Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 172, NWS Tucson, AZ

September 29, 2021Pima County, Arizona

NWS Tucson, AZ issued this flash flood warning at Sep 29, 2021, 11:51 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: Sep 29, 2021, 11:51 PM MST (06:51 UTC)
Expired: Sep 30, 2021, 3:00 AM MST
In force: 3 hr
Issued by: NWS Tucson, AZ
Area: Storm-based polygon
Flood severity: None

County Pima County, AZ

The radar

The Phoenix radar (KIWA), 125 km from the middle of the area, began a volume at 06:53 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, 6.9 hours before the alert went out and 138 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: 314 J/kg
Mixed-layer CIN: -91 J/kg
Mixed-layer LCL: 2898 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 11 m²/s²
0-3 km storm-relative helicity: 31 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

As transmitted.

195 
WGUS55 KTWC 300651
FFWTWC
AZC019-301000-
/O.NEW.KTWC.FF.W.0172.210930T0651Z-210930T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Tucson AZ
1151 PM MST Wed Sep 29 2021

The National Weather Service in Tucson has issued a

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

* Until 300 AM MST.

* At 1151 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. The expected rainfall rate is 1 to 1.5 inches in 1 
  hour. Flash flooding is ongoing or expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

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

* Some locations that will experience flash flooding include...
  Vaya Chin.

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.

&&

LAT...LON 3220 11230 3242 11253 3250 11242 3231 11222

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-1.5 INCHES IN 1 HOUR

$$

JD

1 follow-up statement

628 
WGUS75 KTWC 300950
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
250 AM MST Thu Sep 30 2021

AZC019-301000-
/O.EXP.KTWC.FF.W.0172.000000T0000Z-210930T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pima AZ-
250 AM MST Thu Sep 30 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 3 AM MST EARLY THIS MORNING 
FOR NORTH CENTRAL PIMA COUNTY...

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

LAT...LON 3220 11230 3242 11253 3250 11242 3231 11222

$$

JD

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 29, 11:08 PM MST	Flash Flood Warning Considerable damage threat	TWC	Pima	112 min
Sep 29, 11:25 PM MST	Areal Flood Advisory	TWC	Pima	3 hr
Sep 29, 11:57 PM MST	Severe Thunderstorm Warning	TWC	Pinal	48 min
Sep 30, 12:13 AM MST	Severe Thunderstorm Warning	TWC	Pima	47 min
Sep 30, 12:24 AM MST	Areal Flood Advisory	TWC	Pima, Pinal	3 hr
Sep 30, 12:40 AM MST	Severe Thunderstorm Warning	TWC	Pinal	50 min
Sep 30, 12:57 AM MST	Special Weather Statement	TWC	Pinal	33 min
Sep 30, 3:21 AM MST	Special Weather Statement	TWC		39 min
Sep 30, 4:05 AM MST	Areal Flood Advisory	TWC	Cochise	115 min
Sep 30, 12:58 PM MST	Special Weather Statement	TWC	Santa Cruz	47 min
Sep 30, 2:23 PM MST	Areal Flood Advisory	TWC	Cochise	97 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.