Adam 1,684 Posted January 7, 2020 Share Posted January 7, 2020 An intense mid/upper trough over the Four Corners and northwest Mexico early on Friday will eject eastward into the southern Plains by 12z Saturday. At the surface, low pressure will develop over TX and shift east/northeast toward central AR by 12z Saturday. Ahead of the low, rich Gulf moisture will stream northward across eastern TX/OK and expand eastward across the lower MS Valley and Gulf Coast states through Saturday. 60s F dewpoints are forecast to extend as far north as the lower OH Valley by Saturday morning, with upper 60s to near 70s dewpoints over parts of the Arklatex on Friday into much of LA/MS/AL/GA on Saturday. This anomalously rich and broad warm sector will reside beneath a 50-70 kt southerly low level jet and 80+ kt southwesterly 500 mb jet streak. While some questions remain over how pristine the warm sector ahead of the surface low and cold front will remain, especially on Saturday, this kinematic and thermodynamic parameter-space will support severe thunderstorms capable of all severe hazards from the Arklatex into the TN Valley/Gulf Coast states Friday and Saturday. Quote Link to post Share on other sites
weatherwiz 79 Posted January 7, 2020 Share Posted January 7, 2020 This is quite the setup for early January. Perhaps the most impressive aspect of this is the northward surge of moisture as both the Euro and GFS indicate dews into the lower 60's perhaps into the OV. That's a pretty significant vort max and jet streak moving into what has potential to become a perhaps moderately unstable airmass. Clouds and warm sector precip may limit instability, however, given the presence of some EML air there is the potential forecast models are overdoing clouds/warm sector precip...and given the rich llvl theta-e air any more heating than advertised and instability will sky rocket. At least right now this looks like we could see a widespread damaging wind event with several QLCS tornadoes. Discrete supercells/tornadoes are certainly possible, however, the flow may be a bit too unidirectional...I'm sure there will be some directional aspect in the lowest few thousand feet but I would maybe want to see more overall turning in the lowest 5,000 feet to think a bigger outbreak. I'm actually a little surprised the 30% contour doesn't go farther south into southeastern TX...actually could be a spot for discrete supercells...especially early on in the game. Quote Link to post Share on other sites
Rtd208 3,556 Posted January 8, 2020 Share Posted January 8, 2020 Quote Link to post Share on other sites
weatherwiz 79 Posted January 8, 2020 Share Posted January 8, 2020 The overnight forecast models I think became a bit more impressive with this...especially eastern TX into AR/LA. That is some EML to go along with very strong wind shear, vigorous s/w energy, and potential for > 1500 J/KG of MLCAPE and several hundred J of 0-3km CAPE...maybe even 100-150 J of 0-1km CAPE. A couple intense tornadoes certainly possible Quote Link to post Share on other sites
weatherwiz 79 Posted January 8, 2020 Share Posted January 8, 2020 The 12z runs really have me concerned from eastern TX into LA...starting to get signals too for discrete warm sector convection. 12z NAM/GFS bukit for IAH in particular is extremely ominous with an overlap of large CAPE and shear. NAM indicating > 500 J of 0-6km CAPE with well over 1000 J MLCAPE and shear > 45 m/s...not good. Quote Link to post Share on other sites
Adam 1,684 Posted January 8, 2020 Author Share Posted January 8, 2020 Quote Link to post Share on other sites
Superstorm93 24,592 Posted January 9, 2020 Share Posted January 9, 2020 00z NAM coming in like an absolute tank Quote Link to post Share on other sites
Crossbowftw3 571 Posted January 9, 2020 Share Posted January 9, 2020 Was wondering when I'd see a thread get started. This event, ever since I jumped onto it last Satuday, has had massive potential...the Super Tuesday analog popped as early as Monday. Quote Link to post Share on other sites
Logan Giles 1,740 Posted January 9, 2020 Share Posted January 9, 2020 Lots of linear forcing from the latest NAM. Pumping LLJ Quote Link to post Share on other sites
Crossbowftw3 571 Posted January 9, 2020 Share Posted January 9, 2020 Another thing to remember: no matter WHAT the dominant storm mode is (I favor a nasty QLCS with several embedded tornadoes and potential high-end wind damage with potential for cells out ahead) this is a cool season event, and not a ton of CAPE needs to be realized for this to be a major event. The nighttime Alabama tornadoes on Super Tuesday only needed 200-400. Quote Link to post Share on other sites
Logan Giles 1,740 Posted January 9, 2020 Share Posted January 9, 2020 1 minute ago, Crossbowftw3 said: Another thing to remember: no matter WHAT the dominant storm mode is (I favor a nasty QLCS with several embedded tornadoes and potential high-end wind damage with potential for cells out ahead) this is a cool season event, and not a ton of CAPE needs to be realized for this to be a major event. The nighttime Alabama tornadoes on Super Tuesday only needed 200-400. Wow. Only 200-400 JKG, that is news to me Quote Link to post Share on other sites
Crossbowftw3 571 Posted January 9, 2020 Share Posted January 9, 2020 1 minute ago, Logan Giles said: Wow. Only 200-400 JKG, that is news to me Exceptional shear values were present during the night portion of that event, mind you. Exceptional shear exists once more here--if there's tornadic cells in an undisturbed warm sector out ahead of the line you're going to have a space favorable for strong tornadoes. Quote Link to post Share on other sites
CCB! 35,180 Posted January 9, 2020 Share Posted January 9, 2020 3 minutes ago, Crossbowftw3 said: Another thing to remember: no matter WHAT the dominant storm mode is (I favor a nasty QLCS with several embedded tornadoes and potential high-end wind damage with potential for cells out ahead) this is a cool season event, and not a ton of CAPE needs to be realized for this to be a major event. The nighttime Alabama tornadoes on Super Tuesday only needed 200-400. With a background elevated mixed layer & some of the hodographs depicted, this event has great potential of producing. Quote Link to post Share on other sites
Logan Giles 1,740 Posted January 9, 2020 Share Posted January 9, 2020 1 minute ago, Crossbowftw3 said: Exceptional shear values were present during the night portion of that event, mind you. Exceptional shear exists once more here--if there's tornadic cells in an undisturbed warm sector out ahead of the line you're going to have a space favorable for strong tornadoes. Gotta imagine any storms ahead of the QLCS will have a solid chance of being tornadic. Untapped warm sector with 40-50 its of shear Quote Link to post Share on other sites
Crossbowftw3 571 Posted January 9, 2020 Share Posted January 9, 2020 4 minutes ago, Logan Giles said: Gotta imagine any storms ahead of the QLCS will have a solid chance of being tornadic. Untapped warm sector with 40-50 its of shear 5 minutes ago, CCB! said: With a background elevated mixed layer & some of the hodographs depicted, this event has great potential of producing. This definitely has potential to produce in a big way. Exceptional SRH exists with the line to get numerous spinups, some undoubtedly strong (like the EF2 closer to our neck of the woods Halloween night, would likely be embedded in a larger swath(s) of wind damage), and if cells get ahead of the line, a space favorable for strong tornadoes should and likely will, exist. I've found 400-800 ms2 of helicity on soundings, which would be bonkers on a springtime event...and extreme for a wintertime event. Quote Link to post Share on other sites
Cole Baldwin 678 Posted January 9, 2020 Share Posted January 9, 2020 This potential event serves as a great reminder to people in the south that severe weather can happen at any time of year...even large outbreaks. Severe weather in January is relatively uncommon, but no one is invincible from severe wx even in January Quote Link to post Share on other sites
Logan Giles 1,740 Posted January 9, 2020 Share Posted January 9, 2020 Long range NAM but the shear and SRH is bonkers. Probably will change since it's range but impressive Quote Link to post Share on other sites
Weathergun 1,881 Posted January 9, 2020 Share Posted January 9, 2020 SREF significant tornado and derecho threat Friday afternoon and night. Quote Link to post Share on other sites
weatherwiz 79 Posted January 9, 2020 Share Posted January 9, 2020 You certainly don't need a ton of CAPE in these cool season events when you have tremendous forcing/shear present. However, sometimes shear can be just too much and that can mitigate potential somewhat...but that shouldn't be the case here. Models hinting at 1500+ J/KG of MLCAPE is extremely, extremely significant given these other parameters...hell even if setups with lesser shear 1500+ MLCAPE isn't too bad. One thing to really focus on too in terms of at least instability is 0-3km CAPE...given the robust shear/turning in that level you get robust CAPE in that level given the LCL's...something is bound to produce. what is extremely scary here is the best parameters look to be lining up after dark. Quote Link to post Share on other sites
Superstorm93 24,592 Posted January 9, 2020 Share Posted January 9, 2020 MDT risk introduced for wind Quote Link to post Share on other sites
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