Tn Valley Severe Weather

[jaxjagman]

1 hour ago, nrgjeff said:

Marginal. Saturday. That's a go!

Of course it's garbage weak moisture return and all. However a surface trough and backed winds tracks through (during the daytime - what a novel idea!) Tenn. Could be low top, low probability, but decent visibility. So much for the latter on Thursday, lol! 

If the 12Z guidance is the same to more robust, Saturday might be a chase day. Um, urr, I mean, go to one of those State Parks that are opening.

I was thinking about going also but man those parks are gonna be packed

[nrgjeff]

SPC Day 2 even mentions the Cumberland Plateau. Elevation puts it closer to the LLJ. So, I guess the Cumberland Trail is open?

[jaxjagman]

2 hours ago, nrgjeff said:

SPC Day 2 even mentions the Cumberland Plateau. Elevation puts it closer to the LLJ. So, I guess the Cumberland Trail is open?

Yes,starting today The Cumberland Trail opens from 7AM until sunset

[jaxjagman]

If the NAM is right but could very well be over doing things there would some strong storms in the mid morning in Mid Tn as the LLJ kicks in,then spreads eastward,seems tho there could be some early junk,looks messy

[jaxjagman]

The Euro and GEFS are far apart in the upcoming days with the MJO.Believe ,possible what the GEFS sees is a Kelvin upcoming so it has destructive interference.Models keep showing this other than timing

[PowellVolz]

If we had some return flow, Saturday afternoon would be interesting. Will still have to be watched if we get plenty of sunshine throughout the day.


.

[jaxjagman]

Think this might be the villain tomorrow,but we'll see

[jaxjagman]

You want that to clear out or fall apart,especially east of I-65

[jaxjagman]

More than i thought..lol

Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1237 AM CDT Sat Apr 25 2020

   Valid 251200Z - 261200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   THE TENNESSEE VALLEY AND SOUTHERN APPALACHIANS...

   ...SUMMARY...
   Scattered, strong to severe thunderstorms are expected to develop
   this afternoon across portions of the Tennessee Valley into the
   southern Appalachians. A few strong storms may also develop across
   south Florida.

   ...TN Valley/Southern Appalachians...

   Sharp mid-level speed max is forecast to eject across AR into
   northern AL by 26/00z. This feature is associated with a pronounced
   short-wave trough that should encourage strong-severe convection
   across the TN Valley during the afternoon. Latest model guidance
   continues to suggest a strongly diffluent high-level flow regime
   will develop across the TN Valley ahead of the short wave and a weak
   surface low is expected to track from the Boot Heel of MO toward
   central KY during the afternoon. Very cold mid-level temperatures
   will spread east, along/north of the cyclonic jet such that steep
   lapse rates will be common, especially as some boundary-layer
   warming is anticipated immediately ahead of the Pacific front. While
   moisture is seasonally low across the Gulf States into the TN
   Valley, 50s surface dew points should yield modest SBCAPE north of
   the jet where 500mb temperatures are forecast to be as cool as -18C
   at peak heating. Forecast soundings suggest surface parcels will
   reach convective temperature by 17-18z and isolated thunderstorms
   should initiate within exit region of aforementioned jet. Shear
   profiles favor supercells and hail may be the greatest threat with
   this activity; although, low-level shear appears adequate for some
   tornado potential. Robust convection should spread toward the
   southern Appalachians by evening where it will encounter a wedge
   front anchored east of the mountains. Some erosion of the cool
   boundary layer will be noted across SC into extreme western NC. For
   this reason have adjusted severe probabilities to account for
   destabilization in this region. Otherwise, air mass will struggle to
   recover across the southern Middle Atlantic during the overnight
   hours. Even so, sustained warm advection does warrant some threat
   for a few strong storms late.

[jaxjagman]

2 hours ago, PowellVolz said:

If we had some return flow, Saturday afternoon would be interesting. Will still have to be watched if we get plenty of sunshine throughout the day.


.

This is what i was looking at as well.It's hard to find even PW's even getting to 1.1"

[janetjanet998]

possible sleeper event TN/KY today ,

lots of spin near stacked low and cold 500mb temps

 

 

[Holston_River_Rambler]

12z new HRRR4 or whatever it is now is throwing some sort (I say that because it has a little black swath overhead) of severe storm right over my head at 23 - 0z this evening. Also popping some CAPE and decent (300 -occasionally 400) helicity values in my neck of the woods. 

14z old HRRR looks similar. 

Not sure it will make a difference, but glad there's a ton of sunshine in sight right now. 

 

[Holston_River_Rambler]

Sorry the above should say glad there's **NOT** a ton of sunshine. 

[janetjanet998]

DAY 1 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
1126 AM CDT SAT APR 25 2020  
  
VALID 251630Z - 261200Z  
  
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON  
INTO EARLY TONIGHT FROM EASTERN TN/SOUTHEASTERN KY INTO WESTERN  
NC...  
   
..SUMMARY  
  
ISOLATED SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON  
ACROSS PORTIONS OF THE TENNESSEE VALLEY INTO THE SOUTHERN  
APPALACHIANS. A FEW STRONG STORMS MAY ALSO OCCUR ACROSS SOUTH  
FLORIDA.  
   
..TN/KY TODAY TO NC THROUGH TONIGHT  
  
A MIDLEVEL TROUGH AND SURFACE CYCLONE OVER SOUTHEAST MO THIS MORNING  
WILL PROGRESS EAST-NORTHEASTWARD NEAR THE OH RIVER TODAY, AND REACH  
THE APPALACHIANS OVERNIGHT.  RESIDUAL BOUNDARY-LAYER DEWPOINTS OF  
56-60 F WILL SPREAD NORTHWARD INTO TN/KY IN ADVANCE OF THE SURFACE  
CYCLONE.  SURFACE HEATING WILL BE SOMEWHAT MUTED BY LINGERING  
CLOUDS, BUT GRADUAL BREAKS FROM WEST TO EAST WILL CONTRIBUTE TO  
MLCAPE NEAR 500 J/KG BY MID-LATE AFTERNOON IMMEDIATELY IN ADVANCE OF  
THE MIDLEVEL TROUGH/SURFACE CYCLONE.  THOUGH BUOYANCY WILL BE RATHER  
MODEST, DEEP-LAYER SHEAR AND LOW-LEVEL HODOGRAPH CURVATURE WILL  
FAVOR SUPERCELLS CAPABLE OF PRODUCING AT LEAST ISOLATED LARGE  
HAIL/DAMAGING WINDS, AND A COUPLE OF TORNADOES, DEPENDING ON THE  
DEGREE OF DESTABILIZATION.  STORMS THAT MATURE THIS  
AFTERNOON/EVENING ACROSS EASTERN TN COULD PERSIST INTO WESTERN NC  
BEFORE WEAKENING EARLY TONIGHT.  
  
FARTHER EAST AND OVERNIGHT, SECONDARY CYCLOGENESIS IS EXPECTED ALONG  
A SURFACE WARM FRONT LIKELY TO BE NEAR THE NC/VA BORDER BY 12Z, AND  
AS AN UPSTREAM SPEED MAX OVER THE PLAINS ROTATES THROUGH THE BASE OF  
THE TROUGH APPROACHING THE APPALACHIANS.  GRADUAL AIR MASS  
MODIFICATION IS EXPECTED OFF THE SOUTHEAST ATLANTIC COAST IN THE  
WAKE OF THE PRIOR FRONTAL INTRUSION ACROSS FL.  AS THE LOW LEVELS  
WARM/MOISTEN ACROSS THE COASTAL PLAIN TONIGHT, WIND PROFILES WILL BE  
FAVORABLE FOR SUPERCELLS.  HOWEVER, UNCERTAINTY CENTERS ON FORCING  
FOR ASCENT AND STORM COVERAGE WHERE LOW-LEVEL DESTABILIZATION IS  
MOST PROBABLE (CLOSER TO THE COAST), SO WILL MAINTAIN LOW  
TORNADO/DAMAGING WIND PROBABILITIES FOR THE OVERNIGHT PERIOD ACROSS  
EASTERN NC.  
   

[MattPetrulli]

Like the setup for tornadoes today across the region given CAMs support for low topped supercells and the clearing going on across the Valley.

Lots of sunshine in Pigeon Forge currently. I wish I was going out but probably am not, good luck to anyone that does go out.

[Runman292]

Here’s the latest graphic from MRX:

 

[Runman292]

In a span of 30-45 minutes, it’s gone from cloudy to mostly sunny in South Knoxville. There’s not a lot of clouds now. I have a bad feeling about this.

[nrgjeff]

I agree with MRX above. Was that on NWS MRX page at one point? I saw it elsewhere.

Meanwhile a triple point has pushed from Miss/Bama into southern Middle Tenn. Should continue over the Upper Plateau into northeast Tenn.

Don't let the chart scare though. Still agree with only MRGL/SLIGHT risk thanks to pitiful dewpoints.

[Runman292]

1 minute ago, nrgjeff said:

I agree with MRX above. Was that on NWS MRX page at one point? I saw it elsewhere.

Meanwhile a triple point has pushed from Miss/Bama into southern Middle Tenn. Should continue over the Upper Plateau into northeast Tenn.

I found the graphic on their Facebook page.

[Runman292]

2 minutes ago, nrgjeff said:

I agree with MRX above. Was that on NWS MRX page at one point? I saw it elsewhere.

Meanwhile a triple point has pushed from Miss/Bama into southern Middle Tenn. Should continue over the Upper Plateau into northeast Tenn.

Don't let the chart scare though. Still agree with only MRGL/SLIGHT risk due to pitiful dewpoints.

Also, just out of curiosity, what is the significance of a triple point?

[VOLtage]

 

Concerning...Severe potential...Watch possible 

   Valid 251932Z - 252100Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Convection is expected to gradually intensify this
   afternoon.  A few low-topped supercells could develop and pose a
   hail/tornado risk.  Convective trends will be monitored over the
   next 1-2 hours.

   DISCUSSION...Water-vapor imagery shows a mid-level low slowly
   migrating eastward near the OH/MS River confluence.  Visible
   satellite imagery shows low clouds eroding across southern portions
   of middle and eastern TN in wake of earlier showers.  Surface
   temperatures have warmed into the middle to upper 60s F near
   Chattanooga in response to stronger surface heating.  Surface
   dewpoints remain relatively marginal and range in the lower to
   middle 50s F.

   A couple of weak convective bands are forming across middle TN.  It
   remains uncertain whether developing updrafts will become
   surface-based and intensify into organized/sustained storms. 
   However, model guidance indicates sufficient buoyancy may develop
   over the next few hours for at least an isolated risk for strong to
   severe thunderstorms.  If a few stronger updrafts manage to develop,
   forecast hodographs favor storm organization, including the
   possibility for a few of these updrafts to acquire supercell
   characteristics.  Therefore it appears an increasing risk for
   strong-storm activity will materialize at least on an isolated basis
   later this afternoon.  Hail and possibly a tornado may accompany the
   stronger storms.

[1234snow]

Have our first severe warned storm with up to 1” hail working into Etowah and up the southern portions of the Valley.

[1234snow]

Closeup:

[1234snow]

Etowah storm report of 1.75” hail (golf ball). If in the path northeast of there I would certainly cover vehicles if possible.

Appears Tellico Plains will get squeezed in between the 2 cells. Also a warned storm on the plateau.

[jaxjagman]

Stroms just dont have the umph when they show rotation,the best cell seems to be the cell possibly headed towards Rocky Top

[janetjanet998]

  
BULLETIN - EAS ACTIVATION REQUESTED  
TORNADO WARNING  
NATIONAL WEATHER SERVICE NASHVILLE TN  
446 PM CDT SAT APR 25 2020  
  
THE NATIONAL WEATHER SERVICE IN NASHVILLE HAS ISSUED A  
  
* TORNADO WARNING FOR...  
  CENTRAL SMITH COUNTY IN MIDDLE TENNESSEE...  
  EAST CENTRAL WILSON COUNTY IN MIDDLE TENNESSEE...  
  
* UNTIL 515 PM CDT.  
      
* AT 446 PM CDT, A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO  
  WAS LOCATED NEAR WATERTOWN, OR 11 MILES SOUTHWEST OF CARTHAGE,  
  MOVING EAST AT 35 MPH.  
  

[Holston_River_Rambler]

That plateau one is about to hammer me. Looks like it was bowing out a bit the last few NEXRAD frames

[1234snow]

Tornado warned storm east of Lebanon/Nashville is moving along I-40 with possibly a couplet developing:

[janetjanet998]

TDS

edit: to add update

51 PM CDT SAT APR 25 2020  
  
...A TORNADO WARNING REMAINS IN EFFECT UNTIL 515 PM CDT FOR CENTRAL  
SMITH COUNTY...  
          
AT 450 PM CDT, A CONFIRMED TORNADO WAS LOCATED NEAR I-40 NORTHEAST   
OF WATERTOWN, OR 8 MILES SOUTHWEST OF CARTHAGE, MOVING EAST AT 35   
MPH.  
  
HAZARD...DAMAGING TORNADO AND QUARTER SIZE HAIL.  
  
SOURCE...RADAR CONFIRMED TORNADO.  

[1234snow]

TDS
edit: to add update

51 PM CDT SAT APR 25 2020    ...A TORNADO WARNING REMAINS IN EFFECT UNTIL 515 PM CDT FOR CENTRAL  SMITH COUNTY...            AT 450 PM CDT, A CONFIRMED TORNADO WAS LOCATED NEAR I-40 NORTHEAST   OF WATERTOWN, OR 8 MILES SOUTHWEST OF CARTHAGE, MOVING EAST AT 35   MPH.    HAZARD...DAMAGING TORNADO AND QUARTER SIZE HAIL.    SOURCE...RADAR CONFIRMED TORNADO.  

Just crossed I-40 minutes ago. An area that certainly doesn’t need another tornado this year.