Severe Thunderstorm Warning 219, NWS Nashville, TN

Area Forecast Discussion
National Weather Service Nashville TN
615 PM CST Tue Nov 29 2016

.UPDATE...
FOR MESOSCALE DISCUSSION...

&&

.MESOSCALE DISCUSSION...

W-E Warm front appears to be located across nrn MS at this time
with a sfc low over se AR. Main cold frontal boundary still
located back across western AR and extends southwestward into east
TX.

Upper level features indicate duel jets...the 1st over the deep
south and the 2nd which stretches from OK to OH. Given the
location of each jet maximum, favorable energy appears to match
up along the spine of the aforementioned sfc front. Thus,
amplification, and increased forcing, of the eastward moving front
appears likely with time. Meanwhile, the warm front will lift
north with a modified triple point setting up just north of TN.
Instabilities will be on the increase with 850 mb convergence
becoming quite enhanced by the time the main boundary approaches
our Plateau, around sunrise Wednesday.

Latest HRRR data shows that the shower and thunderstorm activity
that is reaching into our southwestern areas currently, will
expand quickly northward and eastward. At this time it appears
that the more favorable areas for strong to severe storms will be
over southern middle TN, but especially the Plateau.

Helicity values and hodograph plots do support the potential for
tornadic development with maximum levels taking place over the
Plateau around midnight. At that time, some prefrontal forcing
will be in place.

&&

.PREV DISCUSSION.../ISSUED /

Mostly sunny skies across the area this morning and into the early
afternoon but there are clouds working this way from the southwest
as east Texas short wave punches in this direction. Surface winds
have been in the 15 to 20 mph range with higher gusts with good
warm advection into the area riding on a south wind and this will
allow temperatures to reach lower 70's in many areas. Deep cyclone
centered over Minnesota this afternoon with 120 knot upper jet
from Texas to Pennsylvania will undergo anticyclonic curvature
this afternoon and overnight placing Middle Tennessee in the right
rear quadrant for several hours which will aid the development of
convection. Surface cool front will begin to push eastward from
Oklahoma this evening with strengthening low level jet and a
northward surge of moisture along with a warm front currently
draped west to east across Mississippi and Alabama that will move
northward this evening placing Middle Tennessee in the warm sector
by mid evening. We should see convection begin to break out
by 21z across northern Louisiana northward into Arkansas and work
eastward into western Tennessee with convection working up into
Middle Tennessee from Mississippi after 02z and continue to
overspread Middle Tennessee for the next several hours. Storms
rolling northeastward from Mississippi and Alabama this evening
and overnight will need to be monitored closely since dynamics
looks reasonable for a few storms to become severe with damaging
winds being the main threat but a spin up or two is possible
especially southern third of Middle Tennessee from about 03z until
09z. A severe storm or two is also possible elsewhere in Middle
Tennessee tonight especially eastern areas and plateau again
through about 09z. Showers will linger eastern areas and plateau
Wednesday morning before pulling off plateau early afternoon as
cool front moves through. After near record setting temps today
temperatures will cool down closer to climatology through the
weekend into next week. Another good rain chance will come
Saturday night and Sunday to the area.

boyd

&&

.AVIATION...
00Z TAF DISCUSSION.

Continued high confidence of VFR conditions through 03Z, but
flying conditions will deteriorate quickly after 03Z as SHRA/TSRA
spread across the area. Continue to have medium confidence with
respect to timing the onset/ending of SHRA/TSRA. Continue to have
only low to medium confidence with respect to timing the flight
category restrictions and the flight categories themselves.
Still anticipating that several amendments will be possible
through at least this evening and overnight.

&&

.PRELIMINARY POINT TEMPS/POPS...
Nashville      56  62  36  52  33 /  90  20   0   0   0
Clarksville    51  58  34  50  32 /  70  10   0   0   0
Crossville     58  62  33  47  30 /  90  80  10   0   0
Columbia       54  61  35  53  32 / 100  30   0   0   0
Lawrenceburg   55  63  35  53  32 / 100  40   0   0   0
Waverly        50  58  34  51  31 /  80  10   0   0   0

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

DISCUSSION......21
AVIATION........31

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NASHVILLE TN
214 PM CST TUE NOV 29 2016

TNZ005>011-023>034-056>066-075-077>080-093>095-302015-
STEWART-MONTGOMERY-ROBERTSON-SUMNER-MACON-CLAY-PICKETT-HOUSTON-
HUMPHREYS-DICKSON-CHEATHAM-DAVIDSON-WILSON-TROUSDALE-SMITH-
JACKSON-PUTNAM-OVERTON-FENTRESS-PERRY-HICKMAN-LEWIS-WILLIAMSON-
MAURY-MARSHALL-RUTHERFORD-CANNON-DE KALB-WHITE-CUMBERLAND-BEDFORD-
COFFEE-WARREN-GRUNDY-VAN BUREN-WAYNE-LAWRENCE-GILES-
214 PM CST TUE NOV 29 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF MIDDLE
TENNESSEE.

.DAY ONE...TONIGHT

SEVERE THUNDERSTORMS WILL BE POSSIBLE ACROSS ALL OF MIDDLE
TENNESSEE BETWEEN 9 PM AND 4 AM. THE MAIN CONCERN WILL BE
DAMAGING STRAIGHT LINE WINDS, BUT LARGE HAIL UP TO QUARTER SIZE
AND A FEW ISOLATED TORNADOES CANNOT BE RULED OUT. THE HIGHEST
TORNADO THREAT WILL BE SOUTH OF A LINDEN TO MURFREESBORO TO
CROSSVILLE LINE.

EXCESSIVE RUNOFF FROM HEAVY RAINS AS WELL AS LEAF-CLOGGED DRAINS
COULD CAUSE SOME FLOODING.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL LIKELY BE NEEDED TONIGHT.

SPOTTER THUNDERSTORM REPORTING CRITERIA...
TORNADO
FUNNEL CLOUD
FLOODING
HAIL >= 1/2 INCH
WINDS > 50 MPH (MEASURED)
STRUCTURAL DAMAGE
TREES OR POWER LINES DOWN

JACKSON

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NASHVILLE TN
741 PM CST TUE NOV 29 2016

TNZ060-061-094-095-300215-
MARSHALL TN-LAWRENCE TN-MAURY TN-GILES TN-
741 PM CST TUE NOV 29 2016

...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL LAWRENCE...
NORTHWESTERN MARSHALL...NORTHWESTERN GILES AND SOUTHEASTERN MAURY
COUNTIES UNTIL 815 PM CST...

AT 740 PM CST...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 8
MILES NORTHEAST OF LAWRENCEBURG...MOVING NORTHEAST AT 50 MPH.

HALF INCH HAIL AND WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH
THIS STORM.

LOCATIONS IMPACTED INCLUDE...
COLUMBIA...LAWRENCEBURG...SPRING HILL...ETHRIDGE...LYNNVILLE...I-65
EAST OF COLUMBIA AND CULLEOKA.

A TORNADO WATCH ALSO REMAINS IN EFFECT UNTIL MIDNIGHT CST FOR MIDDLE
TENNESSEE.

LAT...LON 3518 8717 3530 8734 3574 8697 3556 8671
TIME...MOT...LOC 0140Z 219DEG 44KT 3530 8721

SHAMBURGER

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NASHVILLE TN
833 PM CST TUE NOV 29 2016

TNZ095-300300-
GILES TN-
833 PM CST TUE NOV 29 2016

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN GILES COUNTY UNTIL
900 PM CST...

AT 831 PM CST...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 10
MILES NORTHWEST OF ATHENS...MOVING NORTHEAST AT 40 MPH.

WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH THIS STORM.

LOCATIONS IMPACTED INCLUDE...
ARDMORE...ELKTON AND PROSPECT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD
TO LOCALIZED FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

&&

A TORNADO WATCH REMAINS IN EFFECT UNTIL MIDNIGHT CST FOR MIDDLE
TENNESSEE.

LAT...LON 3500 8712 3516 8683 3499 8684
TIME...MOT...LOC 0231Z 240DEG 34KT 3494 8704

SHAMBURGER