pinal County line south to 
  Catalina State Park over the next few hours. Flash flooding is 
  ongoing or expected to begin shortly.

  HAZARD...Life threatening flash flooding. Heavy rain producing
           flash flooding.

  SOURCE...Gauges reported.

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

* Some locations that will experience flash flooding include...
  Catalina.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

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 3251 11088 3251 11087 3244 11091 3245 11093
      3251 11089

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

$$

EC

1 follow-up statement

956 
WGUS75 KTWC 010753
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
1253 AM MST Wed Sep 1 2021

AZC019-010803-
/O.EXP.KTWC.FF.W.0162.000000T0000Z-210901T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pima AZ-
1253 AM MST Wed Sep 1 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1 AM MST EARLY THIS MORNING 
FOR NORTHEASTERN PIMA COUNTY...

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

A Flash Flood Watch remains in effect until 500 AM MST Thursday for 
a portion of Southeast Arizona.

LAT...LON 3251 11088 3251 11087 3244 11091 3245 11093
      3251 11089

$$

AH

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 31, 5:05 PM MST	Areal Flood Advisory	TWC	Cochise	3 hr

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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.