tornadotony Posted March 6, 2011 Share Posted March 6, 2011 Time to try my luck at hosting an event thread at American. I had a pretty good Eastern track record (hosted the Parkersburg EF5 thread)... My concerns for Tues/Wed are beginning to increase slowly. I'm still wary of how much moisture will return N, and to me, that is the big question mark. Recent runs of the GFS and especially the NAM have had a better moisture source a bit deeper in the tropics and thus have had more moisture. That is the key. Wind shear, lapse rates, instability are all going to be there. Will the moisture? If the moisture does indeed return (I'm thinking 60-62 will be the threshold needed for this to really become something), then I think we see a significant severe weather, even tornado outbreak evolve across the Red River Valley southward through eastern TX, the Arklatex, LA, and Arklamiss regions Tuesday night and Wednesday. Some capping will be in place, but it does not look nearly as strong as the last system. With the nice broad-based nature of the trough, I would expect copious vertical motion in the free warm sector ahead of the main front, allowing for discrete supercells. I would also expect frontal zone convection to be quasi-discrete with directional shear still rather impressive. Overall, I think this probably is the most concerning of the systems we've seen so far this year. Link to comment Share on other sites More sharing options...
Hoosier Posted March 6, 2011 Share Posted March 6, 2011 excerpt from SWODY3 MEANWHILE...A HIGHER POTENTIAL FOR SUSTAINED SEVERE STORMS WILL EXIST ACROSS WRN/SRN AR...ERN TX AND MUCH OF LA/WRN-SWRN MS TUESDAY NIGHT AMIDST STRONGER INSTABILITY. DEVELOPING SQUALL LINE WILL CONTINUE ESEWD OVERNIGHT...WITH ADDITIONAL DEEPENING STORMS ALONG THE RETREATING WARM FRONT. DAMAGING WINDS WILL BE THE PRIMARY THREAT ALONG THE QLCS...WITH A POSSIBLE TORNADO OR TWO WITH ANY PRE-FRONTAL STORMS EMBEDDED IN AN INCREASINGLY HUMID BOUNDARY LAYER IN LA/SWRN MS. Link to comment Share on other sites More sharing options...
Stebo Posted March 6, 2011 Share Posted March 6, 2011 Like TT said I feel the main issue, the crux of the event will be moisture. I agree that 60-62 dews should be enough to get the job done. The wind fields are excellent for severe/tornadoes. Link to comment Share on other sites More sharing options...
tornadotony Posted March 6, 2011 Author Share Posted March 6, 2011 !!! Link to comment Share on other sites More sharing options...
David Reimer Posted March 6, 2011 Share Posted March 6, 2011 !!! It certainly jumped substantially on this latest run. I'm still concerned with the low level flow veering. Honestly, I don't see a significant tornado threat at this point in East Texas. However, I also remember last Sunday with the very poor model performance, so I'm still quite interested to see how this plays out over the next few days. I don't see why I won't be out chasing on Tuesday. Where that may end up being is still TBD, but I'd rather stay in favorable terrain if possible. The SREF's highest progs are in the hell hole known as Louisiana, where the road network is poor and you can't go five miles without entering a forest. Link to comment Share on other sites More sharing options...
kwt Posted March 6, 2011 Share Posted March 6, 2011 Time to try my luck at hosting an event thread at American. I had a pretty good Eastern track record (hosted the Parkersburg EF5 thread)... My concerns for Tues/Wed are beginning to increase slowly. I'm still wary of how much moisture will return N, and to me, that is the big question mark. Recent runs of the GFS and especially the NAM have had a better moisture source a bit deeper in the tropics and thus have had more moisture. That is the key. Wind shear, lapse rates, instability are all going to be there. Will the moisture? I think thats got to be everyone's main concern at this time of the year, I remember several events last year where the moisture return was over-egged by the models and I always have a nagging doubt in these early set-ups. IF we can get good enough moisture return then obviously things could well get going but still as we all know a little bit to go before we can get more confident about this. Link to comment Share on other sites More sharing options...
brettjrob Posted March 6, 2011 Share Posted March 6, 2011 It certainly jumped substantially on this latest run. I'm still concerned with the low level flow veering. Honestly, I don't see a significant tornado threat at this point in East Texas. However, I also remember last Sunday with the very poor model performance, so I'm still quite interested to see how this plays out over the next few days. I don't see why I won't be out chasing on Tuesday. Where that may end up being is still TBD, but I'd rather stay in favorable terrain if possible. The SREF's highest progs are in the hell hole known as Louisiana, where the road network is poor and you can't go five miles without entering a forest. The only thing keeping me interested at this point is the spread between the NCEP and foreign models. While it's certainly not the Plains setup it appeared to be a few days ago, the NAM/GFS/SREF are all on the fast end of the guidance envelope. The 12z GGEM/UKMET/ECMWF suggest a slower progression of the shortwave, with the Canadian depicting the surface low over PNC at 00z Wed, rather than nearer JLN on the American models. I'd probably be open to chasing N TX between I-35 and PRX if we can keep low-level flow from veering too badly there, or closer to the surface low if it's NW of I-44. I do think it's inevitable that the best parameters will be wasted on the Arklatex region after dark, though. Link to comment Share on other sites More sharing options...
David Reimer Posted March 6, 2011 Share Posted March 6, 2011 I'm in the process of writing up a discussion for Tuesday over on my website, but this simulated sounding coming from the NAM for Tuesday caught my attention. This is for Tyler, Texas at 6 PM. If this is right, then I have certainly neglected the potential here for a few tornadoes. Link to comment Share on other sites More sharing options...
Reed Stough Posted March 6, 2011 Share Posted March 6, 2011 Looking at 60hrs out, it looks like right now that anywhere from LIT to SGF to PAH has the biggest risk for various severe weather modes. Things inhibiting is the would be a lack of deep moisture, and whether or not the warm sector is dirty or not. Link to comment Share on other sites More sharing options...
tornadotony Posted March 7, 2011 Author Share Posted March 7, 2011 MARS goes nuts on this thing... http://www.spc.noaa.gov/exper/mref_mars/ Link to comment Share on other sites More sharing options...
Jim Martin Posted March 7, 2011 Share Posted March 7, 2011 Looking at the 0z NAM tonight, the CAPE is around 2,000 along the Red River Valley in NE Texas. The Energy Helicity Index is around 3. The Lifted Index is around -7. The 1 km helicity is up around 300-400 also in the same region. Put all of these ingredients together, and the situation is setting up possibly for multiple tornadic supercells. Link to comment Share on other sites More sharing options...
David Reimer Posted March 7, 2011 Share Posted March 7, 2011 The 0Z NAM is rather ominous for North/East Texas and Southeast Oklahoma by Tuesday afternoon and evening. I'm starting to get the idea I'll end up on my favorite highway of US-82. The 0Z NAM really backed winds at 925 MB. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 7, 2011 Share Posted March 7, 2011 some amazing looking wind profiles/hodo's just east of Dallas on I-30..north of Tyler. That area just east of the better instability though at 0z. Link to comment Share on other sites More sharing options...
tornadotony Posted March 7, 2011 Author Share Posted March 7, 2011 Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 7, 2011 Share Posted March 7, 2011 wow talk about those numbers increasing fast.. Link to comment Share on other sites More sharing options...
thewxmann Posted March 7, 2011 Share Posted March 7, 2011 some amazing looking wind profiles/hodo's just east of Dallas on I-30..north of Tyler. That area just east of the better instability though at 0z. Agreed. This run of the NAM really raises the bar with instability/lapse rates and low-level backing. LCL heights will preclude a major outbreak, but if those parameters verify, there may be a non-negligible threat of tornadoes in N-Ctrl TX Tuesday afternoon and evening. Link to comment Share on other sites More sharing options...
tornadotony Posted March 7, 2011 Author Share Posted March 7, 2011 Agreed. This run of the NAM really jacks things up with instability/lapse rates and low-level backing. LCL heights will preclude a major outbreak, but if those parameters verify, there may be a non-negligible threat of tornadoes in N-Ctrl TX Tuesday afternoon and evening. ? If we're looking at the NAM verbatim, LCL heights, both SB and ML, are 1000m or less east of the dryline... Link to comment Share on other sites More sharing options...
tornadotony Posted March 7, 2011 Author Share Posted March 7, 2011 MLLCL map: http://www.twisterdata.com/index.php?prog=forecast&model=NAM&grid=221&model_yyyy=2011&model_mm=03&model_dd=07&model_init_hh=00&fhour=48¶meter=HGT&level=LEVEL_OF_ADIABATIC_CONDENSATION_FROM_SFC&unit=none&maximize=n&mode=singlemap&sounding=n&output=image&view=large&archive=false Link to comment Share on other sites More sharing options...
David Reimer Posted March 7, 2011 Share Posted March 7, 2011 Agreed. This run of the NAM really raises the bar with instability/lapse rates and low-level backing. LCL heights will preclude a major outbreak, but if those parameters verify, there may be a non-negligible threat of tornadoes in N-Ctrl TX Tuesday afternoon and evening. LCL's are a lot lower then last Sunday where I got a tornado. I'm not that concerned about them right now. What I am concerned about is the possibility that the dryline ends up west of the metroplex, which would then make a minor event a relatively major one in a jiffy. Link to comment Share on other sites More sharing options...
thewxmann Posted March 7, 2011 Share Posted March 7, 2011 ? If we're looking at the NAM verbatim, LCL heights, both SB and ML, are 1000m or less east of the dryline... Surface temps will probably end up highly underdone. With dewpts in the lower 60's, temps that reach the upper 70's or higher will end up being unfavorable for tornadogenesis. But hey, with my track record it'll probably end up being a non-issue or something else happens. Still, it is worth watching as a potential limiting factor. Link to comment Share on other sites More sharing options...
Stebo Posted March 7, 2011 Share Posted March 7, 2011 Surface temps will probably end up highly underdone. With dewpts in the lower 60's, temps that reach the upper 70's or higher will end up being unfavorable for tornadogenesis. But hey, with my track record it'll probably end up being a non-issue or something else happens. Still, it is worth watching as a potential limiting factor. Lower to middle 60s and if you go closer to the gulf coast middle to upper 60s for dews. I don't expect things to mix out that much that the temps push upper 70's. That would be quite surprising if that were to happen. Link to comment Share on other sites More sharing options...
tornadotony Posted March 7, 2011 Author Share Posted March 7, 2011 I think the big threat is late evening/overnight from the Arklatex to Arklamiss. That area could get really ugly. Link to comment Share on other sites More sharing options...
Stebo Posted March 7, 2011 Share Posted March 7, 2011 I think the big threat is late evening/overnight from the Arklatex to Arklamiss. That area could get really ugly. I never heard of that area being referred to as Arklamiss lol. I certainly expect the new Day 2 to be talked up quite a bit, although I don't expect a Moderate risk quite yet, though it wouldn't surprise me either way. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 7, 2011 Share Posted March 7, 2011 I never heard of that area being referred to as Arklamiss lol. I certainly expect the new Day 2 to be talked up quite a bit, although I don't expect a Moderate risk quite yet, though it wouldn't surprise me either way. I doubt we see a MDT risk with the new day 2, but I'm sure it will be a slight risk with 30% probs with possibly a hatched area. Link to comment Share on other sites More sharing options...
brettjrob Posted March 7, 2011 Share Posted March 7, 2011 Surface temps will probably end up highly underdone. With dewpts in the lower 60's, temps that reach the upper 70's or higher will end up being unfavorable for tornadogenesis. But hey, with my track record it'll probably end up being a non-issue or something else happens. Still, it is worth watching as a potential limiting factor. Agree that surface temperatures will be higher than forecast E of the dryline, especially given the drought conditions throughout the S Plains. It happened last weekend, it will happen Tuesday, and it will probably happen in many other events this year. The possibility of moisture mixing out more than forecast is also a real one. I think you summed it up perfectly: the LCL heights will not totally preclude an afternoon tornado threat ahead of the dryline between I-35 and a PRX-TYR line, but they will likely mitigate a higher-end threat. The real wildcard right now is the speed of the shortwave. There's a significant battle between the NAM/RGEM/GGEM vs. GFS/UKMET so far on tonight's runs. The former have the H5 trough axis around the 100th meridian at 00z Wed, while the latter have it closer to I-35. The slower solution allows low-level flow to remain stronger and less veered through the afternoon hours along the dryline. If the verification looks anything like the GFS, I think we can kiss our chances of tornadoes anywhere outside the Arklatex and before nightfall goodbye. Link to comment Share on other sites More sharing options...
Stebo Posted March 7, 2011 Share Posted March 7, 2011 I doubt we see a MDT risk with the new day 2, but I'm sure it will be a slight risk with 30% probs with possibly a hatched area. Yes I would agree to this, maybe the 1630Z go up more. Link to comment Share on other sites More sharing options...
thewxmann Posted March 7, 2011 Share Posted March 7, 2011 Agree that surface temperatures will be higher than forecast E of the dryline, especially given the drought conditions throughout the S Plains. It happened last weekend, it will happen Tuesday, and it will probably happen in many other events this year. The possibility of moisture mixing out more than forecast is also a real one. I think you summed it up perfectly: the LCL heights will not totally preclude an afternoon tornado threat ahead of the dryline between I-35 and a PRX-TYR line, but they will likely mitigate a higher-end threat. The real wildcard right now is the speed of the shortwave. There's a significant battle between the NAM/RGEM/GGEM vs. GFS/UKMET so far on tonight's runs. The former have the H5 trough axis around the 100th meridian at 00z Wed, while the latter have it closer to I-35. The slower solution allows low-level flow to remain stronger and less veered through the afternoon hours along the dryline. If the verification looks anything like the GFS, I think we can kiss our chances of tornadoes anywhere outside the Arklatex and before nightfall goodbye. And then there was last night's 0Z ECMWF... Link to comment Share on other sites More sharing options...
Stebo Posted March 7, 2011 Share Posted March 7, 2011 I doubt we see a MDT risk with the new day 2, but I'm sure it will be a slight risk with 30% probs with possibly a hatched area. Winner DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1222 AM CST MON MAR 07 2011 VALID 081200Z - 091200Z ...THERE IS A SLGT RISK OF SVR TSTMS OVER ERN PARTS OF THE SRN PLAINS/OZARKS TO THE MID-SOUTH/LOWER MS VALLEY... ...SYNOPSIS... MID-LEVEL WAVE CURRENTLY MOVING INTO THE WRN GREAT BASIN WILL AMPLIFY MONDAY NIGHT IN THE SRN ROCKIES AS ADDITIONAL JET ENERGY DROPS SEWD FROM THE GULF OF AK. THE RESULT WILL BE A STRONG UPPER WAVE THAT WILL TURN ENE INTO THE SRN PLAINS TUESDAY AFTERNOON AND THE MIDWEST/MID-SOUTH BY EARLY WEDNESDAY. PRIMARY SFC LOW WILL TRACK FROM CNTRL OK AT 12Z TUESDAY TO NERN MO/WCNTRL IL BY 12Z WEDNESDAY. ...ERN PARTS OF SRN PLAINS TO THE LOWER/MID MS VALLEY... STRONG RETURN FLOW AHEAD OF THE APPROACHING UPPER WAVE WILL LIKELY DRIVE A CONSIDERABLE AMOUNT OF ELEVATED CONVECTION/CLOUDS THROUGH A GOOD PART OF DAYLIGHT TUESDAY ACROSS THE OZARKS SWD INTO THE WRN GULF COAST REGION. WHILE HAIL CANNOT BE RULED OUT WITH THIS ACTIVITY...PRIMARY SEVERE EVENT SHOULD EVOLVE LATE AFTERNOON/NIGHT. INCREASING SSWLY LOW-LEVEL FLOW WILL TRANSPORT LOWER-MID 50S DEW POINTS AS FAR N AS CNTRL/ERN OK AND SRN MO BY LATE TUESDAY AFTERNOON AND LOWER-MID 60S ACROSS CNTRL/SRN AR SWD TO THE GULF COAST. RETURNING MOISTURE WILL BE CAPPED BY A STOUT ELEVATED MIXED LAYER THROUGH AT LEAST MID-AFTERNOON. FIRST AREA OF ATTENTION WILL FOCUS ON GRADUAL DEVELOPMENT OF SURFACE-BASED STORMS ALONG THE DRYLINE CIRCULATION LATE TUESDAY AFTERNOON. HERE...MODEST DIABATIC HEATING AND COOLING/MOISTENING OF THE MID-LEVELS OWING TO THE APPROACH OF THE UPPER SYSTEM WILL CONTRIBUTE TO WEAKENING CINH AND MLCAPES APPROACHING 1000 J/KG. INITIAL CELLS WILL BE EMBEDDED IN 55-65 KTS OF EFFECTIVE VERTICAL SHEAR AND VERY STEEP LAPSE RATES...SUFFICIENT FOR EVENTUAL SUPERCELLS WITH VERY LARGE HAIL AND POSSIBLY A TORNADO OR TWO. GIVEN ORIENTATION OF THE DEEP LAYER SHEAR VECTORS LARGELY PERPENDICULAR TO THE DRYLINE AND INCREASING LINEAR FORCING SHOULD YIELD QUICK TRANSITION INTO A QLCS. THIS FEATURE WILL ACCELERATE ENE INTO THE MO/AR OZARKS WITH POSSIBLE DAMAGING WINDS/HAIL. INSTABILITY WILL DROP OFF QUICKLY THROUGH THE MO OZARKS AND MID-MS VALLEY SUGGESTING A PRECIPITOUS DECREASE IN THE SVR THREATS THAT FAR N. MEANWHILE...SRN EDGE OF THE QLCS WILL LIKELY THRIVE THROUGH THE EVENING AS IT DEVELOPS FROM SE OK/NE TX INTO CNTRL/SRN AR AND NRN LA. CONCERN HERE IS THAT THE SLY LOW-LEVEL FLOW ACCELERATES TO OVER 45 KTS...EFFECTIVELY RESULTING IN LARGE-CYCLONIC LOOPED HODOGRAPHS. THE BOUNDARY LAYER SHOULD CONTINUE TO MOISTEN/DESTABILIZE AFTER DARK WITH THE WARM FRONT JUMPING INTO PARTS OF CNTRL/SRN AR. BOTH BOW AND EMBEDDED SUPERCELL MODES WILL BE POSSIBLE WITH THREAT FOR TORNADOES /ISOLATED STRONG/ ALONG WITH CORRIDORS OF DAMAGING WINDS AND HAIL. THE ACTIVITY WILL REACH THE MID-SOUTH BY 12Z WEDNESDAY...ALTHOUGH PROBABLY NOT AS FAR E AS THE 00Z GFS SUGGESTS. FINALLY...ANOTHER AREA OF FOCUS WILL BE ACROSS THE LOWER MS VALLEY ALONG THE RETREATING WARM FRONT TUESDAY NIGHT AS MODEST 500 MB HEIGHT FALLS GRAZE THE REGION. ALTHOUGH STRONGEST LOW-LEVEL JET WILL AIM/DEVELOP N OF THE REGION...AT LEAST 35-40 KTS OF SLY CURRENT AMIDST MID-60S DEW POINTS WILL BE FAVORABLE FOR DEEPENING MOIST CONVECTION. THIS ACTIVITY MAY ALSO JOIN SRN FRINGES OF THE AFOREMENTIONED AR STORMS OVERNIGHT. LOW-LEVEL TURNING ALONG THE WARM FRONT WILL BE ESPECIALLY FAVORABLE FOR SUSTAINED STORMS WITH ATTENDANT TORNADO THREATS. Link to comment Share on other sites More sharing options...
ksstormhunter Posted March 7, 2011 Share Posted March 7, 2011 Just ran 07Z run for the severe weather threat in the LA/OK/AR areas. Starting to pick up areas of strong instability forecasts across the Central Oklahoma, S. Louisiana and NC Louisiana areas. Any thoughts on these initial areas. Link to comment Share on other sites More sharing options...
kwt Posted March 7, 2011 Share Posted March 7, 2011 A decent sized slight risk for both day 2/3, wouldn't shock me to see a small moderate region get put up when it comes to day 1 range but we will see... Decent synoptic set-up, just going to depend on those dew points getting high enough. Link to comment Share on other sites More sharing options...
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