Alert archive / Texas / Flash Flood Watches in 2018

Flash Flood Watch 4, NWS Shreveport, LA

September 21, 201813 counties in Texas; 4 parishes in Louisiana; 9 counties in Arkansas

NWS Shreveport, LA issued this flash flood watch at Sep 21, 2018, 3:18 PM CDT for 13 counties in Texas; 4 parishes in Louisiana; 9 counties in Arkansas. It was in force for 48 hr.

The area

The counties it named.

The facts

Issued: Sep 21, 2018, 3:18 PM CDT (20:18 UTC)
Expired: Sep 23, 2018, 3:23 PM CDT
In force: 48 hr
Issued by: NWS Shreveport, LA
Flood severity: None

All 26 counties

Columbia County, AR, Hempstead County, AR, Howard County, AR, Lafayette County, AR, Little River County, AR, Miller County, AR, Nevada County, AR, Sevier County, AR, Union County, AR, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, Webster Parish, LA, Bowie County, TX, Camp County, TX, Cass County, TX, Franklin County, TX, Gregg County, TX, Harrison 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), 83 km from the middle of the area, began a volume at 20:18 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, 8.3 hours before the alert went out and 289 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: 294 J/kg
Mixed-layer CIN: -55 J/kg
Mixed-layer LCL: 805 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: 17 m²/s²
0-3 km storm-relative helicity: 54 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 Sep 21, 12:38 PM CDT, 2 hours 40 minutes earlier.

Area forecast discussion, Sep 21, 12:38 PM CDT, 2 hours 40 minutes before

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Hazardous weather outlook, Sep 21, 1:33 PM CDT, 1 hour 45 minutes before

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In the hours before

Special weather statement, Sep 21, 12:04 PM CDT, 3 hours 14 minutes before

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Special weather statement, Sep 21, 3:01 PM CDT, 17 minutes before

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Special weather statement, Sep 21, 3:05 PM CDT, 13 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 21, 5:02 PM CDT	Special Weather Statement	SHV	Upshur	28 min
Sep 21, 5:31 PM CDT	Special Weather Statement	SHV	Camp	29 min
Sep 21, 3:01 PM CDT	Special Weather Statement	SHV	Sabine	44 min
Sep 21, 3:05 PM CDT	Special Weather Statement	SHV	De Soto	40 min
Sep 21, 4:24 PM CDT	Special Weather Statement	SHV	Grant	36 min
Sep 21, 4:57 PM CDT	Special Weather Statement	SHV	Winn	33 min
Sep 21, 5:29 PM CDT	Special Weather Statement	SHV	Claiborne	31 min
Sep 21, 5:30 PM CDT	Special Weather Statement	SHV	Jackson	30 min
Sep 21, 6:07 PM CDT	Special Weather Statement	SHV	Union	23 min
Sep 21, 6:27 PM CDT	Special Weather Statement	SHV	LaSalle	33 min
Sep 21, 6:48 PM CDT	Special Weather Statement	SHV	LaSalle	42 min
Sep 21, 12:04 PM CDT	Special Weather Statement	SHV	Polk	26 min
Sep 21, 3:50 PM CDT	Special Weather Statement	SHV	Howard, Sevier	40 min
Sep 21, 4:17 PM CDT	Special Weather Statement	SHV	Hempstead	43 min
Sep 21, 5:04 PM CDT	Special Weather Statement	SHV	Nevada	26 min
Sep 21, 6:46 PM CDT	Special Weather Statement	SHV	Union	44 min

Nearby

Flash Flood Watches in Texas, 2018 Flash Flood Watches in Arkansas, 2018 Flash Flood Watches in Louisiana, 2018 Every flash flood watch in 2018

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.