Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 86, NWS Tucson, AZ

August 2, 2021Pima County, Arizona

NWS Tucson, AZ issued this flash flood warning at Aug 2, 2021, 6:55 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 2, 2021, 6:55 PM MST (01:55 UTC)
Expired
Aug 2, 2021, 10:00 PM 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), 4 km from the middle of the area, began a volume at 01:55 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, 1.9 hours before the alert went out and 42 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-pSkew-T log-p diagram, Tuscon, AZ at 00:00Z on 2021-08-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1093 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Tuscon, AZ at 00:00Z on 2021-08-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -18 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
1093 J/kg
Mixed-layer CIN
-27 J/kg
Mixed-layer LCL
2632 m above ground
0-6 km bulk shear
0 kt
0-1 km storm-relative helicity
-18 m²/s²
0-3 km storm-relative helicity
37 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

242 
WGUS55 KTWC 030155
FFWTWC
AZC019-030400-
/O.NEW.KTWC.FF.W.0086.210803T0155Z-210803T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Tucson AZ
655 PM MST Mon Aug 2 2021

The National Weather Service in Tucson has issued a

* Flash Flood Warning for...
  East Central Pima County in southeastern Arizona...

* Until 900 PM MST.

* At 655 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Flash flooding is ongoing or expected to begin 
  shortly.

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

  SOURCE...Radar.

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

* Some locations that will experience flash flooding include...
  mainly rural areas of East Central Pima County along State Highway 
  83.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

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 3195 11070 3195 11054 3173 11055 3174 11073

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

$$

GZ
3 follow-up statements
191 
WGUS75 KTWC 030228
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
728 PM MST Mon Aug 2 2021

AZC019-030400-
/O.CON.KTWC.FF.W.0086.000000T0000Z-210803T0400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pima AZ-
728 PM MST Mon Aug 2 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 9 PM MST THIS EVENING 
FOR EAST CENTRAL PIMA COUNTY...

At 728 PM MST, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 1 and 2 inches of rain have 
fallen. The rain gauge at Empire Peak reported 1.89 inches of 
rainfall in 30 minutes.

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

SOURCE...Radar.

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

Some locations that will experience flash flooding include...
  mainly rural areas of East Central Pima County along State Highway 
  83.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

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 3195 11070 3195 11054 3173 11055 3174 11073

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

$$

GZ
263 
WGUS55 KTWC 030342
FFWTWC
AZC019-030500-
/O.EXT.KTWC.FF.W.0086.000000T0000Z-210803T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Tucson AZ
842 PM MST Mon Aug 2 2021

The National Weather Service in Tucson has extended the

* Flash Flood Warning for...
  East Central Pima County in southeastern Arizona...

* Until 1000 PM MST.

* At 842 PM MST, Doppler radar and automated rain gauges indicated 
  that thunderstorms earlier this evening had produced very heavy 
  rainfall, with between 1 and 2 inches of rain occurring in the 
  warning area. Given this amount of rainfall, the Flash Flood 
  Warning will be extended another hour.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar and automated gauges.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  mainly rural areas of East Central Pima County along State Highway 
  83.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

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 3195 11070 3195 11054 3173 11055 3174 11073

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

GZ
258 
WGUS75 KTWC 030458
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
958 PM MST Mon Aug 2 2021

AZC019-030508-
/O.EXP.KTWC.FF.W.0086.000000T0000Z-210803T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pima AZ-
958 PM MST Mon Aug 2 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 10 PM MST THIS EVENING FOR 
EAST CENTRAL PIMA COUNTY...

The heavy rain has ended. Flash flooding is no longer expected to 
pose a threat. Please continue to heed remaining road closures.

LAT...LON 3195 11070 3195 11054 3173 11055 3174 11073

$$

GZ

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 2, 5:15 PM MSTSpecial Weather StatementTWCSanta Cruz30 min
Aug 2, 5:19 PM MSTDust Storm AdvisoryTWCCochise41 min
Aug 2, 5:33 PM MSTSpecial Weather StatementTWC42 min
Aug 2, 5:48 PM MSTSpecial Weather StatementTWC42 min
Aug 2, 5:51 PM MSTAreal Flood AdvisoryTWCPima114 min
Aug 2, 5:58 PM MSTFlash Flood Warning Considerable damage threatTWCPima3 hr
Aug 2, 6:24 PM MSTAreal Flood AdvisoryTWCPima2 hr
Aug 2, 6:26 PM MSTAreal Flood AdvisoryTWCCochise, Santa Cruz2 hr
Aug 2, 6:31 PM MSTSpecial Weather StatementTWC59 min
Aug 2, 6:37 PM MSTSevere Thunderstorm WarningTWCPima38 min
Aug 2, 7:06 PM MSTAreal Flood AdvisoryTWCPinal114 min
Aug 2, 7:06 PM MSTSpecial Weather StatementTWCCochise39 min
Aug 2, 7:15 PM MSTSpecial Weather StatementTWCSanta Cruz45 min
Aug 2, 7:25 PM MSTSpecial Weather StatementTWC50 min
Aug 2, 7:31 PM MSTSevere Thunderstorm WarningTWCPima44 min
Aug 2, 8:13 PM MSTSevere Thunderstorm WarningTWCPima33 min
Aug 2, 8:14 PM MSTFlash Flood Warning Considerable damage threatTWCPima3 hr

Nearby

Flash Flood Warnings in Arizona, 2021Every 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.