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jaxjagman

Tn Valley Severe Weather 2018-19

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 Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0754 AM CDT Wed Mar 13 2019

   Valid 131300Z - 141200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS
   OF EASTERN ARKANSAS...SOUTHWEST TENNESSEE...NORTHEAST LOUISIANA AND
   NORTHWEST MISSISSIPPI...

   ...SUMMARY...
   Severe thunderstorms associated with wind damage and an isolated
   tornado threat are expected to develop across parts of the lower to
   mid Mississippi Valley this afternoon and evening.  Isolated severe
   storms are also possible over portions of northern Kansas and
   southern Nebraska.

   ...Synopsis...
   Upper-level low pressure over southeast Colorado will deepen early
   Wednesday while lifting northeast towards southeast Nebraska late
   Wednesday night.  Intense surface low pressure will remain
   vertically aligned with the upper system, resulting in very strong
   low/mid-level wind fields across the central/southern Plains east to
   the lower/mid-Mississippi Valley region.  An occluded front will arc
   northeast from the surface low across Iowa by 00Z and then extend
   south/southwest as a cold front from eastern sections of Missouri
   into western Louisiana.  

   ...East Texas/Arklatex to the mid-Mississippi Valley...
   Remnants of overnight linear MCS should continue to weaken this
   morning as instability diminishes with eastward extent, however an
   isolated severe gust will remain possible as stronger convective
   elements developing ahead of the gust front transport higher
   momentum air to the surface in the presence of a very strong (60 kt)
   low-level jet. 

   Despite generally weak mid-level lapse rates, a narrow corridor of
   lower 60s surface dew points will contribute to surface-based
   instability of 500 to locally 1000 J/kg by late afternoon/evening
   just ahead of the cold front from the vicinity of southeast Missouri
   southward. Strong wind fields will result in deep-layer shear on the
   order of 60 kts, with curved low-level hodographs supportive of
   supercells and bowing segments.  One limiting factor remains the
   lack of greater instability, and with large-scale lift shifting
   north of the area with time, there remains uncertainty regarding
   storm coverage. High-resolution guidance suggests that
   redevelopment/re-intensification of thunderstorms with the cold
   front remains possible, along with more discrete thunderstorm
   development within the favorable shear-instability region preceding
   the front.  Damaging winds will be primary threat with these storms,
   and some tornado potential will exist with the more discrete storms
   and QLCS circulations.  No major changes have been made to the risk
   categories/probabilities with this outlook. 

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 Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0754 AM CDT Wed Mar 13 2019

   Valid 131300Z - 141200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS
   OF EASTERN ARKANSAS...SOUTHWEST TENNESSEE...NORTHEAST LOUISIANA AND
   NORTHWEST MISSISSIPPI...

   ...SUMMARY...
   Severe thunderstorms associated with wind damage and an isolated
   tornado threat are expected to develop across parts of the lower to
   mid Mississippi Valley this afternoon and evening.  Isolated severe
   storms are also possible over portions of northern Kansas and
   southern Nebraska.

   ...Synopsis...
   Upper-level low pressure over southeast Colorado will deepen early
   Wednesday while lifting northeast towards southeast Nebraska late
   Wednesday night.  Intense surface low pressure will remain
   vertically aligned with the upper system, resulting in very strong
   low/mid-level wind fields across the central/southern Plains east to
   the lower/mid-Mississippi Valley region.  An occluded front will arc
   northeast from the surface low across Iowa by 00Z and then extend
   south/southwest as a cold front from eastern sections of Missouri
   into western Louisiana.  

   ...East Texas/Arklatex to the mid-Mississippi Valley...
   Remnants of overnight linear MCS should continue to weaken this
   morning as instability diminishes with eastward extent, however an
   isolated severe gust will remain possible as stronger convective
   elements developing ahead of the gust front transport higher
   momentum air to the surface in the presence of a very strong (60 kt)
   low-level jet. 

   Despite generally weak mid-level lapse rates, a narrow corridor of
   lower 60s surface dew points will contribute to surface-based
   instability of 500 to locally 1000 J/kg by late afternoon/evening
   just ahead of the cold front from the vicinity of southeast Missouri
   southward. Strong wind fields will result in deep-layer shear on the
   order of 60 kts, with curved low-level hodographs supportive of
   supercells and bowing segments.  One limiting factor remains the
   lack of greater instability, and with large-scale lift shifting
   north of the area with time, there remains uncertainty regarding
   storm coverage. High-resolution guidance suggests that
   redevelopment/re-intensification of thunderstorms with the cold
   front remains possible, along with more discrete thunderstorm
   development within the favorable shear-instability region preceding
   the front.  Damaging winds will be primary threat with these storms,
   and some tornado potential will exist with the more discrete storms
   and QLCS circulations.  No major changes have been made to the risk
   categories/probabilities with this outlook. 

 

image.png.a185a202c6ef97a89dc962b46cc00b75.png

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 Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1255 AM CDT Wed Mar 13 2019

   Valid 141200Z - 151200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE TENNESSEE
   VALLEY NORTHWARD TO SOUTHERN LOWER MICHIGAN...

   ...SUMMARY...
   Strong to severe thunderstorms are possible from portions of
   Mississippi and Alabama northward through central Tennessee and
   Kentucky into Indiana, western Ohio and southern Michigan. Damaging
   winds, hail and tornadoes will all be possible from midday through
   the evening hours.

   ...Synopsis...
   The intense mid/upper trough over the mid-MO Valley will continue to
   shift east/northeast toward the Great Lakes and eastern Ontario by
   Friday morning. This will maintain a roughly 80-100 kt southwesterly
   midlevel jet streak across the Lower Ohio Valley toward Lake
   Ontario. At the surface, a still strong but filling cyclone will
   spread northeast in tandem with the upper level trough, arriving in
   the vicinity of James Bay by Friday morning. As the low lifts
   northeast, a cold front, oriented south-southwest from eastern IA to
   central AR to near the TX Gulf Coast at the beginning of the period,
   will shift eastward across the Midwest to the Lower MS Valley region
   by Thursday evening. 

   ...Lower Ohio Valley Vicinity...
   A strong south/southwesterly low level jet will transport Gulf
   moisture fairly far northward for this time of year, with at least a
   narrow corridor of low 60s F dewpoints as far north as the Lower
   Ohio River, and low-to-mid 50s F dewpoints into southern Michigan.
   While the better quality moisture will remain confined to the Deep
   South, forcing for ascent and deep layer shear are much more
   impressive from the Ohio Valley into southern MI. Additionally,
   midlevel lapse rates are expected to steepen from KY/IN into MI as
   stronger height falls and colder temperatures aloft overspread the
   region ahead of a midlevel dryslot by midday. 

   All of this combined leads to a narrow warm sector characterized by
   500-1000 J/kg MLCAPE, 6.5-7.5 C/km midlevel lapse rates,
   impressive/large curved low level hodographs and 45+ kt effective
   shear. While this parameter space is more than capable of supporting
   widespread severe, including damaging winds and possible strong
   tornadoes, quite a bit of uncertainty still exists. This is due in
   part to several rounds of showers and thunderstorms expected in the
   Day 1/Wed period, with ongoing convection possible in warm advection
   regime at the start of the Day 2/Thu period. Impacts of this
   convection/residual cloud cover on destabilization, and how
   far/quickly the surface cold front progresses by Thursday morning
   makes for a quite conditional scenario. As a result, have opted to
   expand the Slight risk northward across the Mid-South into southern
   MI. Uncertainty and conditional nature of the threat will preclude
   higher probs at this time across parts of KY/IN/MI/OH, but potential
   certainly exists for a higher-end threat to materialize across this
   region, as implied by various CAMs in the 18-00z time frame.
   Observational and numerical guidance trends will be monitored
   closely. 

   ...TN Valley toward the Central Gulf Coast...

   Poorer lapse rates and much weaker forcing is expected with
   southward extent as the upper trough ejects away from the region.
   Near-neutral height tendancies and warmer temperatures aloft will
   result in weaker lapse rates compared to further north. Still, deep
   layer shear (45+ kt effective shear) will remain more than capable
   of sustaining organized convection. With mid-to-upper 60s F
   dewpoints resulting in 500-1000 J/kg MLCAPE, supporting bowing line
   segments or supercells. Damaging winds and perhaps a tornado will be
   possible with any sustained storms that can develop, but the lack of
   stronger forcing will generally limit storm coverage.

Real Time multivariate MJO Phase Space Diagrams   Michael J  Ventrice  Ph D .png

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Mid levels look a little warm (SPC notes poor lapse rates / neutral heights) and no clear 2nd boundary is noted. Guess there's always the differential heating between CHA and HSV/BNA. 

2 hours ago, jaxjagman said:
 Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1255 AM CDT Wed Mar 13 2019

   Valid 141200Z - 151200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE TENNESSEE
   VALLEY NORTHWARD TO SOUTHERN LOWER MICHIGAN...

   ...TN Valley toward the Central Gulf Coast...

   Poorer lapse rates and much weaker forcing is expected with
   southward extent as the upper trough ejects away from the region.
   Near-neutral height tendancies and warmer temperatures aloft will
   result in weaker lapse rates compared to further north. Still, deep
   layer shear (45+ kt effective shear) will remain more than capable
   of sustaining organized convection. With mid-to-upper 60s F
   dewpoints resulting in 500-1000 J/kg MLCAPE, supporting bowing line
   segments or supercells. Damaging winds and perhaps a tornado will be
   possible with any sustained storms that can develop, but the lack of
   stronger forcing will generally limit storm coverage.

High resolution models show small cells, indicative of warm mid-levels. Perhaps a few storms can get rooted and going, with less coverage. Also 45 knots shear (vs 60 kt) could be slightly less fast storm motion than previous events. Still looks fast though.

Sometimes less coverage in Dixie Alley means less sloppy, but it depends on the cause. This situation could still be meh/mess, but with less rainfall (good). In the Plains less (slop) can mean more (quality). In Dixie less is usually less.

Almost like snow, Dixie seems like all or nothing. Some statistics actually back up that feeling. Remover the big outbreaks and Dixie is less active than the Plains. Keep the outbreaks and they are equal. This is no outbreak, so I think all is good.

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Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1259 AM CDT Thu Mar 14 2019

   Valid 141200Z - 151200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS
   OF THE TENNESSEE AND OHIO VALLEYS...

   ...SUMMARY...
   Strong to severe thunderstorms are possible from a portion of the
   Southeast U.S. into the Ohio Valley and southern Great Lakes.
   Damaging wind and a few tornadoes will be possible along with some
   hail.

   ...Synopsis...

   A very strong upper jet will rotate through the base of a potent
   synoptic upper trough and into the middle MS Valley, Ohio Valley and
   upper Great Lakes. Surface low within the exit region of this jet
   will develop northeastward and occlude over WI this afternoon. The
   trailing cold front will stretch from a surface low in IA early in
   the day southward through the lower MS Valley. This front will
   advance east reaching the lower Great Lakes southwest into the
   middle Gulf coast by the end of this period.

   ...Southeast U.S. through Ohio Valley and Great Lakes...

   Initial band of convection developing along warm conveyor belt from
   the TN Valley into the OH Valley will shift northeast and weaken
   early Thursday. However, ageostropic forcing accompanying an
   upstream jet exit region is already spreading through the Southern
   Plains, contributing to thunderstorms development along the front
   over northeast TX. This zone of ascent will continue to spread
   northeast during the early part of the day, and most models develop
   a secondary band of showers and thunderstorms over the middle MS
   Valley that shifts into the OH Valley by mid day. The timing and
   evolution of this early convection and areas of clouds complicate
   the forecast to some degree. Nevertheless, a corridor of mid-upper
   50s dewpoints will advect north into the OH Valley along a strong
   low-level jet, with mid-upper 60s farther south across the Southeast
   States. MLCAPE should range from 1000+ J/kg over the Southeast
   States, where more diabatic heating is possible and higher dewpoints
   will reside, to around 500 J/kg farther north into the OH Valley and
   southern Great Lakes. Current indications are that additional
   thunderstorms will gradually intensify along and just ahead of the
   progressive front from the OH Valley southward into the TN Valley
   from late morning into the afternoon. The stronger forcing will
   exist along and north of the upper jet exit region over the OH
   Valley where instability will be more limited, while farther south
   weaker forcing will exist, but a destabilizing boundary layer and
   low-level convergence should be sufficient to initiate storms. Wind
   profiles will be very favorable for organized severe storms with 50+
   kt effective bulk shear and 300-500 m2/s2 0-1 km storm relative
   helicity. Both discrete supercells and line segments are possible
   with damaging wind and a few tornadoes the main threats, mainly from
   late morning through early evening.

   ..Dial/Gleason.. 03/14/2019

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 Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0752 AM CDT Thu Mar 14 2019

   Valid 141300Z - 151200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS
   CENTRAL/EASTERN INDIANA...WESTERN OHIO...CENTRAL KENTUCKY...MIDDLE
   TENNESSEE AND NORTHERN ALABAMA...

   ...SUMMARY...
   Severe thunderstorms are likely from portions of the Southeast U.S.
   into the Ohio Valley and southern Great Lakes.  Damaging winds and a
   few tornadoes will be possible along with large hail.

   ...Synopsis...
   An upper-level low over Iowa this morning will gradually evolve into
   an open wave as it lifts northeast across the Great Lakes today,
   while a trailing portion of the trough extends southwest into the
   central Plains.  A deep (983 mb) surface low beneath the upper low
   will lift northeast as a trailing cold front moves rapidly across
   the TN/OH Valley region and the lower MS Valley.  Collectively,
   these surface and upper-level features will result in a broad area
   of favorable vertical wind shear for severe storms.  

   ...Southeast U.S. through Ohio Valley and Great Lakes...
   An expansive area of showers and thunderstorms associated with
   warm/moist advection within the warm sector was in progress at 13Z,
   and the effects of ongoing/early day precipitation casts some
   uncertainty on the details regarding severe potential today and
   tonight.  In general, ongoing precipitation should weaken or lift
   northeast of the risk area by midday, with additional thunderstorm
   development in advance of the cold front by afternoon.  

   Low-level moisture remains a limiting factor, with lower/mid 50s
   surface dew points expected as far north as OH/southeast Lower
   Michigan, and mid 60s/upper across the southeast states. 
   Substantial cloud cover combined with modest mid-level lapse rates
   will temper instability, with MLCAPE ranging from 1000+ J/kg over
   the Southeast States, where more diabatic heating is possible and
   higher dewpoints will reside, to around 300-500 J/kg farther north
   into the OH Valley and southern Great Lakes.  The impressive
   low/mid-level wind fields will result in deep-layer shear averaging
   50 kts across the southeast to in excess of 80 kts across the OH
   Valley/Great Lakes, with low-level (0-1 km) SRH in excess of 300
   m2/s2.  

   Thunderstorms should redevelop or intensify in advance of the cold
   front this afternoon as large-scale ascent within the left exit
   region of a 100-kt jet streak approaches the OH/TN Valley region. 
   Farther south, forcing becomes a bit more nebulous however a more
   favorable thermodynamic environment with lower CINH will be in
   place.  Most CAM guidance maintains discrete or semi discrete storms
   initially, with a transition to a more linear structure across
   northern portions of the risk area with time due to stronger
   large-scale forcing. Primary storm modes for storms that can persist
   within the strong shear environment will be supercells and bowing
   segments, with a risk for damaging winds, tornadoes, and large hail.

   Should a corridor of stronger heating/greater instability develop,
   confidence would increase regarding introduction of a significant
   tornado risk area given the very favorable background environment. 
   This may be needed in later outlooks as the effects of ongoing
   precipitation is assessed.

   ..Bunting/Mosier.. 03/14/2019
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Mesoscale Discussion 0208
   NWS Storm Prediction Center Norman OK
   1147 AM CDT Thu Mar 14 2019

   Areas affected...Northeast Mississippi...Northwest Alabama...and
   southern Tennessee

   Concerning...Severe potential...Tornado Watch likely 

   Valid 141647Z - 141815Z

   Probability of Watch Issuance...80 percent

   SUMMARY...A gradual increase in storms is expected through the
   afternoon. A tornado watch will likely be needed soon.

   DISCUSSION...16Z surface analysis shows much of northeast
   Mississippi and northwest Alabama has warmed 4 to 5 F in the last
   hour despite some cloud cover across the area. This has led to an
   increase in low-level instability to around 750 to 1000 J/kg of
   MLCAPE. Warming is expected to continue with low-level moisture
   advection which will lead to moderate instability by mid-afternoon.
   The recent heating in this area has provided enough instability for
   a reinvigoration of lightning from some of the convection in
   northern Mississippi. Therefore, expect more widespread storm
   coverage within the next hour or two as surface destabilization
   continues to increase. 

   Deep-layer shear in this area is very favorable for supercell and
   low-level mesocyclone development with deep layer effective shear
   around 55 to 60 knots and 0-1 SRH around 350 m2/s2 per GWX VWP.
   Therefore, these storms will pose a tornado threat with the
   potential for strong tornadoes, especially as supercells mature into
   northwest Alabama.

   ..Bentley/Thompson.. 03/14/2019

 

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I got a thread going. Agree with everything in SPC Mesoscale Discussion 208 just above.

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MJO is into the the Maritime but weak signals.The problem with the Euro is with the tropical system(convection) as it moves the MJO  back into the IO.GEFS looks more right to me as it looks to go into phase 4,5 and 6 and potentially into West.Hem./Africa towards the end of the month.

Today there is a trough going through Korea which could give us some thunderstorms into next weekend.The next more bigger potential system right now looks more towards the end of the month,with a trough coming off Mongolia this Wednesday then down into Korea which builds a ridge over Japan.If things teleconnect right this could be a potential good severe.

Tropical Monitoring    North Carolina Institute for Climate Studies.png

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Euro and GFS don't agree with each other,whats new, into the end of next weekend into the first part of the week after.Euro brings the LP basically through Tn while the GFS shows the system into the lower OV.Even if the GFS is right it looks more wind and hail.

 

We seem to be close to avg. with tornadoes so far.Ironically the third best year was 2010 which was coming off of a strong Nino.I'm not really sure how much the tropics had to do with this.There looks to have been two tropical storms in 2010.Bonnie crossed Florida as a TS but weakened as it went into MS/LA as a depression.TS Richard went into Texas.But,there was no impact from a hurricane that year

Spring 2019   Outlooks and Discussions   Page 13   United States   WX Disco.png

 

https://en.wikipedia.org/wiki/Tornado_outbreak_of_April_22–25,_2010

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Similar look from what the  Euro seasonals show to what the RRWT shows through spring.What would look to be HP into the GOA and also HP off the Mid-Atlantic into the Carolina's.-PNA.

Andrew Berrington on Twitter   Looking towards AMJ  the new March ECMWF seasonal forecast is a rather strong signal for an active severe wx season  Also shown is the 2018 AMJ 2 m temperature anom forecast and verific.png

RRWT   Consonant Chaos.png

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