nrgjeff Posted January 9, 2020 Share Posted January 9, 2020 I expect supercells in Texas Friday evening. If things go early enough, maybe late afternoon. Trying to find positives for storm chasers that way, haha. LLJ indeed will increase with time, and do so quickly and substantially. SPC rightly talks about the line possibly breaking up into supercells. We normally discuss the more common opposite, sups congeal to line. However with a rapidly strengthening and backing LLJ lines can and do occasionally break up into supercells. It's most common right after the line develops (as opposed to sup line sup). In this case a line may develop; then within 1-2 hours, actually break up into supercells for a couple hours. In all cases sups eventually go linear (or go back to linear) this weather pattern. You won't see me travelling to chase this. However I know people closer who are watching it. Link to comment Share on other sites More sharing options...
Bob's Burgers Posted January 9, 2020 Share Posted January 9, 2020 20 minutes ago, nrgjeff said: I expect supercells in Texas Friday evening. If things go early enough, maybe late afternoon. Trying to find positives for storm chasers that way, haha. LLJ indeed will increase with time, and do so quickly and substantially. SPC rightly talks about the line possibly breaking up into supercells. We normally discuss the more common opposite, sups congeal to line. However with a rapidly strengthening and backing LLJ lines can and do occasionally break up into supercells. It's most common right after the line develops (as opposed to sup line sup). In this case a line may develop; then within 1-2 hours, actually break up into supercells for a couple hours. In all cases sups eventually go linear (or go back to linear) this weather pattern. You won't see me travelling to chase this. However I know people closer who are watching it. I remember that phenomena happening on May 1st, 2018. Rather unimpressive squall line evolved into a few discrete cells which eventually dropped a massive EF-3 near Salina, KS. 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted January 9, 2020 Share Posted January 9, 2020 1 hour ago, Bob's Burgers said: I looked it up and the Moderate was a Day 1 0600 UTC upgrade. Here is the outlook created on 1730 UTC Jan 21 Wow. One of very few high risks (perhaps the only one in the 21st century) to not be preceded by a Day 2 Moderate. 1 Link to comment Share on other sites More sharing options...
CheeselandSkies Posted January 9, 2020 Share Posted January 9, 2020 3 hours ago, Drz1111 said: This strikes me as a warm-season plains chaser mindset, when this is a cool season Gulf Coast / Dixie Alley setup. "Widely visible tornadoes" isn't really relevant when storms are moving at warp speed and LCLs are scraping the ground. Yeah...it kind of is. That's one of the reasons I geek out about severe weather setups (that I can't chase myself), the possibility of armchair chasing and seeing live streams of video like this. Not to say that it won't be dangerous or capable of producing significant severe weather, just that the likelihood of tornadoes capable of leveling a frame house is not particularly high with this event (not that there couldn't still be a few). Either way this has been and continues to be a fun system to track, both the severe aspect and the potential winter wx aspects for MBY this coming weekend. Link to comment Share on other sites More sharing options...
weunice Posted January 9, 2020 Share Posted January 9, 2020 I am an armchair chaser as well. Often though, storms in the southeast, particularly closer to the gulf look more like this. https://twitter.com/ScottieWAFB/status/1136661292700319745 This is why I doubt I will ever see a tornado in my neck of the woods in my lifetime (I am ~100 miles from the coast). They are almost all rain wrapped or in poor visibility situations. Link to comment Share on other sites More sharing options...
canderson Posted January 9, 2020 Share Posted January 9, 2020 My family is very close to Longview, should be an interesting day. 1 Link to comment Share on other sites More sharing options...
Drz1111 Posted January 9, 2020 Share Posted January 9, 2020 1 hour ago, CheeselandSkies said: Yeah...it kind of is. That's one of the reasons I geek out about severe weather setups (that I can't chase myself), the possibility of armchair chasing and seeing live streams of video like this. Not to say that it won't be dangerous or capable of producing significant severe weather, just that the likelihood of tornadoes capable of leveling a frame house is not particularly high with this event (not that there couldn't still be a few). Either way this has been and continues to be a fun system to track, both the severe aspect and the potential winter wx aspects for MBY this coming weekend. Totally disagree with this. Cool season setups with tons of low-level shear can produce strong tornadoes even out of radar imagery that looks "ugly". Link to comment Share on other sites More sharing options...
Bob's Burgers Posted January 9, 2020 Share Posted January 9, 2020 You can kinda see what the SPC was talking about re/ the reverse evolution of the convective mode on the latest NAM. Link to comment Share on other sites More sharing options...
DanLarsen34 Posted January 9, 2020 Author Share Posted January 9, 2020 5 minutes ago, Bob's Burgers said: You can kinda see what the SPC was talking about re/ the reverse evolution of the convective mode on the latest NAM. An evolution like this can still produce a significant outbreak of tornadoes (see 4-16-11 as a textbook example of a linear mode evolving into a line of semi-discrete cells). Not saying that’s what’s going to happen here, of course, but it’s something to keep in mind. Link to comment Share on other sites More sharing options...
Bob's Burgers Posted January 9, 2020 Share Posted January 9, 2020 Similar evolution appears to be taking place on the 18z HRRR with simulated hail cores up to 70 dbz with significant UH -- further indicative of a mode transition. Only one set of runs though; 00 UTC CAMs will be telling. Link to comment Share on other sites More sharing options...
SmokeEater Posted January 9, 2020 Share Posted January 9, 2020 From the FWD afternoon AFD: THE UPPER LEVEL TROUGH TO OUR WEST WILL CLOSE OFF FRIDAY AND ENTERTHE STATE DURING THE AFTERNOON HOURS. STRONG DYNAMICAL FORCING WILL OVERSPREAD THE REGION WELL AHEAD OF IT AND RESULT IN THE LIFTING OF A WEAK CAP BY EARLY AFTERNOON. ALTHOUGH CIN WILL BE NEGLIGIBLE WITH THE CAP GONE, DETERMINING WHETHER WE WILL HAVE CONVECTIVE INITIATION OUT AHEAD OF A COLD FRONT REMAINS A HUGE FORECAST CHALLENGE SINCE THERE WILL BE NO LEVEL FOCUS TO HELP "TRIGGER" STORMS. SHOULD VIGOROUS CONVECTION DEVELOP IN THIS REGIME WE WILL BE PARTICULARLY CONCERNED ABOUT SUPERCELLS AND THE TORNADO POTENTIAL GIVEN THE HIGH VALUES OF WIND SHEAR IN PLACE AND WELL ORGANIZED CYCLONICALLY CURVING HODOGRAPHS. THE SUPERCELLS THAT FORM IN THESE WEAKLY-FORCED WARM ADVECTION REGIMES OUT AHEADOF THE FRONT ARE THE ONES RESPONSIBLE FOR OUR NOTEWORTHY COOL SEASON TORNADO EVENTS (AND SOME WARM SEASON EVENTS TOO). THE SETUPFOR THIS EVENT CERTAINLY CHECKS ALL THE BOXES FOR WHAT WE LOOK FOR IN A COOL SEASON TORNADO OUTBREAK, WITH PERHAPS THE EXCEPTION OF INSTABILITY BEING JUST A LITTLE LOWER THAN THE BIG EVENTS LIKE DEC 29TH '06 AND DEC 26TH '15 (IF YOU BELIEVE CURRENT MODEL FORECASTS). AND SO WHAT KEEPS US FROM SAYING A TORNADO OUTBREAK ISON THE HORIZON IS THAT THERE ARE COUNTLESS UNNAMED AND FORGOTTEN EVENTS THAT LOOK SIMILAR TO THIS ONE WHICH PRODUCED NO TORNADOES. SO I BELIEVE THE KEY TOMORROW WILL BE THE INSTABILITY - REFLECTEDBY THE DEWPOINT READINGS DURING THE LATE MORNING AND AFTERNOON HOURS. IF UPPER 60S DEWPOINTS CAN MAKE IT INTO THE REGION AND TEMPERATURES CAN CLIMB INTO THE MID 70S, THEN IT WILL LIKELY BE A BAD DAY FOR US. UNTIL THEN THE BEST WE CAN SAY IS THAT THE SEVERE WEATHER THREAT WILL BEGIN IN THE EARLY AFTERNOON HOURS WHEN SOME OF THESE CELLS MAY START TO DEVELOP. THESE EARLY SUPERCELLS COULDDEVELOP ANYWHERE IN NORTH/CENTRAL TEXAS, BUT PROBABLY THE EASTERNHALF OF THE REGION IS MORE FAVORED DUE TO THE EXPECTED HIGHER MOISTURE. THEY WILL BE VERY FAST MOVING, ROCKETING OFF TO THE NORTHEAST AT 50 MPH, AND GIVEN THE EXPECTED LOW CLOUD COVER, VISUAL SPOTTING AND TRACKING WILL BE DIFFICULT.Sent from my SM-G973U using Tapatalk 4 Link to comment Share on other sites More sharing options...
SmokeEater Posted January 10, 2020 Share Posted January 10, 2020 Usually not good when the MIC of FWD posts this....Tom Bradshaw @SoonerTom25sOn 95% of the days in N TX, you can ignore the weather and it doesn’t amount to a hill of beans. Tomorrow falls in that “other special 5%” category. The threat will be real, so PAY ATTENTION. Plan ahead, have a way to get warnings, and know what to do if one’s issued for you.Sent from my SM-G973U using Tapatalk 2 Link to comment Share on other sites More sharing options...
ingyball Posted January 10, 2020 Share Posted January 10, 2020 36 minutes ago, SmokeEater said: Usually not good when the MIC of FWD posts this.... Tom Bradshaw @SoonerTom 25s On 95% of the days in N TX, you can ignore the weather and it doesn’t amount to a hill of beans. Tomorrow falls in that “other special 5%” category. The threat will be real, so PAY ATTENTION. Plan ahead, have a way to get warnings, and know what to do if one’s issued for you. Sent from my SM-G973U using Tapatalk It's been a long time since I've posted here, but I know Tom, and that coming from him definitely highlights the potential seriousness of this event at the Fort Worth office. Link to comment Share on other sites More sharing options...
andyhb Posted January 10, 2020 Share Posted January 10, 2020 Pretty impressed by the parameter space being indicated across the model suite on this one for both days. The NAM is likely underdoing temperatures at least somewhat, which renders a fairly substantial amount of instability for this time of year across essentially the full extent of the warm sector. Dewpoints today have been either on or ahead of schedule across the Texas Gulf Coast north to the Red River. The progged low level shear and hodograph size on Friday night through Saturday is, simply put, extreme. Could be approaching or exceeding all time record 850 mb flow readings on Saturday across multiple stations. I've also seen a few soundings pulled from S of DFW tomorrow that look more April/May like in terms of thermodynamic and shear combinations. Basically everywhere from I-35 east and I-40 south ought to be prepared for this. Storm mode is, as mentioned, the biggest question. I get the feeling it will be both a very strong QLCS full of embedded LEWPs, bows, and mesovortices and a few discrete cells out ahead here or there. I'm also concerned with the evolution of the shear vectors on Saturday becoming more normal to the front, and that we may see some downscale evolution of the QLCS into semi-discrete storms, which would have a 70+ kt LLJ to work with and a decent amount of low level buoyancy. 2 Link to comment Share on other sites More sharing options...
1900hurricane Posted January 10, 2020 Share Posted January 10, 2020 Open warm sector convection tomorrow is a big question mark, but with me able to sneak out of a commitment a little early tomorrow, I might be in as good a position as any to try to catch any possible WAA streamer shower that tries to mature into something more. Open warm sector setup reminds me somewhat of 12/26/2015, which was one of the event mentioned in the FWD discussion posted above. Streamers often take time to become open warm sector convection, perhaps because of capping, so I think it's more likely that I'll be headed north than south. 12/26/2015 had streamers that developed around my area but didn't mature until around the FWD area, to unfortunate consequences. CAMs have been pretty lacking with such storms so far, but the 18Z HRRR did perhaps give it a shot. I'll certainly be watching trends with interest. Not expecting much from a chasing standpoint, but figured it doesn't hurt to try and catch something fairly local. 2 Link to comment Share on other sites More sharing options...
Bob's Burgers Posted January 10, 2020 Share Posted January 10, 2020 Latest HRRR is trying to form cells well into the warm sector near shreveport around 00z Saturday. We'll see how that forecast evolves. Link to comment Share on other sites More sharing options...
andyhb Posted January 10, 2020 Share Posted January 10, 2020 Summed up some thoughts here. This is troublesome to say the least. Not to mention the 00z HRRR coming out with essentially a tornado outbreak near the I-35 corridor with numerous semi-discrete supercells. 1 Link to comment Share on other sites More sharing options...
MUWX Posted January 10, 2020 Share Posted January 10, 2020 Any chance this goes high risk? Link to comment Share on other sites More sharing options...
Bob's Burgers Posted January 10, 2020 Share Posted January 10, 2020 3 minutes ago, MUWX said: Any chance this goes high risk? I would be surprised if they did it at 0600 UTC, but I would imagine a considerable expansion of the MOD would be appropriate. Link to comment Share on other sites More sharing options...
cheese007 Posted January 10, 2020 Share Posted January 10, 2020 Wondering if I should find a way to skip out on orientation tomorrow considering I'd be on the road from 2:15 to 4:15 between Fort Worth and Dallas when it ends Link to comment Share on other sites More sharing options...
ingyball Posted January 10, 2020 Share Posted January 10, 2020 5 minutes ago, MUWX said: Any chance this goes high risk? I'm not sure there will be enough confidence to pull a high risk, but if they find that instability is higher than predicted and that the meso scale models are predicting more discrete cells or a broken line I could see them at the very least increase the tornado threat and hail threat to moderate and extend it westward to the eastern parts of the Metroplex. 1 Link to comment Share on other sites More sharing options...
Bob's Burgers Posted January 10, 2020 Share Posted January 10, 2020 I had to zoom out to the National Level on Pivotal Weather to capture the HRRR total UH swaths. Link to comment Share on other sites More sharing options...
Bob's Burgers Posted January 10, 2020 Share Posted January 10, 2020 More interesting observations is the latest NAM3k --> Successfully launches discrete cells in the open warm sector with UH (rooted, possibly tornadic cells) in LA. Several models have been indicating this could happen but this is the best evidence of it happening undisturbed. Link to comment Share on other sites More sharing options...
ingyball Posted January 10, 2020 Share Posted January 10, 2020 5 minutes ago, Bob's Burgers said: More interesting observations is the latest NAM3k --> Successfully launches discrete cells in the open warm sector with UH (rooted, possibly tornadic cells) in LA. Several models have been indicating this could happen but this is the best evidence of it happening undisturbed. The 0z HRRR does something similar just ahead of the main line at hour 35 and 36. I'm hoping it's wrong since I'd be right in the path of those storms, but it's definitely been my concern. Link to comment Share on other sites More sharing options...
Bob's Burgers Posted January 10, 2020 Share Posted January 10, 2020 NSSL WRF is very aggressive with open warm sector development in two areas: 1. SE Oklahoma 2. Nighttime supercells in the arklatex area, shreveport Link to comment Share on other sites More sharing options...
janetjanet998 Posted January 10, 2020 Share Posted January 10, 2020 SE KS/ NE OK/SW MO with first wave around midday for starters? Link to comment Share on other sites More sharing options...
JasonOH Posted January 10, 2020 Share Posted January 10, 2020 This is a great twitter thread about tomorrow and dynamics in general. 1 Link to comment Share on other sites More sharing options...
Bob's Burgers Posted January 10, 2020 Share Posted January 10, 2020 Reflects the aggressiveness of recent CAMS. You also see a subtle depiction of a 2ndary 15% contour in LA likely representing the chance of warm sector discrete convection. Link to comment Share on other sites More sharing options...
Bob's Burgers Posted January 10, 2020 Share Posted January 10, 2020 Moderate risk area expanded, significant tornado area removed Link to comment Share on other sites More sharing options...
cheese007 Posted January 10, 2020 Share Posted January 10, 2020 1 hour ago, Bob's Burgers said: Moderate risk area expanded, significant tornado area removed Genuinely surprised they removed the sig tor contour Link to comment Share on other sites More sharing options...
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