weatherextreme Posted March 27, 2017 Share Posted March 27, 2017 Lets get this started SPC has an day 3 enhanced and slight risk outlook for parts of NW/W TX on 3-28-17, and a day 4 outlook 15% severe covering large portion of Western/Eastern and Central Texas. (Also included on day 4 are parts of OK, LA and most of ARK.) Edit: Tuesdays Map was updated during this post so will also post the new updated map. I'll also will leave the original one here to compare if needed. Update day 2 map There are still uncertainties regarding the details of this setup. Most models suggest that considerable thunderstorm activity will occur Tuesday morning over the TX Panhandle and northwest OK. This will likely modulate the position of the warm front, and perhaps the northern extent of greatest threat. Therefore will maintain the ongoing ENH risk, with consideration for upgrade to MDT risk in later outlooks. Link to comment Share on other sites More sharing options...
cheese007 Posted March 27, 2017 Share Posted March 27, 2017 DFW potentially under the gun both Tuesday and Wednesday? Was the monster hailstorm Sunday not enough? Link to comment Share on other sites More sharing options...
andyhb Posted March 27, 2017 Share Posted March 27, 2017 A few images from the 00z NCAR ensemble indicating the potential tomorrow has in W-Central TX. Seems reasonable to expect a southern shift given the possibility of earlier convection stalling the warm front. 23z neighbourhood probs of echo tops >35k feet within 25 miles of a point. 23z neighbourhood probs of UH >150 m2/s2 within 25 miles of a point (this is a substantial signal for 47 hours out). 00z probability of STP exceeding 3 within 25 miles of a point. Link to comment Share on other sites More sharing options...
bjc0303 Posted March 27, 2017 Share Posted March 27, 2017 not sure I'm sold on such a southward shift but the NCAR ensemble is interesting. initiates pretty early too. Link to comment Share on other sites More sharing options...
Jim Martin Posted March 27, 2017 Share Posted March 27, 2017 First convective watch of this day. Link to comment Share on other sites More sharing options...
brettjrob Posted March 27, 2017 Share Posted March 27, 2017 2 hours ago, bjc0303 said: not sure I'm sold on such a southward shift but the NCAR ensemble is interesting. initiates pretty early too. Yeah, I wouldn't be sold on it; the NCAR ensemble seems to have problems being under-dispersive, where most or all the members will agree closely on scenarios that end up not verifying. That was the case with its 48 h moisture forecast for yesterday's OK event. I can't get a good handle on tomorrow at all. Widespread early CI looks very likely (doing its best 2015 impression). Interestingly, both NCEP HRW runs develop scary supercells over SW OK by late afternoon that evolve out of storms that initiated much earlier in W TX. This is a true lifting warm front setup with rich moisture, something we don't see all that often in this region and may require some adjustment in expectations (e.g., I very rarely have much faith in Plains convection that initiates before 19-20z ever going on to become interesting). The meridional component of midlevel flow over NW TX/SW OK varies enough between solutions to make a lot of difference in mode and SRH. If we can stay veered of SSW, I think the potential for at least a few tornadoes is substantial. Whether they're pretty or not is another matter. Link to comment Share on other sites More sharing options...
Misstertwister Posted March 27, 2017 Share Posted March 27, 2017 Hello all!! Ready for spring tornado season here in OK. I'm a bit of a noob on a few things although much thanks to many of you who have helped me on reading reports and models and what to focus on. Got a question in reference to abbreviations. when someone posts CI are they referring to cirrus clouds or convective inhibition or initiation. I've most often seen Inhibiton as CINH. Thanks and keep up what everyone does here. It has helped me get over a lot of anxiety by understanding the forecasts better than watching the local mets and preparing friends and family who otherwise are too often don't pay attention living in OK all there lives despite some of the worst events over the years Link to comment Share on other sites More sharing options...
JoMo Posted March 27, 2017 Share Posted March 27, 2017 1 hour ago, Misstertwister said: Hello all!! Ready for spring tornado season here in OK. I'm a bit of a noob on a few things although much thanks to many of you who have helped me on reading reports and models and what to focus on. Got a question in reference to abbreviations. when someone posts CI are they referring to cirrus clouds or convective inhibition or initiation. I've most often seen Inhibiton as CINH. Thanks and keep up what everyone does here. It has helped me get over a lot of anxiety by understanding the forecasts better than watching the local mets and preparing friends and family who otherwise are too often don't pay attention living in OK all there lives despite some of the worst events over the years Depends on context. In reference to what Brett was saying, I believe he is referring to "convective initiation". Link to comment Share on other sites More sharing options...
brettjrob Posted March 27, 2017 Share Posted March 27, 2017 Yeah, sorry, it's always convective initiation when I use it. In AFDs and other NWS/NCEP discussions, it may mean cirrus in some cases (though that shouldn't be an issue anymore, with the recent change to a public-friendly format). Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 28, 2017 Share Posted March 28, 2017 Lots of early/ongoing convection on the HRRR....tomorrow reminds me a little like 5/16/15 in a sense, obviously with lesser moisture tomorrow among some other different things. I remember the night before the HRRR had morning convection but it was able to clear out to the northeast, just had to get as far south as possible with new storms developing south in the steep low level lapse rates. What is interesting is some of that HRRR convection on the souhern end is in fairly decent environment and you could have elevated storms early become suface based as warm front lifts north. Several scenarios on the table with this one tomorrow and not entirely sure which one will play out. Link to comment Share on other sites More sharing options...
bjc0303 Posted March 28, 2017 Share Posted March 28, 2017 17 minutes ago, Thundersnow12 said: Lots of early/ongoing convection on the HRRR....tomorrow reminds me a little like 5/16/15 in a sense, obviously with lesser moisture tomorrow among some other different things. I remember the night before the HRRR had morning convection but it was able to clear out to the northeast, just had to get as far south as possible with new storms developing south in the steep low level lapse rates. What is interesting is some of that HRRR convection on the souhern end is in fairly decent environment and you could have elevated storms early become suface based as warm front lifts north. Several scenarios on the table with this one tomorrow and not entirely sure which one will play out. HRRRX is pretty tame as far as morning convection goes.. And unless I'm mistaken lifts the warm front *well* into OK. Seems unlikley... Link to comment Share on other sites More sharing options...
WhiteoutWX Posted March 28, 2017 Share Posted March 28, 2017 It seems like most models have a very messy looking setup. Maybe you could get lucky targeting the southern end of the line or if a stray storm rides the warm front you could have a chance at seeing something but so far this is just a little too messy looking for me to want to try and chase. I'd take Sunday's setup over this one. Link to comment Share on other sites More sharing options...
bjc0303 Posted March 28, 2017 Share Posted March 28, 2017 8 minutes ago, WhiteoutWX said: It seems like most models have a very messy looking setup. Maybe you could get lucky targeting the southern end of the line or if a stray storm rides the warm front you could have a chance at seeing something but so far this is just a little too messy looking for me to want to try and chase. I'd take Sunday's setup over this one. Yesterday's? I question some model output. As brett noted, some high res guidance is suggestive of serious potential. Models are forecasting an environment supportive of significant severe. NAM 3km in particular produces weak looking convection even for a line. Honestly not sure why - linear mode? Sure, but the storms look very benign for the environment they would be in. Forecast environments look very favorable for all modes of severe with an expected storm mode imo of a mixed mode event. Any discrete/semi-discrete storms would pose significant threats. Short of an early day MCS wrecking the moist sector I cannot see some of these solutions panning out. Could I see a rapid upscale growth evolution? Sure. Link to comment Share on other sites More sharing options...
WhiteoutWX Posted March 28, 2017 Share Posted March 28, 2017 37 minutes ago, bjc0303 said: Yesterday's? I question some model output. As brett noted, some high res guidance is suggestive of serious potential. Models are forecasting an environment supportive of significant severe. NAM 3km in particular produces weak looking convection even for a line. Honestly not sure why - linear mode? Sure, but the storms look very benign for the environment they would be in. Forecast environments look very favorable for all modes of severe with an expected storm mode imo of a mixed mode event. Any discrete/semi-discrete storms would pose significant threats. Short of an early day MCS wrecking the moist sector I cannot see some of these solutions panning out. Could I see a rapid upscale growth evolution? Sure. Yes I meant yesterday. I'm not saying there won't be severe weather or even multiple tornadoes. I was speaking purely from a chasing perspective it looks really messy and could be hard to target any particular storm. I would much prefer a day with only a couple potential targets. Link to comment Share on other sites More sharing options...
Santa Clause Posted March 28, 2017 Share Posted March 28, 2017 Looks like another one of those wait and see days ahead. ENH is the smart play here, and looks like they'll stick with it. Link to comment Share on other sites More sharing options...
CGChaser Posted March 28, 2017 Share Posted March 28, 2017 Could see an upgrade to mod for wind. Link to comment Share on other sites More sharing options...
brettjrob Posted March 28, 2017 Share Posted March 28, 2017 24 minutes ago, WhiteoutWX said: Yes I meant yesterday. I'm not saying there won't be severe weather or even multiple tornadoes. I was speaking purely from a chasing perspective it looks really messy and could be hard to target any particular storm. I would much prefer a day with only a couple potential targets. It's looking more and more that way, as all the CAMs tonight have trended south with the WF and depict a repulsive convective evolution, despite embedded high UH swaths. It looks like a concoction of May 7-8, 2015, and April 9, 2008 (Breckenridge event). Really miserable stuff to be out in, I can say from experience. H5 flow is more meridional tomorrow than any of those events, so I'm still unsure on the substantial tornado potential, but I'd be very surprised if we see any classic, discrete supercells producing them. Link to comment Share on other sites More sharing options...
Chinook Posted March 28, 2017 Share Posted March 28, 2017 The convection-allowing models show storms popping at 19-20z. A couple of chasers may hit tornadoes if storms can become surface based early, before storms get too numerous and messy. The WRF-ARW is very suggestive of large squall lines. Flooding may be an issue. Link to comment Share on other sites More sharing options...
monsoonman1 Posted March 28, 2017 Share Posted March 28, 2017 New day 2 mentions strong tornadoes and MDT upgrade possible for AR/LA on Wednesday. Link to comment Share on other sites More sharing options...
monsoonman1 Posted March 28, 2017 Share Posted March 28, 2017 And the new day 1 has a 10% tornado risk for Wichita Falls and Abilene, TX. Link to comment Share on other sites More sharing options...
Chinook Posted March 28, 2017 Share Posted March 28, 2017 44 minutes ago, monsoonman1 said: New day 2 mentions strong tornadoes and MDT upgrade possible for AR/LA on Wednesday. Day 2 (Wednesday) The NAM and 3km NAM show STP values up to 4, with SRH values of 400 m2/s2, for areas of extreme east Texas. That is within an environment of 70 temp, 70 dew point (near 100% RH) Link to comment Share on other sites More sharing options...
Quincy Posted March 28, 2017 Share Posted March 28, 2017 NCAR ensembles continue to like farther south, showing a strong signal for a cluster of supercells immediately ahead of an arcing dryline in the vicinity of ABI and points east. Unlike Sunday, moisture return will be more favorable leading up, (e.g. low to mid 60s dew-points at peak heating). The ensemble mean shows widespread >2000 J/kg MLCAPE through the warm sector. Another note is that short-term CAMs are less aggressive with morning convection, but still show a very messy evolution of storms up near the low and along the warm front during the afternoon. Things could still get messy with semi-discrete cells farther south, but the best parameter space should be found there. The HRRR is displaced a bit more NW of the NCAR prog below. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 28, 2017 Share Posted March 28, 2017 Everyone will be targeting further north into Texas but man if a storm can go up in the HRRR progged environment from I-10 down to DRT...bulk shear, upper level flow, and shear vectors would favored discrete supercells and I bet the mountain range will fire some in Mexico. Could be a little later show down there and a gamble but very impressive environment and parameter space being modeled. Link to comment Share on other sites More sharing options...
yoda Posted March 28, 2017 Share Posted March 28, 2017 MOD risk issued for hail on 1300 OTLK Quote ...Southern Great Plains... Rich gulf moisture characterized by mean mixing ratios to 14 g/kg per 12Z Del Rio, Corpus Christi, and Lake Charles RAOBs has become prevalent in the broadening warm sector over central/south TX. While diurnal mixing may yield pockets of lower dew points over central/east TX, a plume of lower to middle 60s surface dew points will be sustained along the dryline and warm front. Beneath a stout EML with very steep lapse rates to 9 degree C/km from 700-500 mb per 12Z Del Rio RAOB, moderate to large buoyancy is expected ahead of the dryline. MLCAPE should reach 1500-3000 J/kg across the Edwards Plateau and Big Country. The leading edge of 50-kt 500-mb south-southwesterlies will spread east over this instability axis by late afternoon, yielding an environment favorable for supercells. While elevated storms will increase over the Texas Panhandle through midday, surface-based storms should develop towards mid-afternoon near the surface cyclone. Scattered storms will form farther south along the dryline late afternoon, with WAA-driven storms possible farther east over north-central TX. Initially discrete supercell mode should favor very large hail and localized severe wind gusts. Relatively high confidence in the coverage and location of storms warrants an upgrade to a hail-driven moderate risk from the Big Country into southwest OK. A few tornadic storms appear probable in this similar corridor. However, the temporal overlap of discrete cells with enlarging hodographs may be relatively short in the open warm sector. Low-level hodographs will be quite enlarged along the warm front, but should be coincident with modest low-level lapse rates and predominant cluster to linear mode. As such, an upgrade to 15 percent tornado probabilities does not appeared warranted this outlook. Link to comment Share on other sites More sharing options...
Santa Clause Posted March 28, 2017 Share Posted March 28, 2017 Great read, seems to be a small window for tornadic activity, but clearly chance is present. Link to comment Share on other sites More sharing options...
WhiteoutWX Posted March 28, 2017 Share Posted March 28, 2017 My play would be to sit along the warm front, probably somewhere along Childress to Wichita Falls corridor, and just hope a cell went tornadic as it went by. Fast storm motions plus messy storm mode means it will be very difficult to switch storm targets in any meaningful way. Link to comment Share on other sites More sharing options...
Quincy Posted March 28, 2017 Share Posted March 28, 2017 Substantial (unseasonable) instability already in place this morning across west/southwest Texas. Near record CAPE values for March 28 at MAF / Midland, TX based on 1953-2014 period. Link to comment Share on other sites More sharing options...
David Reimer Posted March 28, 2017 Share Posted March 28, 2017 Two potential plays I'm considering today. Warm front around SPS and convection further west from Floydada to Childress. VBV looks to be an issue, but the HRRR seems to be backing off on how severe it looks. 14Z HRRR had two nice SUPs from NE of Lubbock toward Childress. Also of note and on the past several HRRR runs is a warm-front SUP that forms near SPS and eventually makes it up to Chickasha in the 23Z-02Z timeframe. Link to comment Share on other sites More sharing options...
Zeromus-X Posted March 28, 2017 Share Posted March 28, 2017 So let's say we didn't want to storm chase tornadoes today and didn't want to hit hailstorms, but we did want to get from Winslow Arizona to Indiana (by Friday). How far north is the risk of hitting this stuff effectively mitigated? Link to comment Share on other sites More sharing options...
Quincy Posted March 28, 2017 Share Posted March 28, 2017 31 minutes ago, Zeromus-X said: So let's say we didn't want to storm chase tornadoes today and didn't want to hit hailstorms, but we did want to get from Winslow Arizona to Indiana (by Friday). How far north is the risk of hitting this stuff effectively mitigated? I-40 is under the gun from Amarillo to Oklahoma City through tonight (not much better with the southern I-20 route), so your best bet may be to leave after storms move east. After a break tomorrow morning, the I-44 corridor across the Ozarks will be in the line for severe storms late Wednesday, as well as the southern I-30 route. The northern route (after going north to Denver) doesn't look great either with heavy rainfall across much of Kansas through tomorrow. Link to comment Share on other sites More sharing options...
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