Tn Valley Severe Weather

[jaxjagman]

1 hour ago, Jim Martin said:

20 years ago next month was the famous Nashville, Tennessee tornado that was captured by WSMV Channel 4 and NewsChannel 5 as it moved through.

This was the same storm that also produced a F5 in the southern counties of Tn.In Lawrenceburg it went through the Amish country,don't know how no one died from that community.

 

https://en.wikipedia.org/wiki/Tornado_outbreak_of_April_15–16,_1998

 

 

 

 

 

 

 

 

[Windspeed]

3 hours ago, jaxjagman said:

This was the same storm that also produced a F5 in the southern counties of Tn.In Lawrenceburg it went through the Amish country,don't know how no one died from that community.
 
https://en.wikipedia.org/wiki/Tornado_outbreak_of_April_15–16,_1998

The Lawrenceburg footage is very intense. Perhaps the most violent tornado ever recorded in Tennessee on video. Though the 20 mile path traversed sparsely populated communities, still quite miraculous that it resulted in no deaths.

[John1122]

Two of my nieces had went to visit family in Lawrenceburg that day, they were 5 and 7 years old. The tornado missed them by about 250 yards. They still have vivid memories and hate thunderstorms.

[jaxjagman]

Prognostic Discussion for Week 3-4 Temperature and Experimental Precipitation Outlooks 
NWS Climate Prediction Center College Park MD 
300PM EST Fri Mar 09 2018 

Week 3-4 Forecast Discussion Valid Sat Mar 24 2018-Fri Apr 06 2018 

The Week 3-4 this week is issued against the background of La Nina and an MJO event that continues to propagate eastward with a larger-than-forecast amplitude. Additionally, a high amplitude -AO/NAO event over the past one to two weeks is forecast to be nearer to normal heading into the Week 3-4 period. The recent OLR anomaly maps indicate a large-scale convective structure over the deep tropics that is consistent with La Nina, while the recent evolution of tropical 200-hPa velocity potential anomalies is consistent with the active MJO phase approaching the Maritime Continent, ostensibly resulting in constructive interference with the background ENSO state. Given the observed presence of anomalous tropical forcing mechanisms, statistical guidance that incorporates ENSO and MJO, along with long-term trends, is weighted heavily in both the temperature and precipitation outlooks. 

The dynamical model guidance varies quite a bit, with a very cold North America predicted by the ECMWF, and the CFS and JMA favoring a warmer solution across much of the central and eastern CONUS. The various models from the SubX suite tend to favor the ECMWF solution, but with large differences among them as well. Most dynamical models favor the continuation of positive height anomalies near and northwest of the Aleutians, with negative height anomalies stretching west-east over the Pacific near 30N. The ECMWF solution, however, reintensifies a -NAO signal over the northwest Atlantic, and its upper-level height pattern over North America appears well-teleconnected to that downstream center of action. The CFS maintains low-amplitude anomalous ridging over the east-central CONUS, more consistent with teleconnections upon the upstream centers of action and MJO forcing. Over Alaska the dynamical blend favors high probabilities of below-normal temperatures; in the official outlook these are tempered by long-term trends (including those related to sea ice extent adjacent to the western and northern Alaska). 

The temperature outlook consists of a subjective blend of the correlation-weighted, calibrated dynamical model blend and the multiple linear regression tool that inputs ENSO, MJO, and long-term trend time series. These forecast inputs are the most skillful over the past couple of years. These forecasts conflict over parts of the West and Northeast, where areas of EC are depicted. Given the manifestation of ENSO and MJO in important tropical variables (OLR and VP), it is not obvious that the dynamical guidance should be preferred. An objective blend of statistical and dynamical inputs is under development, and until that is ready a prudent course of action is to consider both on nearly equal footing given recent skill evaluations. 

The aforementioned approach to the temperature outlook is also taken for the precipitation outlook. The various dynamical guidance as well as statistical guidance are in good agreement on above-median rainfall over parts of the Mississippi and Tennessee River Valleys, and to a lesser extent, the northern High Plains. Likewise there is good agreement for increased chances of below-median precipitation over the southwestern CONUS. Over the Northwest and northern California equal chances is depicted due to uncertainty with respect the longitudinal position of the mean trough axis; a slight westward (eastward) shift would favor above-(below-)median precipitation. Below-median precipitation is favored over parts of the Great Lakes, Northeast, and Eastern Seaboard. Dynamical model consensus is the strongest over the Northeast and eastern Great Lakes, while the statistical guidance is more robust over the Southeast coast. 

Sea surface temperatures are slightly above normal for most of the Hawaiian Islands, although below-normal SSTs are showing up just to the northeast. Anomalous troughing is favored to the west of the islands, supporting anomalous southerly flow. This troughing to the west also supports relatively high probabilities for above-normal precipitation across the entire island chain. 

[CheeselandSkies]

At this point I don't want to see any forecasts of a "very cold North America," especially not from King Euro.

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[jaxjagman]

TNI today is the strongest we've seen in awhile -1.3 in 1+2 and -0.3 in region 4,this would be a +1 TNI

[jaxjagman]

[jaxjagman]

Signs of a good system towards the end of March

[jaxjagman]

Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0239 AM CDT Mon Mar 12 2018

   Valid 151200Z - 201200Z

   ...DISCUSSION...
   Late-evening model guidance is gradually evolving toward a
   potentially more active convective pattern by the end of the
   medium-range period. Eastern US trough that will suppress Gulf air
   mass should shift east within a few days allowing
   higher-moisture-content air mass to begin advancing north into TX
   day4-5.  Much of the lower latitudes are expected to moisten
   significantly into early next week.

   Threat of deep convection will begin increasing from the Arklatex
   into the TN Valley during the day5-6 time frame. However, timing of
   individual short waves will prove extremely difficult as
   ECMWF/GFS/UKMET/Canadian exhibit different solutions to the break
   down of the Plains ridge late in the week. While model differences
   will certainly extend into early next week, Plains ridge should
   progress into the MS Valley by day8. If this occurs there is some
   concern organized severe may ultimately materialize across the
   southern Plains/lower MS Valley. Will not introduce 15% severe probs
   given the uncertainty but this scenario will be monitored closely.

[jaxjagman]

Looks like the potential for some good storms to fire up along the dry line in the Southern Plains with a severe drought on going

[nrgjeff]

The PNA is trying to go negative on the extended models, which is bullish severe. Indonesia is stormy, another bullish sign. However the MJO is muddled with other convection in cold zones for NA.

My biggest concern on the bearish side is SSW hangovers usually last longer than forecast. We say that about any blocking, but SSW is the hard liquor or 'shine of blocking.

I am not too concerned about March. April is still ahead. Also we have a few forum members who really do not like severe, so a quiet March would not be a total loss.

[jaxjagman]

Feb. was close to normal for avg tornadoes

[jaxjagman]

Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0400 AM CDT Fri Mar 16 2018

   Valid 191200Z - 241200Z

   ...DISCUSSION...
   Numerical models are in relatively good agreement with the movement
   of a shortwave trough from the southern Plains across the lower MS
   Valley on Monday, with a surface low moving from AR into TN during
   the day or evening. The ECMWF is faster/farther east with the low
   than the GFS, which lends uncertainty. However, the risk area can be
   adjusted in later outlooks.

   On Monday Day 4, a cold front is forecast to stretch roughly from
   middle TN southward across MS by 00Z Tuesday, continuing eastward
   across AL and into GA by Tuesday morning. A warm front will also
   lift north across the region, stretching from northern AL into
   central GA at 00Z. Dewpoints in the 60s F and cool midlevel
   temperatures will result in around 1500 J/kg MUCAPE, with strong
   deep-layer shear profiles supporting organized convection. Low-level
   shear will be maximized near the warm front, and forecast wind
   profiles do support supercells. Conditional on storm mode, a tornado
   threat may exist. The northern threat into TN will depend on
   instability, but otherwise the synoptic setup appears most favorable
   there. To the south, instability will be much greater and one or
   more clusters of storms are expected to spread across AL and GA with
   damaging winds likely given strong mean wind profiles.

   Beyond day 4, severe weather is not expected.

   ..Jewell.. 03/16/2018

[PowellVolz]

MRX disco this morning is interesting....

“Model soundings show the potential of large hail and damaging
winds. MLCAPES of 1000-1500 J/kg, Hail CAPES of 300-600 J/Kg,
lapse rates near 7 C/km, and WBZ Heights near 7kft support large
hail. The 0-6km shear of 60kts also support rotating storms with
more sustain updrafts. SHIP values between 1 and 1.5.

As for the convective damaging winds, melting hail, plenty of dry
mid-level entrainment and mid-level winds of 30-40kts supports
potential of damaging winds.

The potential strong convection will emain during the evening
hours with showers diminishing after midnight”


.

[jaxjagman]

The last run of the GFS shows some better capes,even over 1k in Mid Tn Monday afternoon.If you want to believe the NAM it shows capes of around 3k and a PDS around Nashville

[hlcater]

1 hour ago, jaxjagman said:

The last run of the GFS shows some better capes,even over 1k in Mid Tn Monday afternoon.If you want to believe the NAM it shows capes of around 3k and a PDS around Nashville

I think the NAM is suffering from convective feedback, especially across TN.  Therefore I’d probably take its output with a grain of salt.

[JPOracle]

New Day 3 SPC outlook mentions strong tornadoes being possible but conditional

[1234snow]

SPC outlook today. Large hail and damaging winds the threat this evening across NETN/SWVA.

[nrgjeff]

Monday the NAM appears too amped. What's new? Getting NAM'ed. I favor the less intense GFS/ECWMF combo. They have strong/severe but not a tornado set-up. Spann was tweeting which got my attention, because he does not really hype. For now, as of Saturday, I am not greatly concerned/interested but we'll see how it goes...

I also had Virginia going to the Final, lol!

[Runman292]

From the NWS SPC:

 

[1234snow]

Kingsport needs to watch out for hail over the next hour or so.



Already half inch hail reported. Also some idiot lit a brush fire about 10 minutes ago. Wind is howling.

[McMinnWx]

Tornado warning popped up on my phone around 7:30. That was fun. 

[Stovepipe]

Nice storm rolled by just a tad south of me.




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[uncheelfan]

This is a pretty impressive storm rolling in it seems. Just got issued a severe tstorm warning for Kingsport! The severe season is upon us everyone!!

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[uncheelfan]

This light show is amazing!!!!!!! Kinda of reminds me of how the big storms in Fayetteville N.C. were when i lived there.

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[WeathermanB]

1 minute ago, uncheelfan said:

This light show is amazing!!!!!!! Kinda of reminds me of how the big storms in Fayetteville N.C. were when i lived there.

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Must be nice down there. Is it warm? Can't wait for summer up here for heat lightning and billowing cumulonimbus clouds along with severe t'storm watches.

[Jim Martin]

Surprised none of you in here have mentioned the risk for severe weather on Monday...

[TellicoWx]

Had a possible tornado touchdown just south of Tellico Plains in Coker Creek area. 1 structure damaged alot of trees/power poles snapped. Currently 1048 FLEC customers out of power. No injuries.

[BlunderStorm]

I had just been in Johnson City as the storms hit around dusk when about 30 minutes into one of the storms it began to hail. Luckily (pun intended) the hail was small and no damage was done to any cars or property at least from what I saw. I would say the hail was roughly a centimeter or a little more in diameter and it lasted around 5 minutes. Once the rain died down a little I came outside it looked like it had snowed in the grass. I thought the novelty of seeing significant snow and hail within a few days was pretty amusing truly March at its finest. Unfortunately I did not have a camera on me at the time so I didn't capture anything. It's also worth mentioning I saw some pretty spectacular streaks of lightning too.

[Windspeed]

Surprised none of you in here have mentioned the risk for severe weather on Monday...

SPC is definitely leaving the door open for a possible upgrade as well:

"Given the potential for significant severe storms, a categorical upgrade is possible in later outlooks once predictability increases and the centroid of severe coverage is better established."