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jaxjagman

Tn Valley Severe Weather

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8 minutes ago, CheeselandSkies said:

Not really, just got the first decent event of the winter Friday night into yesterday. 61-page thread (and growing) devoted to tracking that one!

61 pages,, wow.  I’d say you guys earned that one then.  Lol

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Possibly some strong storms next Sunday/Monday,to far out right now to tell but both the GFS AND Euro are showing the DP'S into the lower 60's,with  instabilities showing.

 

ehi03.conus.png

Here’s where tornadoes typically form in February across the United States   U S  Tornadoes.png

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Looks like the GFS has backed off a bit for now. Way too early to tell obviously.

<banter>I'm all too happy to throw in the towel on winter early if that would net an active spring, but I won't hold my breath.</banter>

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Hopefully the ECMWF finds some thunderstorms in the 6-10 day. I'm ready for severe wx season. Reality is a trough hanging out west for multiple days allows moisture return into Dixie. Bring out a shortwave, and boom!

Once I take down the Christmas tree, severe wx season can start anytime.

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Timing differences which should not surprise anyone.CIPS is now showing a chance of thunderstorms.Besides from t-storms the Euro would be a decent rain maker with what it shows with LLShear around 30-35kts and a LLJet 45-50 kts coming through,could be 1.5" to 2" of rn as of today which would be more Tuesday into Wed.

CIPS Extended Analog Guidance.png

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12Z Euro lights up Dixie Alley in less than a week. However it is just one run. If the advancing front is slow enough out of the Midwest, two waves are forecast in three days. Such a solution would give more time for moisture return ahead of the second one.

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The GFS has continually flirted with severe since Jax mentioned it above - less so than the 12z Euro, mercy.

Fitting, as we are almost to the 11 year anniversary of the Super Tuesday outbreak. 

 

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15 minutes ago, Blue Ridge said:

The GFS has continually flirted with severe since Jax mentioned it above - less so than the 12z Euro, mercy.

Fitting, as we are almost to the 11 year anniversary of the Super Tuesday outbreak. 

 

The amount of rain for the month  being depicted by the CFS is nothing short of amazing 

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Trough is showing further back to the west and the heights are rising up.Best shot of any thunderstorms right now looks to be Wed.afternoon into the the early evening,going by the Euro.Not as much rain also with this look.

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Regrettably the Euro has managed to kill the juxtaposition of instability and shear. One of many reasons I'd like to forget any 12Z runs ever happened. Oh well!

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Alright severe people, I'm coming over to play for a week or two. I have access to all these fancy maps and nothing to use them on for now. What would you like to see? I really don't know what to look for in terms of severe weather, so let me know.  But if I'm going to post Kuchera snow maps for winter folks, may as well most CAPE/ shear/ K index (whatever that is, but think has something to do with severe) maps too. 

Euro Surface CAPE:

giphy.gif 

Euro Deep Layer Shear:

giphy.gif

Euro K Index:

giphy.gif 

Here are other Euro products I have access to, but don't know what half of them mean:

giphy.gif 

 

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9 hours ago, Holston_River_Rambler said:

Alright severe people, I'm coming over to play for a week or two. I have access to all these fancy maps and nothing to use them on for now. What would you like to see? I really don't know what to look for in terms of severe weather, so let me know.  But if I'm going to post Kuchera snow maps for winter folks, may as well most CAPE/ shear/ K index (whatever that is, but think has something to do with severe) maps too. 

Euro Surface CAPE:

giphy.gif 

Euro Deep Layer Shear:

giphy.gif

Euro K Index:

giphy.gif 

Here are other Euro products I have access to, but don't know what half of them mean:

giphy.gif 

 

The KI,cape,shear is a good tool(at a starting point),but other indices are involved with the severe thunderstorm aspect and some indices rely  with other indices for severe storms.If you want to learn more about severe  this is a good starting spot .

http://www.theweatherprediction.com/severe/indices/

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Welcome everyone to Severe Weather! In contrast to snow, I find severe wx easier to enjoy from afar. Snow you kind of have to be there. Severe can be tracked by watching radar and following chasers on Twitter or TWC. Scanner Radio is a good app to follow EM radio traffic. Now, here is how I forecast severe.

Extended: I keep it simple. Look for instability and wind shear. Need temps and dews at appropriate levels (70+/60+). CAPE forecasts are available, but I like to look at temps/dews myself. Wind shear I want strong winds at 500/200 mb, preferably from the west/southwest, not really straight south. I need a strong LLJ at 850 mb, preferably south, not west. Need veering with height. 

Within 5 days: Starting looking at more levels in detail. Everything above plus 700 mb and 925 mb. Through all levels need to avoid veer-back-veer. Check forecast soundings. Look for a pretty hodograph forecast (long gentle hook or sickle* shape, no silly kinks). Also temperature profiles on the soundings. Might check 850/700 mb temps, esp 3-4 days out. Thickness can also shed light on cap, no cap, just right cap. 925 mb hints at lowest level wind shear. Looking for cold front, warm front, dry line placement. Do instability, wind shear and surface triggers line up?

Within 2 days: Fine tune forecast. All of the above plus timing issues. Timing is everything. Also look for any rain interactions. Fine line between morning rain bullish outflow boundaries, and midday rain stabilizing things. Models offer more helicity and energy-helicity forecasts this time period. Still I check for wind shear myself by drilling down all the upper level charts. Same day I follow visible satellite trends and surface chart. 

* No hammers though. We're not commies!

This post may be amended for a few days if I think of more stuff. Hopefully real-life will jog my memory, lol!

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Getting closer to the event, I particularly enjoy studying the actual and model soundings for a given location for severe wx; since tons of data is to be had in just one picture.

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Saw a met from another forum saying that the ENSO state and a few other factors  are beginning to look better for severe in the Plains this spring but not so much for the TN Valley/Southeast. 

I can live without severe here personally but can see why people like to track/chase storms. Not much we can do to prevent weather of any kind but we can learn more about it. 

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Sounds good to me. I'd rather travel to the Plains than try to chase Dixie. Euro monthlies have a chaser friendly look to May. BN heights Southwest and AN heights Great Lakes. Give me more of that southwest flow. QPF also hints dry line fires west of I-35 which is the prime chase terrain. Yes please!

As for ENSO, one could infer the TNI is trying to set up right between Nino 1+2 and 4. However it's evolving from weak El Nino. Bullish TNI is usually from La Nina transition. We'll see though. PDO is also trying for a slightly better look. :)

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Day 1 Convective Outlook CORR 1
   NWS Storm Prediction Center Norman OK
   0714 AM CST Wed Feb 06 2019

   Valid 061300Z - 071200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHERN OK/NORTH
   TX TO WESTERN KY/TN...

   CORRECTED FOR DAY OF THE WEEK

   ...SUMMARY...
   Episodic severe storms will be possible from parts of the southern
   Great Plains into the Tennessee and Lower Ohio Valleys, mainly from
   late afternoon through tonight.

   ...Southern Great Plains to TN/Lower OH Valleys...
   A messy, relatively low confidence scenario for severe storms is
   apparent this afternoon through tonight, resulting in maintenance of
   risk area shape but with an overall southward shift. Have decreased
   wind/tor probabilities across the northern portion of the risk areas
   where the polar air mass is likely to remain entrenched. Have
   increased hail probabilities in magnitude and spatially given the
   expectation of at least a few supercells this afternoon/evening and
   for the incipient stage of storm development tonight in the southern
   Great Plains.

   The surface front has remained nearly stationary in an arc across
   northwest TX and far southeast OK, with the portion across AR/MO
   still sinking south with weak cold advection behind it. This
   boundary should fully stall by midday with some drift back to the
   northwest as cyclogenesis occurs in the lee of the southern Rockies.
   A series of cyclones should develop southeast along the front across
   the TX Panhandle into far south-central OK through tonight, before
   consolidating near the AR/MO border by 12Z Thursday. 

   Isentropic ascent/warm advection near the boundary along with weak
   boundary-layer heating of a warm sector characterized by mid 60s
   surface dew points should promote scattered thunderstorms along and
   north of the front through early evening in an arc from southeast OK
   to TN/KY. While elongated hodographs should support a few embedded
   supercell structures later today, seasonably modest low-level winds
   and mid-level lapse rates may curtail a more robust tornado and
   severe threat. 

   Along the western portion of the warm sector in central TX to far
   south-central OK, the 10Z HRRR is an outlier with the depiction of
   intense supercell development near/north of the triple-point region
   along the Red River. This scenario while seemingly unlikely is
   possible given strengthening convergence associated with
   cyclogenesis. Should this occur and a discrete cell or two are able
   to deviate along the boundary, wind profiles would be highly
   favorable for a large hail and tornado threat. While other CAMs do
   not support this scenario, as mid-level height falls finally begin
   to overspread the region, scattered convection should develop
   generally on the cool side of the boundary in OK tonight and
   eventually southward along the developing cold front/remnant dryline
   into north-central TX. Clusters evolving into broader line segments
   appear probable overnight as forcing for ascent intensifies, but a
   strong cap should largely inhibit open warm-sector storm
   development. In addition, the southern extent of storms should
   struggle given the track of the shortwave trough from the southern
   Rockies towards the MO Valley. Still, strengthening low/deep-layer
   shear could sustain an isolated severe risk overnight.

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Arkansas remains the prime areas IMHO. Obviously it is not chasable so I'm relaxing here in Chatty. 

14 hours ago, jaxjagman said:

Short range models are showing some better instability tomorrow for the Valley,we'll see where it goes from here

Shear will be there. Instability depends on convective evolution. Few CAMs have cyclical supercells in western Arkansas, marching across the state. Others, like the NAM, have too much other stuff in the Delta. The latter solution cuts off the cells up on the boundary intersections in western Ark. 

Arctic air is another factor. If that air is right up on the boundaries, cancel supercells. What a mess. Must be February!

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Area Forecast Discussion
National Weather Service Memphis TN
1202 PM CST Wed Feb 6 2019
Interesting:


Past model runs have been too hasty on lifting the front
north out of our CWA...with the 00z runs holding off now until
this evening when the surface low begins it`s shift northeastward.
This delay may provide a better threat/focus for a few severe
storms across our area and heavier rainfall. CAMs suggest a pool
of 800-1200 j/kg of CAPE just south of the boundary this
afternoon with decent shear supporting a Fixed-layer STA of near
4. Interesting and worrisome...one of the CIPs analogs for 07/00z
is the February 5th 2008 outbreak. So what are the limiting
factors? A lack of height falls pushing in for one...perhaps morning
showers limiting the low-level instability keeping a CAP in place
and mediocre midlevel lapse rates. Feel that the upward bump to a
slight risk near the boundary by SPC was a wise decision...and it
may have to be expanded south to the MS state line if pockets of sun
are observed. The threat for severe weather will continue tonight as
the shear increases through midday tomorrow with the cold front
approaching. have added an isolated tornado threat in today`s HWO.
Total rainfall amounts of near 3 inches are still projected near
the KY and Mo borders...with 1-2 farther south. In addition have
issued a wind advisory beginning late tonight into tomorrow across
the western counties as 850mb winds increase to 55-65kts. Above
normal temperatures for the next 30-36 hours...will fall quickly
tomorrow afternoon and evening. Heat indices of 75-80F will
become windchill in the teens in approximately 12 hours.
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Looks like two boundaries, both in their CWA. Synoptic is north of MEM. Another sits south of MEM. Could be a fun afternoon. Still I agree with their reasons limiting the event. Probably just isolated gusty winds. Heavy rain is the other consideration.

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...A TORNADO WARNING REMAINS IN EFFECT UNTIL 830 PM CST FOR
SOUTHWESTERN DAVIDSON...NORTHWESTERN WILLIAMSON AND SOUTH CENTRAL
CHEATHAM COUNTIES...

At 812 PM CST, a severe thunderstorm capable of producing a tornado
was located over Pegram, or 14 miles south of Ashland City, moving
east at 40 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.

This tornadic thunderstorm will remain over mainly rural areas of
southwestern Davidson, northwestern Williamson and south central
Cheatham Counties.

This includes Interstate 40 between mile markers 182 and 197.
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There's tornado warnings and a winter weather advisory going on simultaneously in Southwest Missouri. 

 

image.png.5eaf1167123ddc08420426bed78e3854.png

 

I don't know if I've seen anything like that before.

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1 hour ago, John1122 said:

Lots of thunder here and flooding is pretty bad but nothing severe. I've had about as many days of thunder this winter as I have had frozen falling now. 

We havent heard thunder here in months.

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I have a feeling 2019 will be an active year. Atmosphere often tips its hand early. See if we can get a few more early days. 

Plains may end up being the most active, so I'm not mongering for Dixie. Storm track has been quite active. Low press likes to track over the Ozarks this winter. Shift that north later in spring for Central Plains action.

Mid-South portion of Dixie could be seasonably active early while lows are still going through the Ozarks.

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I'd be down for that. I keep thinking the Plains are overdue for another truly active chase season, with a 10-14 day locked in pattern producing multiple days with multiple cells the caliber of Rozel, DDC/Chapman, Pilger, etc in May, which maybe quiets down for a bit then reloads in June, rather like 2004 and 2008 did in the last decade.

Then every spring the atmosphere says "Nope!"

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