Alert archive / Tennessee / Flash Flood Watches in 2017

Flash Flood Watch 11, NWS Memphis, TN

December 21, 201721 counties in Tennessee; 10 counties in Mississippi; 8 counties in Arkansas

NWS Memphis, TN issued this flash flood watch at Dec 21, 2017, 3:31 PM CST for 21 counties in Tennessee; 10 counties in Mississippi; 8 counties in Arkansas. It took effect at Dec 22, 2017, 9:00 AM CST. It was in force for 21 hr.

The area

The counties it named.

The facts

Issued: Dec 21, 2017, 3:31 PM CST (21:31 UTC)
In effect from: Dec 22, 2017, 9:00 AM CST
Expired: Dec 23, 2017, 6:01 AM CST
In force: 21 hr
Issued by: NWS Memphis, TN
Flood severity: None

All 39 counties

Craighead County, AR, Crittenden County, AR, Cross County, AR, Lee County, AR, Mississippi County, AR, Phillips County, AR, Poinsett County, AR, St. Francis County, AR, Alcorn County, MS, Benton County, MS, Coahoma County, MS, DeSoto County, MS, Marshall County, MS, Panola County, MS, Quitman County, MS, Tate County, MS, Tippah County, MS, Tunica County, MS, Benton County, TN, Carroll County, TN, Chester County, TN, Crockett County, TN, Decatur County, TN, Dyer County, TN, Fayette County, TN, Gibson County, TN, Hardeman County, TN, Hardin County, TN, Haywood County, TN, Henderson County, TN, Henry County, TN, Lake County, TN, Lauderdale County, TN, Madison County, TN, McNairy County, TN, Obion County, TN, Shelby County, TN, Tipton County, TN, Weakley County, TN

The radar

The Memphis radar (KNQA), 36 km from the middle of the area, began a volume at 21:28 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

Nashville Metro, TN (KBNA), launched 12:00Z, 9.5 hours before the alert went out and 274 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 563 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 1 m²/s²
0-3 km storm-relative helicity: 72 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 Memphis, TN wrote its last area forecast discussion before this flash flood watch went out at Dec 21, 3:03 PM CST, 28 minutes earlier.

Area forecast discussion, Dec 21, 3:03 PM CST, 28 minutes before

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Hazardous weather outlook, Dec 21, 3:31 PM CST, 0 minutes before

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The office that day

Everything else NWS Memphis, TN issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 21, 2:41 AM CST	Dense Fog Advisory	MEG	Benton, Carroll, Chester, Crockett, Decatur, Dyer and 15 more	6 hr
Dec 21, 8:56 AM CST	Dense Fog Advisory	MEG	Benton, Carroll, Chester, Crockett, Decatur, Dyer and 12 more	2 hr
Dec 21, 10:59 AM CST	River Flood Warning	MEG	Madison	3 days
Dec 21, 10:59 AM CST	River Flood Warning	MEG	Crockett, Dyer, Lauderdale	9 days
Dec 21, 10:59 AM CST	River Flood Warning	MEG	Fayette, Shelby	53 hr
Dec 21, 10:57 AM CST	River Flood Warning	MEG	Quitman	4 days

Nearby

Flash Flood Watches in Tennessee, 2017 Flash Flood Watches in Mississippi, 2017 Flash Flood Watches in Arkansas, 2017 Every 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.