Alert archive / Texas / Flash Flood Watches in 2017

Flash Flood Watch 4, NWS Shreveport, LA

August 6, 201712 counties in Texas; 4 counties in Arkansas

NWS Shreveport, LA issued this flash flood watch at Aug 6, 2017, 3:47 PM CDT for 12 counties in Texas; 4 counties in Arkansas. It took effect at Aug 6, 2017, 7:00 PM CDT. It was in force for 16 hr.

The area

The counties it named.

The facts

Issued
Aug 6, 2017, 3:47 PM CDT (20:47 UTC)
In effect from
Aug 6, 2017, 7:00 PM CDT
Expired
Aug 7, 2017, 10:59 AM CDT
In force
16 hr
Issued by
NWS Shreveport, LA
Flood severity
None

Counties Howard County, AR, Little River County, AR, Miller County, AR, Sevier County, AR, Bowie County, TX, Camp County, TX, Cass County, TX, Franklin County, TX, Gregg County, TX, Marion County, TX, Morris County, TX, Red River County, TX, Smith County, TX, Titus County, TX, Upshur County, TX, Wood County, TX

The radar

The Shreveport radar (KSHV), 113 km from the middle of the area, began a volume at 20:47 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

Shreveport, LA (KBAD), launched 12:00Z, 8.8 hours before the alert went out and 117 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, Shreveport, LA at 12:00Z on 2017-08-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 468 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Shreveport, LA at 12:00Z on 2017-08-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 87 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
468 J/kg
Mixed-layer CIN
-108 J/kg
Mixed-layer LCL
831 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
87 m²/s²
0-3 km storm-relative helicity
95 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.3

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Shreveport, LA wrote its last area forecast discussion before this flash flood watch went out at Aug 6, 1:20 PM CDT, 2 hours 27 minutes earlier.

Area forecast discussion, Aug 6, 1:20 PM CDT, 2 hours 27 minutes before
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Hazardous weather outlook, Aug 6, 12:06 PM CDT, 3 hours 41 minutes before
Hazardous Weather Outlook
National Weather Service Shreveport LA
1206 PM CDT Sun Aug 6 2017

ARZ050-051-059>061-070>073-LAZ001>006-010>014-017>022-OKZ077-
TXZ096-097-108>112-124>126-136>138-149>153-165>167-071200-
Sevier-Howard-Little River-Hempstead-Nevada-Miller-Lafayette-
Columbia-Union-Caddo-Bossier-Webster-Claiborne-Lincoln-De Soto-
Red River-Bienville-Jackson-Ouachita-Sabine-Natchitoches-Winn-
Grant-Caldwell-La Salle-McCurtain-Bowie-Franklin-Titus-Camp-
Morris-Cass-Wood-Upshur-Marion-Smith-Gregg-Harrison-Cherokee-Rusk-
Panola-Nacogdoches-Shelby-Angelina-San Augustine-
1206 PM CDT Sun Aug 6 2017

This Hazardous Weather Outlook is for portions of south central
Arkansas, southwest Arkansas, north central Louisiana, northwest
Louisiana, southeast Oklahoma, east Texas and northeast Texas.

.DAY ONE...This Afternoon and Tonight...

Showers and thunderstorms will slowly spread southeast across
portions of Northeast Texas, Southern Arkansas, and into extreme
Northern Louisiana this afternoon, along and behind a weak surface
boundary, and ahead of an upper level disturbance over Oklahoma
and extreme Northern Texas. Some of the stronger storms will be
capable of producing locally heavy rainfall and gusty winds, with
minor flooding of low lying, poor drainage areas possible
especially over portions of extreme Northeast Texas. Farther south
across Deep East Texas and Northcentral Louisiana, isolated to
widely scattered showers and thunderstorms will be possible this
afternoon and tonight, with brief heavy rainfall possible.

Additional shower and thunderstorm development will occur later
tonight across Northeast Texas, extreme Southeast Oklahoma,
Southwest Arkansas and possibly extreme Northern Louisiana, as a
series of weak upper level disturbances approach the region from
the west. Locally heavy rainfall and the threat for flash flooding
will be possible.

.DAYS TWO THROUGH SEVEN...Monday through Saturday...

Showers and thunderstorms will be ongoing across much of the
region Monday morning, which should spread southward across Deep
East Texas and Northcentral Louisiana during the day. The threat
for heavy rainfall and localized flash flooding will be possible
Monday, with showers and thunderstorms expected to gradually
diminish late in the day. Additional scattered to numerous shower
and thunderstorm development is possible over the region Tuesday,
as weak upper level disturbances interact with a weak surface
front, which could result in localized flash flooding. Showers
and thunderstorms should become more isolated to scattered
Wednesday through Saturday as the unsettled weather pattern will
continue. Brief heavy rainfall, minor flooding of low lying, poor
drainage areas, and gusty winds will be possible from the stronger
storms Wednesday through Saturday.

.SPOTTER INFORMATION STATEMENT...

Activation of emergency managers, spotter networks, and amateur
radio operators, may be needed tonight over portions of Northeast
Texas, Southeast Oklahoma, Southwest Arkansas, and possibly
extreme Northern Louisiana.

15

In the hours before

Special weather statement, Aug 6, 10:30 AM CDT, 5 hours 17 minutes before
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The office that day

Everything else NWS Shreveport, LA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 6, 4:18 AM CDTLake Wind AdvisorySHVCamp, Cass, Cherokee, Franklin, Gregg, Harrison and 8 more6 hr
Aug 6, 8:39 AM CDTSpecial Weather StatementSHVBowie, Red River51 min
Aug 6, 9:30 AM CDTSpecial Weather StatementSHVBowie60 min
Aug 6, 8:06 AM CDTSpecial Weather StatementSHVSevier54 min
Aug 6, 10:30 AM CDTSpecial Weather StatementSHVNevada30 min

Nearby

Flash Flood Watches in Texas, 2017Flash Flood Watches in Arkansas, 2017Every flash flood watch in 2017

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.