Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 95, NWS Tucson, AZ

August 8, 2021Santa Cruz County, Arizona

NWS Tucson, AZ issued this flash flood warning at Aug 8, 2021, 4:48 PM MST for Santa Cruz 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 8, 2021, 4:48 PM MST (23:48 UTC)
Expired
Aug 8, 2021, 7:45 PM MST
In force
3 hr
Issued by
NWS Tucson, AZ
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Santa Cruz County, AZ

The radar

The Tucson radar (KEMX), 59 km from the middle of the area, began a volume at 23:48 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 12:00Z, 11.8 hours before the alert went out and 88 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 12:00Z on 2021-08-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 359 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 12:00Z on 2021-08-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -31 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
359 J/kg
Mixed-layer CIN
-232 J/kg
Mixed-layer LCL
1832 m above ground
0-6 km bulk shear
9 kt
0-1 km storm-relative helicity
-31 m²/s²
0-3 km storm-relative helicity
51 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

248 
WGUS55 KTWC 082348
FFWTWC
AZC023-090245-
/O.NEW.KTWC.FF.W.0095.210808T2348Z-210809T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Tucson AZ
448 PM MST Sun Aug 8 2021

The National Weather Service in Tucson has issued a

* Flash Flood Warning for...
  Southeastern Santa Cruz County in southeastern Arizona...

* Until 745 PM MST.

* At 448 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts up to 1 inch are possible 
  in the warned area. Flash flooding is ongoing or expected to begin 
  shortly. Although its not raining in Nogales yet, intense 
  thunderstorms producing heavy rainfall will move into the city 
  within the hour.

  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...
  Nogales, Nogales International Airport, Patagonia Lake State Park, 
  Kino Springs and Lochiel.

This includes the following Flash Flood Prone Locations...
Nogales Wash at Doe St Bridge and Nogales Port of Entry Deconcini 
Crossing.

This includes the following streams and drainages...
  Sonoita Creek, Harshaw Creek, Santa Cruz River and Potrero Creek.

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.

&&

LAT...LON 3133 11101 3139 11099 3146 11093 3152 11083
      3154 11069 3146 11064 3142 11050 3133 11049
      3133 11050 3133 11065 3133 11075 3133 11080
      3133 11088 3133 11097 3133 11100

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

$$

JRM
1 follow-up statement
324 
WGUS75 KTWC 090243
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
743 PM MST Sun Aug 8 2021

AZC023-090253-
/O.EXP.KTWC.FF.W.0095.000000T0000Z-210809T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Santa Cruz AZ-
743 PM MST Sun Aug 8 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 745 PM MST THIS EVENING FOR 
SOUTHEASTERN SANTA CRUZ COUNTY...

Flash Flooding threat has diminished, however small stream flooding 
is likely. Increased flows are also being observed on the Santa Cruz 
near Nogales. The Flash Flood Warning will be allowed to expire.

LAT...LON 3133 11101 3139 11099 3146 11093 3152 11083
      3154 11069 3146 11064 3142 11050 3133 11049
      3133 11050 3133 11065 3133 11075 3133 11080
      3133 11088 3133 11097 3133 11100

$$

JRM

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 7, 5:46 PM MSTSpecial Weather StatementTWC44 min
Aug 7, 5:54 PM MSTSpecial Weather StatementTWCGreenlee36 min
Aug 7, 6:19 PM MSTAreal Flood AdvisoryTWCPima116 min
Aug 8, 2:48 PM MSTSevere Thunderstorm WarningTWCPima42 min
Aug 8, 2:54 PM MSTSpecial Weather StatementTWCGreenlee36 min
Aug 8, 3:08 PM MSTFlash Flood Warning Considerable damage threatTWCPima3 hr
Aug 8, 3:42 PM MSTSevere Thunderstorm WarningTWCCochise33 min
Aug 8, 3:46 PM MSTSpecial Weather StatementTWC44 min
Aug 8, 4:11 PM MSTSpecial Weather StatementTWCPima49 min
Aug 8, 4:12 PM MSTSpecial Weather StatementTWCSanta Cruz33 min
Aug 8, 4:19 PM MSTSevere Thunderstorm WarningTWCSanta Cruz86 min
Aug 8, 4:21 PM MSTFlash Flood Warning Considerable damage threatTWCCochise114 min
Aug 8, 4:21 PM MSTSevere Thunderstorm WarningTWCSanta Cruz84 min
Aug 8, 4:26 PM MSTAreal Flood AdvisoryTWCPima2 hr
Aug 8, 4:33 PM MSTSpecial Weather StatementTWCCochise27 min

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.