Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 78, NWS Tucson, AZ

July 29, 2021Pima County, Arizona

NWS Tucson, AZ issued this flash flood warning at Jul 29, 2021, 2:42 PM MST for Pima County, Arizona. It was in force for 2 hr. 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: Jul 29, 2021, 2:42 PM MST (21:42 UTC)
Expired: Jul 29, 2021, 4:45 PM MST
In force: 2 hr
Issued by: NWS Tucson, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Pima County, AZ

The radar

The Yuma radar (KYUX), 183 km from the middle of the area, began a volume at 21:42 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.

What was reported inside it

Time	Report	Where	Remark
Jul 29, 3:00 PM MST	FLASH FLOOD	29 Wsw Pisinemo, AZ	ROAD WITHIN ORGAN PIPE CACTUS NATIONAL MONUMENT WAS IMPASSABLE DUE TO FLOWING WATER.

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, 9.7 hours before the alert went out and 184 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: 153 J/kg
Mixed-layer CIN: -305 J/kg
Mixed-layer LCL: 2293 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: -36 m²/s²
0-3 km storm-relative helicity: 23 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

337 
WGUS55 KTWC 292142
FFWTWC
AZC019-292345-
/O.NEW.KTWC.FF.W.0078.210729T2142Z-210729T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Tucson AZ
242 PM MST Thu Jul 29 2021

The National Weather Service in Tucson has issued a

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

* Until 445 PM MST.

* At 242 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2.5 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...
  Organ Pipe Cactus National Monument and Lukeville.

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 3191 11291 3210 11286 3208 11270 3186 11274
      3188 11280 3188 11283 3190 11288

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

$$

RH

2 follow-up statements

438 
WGUS75 KTWC 292255
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
355 PM MST Thu Jul 29 2021

AZC019-292345-
/O.CON.KTWC.FF.W.0078.000000T0000Z-210729T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pima AZ-
355 PM MST Thu Jul 29 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 445 PM MST THIS 
AFTERNOON FOR WEST CENTRAL PIMA COUNTY...

At 355 PM MST, Doppler radar indicated that while the thunderstorms 
had ended in the warning area, they produced very heavy rainfall, 
with radar estimates of between 2 and 3 inches of rainfall in this 
area.

HAZARD...Flash flooding caused by thunderstorms and heavy
         rainfall.

SOURCE...Radar.

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...
  Organ Pipe Cactus National Monument and Lukeville.

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 3191 11291 3210 11286 3208 11270 3186 11274
      3188 11280 3188 11283 3190 11288

FLASH FLOOD...RADAR INDICATED

$$

GZ

693 
WGUS75 KTWC 292346
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
446 PM MST Thu Jul 29 2021

AZC019-292356-
/O.EXP.KTWC.FF.W.0078.000000T0000Z-210729T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pima AZ-
446 PM MST Thu Jul 29 2021

...FLASH FLOOD WARNING HAS EXPIRED FOR WEST 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 3191 11291 3210 11286 3208 11270 3186 11274
      3188 11280 3188 11283 3190 11288

$$

GZ

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 28, 8:12 PM MST	Areal Flood Advisory	TWC	Cochise	63 min
Jul 29, 1:20 PM MST	Severe Thunderstorm Warning	TWC	Pima	40 min
Jul 29, 1:55 PM MST	Areal Flood Advisory	TWC	Pima	2 hr
Jul 29, 2:06 PM MST	Flash Flood Watch	TWC	Pima, Pinal	39 hr
Jul 29, 2:08 PM MST	Special Weather Statement	TWC		37 min
Jul 29, 2:44 PM MST	Special Weather Statement	TWC	Cochise	61 min
Jul 29, 3:03 PM MST	Areal Flood Advisory	TWC	Cochise	117 min
Jul 29, 3:10 PM MST	Special Weather Statement	TWC	Graham	35 min
Jul 29, 4:54 PM MST	Areal Flood Advisory	TWC	Graham	2 hr
Jul 29, 4:54 PM MST	Special Weather Statement	TWC		36 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.