ClicheVortex2014 Posted March 29, 2016 Share Posted March 29, 2016 College of DuPage's HRRR loop is incredible. Can't wait for tomorrow morning because I'm sure this loop will look much better as the system organizes. http://i.imgur.com/vTLA2Y8.gif Link to comment Share on other sites More sharing options...
RCNYILWX Posted March 29, 2016 Share Posted March 29, 2016 NAM certainly looks interesting for east central IL into west central IN and points east Thursday afternoon. Lots of question marks w.r.t. ongoing convection/debris mucking things up, though if 18z 12km were a perfect prog, would appear to be a window in the early to mid afternoon to destabilize. Don't need as much directional shear in this region to produce vs. Plains but this looks mostly speed shear (impressive at that) driven as has been mentioned by others. With this being said, there is some slight veering between the surface and 850 mb that could help in terms of tornado potential. Farther north, even if slower NAM comes closest to verifying completely unidirectional winds from the sfc to jet level have me thinking maybe a wind threat from linear segments and marginally severe hail owing to the steep midlevel lapse rates. Sent from my SM-G935V using Tapatalk Link to comment Share on other sites More sharing options...
Quincy Posted March 29, 2016 Share Posted March 29, 2016 SSW 10m flow isn't ideal, but as mentioned above, perhaps speed shear can work to overcome that a bit. Link to comment Share on other sites More sharing options...
Hoosier Posted March 29, 2016 Share Posted March 29, 2016 Not really seeing any veer-back issues with the wind profiles aloft either. Link to comment Share on other sites More sharing options...
ClicheVortex2014 Posted March 29, 2016 Share Posted March 29, 2016 SSW 10m flow isn't ideal, but as mentioned above, perhaps speed shear can work to overcome that a bit. Forgive my ignorance, but why isn't SSW 10m ideal? I thought it's good since we have WSW winds in the mid-level Link to comment Share on other sites More sharing options...
Hoosier Posted March 30, 2016 Share Posted March 30, 2016 Forgive my ignorance, but why isn't SSW 10m ideal? I thought it's good since we have WSW winds in the mid-level Personally I'd rather have westerly or wnw mid level flow if we're going to have SSW low level flow...to really increase the tornado threat beyond something localized/isolated. SSW may be workable for some tornadoes but I wouldn't call it "ideal." Link to comment Share on other sites More sharing options...
RCNYILWX Posted March 30, 2016 Share Posted March 30, 2016 Personally I'd rather have westerly or wnw mid level flow if we're going to have SSW low level flow...to really increase the tornado threat beyond something localized/isolated. SSW may be workable for some tornadoes but I wouldn't call it "ideal."Agreed. Also the NAM is closest to due south whereas the other guidance is closer to southwest, so there's uncertainty on how much low level veering there will be. It is possible that isallobaric response could keep winds closer to south though. Link to comment Share on other sites More sharing options...
ClicheVortex2014 Posted March 30, 2016 Share Posted March 30, 2016 Personally I'd rather have westerly or wnw mid level flow if we're going to have SSW low level flow...to really increase the tornado threat beyond something localized/isolated. SSW may be workable for some tornadoes but I wouldn't call it "ideal." Yeah, I didn't mean to suggest SSW is ideal given the circumstances. Bad wording on my part. The vertical shear profile isn't great, but it's also not as bad as it could be; I think it's sufficient. This setup somewhat reminds me of the 11/16 setup out in the Plains. Shear was strong, instability was rather moderate, and SRH was low-end moderate... even weaker than this setup. That turned out to be quite the interesting event. 18z NAM's wind profile beats that in every way. Along the Illinois/Indiana border, there's 200-230 0-3km SRH and 80-90 kt 0-6km shear. But obviously instability is still in question for the next 2 days. That's definitely the deal maker or breaker. Link to comment Share on other sites More sharing options...
Hoosier Posted March 30, 2016 Share Posted March 30, 2016 00z NAM is looking a little slower again. Link to comment Share on other sites More sharing options...
ClicheVortex2014 Posted March 30, 2016 Share Posted March 30, 2016 00z NAM is looking a little slower again. Yeah, I think NAM's also gonna be juicier than previous runs based on what I see on SREF Link to comment Share on other sites More sharing options...
Hoosier Posted March 30, 2016 Share Posted March 30, 2016 This run will undoubtedly heighten the severe threat farther west in Illinois. Also, 60 degree dews up to I-80 in parts of IA/IL at 6z Thursday. Link to comment Share on other sites More sharing options...
ClicheVortex2014 Posted March 30, 2016 Share Posted March 30, 2016 Pretty good NAM run. Not sure if the "line" from 00z-03z is a squall or a broken line of supercells. The parameters support supercells... especially south of I-70. By our luck (E IN/W OH) over the past 15 years, it's probably just a squall. Anxious to see 4km NAM. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted March 30, 2016 Share Posted March 30, 2016 00z NAM is looking a little slower again. Surface low/front is a little further SE across nrn IL though Link to comment Share on other sites More sharing options...
ClicheVortex2014 Posted March 30, 2016 Share Posted March 30, 2016 Only a bit ridiculous Link to comment Share on other sites More sharing options...
Hoosier Posted March 30, 2016 Share Posted March 30, 2016 Surface low/front is a little further SE across nrn IL though Indeed NAM is sort of alone with this trailing low idea, or is at least more noticeable with it than other models. Been showing up on multiple runs. Link to comment Share on other sites More sharing options...
Hoosier Posted March 30, 2016 Share Posted March 30, 2016 4 km NAM looks a bit quicker than the 12 km. Link to comment Share on other sites More sharing options...
Chicago Storm Posted March 30, 2016 Share Posted March 30, 2016 0z NAM in W-C. IN at 21z... Link to comment Share on other sites More sharing options...
tornadohunter Posted March 30, 2016 Share Posted March 30, 2016 Nam 4km. Yikes Link to comment Share on other sites More sharing options...
Hoosier Posted March 30, 2016 Share Posted March 30, 2016 Upward bump in instability on the 00z GFS. Also a bit slower... Link to comment Share on other sites More sharing options...
Stebo Posted March 30, 2016 Share Posted March 30, 2016 Upward bump in instability on the 00z GFS. Also a bit slower... I'd say it is quite a bit slower at 18z the low is over MKE on this run vs over Cadillac on the 18z run. NAM/Euro wins this round. Link to comment Share on other sites More sharing options...
Hoosier Posted March 30, 2016 Share Posted March 30, 2016 I'd say it is quite a bit slower at 18z the low is over MKE on this run vs over Cadillac on the 18z run. NAM/Euro wins this round. Not NAM like but hard to have confidence that it (GFS) is done trending. Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted March 30, 2016 Share Posted March 30, 2016 Any thoughts on what the SPC is gonna do? Link to comment Share on other sites More sharing options...
andyhb Posted March 30, 2016 Share Posted March 30, 2016 Any thoughts on what the SPC is gonna do? Would think they may extend the slight at least to the Ohio River in the D2, maybe add an enhanced further south given the better agreement from the GFS now on solid destabilization with strong vertical shear. That exit region of the upper jet over that region is concerning as it may lead to a secondary low developing within the surface trough extending southwestward. This would increase LLJ strength down there significantly and likely back the surface winds. Link to comment Share on other sites More sharing options...
Hoosier Posted March 30, 2016 Share Posted March 30, 2016 I think there's a pretty good chance of the slight risk being extended north of the OH River. They'd have to be 100% all in with the GFS to not do it and even then you could argue that the GFS may be good enough for a slight risk north of the river. imo an equal if not bigger issue is how far west to put it as the NAM would easily support a severe threat in about the eastern 1/2 of Illinois. Link to comment Share on other sites More sharing options...
Stebo Posted March 30, 2016 Share Posted March 30, 2016 I think there's a pretty good chance of the slight risk being extended north of the OH River. They'd have to be 100% all in with the GFS to not do it and even then you could argue that the GFS may be good enough for a slight risk north of the river. imo an equal if not bigger issue is how far west to put it as the NAM would easily support a severe threat in about the eastern 1/2 of Illinois.I'd bring the slight all the way into southern lower Michigan at this point, all models bust out convection and have decent instability in a strongly sheared environment. Link to comment Share on other sites More sharing options...
Hoosier Posted March 30, 2016 Share Posted March 30, 2016 GFS would even have a nonzero severe threat around Chicago despite its earlier timing. ORD forecast sounding at 15z Thursday has some instability in a strongly speed sheared environment with precip developing out west at that time. Link to comment Share on other sites More sharing options...
ClicheVortex2014 Posted March 30, 2016 Share Posted March 30, 2016 Yeah, all the models are trending toward a more unstable/exciting solution.. but I'd still be very cautious about the influence of debris clouds/remnant showers... especially if an MCS forms. There's no way GFS/NAM/Euro have all that figured out. That's the job for HRRR when it's less than 10 hours out. Link to comment Share on other sites More sharing options...
tornadohunter Posted March 30, 2016 Share Posted March 30, 2016 ..OH VALLEY TO SRN UPPER GREAT LAKES REGION SVR REGIME ACROSS THIS AREA WILL BE CHARACTERIZED BY COLDER AIR ALOFT THAN OVER DIXIE...BUT WEAKER LOW-LEVEL THETAE AND NARROWER WARM SECTOR SHIFTING EWD AHEAD OF AFTN/NEAR-FRONTAL DEVELOPMENT. SVR POTENTIAL MAY BE WINDING DOWN EARLY IN PERIOD WITH MORNING TSTMS MOVING NEWD FROM END OF DAY 1 OUTLOOK AREA. BEHIND THOSE...CONSIDERABLE UNCERTAINTIES REMAIN REGARDING BOTH DIABATIC BOUNDARY-LAYER DESTABILIZATION AND POTENTIAL TRAJECTORIES FOR ADVECTION OF RELATIVELY STABLE AIR OUT OF OUTFLOW FROM COMPLEXES FARTHER S. KINEMATIC ENVIRONMENT WILL FAVOR ALL SVR MODES...INCLUDING TORNADOES. DEEP SHEAR AND LOW-LEVEL HODOGRAPHS EACH SHOULD ENLARGE WITH APCH OF EJECTING MID/UPPER-LEVEL PERTURBATION...AND MOST AGGRESSIVE FCST SOUNDINGS SUGGEST ENOUGH DIURNAL HEATING TO BOOST MLCAPE TO 100-1500 J/KG RANGE. AS SUCH...UNCONDITIONAL 15%/SLGT PROBABILITIES ARE EXTENDED NWD FOR NOW...AND FURTHER EXPANSION/INCREASE MAY BE NEEDED DEPENDING ON WIDTH/STRENGTH OF WARM-SECTOR RECOVERY. Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted March 30, 2016 Share Posted March 30, 2016 Honestly surprised by the cut off on the Day 2 outlook for the Slight Risk. Link to comment Share on other sites More sharing options...
Stebo Posted March 30, 2016 Share Posted March 30, 2016 Honestly surprised by the cut off on the Day 2 outlook for the Slight Risk. I understand why they did it, as they do think there will be a significant squall line across the mid south tomorrow night. They are waiting another model cycle to see if the model trends do hold though, if they do then the risk will move further north. Link to comment Share on other sites More sharing options...
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