Alert archive / Texas / Flash Flood Warnings in 2021

Flash Flood Warning 39, NWS San Angelo, TX

August 18, 2021Callahan County, Texas

NWS San Angelo, TX issued this flash flood warning at Aug 18, 2021, 10:13 AM CDT for Callahan County, Texas. 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 18, 2021, 10:13 AM CDT (15:13 UTC)
Expired
Aug 18, 2021, 1:15 PM CDT
In force
3 hr
Issued by
NWS San Angelo, TX
Area
Storm-based polygon
Flood severity
None

County Callahan County, TX

The radar

The Dyess AFB radar (KDYX), 23 km from the middle of the area, began a volume at 15:16 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

Fort Worth, TX (KFWD), launched 12:00Z, 3.2 hours before the alert went out and 207 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, Fort Worth, TX at 12:00Z on 2021-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 500 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, Fort Worth, TX at 12:00Z on 2021-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -15 square meters per square second.193958Sfc1 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
500 J/kg
Mixed-layer CIN
-33 J/kg
Mixed-layer LCL
580 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
-15 m²/s²
0-3 km storm-relative helicity
-2 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

421 
WGUS54 KSJT 181513
FFWSJT
TXC059-181815-
/O.NEW.KSJT.FF.W.0039.210818T1513Z-210818T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Angelo TX
1013 AM CDT Wed Aug 18 2021

The National Weather Service in San Angelo has issued a

* Flash Flood Warning for...
  Northern Callahan County in west central Texas...

* Until 115 PM CDT.

* At 1011 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen over the past hour or so on top of already saturated 
  soils. This is expected to result in Flash Flooding across the 
  warned area.

  HAZARD...Flash flooding caused by thunderstorms.

  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...
  Clyde, Baird, Putnam, Eula, Dudley and I-20 Near The 
  Callahan-Eastland County Line.

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 3251 9962 3251 9958 3251 9911 3235 9912
      3228 9942 3215 9963

FLASH FLOOD...RADAR INDICATED

$$

SN

The office that day

Everything else NWS San Angelo, TX issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 18, 4:46 AM CDTAreal Flood AdvisorySJTRunnels119 min
Aug 18, 6:54 AM CDTAreal Flood AdvisorySJTCallahan, Coleman2 hr
Aug 18, 8:12 AM CDTFlash Flood Warning Considerable damage threatSJTBrown, Callahan, Coleman3 hr
Aug 18, 11:25 AM CDTAreal Flood AdvisorySJTShackelford3 hr
Aug 18, 12:42 PM CDTFlash Flood WarningSJTRunnels3 hr
Aug 18, 1:13 PM CDTFlash Flood Warning Considerable damage threatSJTCallahan, Coleman3 hr
Aug 18, 1:56 PM CDTAreal Flood AdvisorySJTCoke, Runnels3 hr

Nearby

Flash Flood Warnings in Texas, 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.