huronicane Posted February 24, 2011 Share Posted February 24, 2011 Upper-level low w/ dry slot FTW Sunny skies over Norman, with temperatures rebounding nicely after the rain this morning... Link to comment Share on other sites More sharing options...
Ed Lizard Posted February 24, 2011 Share Posted February 24, 2011 I'd guess Central Arkansas is not the only place that will release balloons today. FWD did a 16Z sounding already. Link to comment Share on other sites More sharing options...
David Reimer Posted February 24, 2011 Share Posted February 24, 2011 From Little Rock 20Z raob time was changed to 18Z to avoid possible contamination of data by thunderstorms later. Balloon has already been launched. That will be very helpful. Thanks for the heads up! Link to comment Share on other sites More sharing options...
CUmet Posted February 24, 2011 Share Posted February 24, 2011 It'll be interesting to see how much clearing there'll be over much of the warm sector tomorrow. The forecasted RH fields in the mid-levels from the NAM, GFS, and RUC (especially) suggest some clearing most likely in the southeastern half of AR, northern MS, and perhaps into SW TN. The 00z 4km WRF run keeps these areas pretty clean through 22z as well. Models did very well with hinting at this possibility, and now we have tons of clearing over the aforementioned areas. Any discrete cells that form out ahead of the main line have the opportunity to produce a few significant tornadoes. It is interesting to note that the global models have all underestimated the surface temps by a substantial degree, and even the ECMWF (with it's higher values) was too low by several degrees at 18z. That'll be important to keep in mind for the next event. Link to comment Share on other sites More sharing options...
Indystorm Posted February 24, 2011 Share Posted February 24, 2011 The long range GFS and models are amazing with storm after storm system It's been awhile since we've had a really active spring season. Maybe this is the year. Link to comment Share on other sites More sharing options...
tornadotony Posted February 24, 2011 Share Posted February 24, 2011 The 16z FWD special sounding has some very steep mid-level lapse rates. 700-500hPa lapse rates on the sounding are 7.3C/km. That's a big deal. Link to comment Share on other sites More sharing options...
Ed Lizard Posted February 24, 2011 Share Posted February 24, 2011 Link to comment Share on other sites More sharing options...
tornadotony Posted February 24, 2011 Share Posted February 24, 2011 SPC meso page has 1000J/kg MLCAPE area increasing over SE AR...the threat for strong tornadoes, even a violent tornado, is increasing...the LZK 18z sounding is going to be very telling... Link to comment Share on other sites More sharing options...
blackjack123 Posted February 24, 2011 Share Posted February 24, 2011 The 16z FWD special sounding has some very steep mid-level lapse rates. 700-500hPa lapse rates on the sounding are 7.3C/km. That's a big deal. What do them lapse rates exactly do? I know anything around 7.0C/km is pretty high. Does that enhance tornado threat when you have all the other ingredients in place(SRH, CAPE, Temps, Dewpoints, LCL, Shear etc.). Link to comment Share on other sites More sharing options...
Indystorm Posted February 24, 2011 Share Posted February 24, 2011 Even a pocket of 1500 Surface based CAPE now showing up in se Arkansas. Getting very worrisome as insolation continues. Pine Bluff 74/62 south winds gusting to 32 Link to comment Share on other sites More sharing options...
blackjack123 Posted February 24, 2011 Share Posted February 24, 2011 SPC meso page has 1000J/kg MLCAPE area increasing over SE AR...the threat for strong tornadoes, even a violent tornado, is increasing...the LZK 18z sounding is going to be very telling... Yeah form what I know you seem like your right. There might be a few EF3 and EF4 tornadoes from looking at that data. I guess you could not rule out an EF5 but I doubt that. Link to comment Share on other sites More sharing options...
Hoosier Posted February 24, 2011 Share Posted February 24, 2011 What do them lapse rates exactly do? I know anything around 7.0C/km is pretty high. Does that enhance tornado threat when you have all the other ingredients in place(SRH, CAPE, Temps, Dewpoints, LCL, Shear etc.). Steeper mid level lapse rates give you a better chance of more CAPE. Link to comment Share on other sites More sharing options...
L.B. LaForce Posted February 24, 2011 Share Posted February 24, 2011 Steeper mid level lapse rates give you a better chance of more CAPE. Yeah, better chance for more CAPE, as well as a stronger updraft due to increased buoyancy. Link to comment Share on other sites More sharing options...
David Reimer Posted February 24, 2011 Share Posted February 24, 2011 Just got on US-82 E Link to comment Share on other sites More sharing options...
Calderon Posted February 24, 2011 Share Posted February 24, 2011 Yeah form what I know you seem like your right. There might be a few EF3 and EF4 tornadoes from looking at that data. I guess you could not rule out an EF5 but I doubt that. well if it hits something... Anyways, the rain has pushed out of the Murfreesboro area and am noticing breaks in the clouds just a county to the SW. Hopefully the warm front gets up here, which I'm sure it will, to get us some action. Link to comment Share on other sites More sharing options...
Indystorm Posted February 24, 2011 Share Posted February 24, 2011 Current RUC has increasing risk of sig tors in east Arkansas and West TN moving northward into west KY as we move into the late evening hours. http://wxcaster4.com/ruc/CENTRAL_RUC236_ATMOS_STP_12HR.gif Link to comment Share on other sites More sharing options...
blackjack123 Posted February 24, 2011 Share Posted February 24, 2011 Temperatures and dewpoints in Crossett and Hamburg Arkansas 80/65. That is pretty high for this time of the year. Link to comment Share on other sites More sharing options...
blackjack123 Posted February 24, 2011 Share Posted February 24, 2011 Steeper mid level lapse rates give you a better chance of more CAPE. Thank you and also sunshine helps with CAPE as well I believe. Makes the environment more unstable. Link to comment Share on other sites More sharing options...
Indystorm Posted February 24, 2011 Share Posted February 24, 2011 Thank you and also sunshine helps with CAPE as well I believe. Makes the environment more unstable. Yes, and increasing instability like this at this time of year coupled with helicity and upper air dynamics we are seeing with this system only increase the threat for significant svr to occur. Link to comment Share on other sites More sharing options...
ArkieOkie Posted February 24, 2011 Share Posted February 24, 2011 SPC meso page has 1000J/kg MLCAPE area increasing over SE AR...the threat for strong tornadoes, even a violent tornado, is increasing...the LZK 18z sounding is going to be very telling... Interestingly enough, today is the 4th anniversary of the Dumas, Arkansas EF3 tornado. (Desha county, southeast AR). My old stomping grounds. Link to comment Share on other sites More sharing options...
Ed Lizard Posted February 24, 2011 Share Posted February 24, 2011 The SPC site won't update the Little Rock soundings. Alternate web sites for an off hour sounding? Link to comment Share on other sites More sharing options...
blackjack123 Posted February 24, 2011 Share Posted February 24, 2011 Current RUC has increasing risk of sig tors in east Arkansas and West TN moving northward into west KY as we move into the late evening hours. http://wxcaster4.com...OS_STP_12HR.gif I wonder why they have a higher threat in parts of western Tennessee. Temps and Dews dont seem very high. Maybe there expected to rise or maybe the wind shear is extremely strong. Link to comment Share on other sites More sharing options...
blackjack123 Posted February 24, 2011 Share Posted February 24, 2011 well if it hits something... Anyways, the rain has pushed out of the Murfreesboro area and am noticing breaks in the clouds just a county to the SW. Hopefully the warm front gets up here, which I'm sure it will, to get us some action. Like some well-built homes being wiped clean off of their foundations. That would probably be at least EF4 damage. Link to comment Share on other sites More sharing options...
Indystorm Posted February 24, 2011 Share Posted February 24, 2011 I wonder why they have a higher threat in parts of western Tennessee. Temps and Dews dont seem very high. Maybe there expected to rise or maybe the wind shear is extremely strong. That link is for late this evening. Svr wx will first hammer Arkansas before moving northeastward and parameters will become more favorable for svr wx in that area this evening. Link to comment Share on other sites More sharing options...
thewxmann Posted February 24, 2011 Share Posted February 24, 2011 Before we talk about EF3s and EF4s, we should probably get some supercells to form first. I am not entirely convinced that the current line configuration will devolve into cells, nor that cells can fire up in the free warm sector. The SPC site won't update the Little Rock soundings. Alternate web sites for an off hour sounding? Isn't the LIT sounding at 20Z? Either that or 18Z soundings haven't been updated yet. The SPC site shows off-hour soundings, as do most sites that offer sounding data. Link to comment Share on other sites More sharing options...
Chicago Storm Posted February 24, 2011 Share Posted February 24, 2011 Isn't the LIT sounding at 20Z? Either that or 18Z soundings haven't been updated yet. The SPC site shows off-hour soundings, as do most sites that offer sounding data. They switched it to 18z. Link to comment Share on other sites More sharing options...
Indystorm Posted February 24, 2011 Share Posted February 24, 2011 There's 0-1 km helicity up to 550 currently with the line as it moves east into increasingly unstable air. I expect the LLJ to ramp up later this evening to maintain plenty of opportunities for spinning supercells, particularly those that form out in front of the line. Pine Bluff 77/62 with winds gusting to 38 from the south Link to comment Share on other sites More sharing options...
baroclinic_instability Posted February 24, 2011 Share Posted February 24, 2011 Before we talk about EF3s and EF4s, we should probably get some supercells to form first. I am not entirely convinced that the current line configuration will devolve into cells, nor that cells can fire up in the free warm sector. Isn't the LIT sounding at 20Z? Either that or 18Z soundings haven't been updated yet. The SPC site shows off-hour soundings, as do most sites that offer sounding data. Yeah right on. The main convective line pushing into AR currently would have issues developing developing into discrete cells. The best threat seems to be later around 21-0z as the approaching wave aloft develops a much stronger low level mass response field and low level convergence ahead of the main convective segment along the warm frontal boundary and perhaps just ahead of the warm front (S). Should some storms initiate along that said boundary--they certainly will have a chance to be significant. Link to comment Share on other sites More sharing options...
thewxmann Posted February 24, 2011 Share Posted February 24, 2011 18Z sounding is out. No doubt the WF has surged passed LIT. Link to comment Share on other sites More sharing options...
ukrocks Posted February 24, 2011 Share Posted February 24, 2011 Rain is ending in my area. Hoping to see some clearing so WKY can get into some of the action. But I have my doubts with temps stuck in the low 50's. Link to comment Share on other sites More sharing options...
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