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Tn Valley Severe Weather


jaxjagman
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Showers percolating in southeast Mississippi are on and south of the Gulf Coast front lifting north, out ahead of the main surface trough and line of storms. Cells could be of interest. Gulf front will continue to lift north into east-central Miss. 

Main line of storms goes from West Miss into Louisiana. It's linear with QLCS tornadoes probable, and likely poor visibility. The new cells out ahead would perhaps provide better visibility; however, typical South challenges of terrain and trees exist. Also even the cells ahead could get into messy groups or clusters. 

HRRR is keying in on those southeast Miss cells 15-16Z runs. 12Z NAM missed them. 12Z FV3 was meh small cells. However one of the 12Z ARWs (NSSL research) hinted at the cells becoming rooted southeast Miss. Then going into Bama like the FV3. Latest HRRR runs have some ARW support. One could say the ARW is with HRRR (her). 

Satellite as of 12:30 Central shows vertical development, and turning with height as the baby anvils shear properly. 

image.png.d7106d107cadfada2ab8b4e98b6dda0d.png

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On 3/24/2022 at 6:58 AM, PowellVolz said:

Maybe a little more active, middle to the end of next week.


.

Yeah  have to wait a couple days and see what kind of instability we get.Wind shear turns SW on Wed and a decent LLJ showing especially by the Euro.It's still 5-6 days away so much can change

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The 00z CAMs have several updraft helicity tracks up by Memphis on Wednesday, with the squall line. It's possible that this segment will have a hard time getting the higher CAPE values and discrete storms, but it still seems like this may be a very active area. This seems to be a very analogous situation to last week (3/22), when several tornado and wind reports happened north of Jackson Mississippi within the large squall line, a little north of the moderate risk contour.

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 Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1230 PM CDT Tue Mar 29 2022

   Valid 301200Z - 311200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   LOUISIANA...EASTERN ARKANSAS...MISSISSIPPI...WESTERN
   TENNESSEE...ALABAMA...AND THE WESTERN FLORIDA PANHANDLE...

   ...SUMMARY...
   A regional outbreak of severe thunderstorms is expected on Wednesday
   across the Lower Mississippi Valley and Southeast. All severe
   hazards are possible, including widespread damaging winds, some over
   75 mph, and several tornadoes, some of which could be strong (EF2+).

   ...Synopsis...
   A shortwave trough will eject from the southern Plains across the
   lower/mid MS Valley on Wednesday while acquiring a negative tilt. An
   80-100+ kt south-southwesterly mid-level jet will accompany the
   shortwave trough passage. Low-level southerly flow is also expected
   to be very strong, with 50-70+ kt winds forecast at 850 mb. The
   primary surface low should be located over IA at the start of the
   period, with a cold front extending southward from this low across
   the central/southern Plains. A secondary surface low in closer
   proximity to the shortwave trough is forecast to develop from
   eastern OK to the Mid-South vicinity by Wednesday evening.

   At least low to mid 60s surface dewpoints are expected to return
   northward across the lower MS Valley and Southeast ahead of the
   secondary surface low, with the surface warm sector becoming
   increasingly pinched off with northward extent into the mid MS and
   OH Valleys. With strong forcing for ascent associated with the
   shortwave trough overspreading the warm sector through the day,
   thunderstorms will develop and move east-northeastward ahead of the
   cold front while posing a threat for both widespread damaging winds
   and several tornadoes.

   ...Lower Mississippi Valley into the Southeast...
   A line of convection aided by strong low-level warm advection will
   likely be ongoing at the start of the period from the Ozarks
   southward across AR to east TX. This activity should continue to
   pose a threat for at least isolated damaging winds and tornadoes as
   it moves eastward Wednesday morning. Fairly widespread cloud cover
   ahead of the line and modest mid-level lapse rates should temper the
   degree of destabilization to some extent. Still, the increasing
   low-level moisture in tandem with filtered diurnal heating are
   expected to aid in sufficient boundary-layer destabilization to
   support surface-based storms. MLCAPE around 500-1000 J/kg should
   develop ahead of the line across LA into MS and surrounding areas by
   early Wednesday afternoon.

   This QLCS should strengthen Wednesday afternoon as it moves across
   northeastern LA, eastern AR, southeastern MO, and into much of the
   lower MS Valley and Mid-South. Aided by strengthening low/mid-level
   flow, increasing low-level and deep-layer shear will both become
   very strong, supporting updraft organization. With a primarily
   linear storm mode expected, widespread severe/damaging winds appear
   likely. The presence of a 50-70+ kt south-southwesterly low-level
   jet, and even stronger flow up to 75 kt at 700 mb, should enhance
   the prospects for significant severe wind gusts of 75+ mph at the
   surface within the most intense portions of the line Wednesday
   afternoon and evening. Very favorable low-level shear and
   elongated/sickle-shaped hodographs in the boundary layer will likely
   also support low-level rotation with embedded mesovorticies within
   the QLCS. Several tornadoes should occur across the lower MS Valley
   and Southeast in this regime, with circulations moving quickly
   east-northeastward.

   The potential for supercells to develop ahead of the line, or
   perhaps embedded within the line with southward extent, remains
   unclear. Any cells that can form ahead of the line would be favored
   to produce tornadoes, but the quick eastward progression of the QCLS
   may limit this possibility. Still, some guidance suggests the
   southern part of the line may become more broken with time Wednesday
   afternoon/evening. If this occurs, then a threat for embedded
   supercells capable of producing multiple strong (EF2+) tornadoes
   would exist. At this point, the greatest tornado potential may focus
   along southern portions of the line in MS/AL where a semi-discrete
   mode seems more plausible. Regardless, a continued threat for both
   damaging winds and tornadoes will likely persist Wednesday evening
   and overnight as convection spreads from the lower MS Valley into
   the TN Valley and Deep South. Thunderstorms should eventually weaken
   with eastward extent early Thursday morning as they outpace the
   low-level moisture return and encounter a less favorable
   thermodynamic environment.

   ...Mid Mississippi Valley into the Ohio Valley...
   Less low-level moisture and weaker instability are forecast across
   the mid MS Valley and OH Valley compared to locations farther south.
   However, enough boundary-layer instability should be present for the
   line of storms to produce scattered to perhaps numerous damaging
   winds as it moves eastward given the strength of the low-level flow.
   A few tornadoes may also occur with favorable low-level shear also
   present. The lack of stronger instability precludes greater severe
   probabilities across this region at this time.

   ..Gleason.. 03/29/2022
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 Day 2 Convective Outlook    NWS Storm Prediction Center Norman OK  1230 PM CDT Tue Mar 29 2022  Valid 301200Z - 311200Z  ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF  LOUISIANA...EASTERN ARKANSAS...MISSISSIPPI...WESTERN  TENNESSEE...ALABAMA...AND THE WESTERN FLORIDA PANHANDLE...  ...SUMMARY...  A regional outbreak of severe thunderstorms is expected on Wednesday  across the Lower Mississippi Valley and Southeast. All severe  hazards are possible, including widespread damaging winds, some over  75 mph, and several tornadoes, some of which could be strong (EF2+).  ...Synopsis...  A shortwave trough will eject from the southern Plains across the  lower/mid MS Valley on Wednesday while acquiring a negative tilt. An  80-100+ kt south-southwesterly mid-level jet will accompany the  shortwave trough passage. Low-level southerly flow is also expected  to be very strong, with 50-70+ kt winds forecast at 850 mb. The  primary surface low should be located over IA at the start of the  period, with a cold front extending southward from this low across  the central/southern Plains. A secondary surface low in closer  proximity to the shortwave trough is forecast to develop from  eastern OK to the Mid-South vicinity by Wednesday evening.  At least low to mid 60s surface dewpoints are expected to return  northward across the lower MS Valley and Southeast ahead of the  secondary surface low, with the surface warm sector becoming  increasingly pinched off with northward extent into the mid MS and  OH Valleys. With strong forcing for ascent associated with the  shortwave trough overspreading the warm sector through the day,  thunderstorms will develop and move east-northeastward ahead of the  cold front while posing a threat for both widespread damaging winds  and several tornadoes.  ...Lower Mississippi Valley into the Southeast...  A line of convection aided by strong low-level warm advection will  likely be ongoing at the start of the period from the Ozarks  southward across AR to east TX. This activity should continue to  pose a threat for at least isolated damaging winds and tornadoes as  it moves eastward Wednesday morning. Fairly widespread cloud cover  ahead of the line and modest mid-level lapse rates should temper the  degree of destabilization to some extent. Still, the increasing  low-level moisture in tandem with filtered diurnal heating are  expected to aid in sufficient boundary-layer destabilization to  support surface-based storms. MLCAPE around 500-1000 J/kg should  develop ahead of the line across LA into MS and surrounding areas by  early Wednesday afternoon.  This QLCS should strengthen Wednesday afternoon as it moves across  northeastern LA, eastern AR, southeastern MO, and into much of the  lower MS Valley and Mid-South. Aided by strengthening low/mid-level  flow, increasing low-level and deep-layer shear will both become  very strong, supporting updraft organization. With a primarily  linear storm mode expected, widespread severe/damaging winds appear  likely. The presence of a 50-70+ kt south-southwesterly low-level  jet, and even stronger flow up to 75 kt at 700 mb, should enhance  the prospects for significant severe wind gusts of 75+ mph at the  surface within the most intense portions of the line Wednesday  afternoon and evening. Very favorable low-level shear and  elongated/sickle-shaped hodographs in the boundary layer will likely  also support low-level rotation with embedded mesovorticies within  the QLCS. Several tornadoes should occur across the lower MS Valley  and Southeast in this regime, with circulations moving quickly  east-northeastward.  The potential for supercells to develop ahead of the line, or  perhaps embedded within the line with southward extent, remains  unclear. Any cells that can form ahead of the line would be favored  to produce tornadoes, but the quick eastward progression of the QCLS  may limit this possibility. Still, some guidance suggests the  southern part of the line may become more broken with time Wednesday  afternoon/evening. If this occurs, then a threat for embedded  supercells capable of producing multiple strong (EF2+) tornadoes  would exist. At this point, the greatest tornado potential may focus  along southern portions of the line in MS/AL where a semi-discrete  mode seems more plausible. Regardless, a continued threat for both  damaging winds and tornadoes will likely persist Wednesday evening  and overnight as convection spreads from the lower MS Valley into  the TN Valley and Deep South. Thunderstorms should eventually weaken  with eastward extent early Thursday morning as they outpace the  low-level moisture return and encounter a less favorable  thermodynamic environment.  ...Mid Mississippi Valley into the Ohio Valley...  Less low-level moisture and weaker instability are forecast across  the mid MS Valley and OH Valley compared to locations farther south.  However, enough boundary-layer instability should be present for the  line of storms to produce scattered to perhaps numerous damaging  winds as it moves eastward given the strength of the low-level flow.  A few tornadoes may also occur with favorable low-level shear also  present. The lack of stronger instability precludes greater severe  probabilities across this region at this time.  ..Gleason.. 03/29/2022


I’m seeing on social media people calling this event a derecho but I thought a derecho actually needed a low pressure or some type of broad meso circulation? Can a squall line meet the criteria? I always thought a derecho was basically a stronger MCS.


.
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5 hours ago, PowellVolz said:


I’m seeing on social media people calling this event a derecho but I thought a derecho actually needed a low pressure or some type of broad meso circulation? Can a squall line meet the criteria? I always thought a derecho was basically a stronger MCS.


.

Usually ours come in the form of smaller clusters or MCS,like you mentiomed.

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15 hours ago, PowellVolz said:


I’m seeing on social media people calling this event a derecho but I thought a derecho actually needed a low pressure or some type of broad meso circulation? Can a squall line meet the criteria? I always thought a derecho was basically a stronger MCS.


.

Derechos come in two major forms, progressive and serial. You're probably thinking of a progressive derecho, which tend to consist of a single large (but usually somewhat more compact vs. a serial derecho) bow echo with an intense rear inflow jet and often a mesolow/wake low.

A serial derecho is associated with a long, narrow squall line (several hundred miles N-S, say from the MS/OH River confluence down to the Gulf Coast) with multiple small bow echos/line-echo wave pattern signatures, and embedded mesovortices and/or supercells. Today's event is expected to be closer to the serial type.

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1 hour ago, AMZ8990 said:

Wind is really ripping here at the house.  Ran into a few spotty squalls on my way home but other than that the heaviest is still an hour or so away.  

My trash can started to tumble down the road about a hour ago,sure hope we keep power

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URGENT - IMMEDIATE BROADCAST REQUESTED
   Tornado Watch Number 80
   NWS Storm Prediction Center Norman OK
   530 PM CDT Wed Mar 30 2022

   The NWS Storm Prediction Center has issued a

   * Tornado Watch for portions of 
     Northern and Central Alabama
     Middle Tennessee

   * Effective this Wednesday afternoon and Thursday morning from
     530 PM until 100 AM CDT.

   * Primary threats include...
     A few tornadoes likely with a couple intense tornadoes possible
     Widespread damaging winds expected with isolated significant
       gusts to 80 mph possible

   SUMMARY...A fast-moving line of storms will continue quickly
   east-northeastward this evening into Middle TN and northern/central
   Alabama. Very strong low-level/deep-layer winds will support the
   potential for tornadoes and widespread damaging winds as additional
   moistening occurs into the region.
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To go along with the severe threat, we have fires on the west slope of GSMNP in Wears Valley.  They are being driven by high winds which are preceding the storms.  Not good.  I mentioned in the obs thread...we have had maybe 3 severe threats during the past 4-5 years which have included bad fires.  This is the second fire in that area this year.

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1 hour ago, Carvers Gap said:

Just saw a twitter report on WATE...that is a long, long fire line.

Terrible situation. I hope short range models are wrong, because they try to really increase wind gusts near that area over the next few hours.  I'm hoping there's some limiting factor that keeps the higher end mountain waves winds from materializing.

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