nrgjeff

Yeah @Carvers Gap seems somebody in Riverton with my view of the world wrote that AFD, lol! 

Smoke has reached Tennessee, but nothing intense. Low dewpoints on the east wind is nice, but the high press up North is funneling in smoke. Sky is milky where it's blue. 

For a minute I was missing deep blue sky; however, the only path to that now is a pure tropical airmass. Eh, I'll take smoke (mild of course) over 70 Td.

Outflow boundary and backed winds there gives those storms just enough to rotate. Most of the tornado warnings today are riding that outflow boundary to the ESE. 

Part of me wants to be on the stretch of I-75 north of Knoxville, close to Kentucky, that's up on a high ridge. One can see forever. Pretty sure neat things could be photographed up there, even if just clouds and lightning. 

Otherwise most of the terrain up there is unfavorable. I would like the intersection of the East KY outflow with the synoptic front, but I have to pass. Though not common, severe wx can and does happen in the mountains. 

Yes @Carvers Gap @PowellVolz the thunderstorms have a more summer feel than spring right now. Feels early, but we need the rain. Northwest flow is morphing into zonal with waves kicking out of the Plains. 

This week into the weekend looks warm. Next week temps should back down closer to normal. That NW flow may be the dry version. Wind should calm down when the pattern is less active.

Weather patterns like to get more amplified coming out of winter into spring. Following the warm winter, the Arctic plays games on the spring jet stream. Autumn has not changed as much as spring, because the Arctic was always mild coming out of summer. Now I hand off to the Climate Change section of the forum.

Totally separately, WSJ reports a freight recession, smaller cargo loads, and fewer big rigs. Hmmm. I don't see that here. Who else still observes trucks clogging the Interstates? My guess is WSJ has national stats. Our regional economy remains strong. Silver lining to all these trucks everywhere, lol!

The extended forecast storm track Apr. 25-30 would be nice in winter. 

If you liked Monday and Tuesday, you'll love next week. Looks like a few days of cool nights/mornings and mild afternoons. More than a pair of days, but not quite several days. 

These warm days are nice too. Does not feel anything like summer, barely even late spring. Dewpoints are very low and the sun angle is not quite there yet. It's just over half way. The warm side of that glass half something, I concede that's also late August going into Labor Day sun angle. Explains some AC even though it's nice out.

OK back to my Severe Weather thread safe space. Virtue signaling has been a little smug recently.

Yeah, High Risk isn't something we see every day. In fact the Region sometimes skips a year. Only 2-3 nationwide each year. 

Arc of soon to be supercells is developing from Missouri to Arkansas as I type (Noon or just after Central Time). Morning showers left outflow boundaries OFBs. Atmo will destabilize with broken sun. Prefrontal trough(s) to intersect OFBs.

SPC seems to key on southeast of the synoptic triple point TP Iowa/Illinois. Southern stream TP is forecast Mid-South. Some of it is mesoscale, but also southern forcing aloft. 

Not much else to add to SPC. Today is not a chase day. Thinking of those in the risk areas.

Work calls too. This is likely my only post until the true weekend.

I see why SPC is 'concerned' about the Mid-South. However this RRFS is just one model. Others have a broken line, but not this brutal line of kidney beans. Line is on a prefrontal trough. 

HRRR is beefy (no surprise) but not as intense as the RRFS. ARWs (research WRFs) are split. Old is beefy with some sups, new ARW2 gets sloppy fast. Ditto FV3, which is interesting* because it does OK with storm mode. NAM is doing NAM things, over forced and probably not enough CAPE.

*Interesting in that the sometimes bullish FV3 is a little less intense than some others this time. Still regardless of radar simulations, the environment will be robust CAPE and shear.

At the low levels, surface moisture will surge north. Morning and midday showers should leave outflow boundaries, but cool air may not linger. Strong synoptic system should advect unstable air in as boundaries retreat. One or two pre-frontal troughs is forecast. Boundaries and their intersections will be concerns.

Either way the CAPE will probably be 'skinny' on the Nashville Skew-T overnight, without diurnal heat. Low level CAPE will depend on steady temps after the initial sunset drop.

General wind shear aloft is forecast overnight into Middle Tenn. As usual overnight shear can endure when CAPE fades. Still early to forecast low level shear and boundaries though.

Mid-South late Friday afternoon into early evening is a bigger concern. CAPE and shear will be juxtaposed. A prefrontal trough or convergence zone could be surface drivers. Such details are still TBD.

A true Gulf Coast warm front lifted through Mississippi last night. Appears it intersected a couple pre-trough convergence lines. Due to the deep moisture with a Gulf WF instability remains overnight. 

Separately In the satellite chart on my Friday post, appears a couple dark lines in central Mississippi make a T. That could have been another subtle boundary intersection, but at the time a little dry air just off the surface kept it in check during the day.

The loss of life is tragic. Agree with Matthew that in the South significant tornado events are usually bad news.

Back here in Tennessee the lifting outflow boundary (well north of the Gulf boundary) tended to focus straight line winds. However some QLCS tornadoes were reported in North Alabama. Got sideways rain on straight line wind at 3am in Chattanooga.

0656  65  4 ESE CHATTANOOGA

HAMILTON TN  CHATTANOOGA ASOS RECORDED A 65 MPH WIND GUST. (MRX)

Outflow boundary OFB re-lifting now through the Mid-South is going to be trouble.

Initial line coming into Memphis might not have the moisture yet. Dry pocket aloft Mississippi means the best 850 mb moisture has to sneak up the Delta. It should be there late afternoon, along with the SRH on that outflow boundary. Hopefully for MEM, the OFB is elsewhere later. It is lifting north but could stall or sink with the early afternoon precip.

OFB should also snake through Middle Tennessee later this evening. By then storms could be more QCLS than sups. Also have to watch the synoptic warm front if the air between the OFB and WF can warm up. Otherwise it's a big ol' Southern line overnight.

Fountain beat me to it. Not too upset to see the system vanish days 5-6. Note that WPC still has QPF those days.

I'd be happy to see the system show up again, without a mega-cut knuckle ball. Carvers STL captures that idea, lol!

Never take anything off the table in the Southeast. 

12Z Euro update. Nah, I'll tell you what's gonna happen. Spoiled NC whiners will get one on the coast. Is that even worse than the STL cut?

They are in way better shape than me. I can watch college basketball, lol! How about Vanderbilt?
Love how the odds makers treat Vandy like an Ivy League school. Yes it's an excellent academic university; but, it's also SEC!

ECMWF can't decide whether to bury that thing or bring it up with no cold air supply. Maybe the 12Z will offer some clarity. GFS/Canadian sure like it!

Southeast ski areas would like it. I'm surprised to see Sugar is still making snow. Usually they punt by March 10, but perhaps they hope to benefit from the extended forecast. I did not check other areas, but Sugar generally takes care of their snow best late-season.

Middle Finger is also the NCAA selection committee to Kansas. West? Even after Houston lost. Really? Too lazy to use contingency bracket!

So, that puts Kansas in a possible game with UCLA, in Las Vegas. No other 1-seed is so far from home. Midwest would have been KCMO which is basically a home game, but KU deserves it. 

Well Jax hopefully KCMO will welcome Auburn for some Regional action. Tennesse and Kentucky will have to travel a bit. Alabama has good locations but not an easy bracket.

TA&M 7-seed is the other middle finger. Penn State got hosed there too 10-seed, so really a dual screw job. Both teams are basically playing a 4-seed first round. SMH

Yes @PowellVolz the warm mid-levels ML might have played a role in mitigating storm intensity in East Tenn. ML was even warmer AL/GA, but their surface was much warmer - netting greater CAPE. Then Kentucky got more dynamics and less warm ML, another net bullish outcome despite lower surface Ts. 

Southeast Tennessee had a little more action. AL/GA boundary that likes to wrap around the southern Apps lifted up into and through Chattanooga. We are lucky* it was not a few degrees warmer. Dews made it in here. 

*Layperson and Public perspective. Storm chasers might have a different view, haha! However that close to home, I'm with the Public.

Well there is one good thing about the lack of snow in the South. We stopped having heart burn a couple weeks ago. How about some March Madness?

Lady Mocs (UT Chatt) are in the Women's Big Dance! Tonight I hope the men join them. Mocs have to win the SoCon Tourney to punch a ticket to the Big Dance. Game is 7p Eastern, 6p Central on ESPN+ but also the Main ESPN!

The above likely happened with non-thunderstorm winds ahead of the line. That area was always the ahead of the line non-thunderstorm winds. More later. 

On 3/3/2023 at 10:57 AM, nrgjeff said:

Nashville is just a hair east of the 10% hatched, and I agree. Lines up best with daytime heating going into afternoon. Also the Plateau elevation gives it better access to inflow wind. I don't normally share from EM briefings, but it's basically an adjusted 10% which is public on SPC. Please don't re-share though...

On 3/3/2023 at 11:26 AM, kayman said:

I don't know about all that being accurate. Nashville is smack dab in the center of the 10% significant hatched in areas that came out in the past hour from the SPC. Louisville and Bowling Green are there too.  The wind shear profiles and helocity values are going up right now and the storm bands are still at least an hour west of Greater Nashville. The lines are starting to break up into individual storms that are becoming more discrete. 

This is a good example of the importance of communication. Could I have been more clear? I refer to Nashville Forecasters.
Kayman refers to the City of Nashville. While I could have written more clearly, context clues are somewhat evident. Also it's common to refer to NWS offices just by their location. 

In the end despite parameters, OHX Forecasters and I were more correct than not. There is more to it than parameters. Note the minimum in Middle Tennessee compared to AL/GA. East Tenn is concentrated southeast Tenn. Still the bias east that OHX highlighted in red on the chart had some validity. By late morning it was apparent that the diurnal intensity max was going to be east. Pattern recognition is vital to add value over parameters and models. 

Moving along to the non-thunderstorm wind. It was impressive. Except for the Mountains, where we had the strong south winds through and below passes ahead of the line of storms/front, most of the strongest winds were behind the line. 

Once again pattern recognition says behind the line of storms, where the mixing is maximized behind the dry line. I never got the ahead of the line wording from some EM briefings (except for Mountains). Yes, it was breezy ahead of the line. However the strongest winds behind the line always seemed self-evident to me. Could be the advantage of Great Plains experience. Friday was unusual for here, but it is somewhat common in the Plains. 

Nashville is just a hair east of the 10% hatched, and I agree. Lines up best with daytime heating going into afternoon. Also the Plateau elevation gives it better access to inflow wind. I don't normally share from EM briefings, but it's basically an adjusted 10% which is public on SPC. Please don't re-share though.

Chart is just the diurnal / daytime heating timing. One could drag the red line through Chattanooga and even into northwest Georgia. Don't forget Sand Mountain, AL which is another elevated area. Reasoning below.

Other considerations for more specific targets include North Georgia boundary (there as usual) and the Gulf moisture boundary lifting through Alabama. Both should get into Tennessee with a dynamic negatively tilted system (promotes lifting boundaries WF OFB or otherwise).

Either intersecting with the prefrontal trough PFT is an area of interest. Interesting with temps/dews the PFT is more quasi-dry line DL today. Anything like a DL always piques my interest in the South. On the other hand very fast storm motion might favor the porch chase. 

Another scenario is a more forced line with fewer sups. Would favor straight line wind, but it can be particularly strong by leveraging the background wind. High Wind Warning things. 

Tonight could be dicey in the Mid-South. Ingredients are there as a LLJ interacts with warm front. Mess mode could be a saver overnight.

Thursday daylight is mainly an Arkansas (and points southwest) event. However an organized squall line QLCS should slam into the Mid-South late Thursday night. Line survives into Friday morning...

Key to Friday is the LLJ hanging around long enough. Some NWP ejects the backed part of it in a hurry, which would still leave a line of thunderstorms and straight line wind. Low and mid-level winds remain strong all day Friday, which would support severe. 

Tornado question has a lot to do with if the backed portion of the LLJ remains in East Tennessee and North Georgia into Friday afternoon. I'm not sure for what I wish. Chaser on a Friday. Keep family safe any day. My gut says just wind East Tenn. Makes it a moot point.

Don't worry about Ryan Maue. How much of that is a forecast, and how much is his climate argument? He and Hothead are the best Twitter drama - angry and oppose each other. I like both their severe wx takes better. Maybe I just have severe wx on the brain!

Stratosphere doubled down over the last few days. March is likely going to average cooler than normal. Just need the -PNA to relax for the Southeast, which it's forecast to do so. Arctic gets blocky. Could March observed actually be cooler than February observed? Not likely, but it has happened before. 

I'm not a fan of the Strato derailing severe; however, another shot at Southeast skiing (NC/WV) would be nice. Also the pattern might not wreck the Deep South toward April. In fact it could extend South season at the expense of the Plains.

Yes if those storms inflow does not get disrupted by central Alabama activity, they are near the other lifting boundary I wrote of at about now near the River. Prefrontal trough is also there near Corinth MS into Tenn, ahead of the main front. It's a boundary intersection.

Also possible the north (Tenn Miss) and south (cental Bama) coexist with the SSW LLJ vs one from the SSE. Again central Bama has the intersection of pre-trough convergence and Gulf front/OFB.

Tennessee was going to hang on. Pain of two buzzers makes strong motivation. Plus yeah, #1 on the road is a recipe for oof!

Kansas fans know that well, haha! So we have a hot race setting up in the SEC. They talk A&M and Bama, but we have enough games left for Tennessee to be in the mix.

Big 12 is similar. Kansas got some help when Texas lost. We still need to gain a game.

Radar loop @Holston_River_Rambler shared on the previous page still has validity. Some other CAMs have shown it off and on. Central Alabama!

Gulf front was reinforced last night by outflow OFB from showers yesterday. It is lifting northward in Alabama. While some sort of east-west boundary made it to northwest Alabama, differential heating/dews is evident central Alabama. Prefrontal convergence is also ahead of the main front - Alabama Mississippi border as usual.

As for the positive tilt, it probably mitigates some risk. Enhanced is right. No MDT today. Also the LLJ is lifting away, which could keep even central Bama in check. However I always watch boundary intersections out ahead of the synoptic ones.

All that said, with greater instability, positive tilt can go in the South and Ohio Valley. Plains is more fickle needing neutral due to dewpoint trajectories. Here southwest is still moist flow.