trapperman Posted April 13, 2012 Share Posted April 13, 2012 Lacrosse radar is down for the weekend for dual pol upgrade. Facepalm Link to comment Share on other sites More sharing options...
cyclone77 Posted April 13, 2012 Share Posted April 13, 2012 Since I'm taking on the roll of Mr. Negativity tonight I guess I'll post this. Sorry guys, but this is just plain faggy. Sure hope this doesn't come to fruition. LSX WRF. Link to comment Share on other sites More sharing options...
wisconsinwx Posted April 13, 2012 Share Posted April 13, 2012 Lacrosse radar is down for the weekend for dual pol upgrade. Facepalm I'm sure confidence has gone up in a tornado outbreak for that CWA for that exact reason. I'm glad we got ours in earlier in April, when it is very unlikely for us to see severe. Link to comment Share on other sites More sharing options...
Hoosier Posted April 13, 2012 Share Posted April 13, 2012 If you figure that you typically look for ~100J/kg or higher for significant tornado development and your shear vectors will be fairly perpendicular to the front...yeah... The NAM 0-3km CAPE progs are pretty concerning. We may be able to get away with relatively unimpressive total CAPE values if the low level CAPE is similar to what is being shown. Link to comment Share on other sites More sharing options...
Stebo Posted April 13, 2012 Share Posted April 13, 2012 I think that the models are under doing the amount of potential instability for Sunday, the only one that is close is the NAM, the GFS is apparently forecasting for another planet on this one... Also note you don't need ungodly amounts of instability as Tony mentioned 750-1000 J/kg with the amount of shear that is forecasted to be in place will be more than enough. Lastly those 0-3KM CAPE values are pretty significant enough to get the job done and then some. Link to comment Share on other sites More sharing options...
cyclone77 Posted April 13, 2012 Share Posted April 13, 2012 Apparently I'm missing something as the NAM isn't that much more impressive on instability compared to the GFS. 1000-1250j/kg vs 500-750j/kg? Link to comment Share on other sites More sharing options...
Stebo Posted April 13, 2012 Share Posted April 13, 2012 Apparently I'm missing something as the NAM isn't that much more impressive on instability compared to the GFS. 1000-1250j/kg vs 500-750j/kg? That is a pretty big difference when we are talking severe weather with the amount of shear forecasted to be in place, GFS hangs to close to climatology with respect to the surface temperatures, thus the lower amounts of instability. Link to comment Share on other sites More sharing options...
Hoosier Posted April 13, 2012 Share Posted April 13, 2012 Day 2 HIGH risk for areas west of this subforum, only the second one ever issued. Link to comment Share on other sites More sharing options...
Hoosier Posted April 13, 2012 Share Posted April 13, 2012 I've never seen wording like this before for an event more than 24 hours away. AFTER COLLABORATION WITH WFOS WICHITA...NORMAN...TOPEKA...TULSA AND DODGE CITY...A HIGH RISK WILL BE ISSUED DUE TO THE POTENTIAL FOR A HIGH-END LIFE THREATENING EVENT ACROSS THE SRN AND CNTRL PLAINS. Link to comment Share on other sites More sharing options...
tornadotony Posted April 13, 2012 Share Posted April 13, 2012 That is a pretty big difference when we are talking severe weather with the amount of shear forecasted to be in place, GFS hangs to close to climatology with respect to the surface temperatures, thus the lower amounts of instability. What I think the GFS does (I had a lightbulb moment tonight) is that it saturates the upper levels of the atmosphere much too strongly. Every run it does this. This prevents an accurate estimate of radiation received at the sfc, thus limiting how much the sfc warms and radiates back into the low-levels of the atmosphere. If you adjust the GFS forecast soundings for the NWS predicted temps at 7 PM CDT Sunday evening, you have plenty of low-level CAPE to cause significant issues. Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Share Posted April 13, 2012 I've never seen wording like this before for an event more than 24 hours away. AFTER COLLABORATION WITH WFOS WICHITA...NORMAN...TOPEKA...TULSA AND DODGE CITY...A HIGH RISK WILL BE ISSUED DUE TO THE POTENTIAL FOR A HIGH-END LIFE THREATENING EVENT ACROSS THE SRN AND CNTRL PLAINS. The second part reads like a few MCDs I've seen on major outbreak days... Link to comment Share on other sites More sharing options...
RCNYILWX Posted April 13, 2012 Share Posted April 13, 2012 What I think the GFS does (I had a lightbulb moment tonight) is that it saturates the upper levels of the atmosphere much too strongly. Every run it does this. This prevents an accurate estimate of radiation received at the sfc, thus limiting how much the sfc warms and radiates back into the low-levels of the atmosphere. If you adjust the GFS forecast soundings for the NWS predicted temps at 7 PM CDT Sunday evening, you have plenty of low-level CAPE to cause significant issues. Hopefully SPC realizes this too when putting together the Day 3 SWO. I'm assuming they'll be sufficiently concerned about the extreme low level shear and just mention the uncertainty over instability. But if the low level CAPE is there, it could be a very bad evening and night. Also, if I'm not mistaken an analysis around the time of the Henryville tornado found only 1000-1250 J/kg of MLCAPE, so again echoing what's been written before, you don't need huge CAPE if you have huge shear, especially if the CAPE is in the right place. Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Share Posted April 13, 2012 This MCD from March 2nd comes to mind when thinking about relatively low MLCAPE in an outbreak situation (They are referring to the West Liberty supercell in the first paragraph): MESOSCALE DISCUSSION 0220NWS STORM PREDICTION CENTER NORMAN OK 0513 PM CST FRI MAR 02 2012 AREAS AFFECTED...ERN KY INTO EXTREME SRN OH AND WRN WV CONCERNING...TORNADO WATCH 58...62... VALID 022313Z - 030015Z THE SEVERE WEATHER THREAT FOR TORNADO WATCH 58...62...CONTINUES. DAMAGING TORNADO OUTBREAK UNDERWAY ACROSS ERN KY WITH SEVERAL SUPERCELLS LIKELY CONTAINING STRONG TO VIOLENT TORNADOES. SUPERCELL OVER MORGAN COUNTY KY IS MOVING INTO LAWRENCE COUNTY AND LIKELY CONTAINS A VERY DAMAGING TORNADO. THIS STORM SHOULD EVENTUALLY CONTINUE EWD INTO WAYNE COUNTY WV. SUPERCELLS MOVING THROUGH ERN KY WILL CONTINUE THROUGH AN ENVIRONMENT VERY FAVORABLE FOR STRONG TO VIOLENT TORNADOES AS THE LLJ STRENGTHENS TO IN EXCESS OF 60 KT. LAST VWP DATA FROM JACKSON KY INDICATE VERY LARGE 0-1 KM HODOGRAPHS WITH STORM RELATIVE HELICITY ON THE ORDER OF 800 M2/S2 AND 500 J/KG MLCAPE. THESE PARAMETERS ALONG WITH THE DISCRETE NATURE OF THE CONVECTION WILL CONTINUE TO PROMOTE A THREAT OF TORNADOES...VERY LARGE HAIL AND DAMAGING WIND NEXT FEW HOURS. ..DIAL.. 03/02/2012 Link to comment Share on other sites More sharing options...
tornadotony Posted April 13, 2012 Share Posted April 13, 2012 Hopefully SPC realizes this too when putting together the Day 3 SWO. I'm assuming they'll be sufficiently concerned about the extreme low level shear and just mention the uncertainty over instability. But if the low level CAPE is there, it could be a very bad evening and night. Also, if I'm not mistaken an analysis around the time of the Henryville tornado found only 1000-1250 J/kg of MLCAPE, so again echoing what's been written before, you don't need huge CAPE if you have huge shear, especially if the CAPE is in the right place. Adjusting a 7 PM CDT sounding at Rockford for a 69°F sfc temp yields a sfc-based LI of -5. With 509.1m2s-2 0-1km SRH. Link to comment Share on other sites More sharing options...
Stebo Posted April 13, 2012 Share Posted April 13, 2012 What I think the GFS does (I had a lightbulb moment tonight) is that it saturates the upper levels of the atmosphere much too strongly. Every run it does this. This prevents an accurate estimate of radiation received at the sfc, thus limiting how much the sfc warms and radiates back into the low-levels of the atmosphere. If you adjust the GFS forecast soundings for the NWS predicted temps at 7 PM CDT Sunday evening, you have plenty of low-level CAPE to cause significant issues. You know now that you mention this, I have noticed this popping up several times ever since the last upgrade. Link to comment Share on other sites More sharing options...
Hoosier Posted April 13, 2012 Share Posted April 13, 2012 Hopefully SPC realizes this too when putting together the Day 3 SWO. I'm assuming they'll be sufficiently concerned about the extreme low level shear and just mention the uncertainty over instability. But if the low level CAPE is there, it could be a very bad evening and night. Also, if I'm not mistaken an analysis around the time of the Henryville tornado found only 1000-1250 J/kg of MLCAPE, so again echoing what's been written before, you don't need huge CAPE if you have huge shear, especially if the CAPE is in the right place. You may have gotten that Henryville range from me lol. I came up with something like that based on my limited analysis right after the event. These low CAPE/high shear events are always tough. Most tornadoes may occur with a better balance of CAPE/shear but there's definitely a sizable subset that don't. Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Share Posted April 13, 2012 The Van Wert, OH tornado on 11/10/02 may be another violent tornado case with relatively low CAPE, although I'm not quite certain. The video from the New Pekin/Henryville tornado reminded me of that one a lot. Link to comment Share on other sites More sharing options...
PatrickSumner Posted April 13, 2012 Share Posted April 13, 2012 SPC says moderate with the text...the maps look screwy... EDIT: I was wrong. It is just a slight for now... Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Share Posted April 13, 2012 It's a Slight, that was for Saturday from last night. I find it a bit strange they didn't go with higher probs/hatched area, considering this discussion: ...UPPER MS VALLEY/SRN GREAT LAKES...AN UPPER-LEVEL LOW IS FORECAST TO MOVE INTO THE UPPER MS VALLEY SUNDAY AFTERNOON AS A 90 TO 110 MID-LEVEL JET NOSES IN THE UPPER MS VALLEY. AT THE SFC...A WARM FRONT SHOULD EXIST ACROSS MN AND WI WHERE THUNDERSTORMS ARE FORECAST TO BE ONGOING SUNDAY MORNING. NEW CONVECTION SHOULD INITIATE AROUND MIDDAY TO THE SOUTH OF THE WARM FRONT AS SFC TEMPS WARM AND AHEAD OF A COLD FRONT APPROACHING THE REGION FROM THE WEST. STORMS SHOULD PROGRESS EWD ACROSS THE SLIGHT RISK AREA DURING THE AFTERNOON. FORECAST SOUNDINGS AT 21Z SUNDAY FROM MADISON WI SWD INTO ERN IA AND FAR NW IL SHOW MODERATE INSTABILITY WITH SBCAPE VALUES OF 1000 TO 1500 J/KG. IN ADDITION...THE EXIT REGION OF THE MID-LEVEL JET WILL HELP TO CREATE STRONG DEEP LAYER SHEAR PROFILES FAVORABLE FOR ORGANIZED STORMS. THIS SHEAR ENVIRONMENT ALONG WITH COLD TEMPS ALOFT IN PROXIMITY TO THE UPPER-LEVEL LOW SHOULD BE FAVORABLE FOR LARGE HAIL. FORECAST SOUNDINGS SUNDAY AFTERNOON NEAR AND TO THE SOUTH OF THE FRONT ALSO SHOW LOOPED HODOGRAPHS WITH STRONG LOW-LEVEL SHEAR. THIS MAY SUPPORT A TORNADO THREAT WITH CELLS THAT REMAIN DISCRETE AND HAVE ACCESS TO MODERATE INSTABILITY. AN ISOLATED SEVERE THREAT MAY EXTEND EWD ALONG AND TO THE SOUTH OF A WARM FRONT INTO LOWER MI WHERE FORECAST SOUNDINGS DEVELOP SOME INSTABILITY. Link to comment Share on other sites More sharing options...
CUmet Posted April 13, 2012 Share Posted April 13, 2012 You know now that you mention this, I have noticed this popping up several times ever since the last upgrade. It's more than just the last upgrade though...for at least the past 5 years the GFS has had issues with underdoing warm sector temps. It almost never fails to do so. Link to comment Share on other sites More sharing options...
Stebo Posted April 13, 2012 Share Posted April 13, 2012 It's more than just the last upgrade though...for at least the past 5 years the GFS has had issues with underdoing warm sector temps. It almost never fails to do so. Yeah that would be due to the climatology influences I mentioned a page or so back, though combined with the issue Tony brings up, it is a double whammy to the surface temperatures. Link to comment Share on other sites More sharing options...
Stebo Posted April 13, 2012 Share Posted April 13, 2012 06Z NAM ticked up the instability some especially over Lower Michigan and along the warm front in WI and into MN/IA Link to comment Share on other sites More sharing options...
Geos Posted April 13, 2012 Share Posted April 13, 2012 6z NAM leaves S WI and N IL high and dry for the most part. Looks like the best support for storms is north of here or downstate IL then back to the west. 6z GFS blows up some storms around Chicago at the last minute before heading eastward towards MI. Link to comment Share on other sites More sharing options...
TimChgo9 Posted April 13, 2012 Share Posted April 13, 2012 Outlooks for today through Sunday show NE IL out of the risk areas for now. The setup looks pretty impressive throughout the S Plains, and through IA, NW IL, S WI, but NE IL looks out of it for now, unless that changes in later updates. Strong wording from some of the forecast offices, kind of makes me wonder what the potential is for Sat/Sun in this area. Going to go get some flashlights just in case. Link to comment Share on other sites More sharing options...
tornadotony Posted April 13, 2012 Share Posted April 13, 2012 12z NAM even more unstable. Link to comment Share on other sites More sharing options...
RCNYILWX Posted April 13, 2012 Share Posted April 13, 2012 12z NAM even more unstable. Looks like pretty good 0-3km CAPE as well. Link to comment Share on other sites More sharing options...
wisconsinwx Posted April 13, 2012 Share Posted April 13, 2012 The GFS continues the meager instability. Looks like it has 1000 J/K or so of CAPE around 18z Sunday in C Wisconsin, but it disappears quickly thereafter. What's the biggest determining factor of ML and SB CAPE? Link to comment Share on other sites More sharing options...
wisconsinwx Posted April 13, 2012 Share Posted April 13, 2012 Btw, Dr. Forbes going with a TorCon of 5 in C Wisconsin as his highest risk on Sunday. Based on that being practically the only area in the Midwest with even decent CAPE, I'd tend to agree with that being the biggest threat area. Link to comment Share on other sites More sharing options...
trapperman Posted April 13, 2012 Share Posted April 13, 2012 The GFS continues the meager instability. Looks like it has 1000 J/K or so of CAPE around 18z Sunday in C Wisconsin, but it disappears quickly thereafter. What's the biggest determining factor of ML and SB CAPE? Inside of 48 hours I never look at the GFS, ever. Unles I am wishcasting something. Need a much higher resolution model. Link to comment Share on other sites More sharing options...
wisconsinwx Posted April 13, 2012 Share Posted April 13, 2012 Inside of 48 hours I never look at the GFS, ever. Unles I am wishcasting something. Need a much higher resolution model. Well in this case I guess it'd be bittercasting then, since the GFS only seems bullish on the wind shear, nothing else. Link to comment Share on other sites More sharing options...
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