Stebo Posted February 19, 2014 Share Posted February 19, 2014 Odds are the SPC will have to pull the slight risk back NW deeper into IL/IN once again. ...And add on to the hatched area up to a Terre Haute line. Agree hard with this. Link to comment Share on other sites More sharing options...
blue60007 Posted February 19, 2014 Share Posted February 19, 2014 Odds are the SPC will have to pull the slight risk back NW deeper into IL/IN once again. ...And add on to the hatched area up to a Terre Haute line. Agree. FWIW latest hi res NAM brings a tongue of SBCAPE up to LAF and just north. Link to comment Share on other sites More sharing options...
Hoosier Posted February 19, 2014 Author Share Posted February 19, 2014 interesting comment from IWX ..... NAM12 SHOWING MUCAPES OF 400 TO 600 J/KG WITH IMPRESSIVE SHEAR VALUES. AFTERNOON TEMPS EXPECTED TO CLIMB INTO 40S WITH 50S OVER SOUTHERN CWA. LATEST HIGH RES GUIDANCE SUGGEST DEEPEST LIFT AND INSTABILITY WILL REMAIN JUST SOUTH OF OUR AREA. HOWEVER...ISOLATED WIND GUSTS TO SEVERE LIMITS REMAIN POSSIBLE...ESPECIALLY IN OUR SOUTHERN THIRD OF CWA AS A TYPICAL COLD SEASON FINE LINE EXPECTED ALONG COLD FRONT. LOCAL RESEARCH HAS NOT YIELDED ANY CASES OF SEVERE WEATHER EPISODES WITH SNOW DEPTHS EVEN CLOSE TO WHAT WE HAVE SO THIS IS A BIT OF UNCHARTED TERRITORY AT LEAST CLIMATOLOGICALLY SPEAKING. BOTTOM LINE IS THIS REMAINS A VERY IMPRESSIVE AND RAPIDLY DEEPENING STORM SYSTEM SO COMBINATION OF GRADIENT WINDS AND THIN LINE COULD PRODUCE ISOLATED SEVERE WIND GUSTS. Link to comment Share on other sites More sharing options...
Stebo Posted February 19, 2014 Share Posted February 19, 2014 18z NAM has 700-500 mb lapse rates of 8 C/km in part of the warm sector tomorrow. 4km NAM is coming in huge with instability in the warm sector not too far from you guys in LAF Also I would be very concerned about the area from Paducah to Memphis of lighting up with semi discrete stuff especially with these SBCAPE values. Honestly if this continues to be modeled as such, I could see that area getting a MDT risk tomorrow. Link to comment Share on other sites More sharing options...
Hoosier Posted February 19, 2014 Author Share Posted February 19, 2014 4km NAM is coming in huge with instability in the warm sector not too far from you guys in LAF Also I would be very concerned about the area from Paducah to Memphis of lighting up with semi discrete stuff especially with these SBCAPE values. Honestly if this continues to be modeled as such, I could see that area getting a MDT risk tomorrow. Looks like those maps are based on temps in the low 50s here. If we end up closer to 60 then we will get into some of that instability that's shown farther south. Challenging to try to figure out the northward extent of surface based instability given the snowpack and likely widespread clouds but this system has a lot going for it with strong wind fields/forcing/rapid deepening and if anything could buck climo in terms of getting damaging wind reports in snow covered areas, it's this one. Link to comment Share on other sites More sharing options...
Stebo Posted February 19, 2014 Share Posted February 19, 2014 Looks like those maps are based on temps in the low 50s here. If we end up closer to 60 then we will get into some of that instability that's shown farther south. Challenging to try to figure out the northward extent of surface based instability given the snowpack and likely widespread clouds but this system has a lot going for it with strong wind fields/forcing/rapid deepening and if anything could buck climo in terms of getting damaging wind reports in snow covered areas, it's this one. Yeah I agree, especially when you have 50 to 60kts at 925mb, the winds are going to be screaming just above the surface. Link to comment Share on other sites More sharing options...
chase_stormz Posted February 19, 2014 Share Posted February 19, 2014 Has anyone seen the 18z 4km Nam!? Link to comment Share on other sites More sharing options...
Disc Posted February 19, 2014 Share Posted February 19, 2014 18z 4km NAM looks like it's trying to form some discrete stuff out in front of the line before everything goes linear later on. Link to comment Share on other sites More sharing options...
chase_stormz Posted February 19, 2014 Share Posted February 19, 2014 18z 4km NAM looks like it's trying to form some discrete stuff out in front of the line before everything goes liner later on. Yea, I'm really liking the look of that! And honestly, it keeps those things discrete for about 3 hours. I'm not sure that can happen though if the cold front starts surging. Link to comment Share on other sites More sharing options...
Hoosier Posted February 19, 2014 Author Share Posted February 19, 2014 Forecast soundings look pretty impressive in the Ohio Valley. Anything discrete/semi-discrete would certainly be capable of producing strong tornadoes. Link to comment Share on other sites More sharing options...
chase_stormz Posted February 19, 2014 Share Posted February 19, 2014 Forecast soundings look pretty impressive in the Ohio Valley. Anything discrete/semi-discrete would certainly be capable of producing strong tornadoes. 0z models run are going to go a long way in determining what the SPC does with their upcoming outlook. I'd be pretty surprised if they don't go with a MOD for wind. Not too confident they will go with anything more than a 5% for tornadoes but you never know. Link to comment Share on other sites More sharing options...
wxmeddler Posted February 19, 2014 Share Posted February 19, 2014 Yikes. Link to comment Share on other sites More sharing options...
Indystorm Posted February 19, 2014 Share Posted February 19, 2014 Elevated convection now getting started in the svr highlighted SPC area south of KC this late Wed. afternoon. Will definitely be interesting to see how this system intensifies on Thursday, Link to comment Share on other sites More sharing options...
snowlover2 Posted February 19, 2014 Share Posted February 19, 2014 ILN mentions the possible storms ahead of the squall line. SHOWERS AND SCATTERED STORMS WILL INCREASE WEST OF THE REGION AHEADOF A COLD FRONT LATER IN THE DAY. LOOKS LIKE PRE FRONTAL ACTIVITYMAY START TO MOVE INTO WESTERN COUNTIES EARLY IN THE EVENING ANDTHEN QUICKLY PUSH ACROSS THE REGION. A LINE OF CONVECTION WILLFOLLOW ALONG THE COLD FRONT WHICH SHOULD MOVE EAST OF THE FORECASTAREA BY 06Z-08Z. THIS IS A HIGH SHEAR/LOW INSTABILITY ENVIRONMENTTHAT IS FAVORABLE FOR DAMAGING WINDS AND ISOLATED SPIN UPTORNADOES. QUESTION IS HOW STRONG THE INVERSION AT THE SURFACEWILL BE ESPECIALLY IF SOME NORTHERN LOCATIONS STILL HAVE SNOWCOVER AND WHETHER STRONGER WINDS WILL BE ABLE TO PUNCH THROUGHTHAT. Link to comment Share on other sites More sharing options...
oldlogin Posted February 19, 2014 Share Posted February 19, 2014 15Z SREF Link to comment Share on other sites More sharing options...
thewxmann Posted February 20, 2014 Share Posted February 20, 2014 0z models run are going to go a long way in determining what the SPC does with their upcoming outlook. I'd be pretty surprised if they don't go with a MOD for wind. Not too confident they will go with anything more than a 5% for tornadoes but you never know. Personally I'd go 10% for tornadoes... with such high helicities in place it's not going to take much for spin-up tornadoes along the QLCS. Link to comment Share on other sites More sharing options...
Hoosier Posted February 20, 2014 Author Share Posted February 20, 2014 00z NAM has MUCAPE of 600-700 J/kg up to Chicago at 00z Fri. Link to comment Share on other sites More sharing options...
LouWX Posted February 20, 2014 Share Posted February 20, 2014 Based on 0Z NAM... 500 flow and shear vectors aren't bad for discrete formation when using 'rule of thumb' comparisons to boundary orientation. In addition 4KM hi-res model shows discrete convection in KY. 70+ temps as well. LL CAPE isn't the best based on the sounding I pulled SW of SDF but still a bit of an ominous looking scenario as progged by this particular model anyway. Link to comment Share on other sites More sharing options...
andyhb Posted February 20, 2014 Share Posted February 20, 2014 It's far out, but the 18 hr 00z RAP indicates that most model guidance is substantially underestimating the degree of low level shear/helicity present across essentially the entire warm sector tomorrow. Of course, it has been noted numerous times that the NAM/etc. tends to low-ball this until right before an event. Link to comment Share on other sites More sharing options...
Hoosier Posted February 20, 2014 Author Share Posted February 20, 2014 Looks like the 00z GFS bumped up CAPE values a bit. Link to comment Share on other sites More sharing options...
Geos Posted February 20, 2014 Share Posted February 20, 2014 Wow, GFS take the SLP over Houghton, MI on this run. 971mb Link to comment Share on other sites More sharing options...
Stebo Posted February 20, 2014 Share Posted February 20, 2014 4km NAM maintaining high amounts of SBCAPE from I-70 and south in IL all the way down to Memphis and Arkansas. I would also expect the risk area to be shifted both north and west. Link to comment Share on other sites More sharing options...
hm8 Posted February 20, 2014 Share Posted February 20, 2014 RAP/HRRR want to push an area of 1000+ j/kg MUCAPE into N.IL/WI.... Also, Link to comment Share on other sites More sharing options...
chase_stormz Posted February 20, 2014 Share Posted February 20, 2014 Wow, that's way West! Link to comment Share on other sites More sharing options...
tornadotony Posted February 20, 2014 Share Posted February 20, 2014 Wow, that's way West! Probably a bit too far west... Link to comment Share on other sites More sharing options...
chase_stormz Posted February 20, 2014 Share Posted February 20, 2014 Probably a bit too far west... Today's runs however, especially the 0z runs have definitely got me a bit more concerned about a window for semi-discrete activity from North Mississippi up into Western Kentucky. Link to comment Share on other sites More sharing options...
tornadotony Posted February 20, 2014 Share Posted February 20, 2014 Today's runs however, especially the 0z runs have definitely got me a bit more concerned about a window for semi-discrete activity from North Mississippi up into Western Kentucky. With the shear profiles (especially in the Tennessee Valley), I'd be concerned about embedded supercells even within a QLCS. Link to comment Share on other sites More sharing options...
andyhb Posted February 20, 2014 Share Posted February 20, 2014 RAP/HRRR want to push an area of 1000+ j/kg MUCAPE into N.IL/WI.... Also, Well hot damn (not much else to say to that). Link to comment Share on other sites More sharing options...
SirSonic Posted February 20, 2014 Share Posted February 20, 2014 A wonder if we could see storms fire ahead of the main line in places like IN,OH,PA i saw some of the simulated radars show signs of rotating cells from the warm front and to the west. I say the warm front will be placed over PA/N OH/S MI, could see some spinners, by looking at the models Link to comment Share on other sites More sharing options...
Hoosier Posted February 20, 2014 Author Share Posted February 20, 2014 This is probably one of the more frustrating setups for me in recent memory as far as trying to ascertain the level of threat locally. There's still several inches of snow on the ground all the way down to IND. How quickly will the snow field melt/recede and will the sheer strength of advective processes win out? Obviously the greater threat looks to be south of I-70 but concerned about a bit of a sneak attack here if temps/dews respond better than models suggest. My key values to watch for are temps near 60 and dews in the mid-upper 50s...if we get that then the damaging wind threat would go up big time and the tor threat could start to increase as well. Link to comment Share on other sites More sharing options...
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