Alert archive / Tennessee / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 148, NWS Morristown, TN

July 21, 20184 counties in Tennessee

NWS Morristown, TN issued this severe thunderstorm warning at Jul 21, 2018, 12:24 AM EDT for 4 counties in Tennessee. It was in force for 51 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Jul 21, 2018, 12:24 AM EDT (04:24 UTC)
Expired: Jul 21, 2018, 1:15 AM EDT
In force: 51 min
Issued by: NWS Morristown, TN
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Bradley County, TN, McMinn County, TN, Meigs County, TN, Polk County, TN

The radar

The Northeast Alabama radar (KHTX), 132 km from the middle of the area, began a volume at 04:27 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 20, 8:02 PM EDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Nashville Metro, TN (KBNA), launched 00:00Z, 4.4 hours before the alert went out and 194 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: 3305 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 1217 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 90 m²/s²
0-3 km storm-relative helicity: 169 m²/s²
Significant tornado parameter: 2.2
Supercell composite: 11.6

Open this sounding in Storm Lab

What forecasters said that day

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

NWS Morristown, TN wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 20, 8:38 PM EDT, 3 hours 46 minutes earlier.

Area forecast discussion, Jul 20, 8:38 PM EDT, 3 hours 46 minutes before

Area Forecast Discussion
National Weather Service Morristown TN
838 PM EDT Fri Jul 20 2018

.DISCUSSION...Showers and storms currently across southeastern KY
and the northern Cumberland Plateau will continue to drift east
southeast into the TN Valley this evening. The highest
instability values remain across the central TN Valley and
westward back toward the Cumberland Plateau. This area of moderate
instability combined with 40 to 50 Knots of effective bulk shear
will allow storms to maintain their strength as they drop down
into our area. Low level shear is lacking right now so expect any
rotation to remain confined to the mid levels unless a storm can
latch onto a good boundary. Models do show low level shear
increasing here in a few hours though, thus allowing for the
current tornado watch. Wind damage and large hail will be the
main threats with these storms but there is also the possibility
of an isolated tornado due to the shear in place. Models still
uncertain what happens later tonight after this first wave of
storms rolls. However, thinking as of now is this line that is
currently moving in will be the main show. New zones issued for
tornado watch wording.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             72  89  70  85 /  60  60  60  50
Knoxville McGhee Tyson Airport, TN  70  85  68  82 /  60  60  60  70
Oak Ridge, TN                       70  85  68  82 /  70  60  60  70
Tri Cities Airport, TN              66  82  65  79 /  60  70  70  70

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...None.
TN...None.
VA...None.
&&

SR

Hazardous weather outlook, Jul 20, 3:21 PM EDT, 9 hours 3 minutes before

Hazardous Weather Outlook
National Weather Service Morristown TN
321 PM EDT Fri Jul 20 2018

NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002-
005-006-008-211930-
Cherokee-Clay-Scott TN-Campbell-Claiborne-Hancock-Hawkins-
Sullivan-Johnson-Morgan-Anderson-Union-Grainger-Hamblen-
Northwest Cocke-Cocke Smoky Mountains-Northwest Greene-
Southeast Greene-Washington TN-Unicoi-Northwest Carter-
Southeast Carter-Roane-Loudon-Knox-Jefferson-NW Blount-
Blount Smoky Mountains-North Sevier-Sevier Smoky Mountains-
Sequatchie-Bledsoe-Rhea-Meigs-McMinn-Northwest Monroe-
Southeast Monroe-Marion-Hamilton-Bradley-West Polk-East Polk-Lee-
Wise-Scott-Russell-Washington-
321 PM EDT Fri Jul 20 2018 /221 PM CDT Fri Jul 20 2018/

This Hazardous Weather Outlook is for portions of Southwest North
Carolina...East Tennessee and Southwest Virginia.

.DAY ONE...This Afternoon and Tonight

Showers and thunderstorms are likely tonight across much of the
area, some of which may reach severe levels. The strongest storms
are expected to move out of Kentucky into middle and east
Tennessee late tonight, moving quickly into southeast Tennessee
and southwest North Carolina into early morning Saturday. Some of
these thunderstorms will be capable of producing damaging winds,
large hail, and brief heavy rainfall. An isolated tornado cannot
be ruled out, particularly across southern portions of the
Tennessee Valley.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

The atmosphere will remain unstable into Saturday and strong to
severe thunderstorms will again be possible Saturday afternoon
into the evening. The main threats with any stronger storms will
be damaging winds, large hail and brief heavy rainfall.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed tonight.

In the hours before

Local storm report, Jul 20, 11:31 PM EDT, 53 minutes before

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Local storm report, Jul 20, 11:32 PM EDT, 52 minutes before

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Local storm report, Jul 20, 11:44 PM EDT, 40 minutes before

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Special weather statement, Jul 21, 12:02 AM EDT, 22 minutes before

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Local storm report, Jul 21, 12:11 AM EDT, 13 minutes before

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Special weather statement, Jul 21, 12:14 AM EDT, 10 minutes before

Special Weather Statement
National Weather Service Morristown TN
1214 AM EDT SAT JUL 21 2018

TNZ012-210500-
Scott TN-
1214 AM EDT SAT JUL 21 2018

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN SCOTT COUNTY UNTIL 100
AM EDT...

At 1213 AM EDT, Doppler radar was tracking a strong thunderstorm 7
miles west of Helenwood, or 11 miles southwest of Oneida, moving
southeast at 30 mph.

Dime size hail and wind gusts up to 50 mph will be possible with this
storm.

Locations impacted include...
Huntsville, Helenwood, Smokey Junction, Honey Creek State Park,
Norma, Elgin, Robbins, Slick Rock and Rugby State Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

A Tornado Watch remains in effect until 400 AM EDT for east
Tennessee.

LAT...LON 3647 8470 3634 8433 3628 8433 3626 8438
      3623 8437 3616 8443 3616 8444 3621 8448
      3623 8456 3626 8457 3628 8459 3627 8461
      3632 8466 3637 8470 3640 8466 3644 8469
TIME...MOT...LOC 0413Z 300DEG 26KT 3640 8467

DGS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 20, 9:02 PM EDT	Severe Thunderstorm Warning	MRX	Claiborne, Hancock	58 min
Jul 20, 9:12 PM EDT	Severe Thunderstorm Warning	MRX	Campbell, Claiborne, Scott	48 min
Jul 20, 9:42 PM EDT	Severe Thunderstorm Warning	MRX	Grainger, Hamblen, Hawkins	63 min
Jul 20, 9:56 PM EDT	Severe Thunderstorm Warning	MRX	Anderson, Campbell, Claiborne, Union	49 min
Jul 20, 10:10 PM EDT	Severe Thunderstorm Warning	MRX	Cocke, Greene, Jefferson, Sullivan, Unicoi, Washington	65 min
Jul 20, 10:17 PM EDT	Severe Thunderstorm Warning	MRX	Anderson, Blount, Knox, Sevier	58 min
Jul 20, 10:31 PM EDT	Tornado Warning	MRX	Bledsoe, Rhea	44 min
Jul 20, 10:44 PM EDT	Severe Thunderstorm Warning	MRX	Hamblen	16 min
Jul 20, 10:48 PM EDT	Severe Thunderstorm Warning	MRX	Carter, Johnson, Unicoi	57 min
Jul 20, 11:10 PM EDT	Tornado Warning	MRX	Bledsoe, Meigs, Rhea	50 min
Jul 20, 11:13 PM EDT	Severe Thunderstorm Warning	MRX	Cocke, Sevier	32 min
Jul 20, 11:18 PM EDT	Severe Thunderstorm Warning	MRX	Bledsoe, Rhea	42 min
Jul 20, 11:42 PM EDT	Severe Thunderstorm Warning	MRX	Bradley, McMinn, Meigs, Rhea	48 min
Jul 20, 11:47 PM EDT	Areal Flood Advisory	MRX	Bledsoe, Meigs, Rhea, Roane	3 hr
Jul 21, 12:02 AM EDT	Special Weather Statement	MRX	Bledsoe	43 min
Jul 21, 12:11 AM EDT	Severe Thunderstorm Warning	MRX	Bledsoe, Hamilton, Rhea, Sequatchie	49 min
Jul 21, 12:14 AM EDT	Special Weather Statement	MRX	Scott	46 min
Jul 21, 12:55 AM EDT	Severe Thunderstorm Warning	MRX	Bledsoe, Hamilton, Meigs, Rhea	50 min
Jul 21, 12:58 AM EDT	Areal Flood Advisory	MRX	McMinn, Meigs, Rhea	3 hr
Jul 21, 12:58 AM EDT	Severe Thunderstorm Warning	MRX	Polk	62 min
Jul 21, 1:16 AM EDT	Areal Flood Advisory	MRX	Bledsoe, Rhea	3 hr
Jul 21, 1:21 AM EDT	Severe Thunderstorm Warning	MRX	Bledsoe, Rhea	39 min
Jul 21, 1:27 AM EDT	Severe Thunderstorm Warning	MRX	Anderson, Campbell, Claiborne, Scott	48 min
Jul 21, 1:28 AM EDT	Severe Thunderstorm Warning	MRX	Bradley, McMinn	47 min
Jul 21, 2:02 AM EDT	Severe Thunderstorm Warning	MRX	Bradley, Polk	28 min
Jul 21, 2:11 AM EDT	Severe Thunderstorm Warning	MRX	Anderson, Campbell, Morgan, Roane, Scott	52 min
Jul 21, 2:16 AM EDT	Severe Thunderstorm Warning	MRX	Anderson, Campbell, Claiborne, Grainger, Knox, Union	59 min
Jul 21, 2:39 AM EDT	Areal Flood Advisory	MRX	Bradley, McMinn, Polk	3 hr
Jul 21, 2:54 AM EDT	Special Weather Statement	MRX	Blount, Loudon, Roane	66 min
Jul 21, 3:06 AM EDT	Severe Thunderstorm Warning	MRX	Bledsoe, Rhea	39 min
Jul 21, 3:10 AM EDT	Special Weather Statement	MRX	Cocke, Grainger, Hamblen, Jefferson	50 min
Jul 21, 3:30 AM EDT	Severe Thunderstorm Warning	MRX	Bledsoe, Hamilton, Meigs, Rhea	45 min
Jul 21, 3:36 AM EDT	Areal Flood Warning	MRX	Bledsoe, Bradley, Hamilton, McMinn, Meigs, Rhea	3 hr
Jul 21, 3:41 AM EDT	Severe Thunderstorm Warning	MRX	Hamilton, Marion, Sequatchie	48 min
Jul 21, 3:53 AM EDT	Severe Thunderstorm Warning	MRX	McMinn, Monroe	41 min
Jul 21, 4:05 AM EDT	Severe Thunderstorm Warning	MRX	Bradley, Hamilton, McMinn, Polk	40 min
Jul 21, 4:33 AM EDT	Areal Flood Advisory	MRX	Bradley, Hamilton, Marion, Polk	117 min
Jul 21, 6:39 AM EDT	Severe Thunderstorm Warning	MRX	Bledsoe	36 min
Jul 21, 7:05 AM EDT	Severe Thunderstorm Warning	MRX	Bledsoe, Hamilton, Meigs, Rhea	25 min
Jul 21, 7:24 AM EDT	Special Weather Statement	MRX	Bradley, Polk	36 min
Jul 21, 4:06 PM EDT	Special Weather Statement	MRX	Knox	39 min
Jul 21, 4:17 PM EDT	Special Weather Statement	MRX	Monroe	43 min
Jul 21, 4:45 PM EDT	Special Weather Statement	MRX	Hancock, Hawkins	60 min
Jul 21, 4:47 PM EDT	Special Weather Statement	MRX	Sevier	58 min
Jul 21, 5:12 PM EDT	Special Weather Statement	MRX	Bradley	63 min
Jul 21, 5:19 PM EDT	Severe Thunderstorm Warning	MRX	Bradley, Hamilton, McMinn, Meigs	56 min
Jul 21, 5:33 PM EDT	Special Weather Statement	MRX	Monroe	42 min
Jul 21, 5:44 PM EDT	Special Weather Statement	MRX	Grainger	46 min
Jul 21, 5:49 PM EDT	Special Weather Statement	MRX	Bradley	26 min
Jul 21, 5:53 PM EDT	Severe Thunderstorm Warning	MRX	Bradley, Hamilton	37 min
Jul 21, 6:07 PM EDT	Special Weather Statement	MRX	Polk	53 min
Jul 21, 6:24 PM EDT	Special Weather Statement	MRX	Monroe	51 min
Jul 21, 6:26 PM EDT	Severe Thunderstorm Warning	MRX	Polk	49 min
Jul 21, 7:00 PM EDT	Special Weather Statement	MRX	Blount	30 min
Jul 21, 7:15 PM EDT	Severe Thunderstorm Warning	MRX	Blount, Sevier	34 min
Jul 20, 8:14 PM EDT	Special Weather Statement	MRX	Scott, Wise, City of Norton	46 min
Jul 20, 9:23 PM EDT	Severe Thunderstorm Warning	MRX	Lee	37 min
Jul 20, 11:50 PM EDT	Areal Flood Advisory	MRX	Wise, City of Norton	3 hr
Jul 21, 4:15 PM EDT	Special Weather Statement	MRX	Russell	45 min
Jul 21, 4:59 PM EDT	Special Weather Statement	MRX	Scott	61 min
Jul 21, 5:43 PM EDT	Special Weather Statement	MRX	Russell	47 min
Jul 21, 6:34 PM EDT	Special Weather Statement	MRX	Smyth	41 min
Jul 21, 6:10 PM EDT	Special Weather Statement	MRX	Cherokee	50 min

Nearby

Severe Thunderstorm Warnings in Tennessee, 2018 Every severe thunderstorm warning 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.