Alert archive / Alabama / Flash Flood Watches in 2017

Flash Flood Watch 2, NWS Huntsville, AL

July 27, 201711 counties in Alabama; Franklin County, Lincoln County, Moore County, Tennessee

NWS Huntsville, AL issued this flash flood watch at Jul 27, 2017, 3:27 PM CDT for 11 counties in Alabama; Franklin County, Lincoln County, Moore County, Tennessee. It took effect at Jul 28, 2017, 6:00 AM CDT. It was in force for 15 hr.

The area

The counties it named.

The facts

Issued: Jul 27, 2017, 3:27 PM CDT (20:27 UTC)
In effect from: Jul 28, 2017, 6:00 AM CDT
Expired: Jul 28, 2017, 9:00 PM CDT
In force: 15 hr
Issued by: NWS Huntsville, AL
Flood severity: None

Counties Colbert County, AL, Cullman County, AL, DeKalb County, AL, Franklin County, AL, Jackson County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Marshall County, AL, Morgan County, AL, Franklin County, TN, Lincoln County, TN, Moore County, TN

The radar

The Northeast Alabama radar (KHTX), 69 km from the middle of the area, began a volume at 20:27 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

Birmingham, AL (KBMX), launched 12:00Z, 8.5 hours before the alert went out and 170 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: 1507 J/kg
Mixed-layer CIN: -35 J/kg
Mixed-layer LCL: 873 m above ground
0-6 km bulk shear: 8 kt
0-1 km storm-relative helicity: 21 m²/s²
0-3 km storm-relative helicity: 12 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

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 Huntsville, AL wrote its last area forecast discussion before this flash flood watch went out at Jul 27, 3:15 PM CDT, 12 minutes earlier.

Area forecast discussion, Jul 27, 3:15 PM CDT, 12 minutes before

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Hazardous weather outlook, Jul 27, 4:38 AM CDT, 10 hours 49 minutes before

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In the hours before

Special weather statement, Jul 27, 11:10 AM CDT, 4 hours 17 minutes before

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The office that day

Everything else NWS Huntsville, AL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 26, 8:04 PM CDT	Special Weather Statement	HUN	Morgan	26 min
Jul 27, 11:10 AM CDT	Special Weather Statement	HUN	Franklin	35 min

Nearby

Flash Flood Watches in Alabama, 2017 Flash Flood Watches in Tennessee, 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.