Alert archive / Tennessee / Severe Thunderstorm Warnings in 2007

Severe Thunderstorm Warning 196, NWS Morristown, TN

August 28, 2007Polk County, Tennessee

NWS Morristown, TN issued this severe thunderstorm warning at Aug 28, 2007, 5:13 PM EDT for Polk County, Tennessee. It was in force for 62 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
Aug 28, 2007, 5:13 PM EDT (21:13 UTC)
Expired
Aug 28, 2007, 6:15 PM EDT
In force
62 min
Issued by
NWS Morristown, TN
Area
Counties, with a storm outline in the text

County Polk County, TN

The radar

The Northeast Alabama radar (KHTX), 144 km from the middle of the area, began a volume at 21:16 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

Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 9.2 hours before the alert went out and 195 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-pSkew-T log-p diagram, Peachtre/Fal Fld, GA at 12:00Z on 2007-08-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 512 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Peachtre/Fal Fld, GA at 12:00Z on 2007-08-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 22 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
512 J/kg
Mixed-layer CIN
-15 J/kg
Mixed-layer LCL
611 m above ground
0-6 km bulk shear
6 kt
0-1 km storm-relative helicity
22 m²/s²
0-3 km storm-relative helicity
15 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 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 Aug 28, 2:45 PM EDT, 2 hours 28 minutes earlier.

Area forecast discussion, Aug 28, 2:45 PM EDT, 2 hours 28 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
245 PM EDT TUE AUG 28 2007

.SHORT TERM...(TONIGHT AND WEDNESDAY)...
OPERATIONAL MODELS AND SREF PROJECT INCREASING MOISTURE ADVECTION
INTO THE SOUTHERN APPALACHIAN REGION AS RETURN FLOW AROUND SURFACE
HIGH PRESSURE NEAR THE ATLANTIC COAST COMMENCES. HOWEVER...AM
SKEPTICAL OF THE RELATIVELY HIGH POPS PROJECTED BY GFS GUIDANCE IN
THE FIRST PERIOD AND HAVE GENERALLY UNDERCUT THOSE SOMEWHAT. POPS
FOR THE SECOND PERIOD LOOK MORE REASONABLE AS SCATTERED DIURNAL
CONVECTION DEVELOPS IN MOIST ATMOSPHERE REGIME...WITH SOMEWHAT
BETTER COVERAGE EXPECTED IN THE SOUTHERN TIER. GFS GUIDANCE TEMPS
LOOK REASONABLE FOR THE MOST PART AND DID NOT STRAY TOO FAR FROM
THOSE VALUES. ANTICIPATE THE EXPECTED INCREASE IN MOISTURE AND THE
CORRESPONDING INCREASE IN CLOUD COVER WILL TEND TO HOLD TEMPS DOWN
IN THE SECOND PERIOD TO SOME DEGREE AS DEPICTED IN THE GUIDANCE.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)...
MORE ORGANIZED LIFT SHOULD INCREASE THE CHANCES OF RAIN ON THURSDAY
AS THE UPPER RIDGE IS SUPPRESSED TO THE SOUTH AND WEST BY AN UPPER
TROUGH OVER THE GREAT LAKES REGION. THE FLOW REMAINS WEAK AND THE
TROUGH IS RATHER BROAD...SO WILL KEEP POPS IN THE CHANCE RANGE FOR
THURSDAY AFTERNOON/EVENING. BEST PRECIP CHANCES LOOK TO BE IN
SOUTHERN SECTIONS CLOSER TO A WEAK 850 MB LOW. SURFACE COLD FRONT
LOOKS LIKE IT STALLS ACROSS THE OHIO VALLEY AND NEVER REACHES OUR
AREA...SO THERE WILL BE NO SIGNIFICANT CHANGE IN AIR MASS THROUGH
THE WEEKEND. THE GFS TAKES A WEAK 850 LOW OVER ALABAMA TO THE
WEST...WHICH SUPPLIES MOISTURE TO THE AREA THROUGH TUESDAY. THE DEEP
MOISTURE FROM THIS LOW IS A NEW FEATURE ON THE 12Z GFS...AND GIVEN
THE DRY PATTERN WE HAVE BEEN STUCK IN...WILL AWAIT BETTER MODEL
CONTINUITY BEFORE BITING ON HIGH POPS.

&&

.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN             72  89  72  87  70 /  40  50  20  50  50
KNOXVILLE MCGHEE TYSON AIRPORT, TN  70  91  69  85  70 /  20  20  20  40  40
OAK RIDGE, TN                       70  92  69  85  69 /  20  20  20  40  40
TRI CITIES AIRPORT, TN              66  91  66  86  65 /  10  10  10  30  30

&&

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

LCM/DGS

In the hours before

Special weather statement, Aug 28, 4:03 PM EDT, 1 hour 10 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MORRISTOWN TN
403 PM EDT TUE AUG 28 2007

TNZ099-282100-
HAMILTON-
403 PM EDT TUE AUG 28 2007

...STRONG THUNDERSTORMS WILL AFFECT HAMILTON COUNTY THROUGH 5 PM...

AT 401 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
CLUSTER OF STRONG THUNDERSTORMS OVER HAMILTON COUNTY...DRIFTING
SLOWLY NORTHWEST AROUND 5 MPH.

WINDS UP TO 40 MPH AND LOCALLY HEAVY RAINFALL ARE EXPECTED WITH
THESE STORMS.

IN ADDITION TO SMALL HAIL AND GUSTY WINDS...CONTINUOUS CLOUD TO
GROUND LIGHTNING IS OCCURRING WITH THIS STORM. MOVE INDOORS
IMMEDIATELY LIGHTNING IS ONE OF NATURES PRIMARY KILLERS. REMEMBER...
IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY
LIGHTNING.

DMG
Special weather statement, Aug 28, 4:49 PM EDT, 24 minutes before
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Special weather statement, Aug 28, 5:01 PM EDT, 12 minutes before
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      <h1 id="headline">This service is currently unavailable.</h1>
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        The site you requested is temporarily down for maintenance or an unexpected outage.
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The office that day

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

IssuedProductOfficeCountiesLasted
Aug 28, 4:28 PM EDTSevere Thunderstorm WarningMRXHamilton62 min

Nearby

Severe Thunderstorm Warnings in Tennessee, 2007Every severe thunderstorm warning in 2007

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.