Chicago Storm Posted April 15, 2013 Share Posted April 15, 2013 Next potential is here. As mentioned in the C/W thread, this might be the last "ok" chase opportunity for a while given the upcoming pattern. I'm already watching Wed as a potential chase day. Link to comment Share on other sites More sharing options...
RCNYILWX Posted April 15, 2013 Share Posted April 15, 2013 Next potential is here. As mentioned in the C/W thread, this might be the last "ok" chase opportunity for a while given the upcoming pattern. I'm already watching Wed as a potential chase day. Looks like decent potential for some warm front action. Link to comment Share on other sites More sharing options...
andyhb Posted April 15, 2013 Share Posted April 15, 2013 00z GFS is coming in with a much stronger secondary sfc low for Thursday. Link to comment Share on other sites More sharing options...
RCNYILWX Posted April 15, 2013 Share Posted April 15, 2013 00z GFS is coming in with a much stronger secondary sfc low for Thursday. Thought Thursday could get interesting too, strong secondary low development is something the 12z GEM showed as well. Link to comment Share on other sites More sharing options...
Stebo Posted April 15, 2013 Share Posted April 15, 2013 Thought Thursday could get interesting too, strong secondary low development is something the 12z GEM showed as well. 00z GEM continues that trend as well as the 00z GFS, I am really starting to like these trends in this potential. If you were to get such a strong secondary cyclogenesis we could really start to back the low level winds across the GLOV. Link to comment Share on other sites More sharing options...
Stebo Posted April 15, 2013 Share Posted April 15, 2013 SPC has the day 3 nosing into part of the region, of course the higher probabilities are across The Plains DAY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0224 AM CDT MON APR 15 2013 VALID 171200Z - 181200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS OK/SERN KS/SWRN MO... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM NWRN TX INTO CNTRL IL... ...SIGNIFICANT SEVERE WEATHER EVENT IS POSSIBLE ACROSS PARTS OF THE SOUTHERN PLAINS INTO THE MID MS VALLEY WEDNESDAY... ...SRN PLAINS TO MID MS VALLEY... LATEST MODEL GUIDANCE CONTINUES TO SUGGEST A CORRIDOR OF STRONG SWLY FLOW ALOFT WILL SPREAD ACROSS THE PLAINS WEDNESDAY AFTERNOON. THIS LARGE SCALE INCREASE IN HIGH LEVEL FLOW IS CONSISTENT AMONG THE NAM/GFS/ECMWF. OF PARTICULAR CONCERN ARE THE DIFFERENCES REGARDING THE SYNOPTIC POSITIONS OF THE COLD FRONT WITH THE ECMWF BEING THE MOST AGGRESSIVE...ALBEIT SLOWER THAN EARLIER RUNS...AND THE GFS CONSIDERABLY SLOWER WITH THE PRIMARY FRONTAL ZONE AT 18/00Z FROM SERN NEB ACROSS NWRN KS INTO SERN CO. LATEST THINKING IS THE NAM MAY BE MORE ACCURATE DEPICTING AN EARLY FRONTAL SURGE THAT WILL STALL ACROSS THE SRN PLAINS DURING THE DAY1-2 TIME FRAME BEFORE SLOWLY RETREATING INTO SERN KS/NWRN OK BY LATE AFTERNOON. GIVEN THIS SCENARIO THE GREATEST BUOYANCY WILL EXIST ACROSS THE BODY OF OK WHERE STEEPEST LAPSE RATES WILL RESIDE...WHILE SIGNIFICANT INSTABILITY SHOULD EXTEND DOWNSTREAM INTO PORTIONS OF THE MID MS VALLEY REGION. EARLY IN THE PERIOD 50KT+ LLJ WILL BE FOCUSED ACROSS OK/KS. SCATTERED ELEVATED STRONG STORMS MAY BE ONGOING ACROSS KS INTO PORTIONS OF EXTREME NWRN MO. THIS SHOULD SERVE TO MAINTAIN AFOREMENTIONED BOUNDARY ACROSS SERN KS/NWRN OK WHICH WILL BECOME THE PRIMARY FOCUS FOR RENEWED SEVERE THUNDERSTORM DEVELOPMENT LATER IN THE DAY. ADDITIONALLY...STRONG HEATING WILL SHARPEN A DRYLINE NEAR THE TX PANHANDLE/OK BORDER...SSWWD INTO WEST TX. LARGE SCALE PATTERN APPEARS FAVORABLE FOR SCT-NUMEROUS THUNDERSTORMS FROM LATE AFTERNOON INTO THE NIGHTTIME HOURS FROM OK NEWD INTO MO. ANY STORMS THAT DEVELOP SOUTH OF THE SRN MOST STALLED BOUNDARY WILL POSE THE GREATEST RISK OF MAINTAINING SUPERCELL CHARACTERISTICS THAT WILL FAVOR VERY LARGE HAIL/DAMAGING WINDS AND TORNADOES. DURING THE OVERNIGHT HOURS A SECONDARY STRONG COLD FRONTAL PUSH WILL ENCOURAGE A FORCED LINE OF THUNDERSTORMS ALONG THE WIND SHIFT THAT WILL PROPAGATE SEWD. BY EARLY THURSDAY AN EXTENSIVE CORRIDOR OF CONVECTION MAY BE NOTED FROM NRN IL...SWWD ACROSS MO INTO NWRN TX. Link to comment Share on other sites More sharing options...
LouWX Posted April 15, 2013 Share Posted April 15, 2013 The worst severe weather in this region is probably going to occur Thu-Fri AM. Strongly forced squall line with helicity supporting QLCS tornadoes look probable on the front being pushed east by neg tilt trof. Models likely underestimating instability at night (Jan 30th temperatures jumped to the low 70s ahead of the line in KY despite model depictions of low to mid 60s). Modified saturated soundings support some LL cape. Could be high-impact especially MO/AR/IL/KY/IN/TN. Link to comment Share on other sites More sharing options...
RCNYILWX Posted April 15, 2013 Share Posted April 15, 2013 Without looking at the various severe parameters, the 12z gfs verbatim would be a big problem for northern IL. 60 deg dewpoints get into southern WI and the 850 mb jet ramps up to 50 to 60kt by 84 hrs (00z Friday). Also proximity to 994 mb surface low, which then deepens to 989 mb by 06z. H5 winds go from 50 to 60 kt at 00z to 80 to 90 kt at 06z. Certainly see potential for a tornado threat, but wind threat could also be higher end in a squall line with such a screaming LLJ. Also big time flooding concerns. Link to comment Share on other sites More sharing options...
Stebo Posted April 15, 2013 Share Posted April 15, 2013 Without looking at the various severe parameters, the 12z gfs verbatim would be a big problem for northern IL. 60 deg dewpoints get into southern WI and the 850 mb jet ramps up to 50 to 60kt by 84 hrs (00z Friday). Also proximity to 994 mb surface low, which then deepens to 989 mb by 06z. H5 winds go from 50 to 60 kt at 00z to 80 to 90 kt at 06z. Certainly see potential for a tornado threat, but wind threat could also be higher end in a squall line with such a screaming LLJ. Also big time flooding concerns. My biggest concern is that the models, namely the GFS are grossly underdoing the instability around 00z Friday, you take these wind parameters and then you throw around 1000 J/kg into the mix, it could end up being a very strong potential. Link to comment Share on other sites More sharing options...
cyclone77 Posted April 15, 2013 Share Posted April 15, 2013 My biggest concern is that the models, namely the GFS are grossly underdoing the instability around 00z Friday, you take these wind parameters and then you throw around 1000 J/kg into the mix, it could end up being a very strong potential. Yeah conditionally the threat is pretty big. Just gotta wonder how much the atmosphere will be able to destabilize with potential clouds/precip hampering things, which is pretty typical it seems. At 00z Fri the GFS shows only a small pocket or two of around 500j/kg, whereas the NAM shows widespread 1000-1500j/kg. Link to comment Share on other sites More sharing options...
Stebo Posted April 15, 2013 Share Posted April 15, 2013 Yeah conditionally the threat is pretty big. Just gotta wonder how much the atmosphere will be able to destabilize with potential clouds/precip hampering things, which is pretty typical it seems. At 00z Fri the GFS shows only a small pocket or two of around 500j/kg, whereas the NAM shows widespread 1000-1500j/kg. Even look at 18z and 21z on the GFS, widespread 1000-1500 J/kg, that just goes down by as much as 750J/kg by 00z, I just don't see the instability dying as dramatically as the GFS is showing, sure it will weaken slightly due to diurnal effects but I don't quite think it will be that dramatic. Link to comment Share on other sites More sharing options...
cyclone77 Posted April 15, 2013 Share Posted April 15, 2013 Even look at 18z and 21z on the GFS, widespread 1000-1500 J/kg, that just goes down by as much as 750J/kg by 00z, I just don't see the instability dying as dramatically as the GFS is showing, sure it will weaken slightly due to diurnal effects but I don't quite think it will be that dramatic. Yeah that was a bit odd. One thing's for sure, deep moisture won't be a problem (unlike yesterday @#$@#$@#%@!! lol). Link to comment Share on other sites More sharing options...
LouWX Posted April 15, 2013 Share Posted April 15, 2013 It'll be in the 70s ahead of the line from IN/IL southward. LLJ is >50kt at 925... that'll promote perhaps even dry adiabatic mixing. Low level moisture may mix out a little but should be replenished with the good Gulf fetch. Models are definitely under-doing the CAPEs. Again referring to the Jan 29/30 event with TOR's along the I-65 corridor IN/KY/TN... the 0Z RAOB analysis showed a similar picture to what we're looking at for this Thursday's event... some subtle capping ahead of the line and temperatures steady/rising at night. Low CAPE but with extreme LL shear there were still several TOR reports. Hopefully SPC doesn't play this down... it's got huge potential. Link to comment Share on other sites More sharing options...
andyhb Posted April 15, 2013 Share Posted April 15, 2013 I posted this over at C/W to get the idea of what we might be dealing with on Wednesday, but you can see the entire warm sector is being primed on Wednesday across a large area as theta-e inflow increases. Increased instability + this = well I think everyone knows... Link to comment Share on other sites More sharing options...
Indystorm Posted April 15, 2013 Share Posted April 15, 2013 I like the Caribbean connection to that moisture fetch. Deep moisture will not be lacking for this event. Link to comment Share on other sites More sharing options...
RCNYILWX Posted April 15, 2013 Share Posted April 15, 2013 I like the Caribbean connection to that moisture fetch. Deep moisture will not be lacking for this event. Mid 60s dewpoints on the ECMWF, which tends to do a better job than the GFS with dewpoints. Synoptically speaking, the the Euro looks just as potentially signifcant as the GFS with severe aspects over Illinois and Indiana. Link to comment Share on other sites More sharing options...
LouWX Posted April 15, 2013 Share Posted April 15, 2013 One thing to monitor: the models are going SSE with the sfc winds and dropping dewpoints some with more of a dry advection pattern. Will be interesting the next 3/4 model cycles to see how strong the sfc low is and what the wind directions do. Of course if the sfc cape is there there is a lot of 0-1 helicity to work with. Link to comment Share on other sites More sharing options...
andyhb Posted April 15, 2013 Share Posted April 15, 2013 Quite frankly I'm trying to remember the last time we had wind fields this strong progged in the Central Great Lakes (IL/IN/MI) region in April over the past however many years and I'm coming up empty... Link to comment Share on other sites More sharing options...
LouWX Posted April 15, 2013 Share Posted April 15, 2013 Quite frankly I'm trying to remember the last time we had wind fields this strong progged in the Central Great Lakes (IL/IN/MI) region in April over the past however many years and I'm coming up empty... It's impressive and i think the worst will be in IL/MO/w KY (farther west). Timing is not in their favor. Farther east it'll be a race with what instability is left. No doubt the forcing with the neg tilt trough will be great. Hard to believe we will lose the LL moisture and warmth like the models suggest. Link to comment Share on other sites More sharing options...
A-L-E-K Posted April 15, 2013 Share Posted April 15, 2013 Quite frankly I'm trying to remember the last time we had wind fields this strong progged in the Central Great Lakes (IL/IN/MI) region in April over the past however many years and I'm coming up empty... IDK seems like we see wind fields like this quite often ... instability is always the bigger issue this early in the season this far north and will be the reason this is not a major event for the lakes. Link to comment Share on other sites More sharing options...
RCNYILWX Posted April 16, 2013 Share Posted April 16, 2013 IDK seems like we see wind fields like this quite often ... instability is always the bigger issue this early in the season this far north and will be the reason this is not a major event for the lakes. Agree instability will be the issue but I don't think you can make that call now that it won't be a significant event. A lot of the pieces are progged to be in place. Also if there's sufficient low level CAPE with the insane helicity values you won't need tremendous total CAPE to get a big event. #3 CIPS analog from the GFS is 3/12/06 and #4 is 5/10/03. Link to comment Share on other sites More sharing options...
SchaumburgStormer Posted April 16, 2013 Share Posted April 16, 2013 Hopefully SPC doesn't play this down... it's got huge potential. Well they are rocking a day 3 moderate risk, so I dont think they are playing it down. Link to comment Share on other sites More sharing options...
Stebo Posted April 16, 2013 Share Posted April 16, 2013 IDK seems like we see wind fields like this quite often ... instability is always the bigger issue this early in the season this far north and will be the reason this is not a major event for the lakes. Yeah I disagree with this call right now, you don't see this type of kinematics this late in the spring up in this region, even with limited instability it could be a major event. Even at that all the models show sufficient instability to sustain the potential of a major event, as RCNYILWX mentioned you won't need a huge amount of CAPE to make things go in a big way. Link to comment Share on other sites More sharing options...
andyhb Posted April 16, 2013 Share Posted April 16, 2013 Well they are rocking a day 3 moderate risk, so I dont think they are playing it down. I believe he was talking about Thursday specifically. Link to comment Share on other sites More sharing options...
SchaumburgStormer Posted April 16, 2013 Share Posted April 16, 2013 I believe he was talking about Thursday specifically. Ah my mistake. Link to comment Share on other sites More sharing options...
andyhb Posted April 16, 2013 Share Posted April 16, 2013 The 00z GFS has some sick wind fields as the LL profile responds to the maturing secondary sfc cyclone in Western IL. The NAM is slower to do this as the secondary low is slower to develop, but what it does have is 1000-2000 J/kg of SBCAPE in a broad swath including basically all of the Lower and Mid MS Valleys, the Lower OH Valley and the Wabash Valley (and this is at 00z Friday). Both models continue to advertise a favorable coupled UL jet setup across much of the risk area as well. If you were to juxtapose the NAM thermos with the GFS shear, you have quite the situation setting up there on Thursday. Link to comment Share on other sites More sharing options...
andyhb Posted April 16, 2013 Share Posted April 16, 2013 Not to go on too much of a bashing attitude here, but that was not the greatest D3 outlook just put out for Thursday. Link to comment Share on other sites More sharing options...
RCNYILWX Posted April 16, 2013 Share Posted April 16, 2013 Not to go on too much of a bashing attitude here, but that was not the greatest D3 outlook just put out for Thursday. Was expecting at least part of the LOT CWA to be in a slight risk, but given the strength of the wind fields, surprised there wasn't a hatched area included. There's uncertainty over how much instability there will be, but I think the conditional threat is pretty high end if there's enough instability. And there doesn't have huge CAPE for there to be big problems, just sufficient CAPE in the right area. Link to comment Share on other sites More sharing options...
A-L-E-K Posted April 16, 2013 Share Posted April 16, 2013 Spc is right to remain gaurded over LOT. We've all seen this play out before. The front is going to be so convectively active, I'll be surprised if there is much more than 100-200 cape. Link to comment Share on other sites More sharing options...
harrisale Posted April 16, 2013 Share Posted April 16, 2013 Ontario crew, seems as though we may have a long shot at severe on the 18th if some of that instability can make it over from MI. Long shot as I said, but the NAM shows some unstable air before sundown and plenty of bulk shear; helicity into the 300m2/s2 at 00Z Friday. Link to comment Share on other sites More sharing options...
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