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Tn Valley Severe Weather


jaxjagman
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 Mesoscale Discussion 0230
   NWS Storm Prediction Center Norman OK
   0705 PM CDT Tue Mar 24 2020

   Areas affected...northern AL...southern TN...northwestern GA

   Concerning...Tornado Watch 61...

   Valid 250005Z - 250100Z

   The severe weather threat for Tornado Watch 61 continues.

   SUMMARY...A new convective watch is possible to the east of Tornado
   Watch #61.  A tornado risk will continue this evening for portions
   of northern AL and southern middle TN.

   DISCUSSION...Trends in KHTX VAD show further intensification of the
   low-level wind profile during the past 1-2 hours.  0-1 km SRH has
   increased from around 300 m2/s2 to over 600 m2/s2.  Surface analysis
   indicates the area with the lowest temperature/dewpoint spreads (10
   deg F) is in the counties adjacent to the TN border in northern AL. 
   Farther south, warmer temperatures have resulted in spreads in the
   15-20 deg F range which would lessen but not nullify tornado
   potential.  Given the strengthening low-level shear for mesocyclone
   organization/persistence, it seems plausible the tornado risk will
   eventually include the eastern counties of Tornado Watch #61 later
   this evening.  An additional convective watch issuance is possible
   to the east of the ongoing watch during the next hour or so

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Probably watch the models tonight and even in the morning.Some of the cams show some discrete

 cells after the cap breaks in the afternoon,We could possibly hit 85 tomorrow which would break our record.Nashville sure sounds concerned

 

National Weather Service Nashville TN
234 PM CDT Fri Mar 27 2020

.DISCUSSION...

As a citizen of Middle TN, I hate writing these AFDs. However, as a
met and a scientist, they`re the ones you wait for. Now look,
tomorrow isn`t going to be an April 2011 kind of day, nor do I
expect for us to have a repeat of March 3rd. However, tomorrow
evening, despite the differences in the models warrants everyone in
Middle TN, especially those along and west of I-65 (this includes
but is not limited to the Metro area) to be very weather aware
tomorrow evening. Let`s start with what`s going on now:

A mix of sun of clouds and a warm breeze is making for a great day
across Middle TN. Temperatures are running about 20 degrees above
average which is a welcomed increase in temperatures for spring. The
southerly winds will continue to blow overnight. Not gusty, but the
warmth and persistent increase of low-level moisture will continue.
I have 67 for a morning low tomorrow and while I don`t expect us to
remain above 70, the record max low temperature for March 28th is 70
degrees set in 1907. Unexpected cloud cover in the morning would
likely help us break that record, but as I said, unexpected.

As we get into the afternoon hours tomorrow and the boundary layer
continues to warm and low-level moisture increases, temperatures
should be as warm or warmer than today. That means tomorrow`s high
temperature will also be under assault. I have 83 in there and the
record is only 85 set in 2012. If you`re a regular reader of the
AFD, you see where we`re headed here...

Throughout the day tomorrow, an intensifying low pressure system
will continue to develop over the Plains. In the afternoon, those
well north of us will be dealing with problems of their own, but as
the front nears Middle TN tomorrow evening, we very well could have
issues, too.

I alluded to it earlier, forecast soundings aren`t in great
agreement, but the only thing they aren`t in great agreement about
is how bad it`ll be. As is normal, the NAM is the outlier in this
situation. It`s a little slower, it has winds out of the south
(which would increase the low-level helicity and in turn, the
discrete supercell potential) as well as instability that is
considerably higher than other models. Fingers crossed that the GFS
and Euro are closer to the actual solution. That wouldn`t absolve us
from a severe weather threat, just the overall severity of it. GFS
soundings show surface winds that are veered compared to the NAM.
This means more of a QLCS and a straight-line wind threat (but still
NOT a zero tornado threat). All of that said, I`m leaning towards
the GFS solution. The main surface low is well north of us and the
overall system is very wrapped up, becoming occluded at the point
when the the front starts to near Middle TN. We don`t TYPICALLY get
discrete cell development in this scenario. A NAM solution would
require the development of a secondary surface low closer to the mid-
state and right now, the likelihood of that is low.

So the main thing we`re going to want to monitor tomorrow afternoon
and early evening: what are the surface winds doing? The more
southerly they are, the better chance of discrete development (and a
better tornado threat). More of a southwesterly component, we should
be looking at the development of a line, less low-level helicity and
a reduced chance of things getting out of hand -- but still a severe
wind threat.

Here`s the next problem: models continue to show this as another
nocturnal event. That means it`s going to be after dark before the
cap can break and develop occurs (no matter what kind). I`m looking
at a 6 pm to midnight event, and 6 pm might be a touch early. This
means today is the day to make sure you have multiple ways to get
warnings. A properly programmed NOAA Weather Radio, your cell phone
(make sure it`s turned on and up) and preferably one other way --
all something that will wake you up if you go under a warning and
you`re sleeping.

Storms/rain should be off the Plateau before sunrise and we`ll
return to these fantastic dry conditions we`ve been experiencing the
last couple of days. Our next shot at rain won`t be until Tuesday.
Current trajectories keep Tuesday`s system from being severe for us,
but will need to be monitored over the coming days.

&&
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 Mesoscale Discussion 0255
   NWS Storm Prediction Center Norman OK
   0459 PM CDT Sat Mar 28 2020

   Areas affected...Eastern AR...Northern MS...Western
   TN/KY...Southeast MO/IL

   Concerning...Tornado Watch 68...70...

   Valid 282159Z - 282300Z

   The severe weather threat for Tornado Watch 68, 70 continues.

   SUMMARY...Tornado threat will shift east of WWs 68/69 over the next
   few hours. New tornado watch may be warranted soon.

   DISCUSSION...Latest NAM guidance suggests LLJ will strengthen across
   the western TN Valley this evening as 500mb speed max increases in
   excess of 100kt from AR into western KY over the next 03-06hr.
   Earlier trends suggesting a QLCS might be evolving across AR now
   favor a mix of discrete supercells and clusters. This may be in part
   to expected strengthening wind fields. Over the next few hours,
   ongoing corridor of supercells over eastern portions of ww68 should
   approach, then spread east of the watch. This will necessitate a new
   tornado watch soon.
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   URGENT - IMMEDIATE BROADCAST REQUESTED
   Tornado Watch Number 71
   NWS Storm Prediction Center Norman OK
   635 PM CDT Sat Mar 28 2020

   The NWS Storm Prediction Center has issued a

   * Tornado Watch for portions of 
     Far eastern Arkansas
     Far southwest Indiana
     Western Kentucky
     Missouri Boothell
     Northwest Mississippi
     Western Tennessee

   * Effective this Saturday night and Sunday morning from 635 PM
     until 200 AM CDT.

   * Primary threats include...
     A few tornadoes likely with a couple intense tornadoes possible
     Scattered damaging wind gusts to 70 mph likely
     Isolated large hail events to 1.5 inches in diameter possible

   SUMMARY...Extensive clusters of thunderstorms will evolve
   east-northeast tonight. Tornado risk through mid-evening will be
   greatest across the Kentucky and Tennessee portions of the watch,
   with an increasing risk towards late evening across Mississippi.

   The tornado watch area is approximately along and 60 statute miles
   east and west of a line from 15 miles north of Evansville IN to 25
   miles south of Greenville MS. For a complete depiction of the watch
   see the associated watch outline update (WOUS64 KWNS WOU1).
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 Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0758 PM CDT Sat Mar 28 2020

   Valid 290100Z - 291200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM A PORTION
   OF THE TENNESSEE AND OHIO VALLEYS INTO THE MIDWEST REGION...

   ...SUMMARY...
   Scattered severe storms posing a threat for tornadoes, damaging wind
   and large hail will continue this evening into the overnight from a
   portion of the Tennessee and Ohio Valleys into the Midwest region.

   ...Midwest region...

   The warm sector is in the process of being pinched off across
   northeast IA suggesting the tornado threat in this region should end
   by 02Z. However...additional storms are developing farther south
   across northwestern and west central IL and will move eastward into
   central and eastern IL where the 00Z RAOB from Lincoln indicated
   around 800 J/kg MLCAPE, large low-level hodographs and 80 kt
   effective bulk shear. This environment will continue to support
   organized storms incuding supercells capable of producing tornadoes,
   a couple of which could be strong this evening.  

   ...Tennessee and Ohio Valleys...

   A secondary branch of the low-level jet is forecast to strengthen
   tonight from middle TN into the OH Valley in association with a
   strong upper jet moving through the base of a progressive trough
   situated across the Midwest. This will contribute to modest
   low-level theta-e advection with MUCAPE from 500 to 1000 J/kg as
   well as large hodographs with 300-400 m2/s2 0-1 km storm-relative
   helicity within an otherwise strongly sheared environment. The band
   of scattered storms developing along the warm conveyor belt from
   southwest IN into western TN and northwest MS will likely maintain
   embedded organized structures including supercells and bowing
   segments capable of tornadoes, damaging wind and large hail as they
   develop eastward into the overnight.

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 Mesoscale Discussion 0262
   NWS Storm Prediction Center Norman OK
   0825 PM CDT Sat Mar 28 2020

   Areas affected...Northern MS...Northwest AL...Western/Middle TN

   Concerning...Tornado Watch 71...

   Valid 290125Z - 290300Z

   The severe weather threat for Tornado Watch 71 continues.

   SUMMARY...Squall line is organizing and shifting east across ww71.
   New tornado watch will likely be issued by 0230z.

   DISCUSSION...Large-scale forcing appears to be aiding upward
   evolving squall line across the Mid-South this evening. Over the
   last few hours a slow maturation has been noted and its forward
   propagation is on the order of 35kt to the east. This speed/movement
   would place the leading edge of strongest convection near the
   eastern edge of ww71 around 03z and through much of Middle TN into
   northwestern AL by 06z. New tornado watch will likely be issued by
   0230z.
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Tornado Warning
TNC069-075-113-290215-
/O.NEW.KMEG.TO.W.0023.200329T0148Z-200329T0215Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Memphis TN
848 PM CDT Sat Mar 28 2020

The National Weather Service in Memphis has issued a

* Tornado Warning for...
  Northwestern Hardeman County in western Tennessee...
  Southeastern Haywood County in western Tennessee...
  Southwestern Madison County in western Tennessee...

* Until 915 PM CDT.

* At 848 PM CDT, doppler radar indicated severe thunderstorms
  producing both tornadoes and extensive straight line wind damage
  were located over Hillville, or 13 miles south of Brownsville,
  moving northeast at 55 mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without
           shelter. Mobile homes will be damaged or destroyed.
           Damage to roofs, windows, and vehicles will occur.  Tree
           damage is likely.

* Locations impacted include...
  Jackson, Bemis, Hillville, Cloverport, Mercer, Medon, Neely,
  Pinson, Malesus, Parkburg, Huntersville, Cedar Chapel, Vildo,
  Hatchie, Westover, Madison Hall, Uptonville, Denmark and Leighton.
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  URGENT - IMMEDIATE BROADCAST REQUESTED
   Tornado Watch Number 74
   NWS Storm Prediction Center Norman OK
   935 PM CDT Sat Mar 28 2020

   The NWS Storm Prediction Center has issued a

   * Tornado Watch for portions of 
     Middle Tennessee

   * Effective this Saturday night and Sunday morning from 935 PM
     until 400 AM CDT.

   * Primary threats include...
     A few tornadoes and a couple intense tornadoes possible
     Scattered damaging wind gusts to 70 mph likely

   SUMMARY...Line of strong to severe thunderstorms over western
   Tennessee will progress east across middle Tennessee tonight with a
   risk for damaging winds and a few tornadoes.

   The tornado watch area is approximately along and 60 statute miles
   east and west of a line from 80 miles south southwest of Nashville
   TN to 40 miles northeast of Nashville TN. For a complete depiction
   of the watch see the associated watch outline updat
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Fairly quiet looking pattern upcoming the next several days in our parts.Like Jeff mentioned in another thread ,we're getting into a -NAO,for a few days anyways,.The AAM is going in the wrong direction.The MJO is fixing to lose signals.To top all that off that EPS is hinting at an Upper Level Ridge building in the long range.After that seemingly around day 10 right now the ULR might weaken or get kicked out to the east.SIPS shows a more severe pattern could possibly be back during this time.Does not mean we cant get severe,it's spring,its not a great look right now for several days IMO

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Jonesboro tornado trolled all the Illinois and Iowa chasers. Thankfully nobody was killed, but news says some serious injuries.

OK we get a break this week. Probably a good thing. Models saw the East trough last week, and it's in progress now.

Next week could get active again. Convection is coming out of the Indian Ocean toward Indonesia (maritime sub-continent). Lead by the ECMWF all models are coming around to a West trough. Euro verbatim favors Plains/Midwest. Getting into April it could go north, south and/or both.

I don't have any plan to chase anything beyond 2 hours. Dixie just isn't worth the drive, lol. 

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Boring looking pattern for severe,for us anyways in the Valley.The Euro seemingly is flip flopping quite a bit recently. Probably are going to have to wait several more days this is when the MJO goes into 8-1-2 outside the COD.Today it looks more like the trough axis is going to basically be around the Valley somewhere mid range and possibly beyond with BN temps,least that how it looks today

 

ECMWF minus Climo FORECAST FOR: BNA    LAT=  36.12 LON=  -86.68 ELE=   591

                                            12Z APR04
                 2 M     850     SFC     SFC     700    6 HR     500    1000 
                 TMP     TMP     PRS     RHU     RHU     QPF     HGT     500 
                 (C)     (C)    (MB)    (PCT)   (PCT)   (IN)    (DM)     THK 
SAT 12Z 04-APR   0.2     1.8       1              36               3       2    
SAT 18Z 04-APR  10.0     2.0       0              29               4       4    
SUN 00Z 05-APR   5.4     3.3      -1    1073      26   39.33       3       4    
SUN 06Z 05-APR   0.6     3.2       0    1087      33   39.33       3       3    
SUN 12Z 05-APR  -1.8     2.9       1    1096      18   39.33       3       2    
SUN 18Z 05-APR  10.2     2.8       1    1051       7   39.33       5       3    
MON 00Z 06-APR   6.2     3.3       1              13               5       5    
MON 06Z 06-APR   0.0     3.6       2               6               6       4    
MON 12Z 06-APR  -1.7     3.2       3              -2               7       4    
MON 18Z 06-APR  10.6     3.0       2              -5               8       6    
TUE 00Z 07-APR   6.9     4.8      -1               3               7       8    
TUE 06Z 07-APR   3.2     5.4      -2              32               7       8    
TUE 12Z 07-APR   2.7     5.6      -2              42               7       9    
TUE 18Z 07-APR  12.7     5.8      -4             -20               8      11    
WED 00Z 08-APR   8.2     7.9      -7              -7               7      12    
WED 06Z 08-APR   5.8     8.8      -7             -20               7      13    
WED 12Z 08-APR   6.1     6.8      -6             -17               5      10    
WED 18Z 08-APR  12.5     8.0      -7             -24               5      11    
THU 00Z 09-APR   9.3     8.2     -10             -23               4      12    
THU 06Z 09-APR   6.1     8.3     -12             -23               2      12    
THU 12Z 09-APR   3.5     3.8      -8              22               0       7    
THU 18Z 09-APR   4.2     0.9      -5              -6              -1       3    
FRI 00Z 10-APR  -0.2    -3.3      -5               4              -4       0    
FRI 06Z 10-APR  -5.1    -6.6      -2              31              -6      -4    
FRI 12Z 10-APR  -8.3    -9.9       0              -8              -8      -8    
FRI 18Z 10-APR  -0.9    -8.8      -1             -42              -8      -7    
SAT 00Z 11-APR  -3.6    -7.2      -3             -39              -9      -7    
SAT 06Z 11-APR  -8.9    -8.4      -1             -32             -10      -9    
SAT 12Z 11-APR  -9.5    -9.3       1              -1             -10     -10    
SAT 18Z 11-APR   0.1    -7.7       0              -4              -9      -9    
SUN 00Z 12-APR  -3.2    -6.2      -1             -13              -8      -7    
SUN 06Z 12-APR  -7.9    -3.9       0              -1              -7      -7    
SUN 12Z 12-APR  -8.9    -1.4       0               4              -5      -5    
SUN 18Z 12-APR   5.4    -0.7      -1               1              -2      -1    
MON 00Z 13-APR   1.7     0.2      -1              21              -1       1    
MON 06Z 13-APR  -5.1    -0.9       4              27               0      -3    
MON 12Z 13-APR  -6.7    -4.8       7              34              -1      -6    
MON 18Z 13-APR  -2.6    -6.1       9              34               1      -6    
TUE 00Z 14-APR  -7.3    -7.1      10    1059      39   39.34       0      -8    
TUE 06Z 14-APR  -9.5    -7.8      10    1071      41   39.34      -1      -8    
TUE 12Z 14-APR  -8.5    -8.1      10    1055      44   39.33      -2     -10    

 

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Boring looking pattern for severe,for us anyways in the Valley.The Euro seemingly is flip flopping quite a bit recently. Probably are going to have to wait several more days this is when the MJO goes into 8-1-2 outside the COD.Today it looks more like the trough axis is going to basically be around the Valley somewhere mid range and possibly beyond with BN temps,least that how it looks today
 
ECMWF minus Climo FORECAST FOR: BNA    LAT=  36.12 LON=  -86.68 ELE=   591                                           12Z APR04                2 M     850     SFC     SFC     700    6 HR     500    1000                 TMP     TMP     PRS     RHU     RHU     QPF     HGT     500                 (C)     (C)    (MB)    (PCT)   (PCT)   (IN)    (DM)     THK SAT 12Z 04-APR   0.2     1.8       1              36               3       2    SAT 18Z 04-APR  10.0     2.0       0              29               4       4    SUN 00Z 05-APR   5.4     3.3      -1    1073      26   39.33       3       4    SUN 06Z 05-APR   0.6     3.2       0    1087      33   39.33       3       3    SUN 12Z 05-APR  -1.8     2.9       1    1096      18   39.33       3       2    SUN 18Z 05-APR  10.2     2.8       1    1051       7   39.33       5       3    MON 00Z 06-APR   6.2     3.3       1              13               5       5    MON 06Z 06-APR   0.0     3.6       2               6               6       4    MON 12Z 06-APR  -1.7     3.2       3              -2               7       4    MON 18Z 06-APR  10.6     3.0       2              -5               8       6    TUE 00Z 07-APR   6.9     4.8      -1               3               7       8    TUE 06Z 07-APR   3.2     5.4      -2              32               7       8    TUE 12Z 07-APR   2.7     5.6      -2              42               7       9    TUE 18Z 07-APR  12.7     5.8      -4             -20               8      11    WED 00Z 08-APR   8.2     7.9      -7              -7               7      12    WED 06Z 08-APR   5.8     8.8      -7             -20               7      13    WED 12Z 08-APR   6.1     6.8      -6             -17               5      10    WED 18Z 08-APR  12.5     8.0      -7             -24               5      11    THU 00Z 09-APR   9.3     8.2     -10             -23               4      12    THU 06Z 09-APR   6.1     8.3     -12             -23               2      12    THU 12Z 09-APR   3.5     3.8      -8              22               0       7    THU 18Z 09-APR   4.2     0.9      -5              -6              -1       3    FRI 00Z 10-APR  -0.2    -3.3      -5               4              -4       0    FRI 06Z 10-APR  -5.1    -6.6      -2              31              -6      -4    FRI 12Z 10-APR  -8.3    -9.9       0              -8              -8      -8    FRI 18Z 10-APR  -0.9    -8.8      -1             -42              -8      -7    SAT 00Z 11-APR  -3.6    -7.2      -3             -39              -9      -7    SAT 06Z 11-APR  -8.9    -8.4      -1             -32             -10      -9    SAT 12Z 11-APR  -9.5    -9.3       1              -1             -10     -10    SAT 18Z 11-APR   0.1    -7.7       0              -4              -9      -9    SUN 00Z 12-APR  -3.2    -6.2      -1             -13              -8      -7    SUN 06Z 12-APR  -7.9    -3.9       0              -1              -7      -7    SUN 12Z 12-APR  -8.9    -1.4       0               4              -5      -5    SUN 18Z 12-APR   5.4    -0.7      -1               1              -2      -1    MON 00Z 13-APR   1.7     0.2      -1              21              -1       1    MON 06Z 13-APR  -5.1    -0.9       4              27               0      -3    MON 12Z 13-APR  -6.7    -4.8       7              34              -1      -6    MON 18Z 13-APR  -2.6    -6.1       9              34               1      -6    TUE 00Z 14-APR  -7.3    -7.1      10    1059      39   39.34       0      -8    TUE 06Z 14-APR  -9.5    -7.8      10    1071      41   39.34      -1      -8    TUE 12Z 14-APR  -8.5    -8.1      10    1055      44   39.33      -2     -10    

 

FWIW, I've read data ingestion for the major models is being affected by a lack of global flights. I do not know how accurate this is or, if an issue, how wacky mid-to-long range modeling will become as we go forward the next month.
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It's probably usable NWP, even with some degradation. We been modelling 500 mb for over 50 years. The pattern is obviously quiet upstairs.

Chaser be like, fine. Get the garbage pattern over with while we can't go out anyway. No matter what, I'm out of the field through April 30, or later if state level guidance goes longer.

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