Alert archive / Tennessee / Special Weather Statements in 2017

Special Weather Statement, NWS Huntsville, AL

April 18, 2017Franklin County, Tennessee

NWS Huntsville, AL issued this special weather statement at Apr 18, 2017, 2:21 PM CDT for Franklin County, Tennessee. It was in force for 24 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Apr 18, 2017, 2:21 PM CDT (19:21 UTC)
Expired: Apr 18, 2017, 2:45 PM CDT
In force: 24 min
Issued by: NWS Huntsville, AL

County Franklin County, TN

The radar

The Northeast Alabama radar (KHTX), 19 km from the middle of the area, began a volume at 19:21 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, 7.4 hours before the alert went out and 122 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: 39 J/kg
Mixed-layer CIN: -84 J/kg
Mixed-layer LCL: 638 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 57 m²/s²
0-3 km storm-relative helicity: 39 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement 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 special weather statement went out at Apr 18, 11:34 AM CDT, 2 hours 47 minutes earlier.

Area forecast discussion, Apr 18, 11:34 AM CDT, 2 hours 47 minutes before

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Hazardous weather outlook, Apr 18, 1:38 PM CDT, 43 minutes before

Hazardous Weather Outlook
National Weather Service Huntsville AL
138 PM CDT Tue Apr 18 2017

ALZ001>010-016-TNZ076-096-097-191100-
Lauderdale-Colbert-Franklin AL-Lawrence-Limestone-Madison-Morgan-
Marshall-Jackson-De Kalb-Cullman-Moore-Lincoln-Franklin TN-
138 PM CDT Tue Apr 18 2017

This Hazardous Weather Outlook is for north Alabama and portions of
southern middle Tennessee.

.DAY ONE...This afternoon and Tonight...

Thunderstorms will continue to develop this afternoon in the
vicinity of a weak front stalled across northern Alabama. The
activity is expected to diminish shortly after sunset. Wind gusts of
30 mph and small hail will be possible with the strongest storms.
However, the main hazards will be cloud to ground lightning and
locally heavy rainfall.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday...

There is the potential for isolated thunderstorms on Wednesday,
Wednesday night, and Thursday mainly over northeast Alabama and
portions of Southern Middle Tennessee.

However, the threat for storms will increase early Friday morning and
continue through Friday evening as another cold front drifts
southward into the Tennessee Valley before stalling. Some of these
storms could be strong with gusty winds the primary threat.

Numerous storms are expected on Saturday through Saturday night with
arrival of a stronger cold front. A few strong to severe storms will
be possible with the passage of this front from late Saturday
afternoon into Saturday night.

.SPOTTER CALL TO ACTION STATEMENT...

Activation of storm spotters and emergency management personnel is
not anticipated at this time.

In the hours before

Special weather statement, Apr 18, 2:21 PM CDT, 0 minutes before

Special Weather Statement
National Weather Service Huntsville AL
221 PM CDT TUE APR 18 2017

TNZ097-181945-
Franklin TN-
221 PM CDT TUE APR 18 2017

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN FRANKLIN COUNTY
UNTIL 245 PM CDT...

At 221 PM CDT, Doppler radar was tracking a strong thunderstorm near
Huntland, or 15 miles southwest of Winchester, moving northeast at 15
mph.

Penny size hail...heavy rainfall...frequent lightning...and winds in
excess of 30 mph will be possible with this storm.

Locations impacted include...
Winchester, Huntland, Tims Ford Lake, Lexie Crossroads, Harmony,
Maxwell, Beans Creek and Belvidere.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Very heavy rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike several miles away from a thunderstorm. Seek a
safe shelter inside a building or vehicle.

&&

LAT...LON 3509 8598 3499 8614 3499 8632 3514 8632
      3525 8625
TIME...MOT...LOC 1921Z 216DEG 13KT 3501 8627

SL.77

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 18, 2:56 PM CDT	Special Weather Statement	HUN	Lauderdale	34 min
Apr 18, 5:03 PM CDT	Special Weather Statement	HUN	Jackson	27 min
Apr 18, 2:51 PM CDT	Severe Thunderstorm Warning	HUN	Franklin	24 min
Apr 18, 3:12 PM CDT	Severe Thunderstorm Warning	HUN	Franklin	33 min
Apr 18, 3:36 PM CDT	Special Weather Statement	HUN	Moore	24 min

Nearby

Special Weather Statements in Tennessee, 2017 Every special weather statement 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.