Today begins one of the U.S.’s largest severe weather risks of the year so far, of which Middle Tennessee is just on the outskirts of. However, just because we are on the outskirts does not make us exempt from severe weather. The National Weather Service and the Storm Prediction Center agree that we do have enough of a risk to warrant the need to watch the weather.
What the Storm Prediction Center says:
This is the Enhanced Thunderstorm Outlook, which is valid until 2 P.M. today. However, below is the SPC’s tornado outlook for today.
This is the text from the SPC regarding our area specifically. Head over to the SPC page for the rest.
...NE TX/ERN OK/SE KS INTO MO/AR AND THE MS VLY TODAY/TONIGHT...
LOW-LVL MOISTENING WILL CONTINUE NWD AHEAD OF MERGING COLD FRONT/DRY
LINE TODAY/TONIGHT...WITH SFC DEWPOINTS IN THE UPR 50S F EXPECTED BY
LATE AFTN OVER ERN OK/AR. A SEPARATE AREA OF RELATIVELY MOIST AIR
WILL SPREAD N FROM THE AR/MS DELTA INTO SE MO AND WRN KY/TN.
COUPLED WITH SFC HEATING AND COOL MID LVL TEMPERATURES...SETUP
SHOULD YIELD SBCAPE OF 1000-1500 J/KG IN AR...AND VALUES AOA 1000
J/KG FROM ERN OK INTO SRN MO/W TN.
COMBINATION OF DESTABILIZATION AND STRONG ASCENT AHEAD OF NM UPR
VORT SHOULD SUPPORT VIGOROUS STORM DEVELOPMENT ALONG AND AHEAD OF
THE FRONT FROM SE KS THROUGH ERN OK INTO NE TX BY MID/LATE AFTN.
THE STORMS SHOULD CONSOLIDATE INTO BROKEN BANDS AND MOVE/DEVELOP
E/NE INTO MO/AR BY EARLY EVE.
BAND OF 80+ KT SSWLY 500 MB FLOW SHIFTING ENE ATOP LOW-LVL SLY FLOW
WILL BE FAVORABLE FOR SUPERCELLS. HOWEVER...SUBSTANTIAL
SPATIAL/TEMPORAL VARIATION OF WIND FIELD AHEAD OF COMPACT UPR
VORT...AND NW-TO-SE VARIATION OF MOISTURE AVAILABILITY ACROSS REGION
COMPLICATE FORECAST OF DOMINANT STORM MODE. NEVERTHELESS...OVERALL
COMBINATION OF STRENGTHENING INSTABILITY...SHEAR...AND LIFT SUGGEST
STRONG LIKELIHOOD FOR SVR WEATHER...ESPECIALLY LARGE HAIL.
TORNADOES ALSO WILL BE POSSIBLE...NOT ONLY WITH THE MORE DISCRETE
STORMS THIS AFTN...BUT ALSO WITH BROKEN BANDS/LEWPS OVER AR/MO AND
PERHAPS WRN TN TONIGHT/EARLY THU AS THE ACTIVITY ENCOUNTERS
INCREASING MOISTURE MOVING N UP THE MS RVR VLY.
I have taken a look at the models, and it looks like we have a possible area of CAPE ranging in the 1000 J/Kg, but in mostly western Mid Tn areas. Lift index values are in the -5 area, and we have some 35-40 kt wind shear over Middle Tennessee. Storm motion will be east-northeast, and it looks like we have some ok levels of vorticity. Now I barely only have a clue to what vorticity is, so don’t ask me! All I know is it is a good ingredient to have for tornadoes. Today will also be an ok day because we have some decent moisture in the area, with temperatures reaching near 70. All of these things are why the SPC has included us in the 2% tornado risk, because there are enough ingredients there to have a a chance of a tornado. Mind you, it was only a few days ago in Oklahoma with a 2% risk that a large, stove-pipe tornado touched down! This is why you need to keep an eye on things today, because we are NOT exempt.
This is the hail probability graphic today, which we are also included in.
This is what our WFO in Nashville has to say about things…
THIS HAZARDOUS WEATHER OUTLOOK IS FOR MIDDLE TENNESSEE.
.DAY ONE…TODAY AND TONIGHT A STRONG COLD FRONT WILL PASS THROUGH MIDDLE TENNESSEE LATE TONIGHT. AS A RESULT, WIDESPREAD THUNDERSTORMS ARE EXPECTED ACROSS THE MID STATE. A FEW OF THESE STORMS MAY EVEN BECOME SEVERE, ESPECIALLY IN AREAS ALONG AND NEAR THE TENNESSEE RIVER. HEAVY RAIN AND PONDING OF WATER ON ROADS MAY ALSO OCCUR WITH THESE STORMS.
.DAYS TWO THROUGH SEVEN…THURSDAY THROUGH TUESDAY LOOK FOR ANOTHER ROUND OF STORMS ON FRIDAY. IT IS POSSIBLE THAT SOME OF THESE STORMS MAY PRODUCE HAIL.
.SPOTTER INFORMATION STATEMENT… EVEN THOUGH ANY SEVERE THUNDERSTORMS ARE EXPECTED TO BE BRIEF AND ISOLATED, SPOTTERS ARE ENCOURAGED TO CLOSELY MONITOR WEATHER CONDITIONS AND BE PREPARED TO CALL IN ANYTHING REACHING REPORTING CRITERIA.
$ SPOTTER THUNDERSTORM REPORTING CRITERIA…
TORNADO
FUNNEL CLOUD
FLOODING
HAIL >= 1/2 INCH
WINDS > 50 MPH (MEASURED)
STRUCTURAL DAMAGE
TREES OR POWER LINES DOWN
So, in summery, we do not have a “large” risk as it were, but there is still enough of a risk to warrant caution. Just get yourself prepared, keep an eye on the news and weather, change the batteries in your weather radio, etc, etc. Be expecting this storm system to move in LATE TONIGHT, and not this afternoon. I feel like that is what gives this storm system its danger, because the main force of it will occur after midnight through Friday morning. Nighttime thunderstorms are usually the killers. Now I am not saying we have some large risk and we need to run for the hills, but I do feel the need to warrant caution tonight.
