JoMo Posted April 13, 2012 Share Posted April 13, 2012 I suppose this would be a good time for OUN to start mentioning tornadoes in their HWO for Saturday... Seems like a good time. They seem really concerned about flooding though. Link to comment Share on other sites More sharing options...
CUmet Posted April 13, 2012 Share Posted April 13, 2012 Glad to see you all have come to the dark side (using vv's) Haha None of us were suggesting not to use the model vertical velocities at all, but only that we must be careful about what we can and cannot infer from them. Link to comment Share on other sites More sharing options...
QVectorman Posted April 13, 2012 Share Posted April 13, 2012 Good point. However, GFS has weaker vv's and still breaks the "cap" while the NAM doesn't. It could have something to do with grid spacing and thresholds, but still, something to watch. My only issue with vv's is that they look at a single layer without reference to the entire column. Chip well you can always look at 850 and 500 vv's if you want. They are out there. I like to cross reference 700 to 500 just for added confidence but that's just my personal preference Link to comment Share on other sites More sharing options...
Thundersnow12 Posted April 13, 2012 Share Posted April 13, 2012 Don't know if this was mentioned but SPC made history with this, earliest ever High risk. The other Day 2 High was with the afternoon outlook. Link to comment Share on other sites More sharing options...
Chinook Posted April 13, 2012 Share Posted April 13, 2012 Is there some sort of record for the significant tornado parameter? (STP) I think I saw STP=10 last year on April 27th. There definitely should be some unbelievable shear/helicity values somewhere in the middle of the risk area, with CAPE around 2000. Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Author Share Posted April 13, 2012 Is there some sort of record for the significant tornado parameter? (STP) I think I saw STP=10 last year on April 27th. There definitely should be some unbelievable shear/helicity values somewhere in the middle of the risk area, with CAPE around 2000. I pulled a sounding from Earl's sounding page from the 00z NAM at 03z Saturday evening from ICT that had an STP of 14.1... STP was somewhere in the vicinity of 13-15 across some of the hardest hit areas on 4/27. Link to comment Share on other sites More sharing options...
CUmet Posted April 13, 2012 Share Posted April 13, 2012 Those are some pretty decent vertical velocities being spit out by both the GFS and NAM by 00z. And they only get stronger after dark, without the boundary layer being decoupled. Unfortunately, the worst of this will probably be quite bad and be at night. Throw the book out the window in term of your diurnal plains tornado climatology on this one, folks. With 65+ dews and a 60kt LLJ, your SB instability is going nowhere after dark. This is another reason why the scattered nature of the convection and the lower density of cells might not necessarily mean a lower risk. Usually with a higher storm density, you inevitably get cell mergers and a gradual transition to a linear convective mode, but this may be a more difficult and delayed process if the cells are all on an island on their own. Link to comment Share on other sites More sharing options...
CUmet Posted April 13, 2012 Share Posted April 13, 2012 Is there some sort of record for the significant tornado parameter? (STP) I think I saw STP=10 last year on April 27th. There definitely should be some unbelievable shear/helicity values somewhere in the middle of the risk area, with CAPE around 2000. I recall there being a ridiculous STP of 26 or so off of either a NAM or RUC forecast sounding for the Greensburg event. Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Author Share Posted April 13, 2012 There ya go: Link to comment Share on other sites More sharing options...
tornadotony Posted April 13, 2012 Share Posted April 13, 2012 This is another reason why the scattered nature of the convection and the lower density of cells might not necessarily mean a lower risk. Usually with a higher storm density, you inevitably get cell mergers and a gradual transition to a linear convective mode, but this may be a more difficult and delayed process if the cells are all on an island on their own. This also has significant implications for regions to the east on Sunday... Link to comment Share on other sites More sharing options...
QVectorman Posted April 13, 2012 Share Posted April 13, 2012 Is there some sort of record for the significant tornado parameter? (STP) I think I saw STP=10 last year on April 27th. There definitely should be some unbelievable shear/helicity values somewhere in the middle of the risk area, with CAPE around 2000. I think I have seen 12 or 13 before but it was a year or two ago and it ended up busting. As I recall the EHI 1 km was through the roof too. Link to comment Share on other sites More sharing options...
turtlehurricane Posted April 13, 2012 Share Posted April 13, 2012 Don't know if this was mentioned but SPC made history with this, earliest ever High risk. The other Day 2 High was with the afternoon outlook. I was thinking that this must be rare to have a high risk on a day 2 outlook. I think it's a gutsy call considering the upper level energy that will drive this is over the Pacific and Mountain West right now, lots of data gaps in those regions, and the mountains can cause a quick butterfly effect if something is a little off. Doesn't take much to knock a high risk down to a normal day of severe weather. I'm not going to agree with the call until about a day from now if model trends hold. Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Author Share Posted April 13, 2012 I think I have seen 12 or 13 before but it was a year or two ago and it ended up busting as I call the EHI 1 km was through the roof too 4/27 was among the highest I've seen. I think 4/26 of last year also had insane values, but LCL heights/weaker low level shear upon initiation became a problem across the areas of highest instability. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted April 13, 2012 Share Posted April 13, 2012 Is there some sort of record for the significant tornado parameter? (STP) I think I saw STP=10 last year on April 27th. There definitely should be some unbelievable shear/helicity values somewhere in the middle of the risk area, with CAPE around 2000. I saw a 16 on 5/10/10 I believe on one of the earl barker soundings Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Author Share Posted April 13, 2012 I saw a 16 on 5/10/10 I believe on one of the earl barker soundings 5/24 of last year must have been up there as well. Link to comment Share on other sites More sharing options...
QVectorman Posted April 13, 2012 Share Posted April 13, 2012 4/27 was among the highest I've seen. I think 4/26 of last year also had insane values, but LCL heights/weaker low level shear upon initiation became a problem across the areas of highest instability. probably. You have pretty sharp memory. It all blurs together for me lol. I should probably start saving images of stuff like that. Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Author Share Posted April 13, 2012 The SPC mesoanalysis may max it out at 13, although I remember Spann pulling up his real time analysis on the Cordova supercell and it had a 17.6 Significant Tornado Index, which I believe may be the same/similar as the STP: Link to comment Share on other sites More sharing options...
CUmet Posted April 13, 2012 Share Posted April 13, 2012 This also has significant implications for regions to the east on Sunday... Yeah, something that is getting lost in all the hype regarding Saturday is that the Sunday event is looking more and more ominous. The NAM, GFS, and to a lesser extent the ECMWF all reintensify the system on Sunday, resulting in incredible wind fields and substantial low-mid level CAPE as a result of the cooling aloft. I'd probably wait myself, but I wouldn't be shocked to see a Day 3 Moderate Risk put out shortly, perhaps for portions of eastern IA, southern WI, and northern IL, and it does have eventual high risk potential. Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Author Share Posted April 13, 2012 Yeah, something that is getting lost in all the hype regarding Saturday is that the Sunday event is looking more and more ominous. The NAM, GFS, and to a lesser extent the ECMWF all reintensify the system on Sunday, resulting in incredible wind fields and substantial low-mid level CAPE as a result of the cooling aloft. I'd probably wait myself, but I wouldn't be shocked to see a Day 3 Moderate Risk put out shortly, and it does have eventual high risk potential. Going to be one hell of a weekend... Link to comment Share on other sites More sharing options...
Hoosier Posted April 13, 2012 Share Posted April 13, 2012 Yeah, something that is getting lost in all the hype regarding Saturday is that the Sunday event is looking more and more ominous. The NAM, GFS, and to a lesser extent the ECMWF all reintensify the system on Sunday, resulting in incredible wind fields and substantial low-mid level CAPE as a result of the cooling aloft. I'd probably wait myself, but I wouldn't be shocked to see a Day 3 Moderate Risk put out shortly, perhaps for portions of eastern IA, southern WI, and northern IL, and it does have eventual high risk potential. We've been discussing the CAPE progs for Sunday in the Lakes/OV subforum. Overall CAPE is certainly much less than Saturday but it's concerning to see the NAM spitting out the 0-3 km CAPE that it is. Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Author Share Posted April 13, 2012 Day 3 is...weird...especially considering the language used regarding the northern area. Link to comment Share on other sites More sharing options...
JoMo Posted April 13, 2012 Share Posted April 13, 2012 Day 3 slight Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Author Share Posted April 13, 2012 Although I do agree with the southern area, with potential for a QLCS with a tornado threat either embedded within or ahead of the line considering strong low level shear. Link to comment Share on other sites More sharing options...
tornadotony Posted April 13, 2012 Share Posted April 13, 2012 I'll just be blunt and say I do not at all agree with the northern half of the day 3 area. Adjust the GFS to realistic PBL conditions and you've got a much higher threat than currently indicated. Link to comment Share on other sites More sharing options...
EquusStorm Posted April 13, 2012 Share Posted April 13, 2012 The Day Two is terrifying. As I'm sure many others have said, this is the earliest Day Two HIGH in history (the only other one, for 4/7/06, was upped to HIGH on the noon Day Two update) and, unlike the 4/7/06 outlook, followed a Day Three MDT. Therefore, while perhaps not the strongest wording ever written in an outlook, it is most certainly the earliest such outlook ever issued. And considering how many outbreaks only got a HIGH (or MDT even) on Day One, I would be pretty nervous were I in OK or KS at the moment. Will probably be working this weekend but when I get off I'll most definitely be monitoring it. You guys save some radar images for me should I have to work through the outbreak, heh. Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Author Share Posted April 13, 2012 The environment on the NAM verifies barring previous convection and you're probably looking at 1000-2000 J/kg CAPE across the strongly sheared environment in the Upper MS Valley/GL area, along with formidable 0-3 km CAPE values, after dark as well, in conjunction with 50-70 kts of 0-6 km bulk shear, with favorable vectors for discrete activity. Link to comment Share on other sites More sharing options...
Jim Marusak Posted April 13, 2012 Share Posted April 13, 2012 canadian regional model 00Z output is looking even nastier for saturday. showing discrete supercells blossoming just after 18Z between YKN and SPS on the gridded pcp panels, and sticking out like a sore thumb as separate cells thru the end of the 48 hour run. Link to comment Share on other sites More sharing options...
andyhb Posted April 13, 2012 Author Share Posted April 13, 2012 canadian regional model 00Z output is looking even nastier for saturday. showing discrete supercells blossoming just after 18Z between YKN and SPS on the gridded pcp panels, and sticking out like a sore thumb as separate cells thru the end of the 48 hour run. So I just took a look at that...and oh my god... Link to comment Share on other sites More sharing options...
JoMo Posted April 13, 2012 Share Posted April 13, 2012 06z NAM not showing much difference in thinking for tomorrow. W-NW OK looks like the place to be. Link to comment Share on other sites More sharing options...
iowahawkeyedave Posted April 13, 2012 Share Posted April 13, 2012 canadian regional model 00Z output is looking even nastier for saturday. showing discrete supercells blossoming just after 18Z between YKN and SPS on the gridded pcp panels, and sticking out like a sore thumb as separate cells thru the end of the 48 hour run. Would love to see the image for that. I googled canadian regional model and it took me to http://www.weatheroffice.gc.ca/model_forecast/index_e.html but I must be looking at the wrong site. Thanks, David Link to comment Share on other sites More sharing options...
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