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Everything posted by purduewx80

  1. tennis-ball-sized hail in WI in the general thunder outlook (one unconfirmed photo showing a stone 3"+). 12Z soundings indicate mid-level lapse rates of 7-8.5C/km. shear 40-50KT+. pretty good indication to me the outlook is underplaying today.
  2. That is most definitely not how you read that. It's the altimeter, which was 29.22" or around 989.5mb. Looks like he deleted both tweets fortunately.
  3. The HRRR late-CI bias is in full effect today given TS in the QC already. Its coverage is probably too low given the lake breeze boundary and strong MCV moving in during peak heating, but it overall seems to have the right idea for IL/IN this eve. Probably some pulse severe wind but mainly heavy rain given the weak shear and slow storm motions. Definitely some uncertainty tomorrow on the best overlap of shear and CAPE - SPC seems to be playing the farther S scenario for now which make sense if the effective front is shoved south by TS tonight. On the other hand, the 18Z HRRR is definitely showing a D-word scenario up into SE MN. IMO the training/flood setup tomorrow night has a pretty high ceiling in parts of the region.
  4. Today has definitely been an interesting setup that relied 100% on nowcasting. In aviation we try to come up with a convective forecast that helps the FAA plan routes in and out of the area (mainly for ORD) - been one of the lower confidence days of the summer given zero model support. If you read through all of LOT's AFDs today, you'll see how the forecast has been evolving back and forth as conditions change. At one point we thought the dry air observed on the 12Z OAX sounding would inhibit TS this far south, but it seems to me the corn belt helped with moisture flux from the surface up to the 925-800mb level. This all resulted in MLCAPE rapidly increasing this afternoon (which the NAM has done well with despite mostly missing the actual wx). Definitely not the best time to be flying into O'Hare today.
  5. Supercells on the N side of the outflow boundary are pretty interesting. Looks like a fairly narrow corridor of extreme low-level shear w/ NNE winds on the cold side of the boundary and SSW winds just above.
  6. Destabilizing very quickly now thanks to incredibly steep mid-level lapse rates and strong low-level moisture transport. I don't really see the stratus the SPC mentions in their latest discussion as a hindrance to an increase in TS development this evening given the advective processes ahead of several well-established mesocyclones. Confirmed tornado east of Mineral Point now - in the worst spot for radar detection, but the meso is obviously impressive (via KDVN).
  7. that one is so close. once it moves right and interacts with the boundary in the next hour, look out. Any of these tail-end charlies have the best chance of remaining more discrete and interacting with the outflow from this morning.
  8. Looks like a wake low is developing behind the line. Pressure falls in the western burbs now with gusty SE winds developing.
  9. Impressive rear inflow jet and cold pool - ARR dewpoint down to 62F with 40KT winds continuing well behind the outflow. SPC may need to adjust the ENH to southern MI and another farther W into NE IA. 12Z guidance has the cold pool but they all handle it differently. Some show rapid recovery like the HRDPS, others show the recovery around the bubble high taking longer, which may lower the severe risk in some areas of IL/IN if true.
  10. Definitely a cold pool developing with it. I wonder if the synoptic fields being stronger today will help trigger a quick recovery behind it. Lapse rates and shear are more impressive today, which could help make up for a potential lack of 75-80 dews. As some mentioned last night, the boundary this sends north towards the front should locally enhance sfc vorticity and the wind field, probably in S WI. The 06Z HRDPS is doing well with that cluster this morning and shows a quick recovery during the mid- to late afternoon.
  11. Higher sup/tornado risk may be getting into North Woods territory but could be decent in central WI over to Green Bay. Probably a conditional risk closer to us depending on boundaries/destabilization, but at least for now anything local may be in the south-moving QLCS overnight.
  12. This turned out to be the best way to see where and when things would pop today. Pretty much nailed the timing of things coming into ORD if you just followed that vort.
  13. Don't see how tomorrow isn't at least an enhanced risk day. Whatever convection is around through the morning will lay out boundaries ahead of the front and increasing shear dropping south. Even the guidance w/ AM storms destabilizes things quickly behind it.
  14. There's a well-defined MCV/shortwave over western IA that the RAP has adequately analyzed. That will easily promote development across the area this afternoon. Seems like the 12Z models all have a similar evolution but with significant timing differences.
  15. Flooding probably going to be newsworthy in addition to the severe threat. Radar estimating some 3" totals near and east of Rockford this morning. The real urban flood threat is this evening imo when we'll have HP sups in the area. WPC MD out.
  16. Differential heating caused by the thicker smoke moving into northern Lower Michigan has helped focus thunderstorms over the cleaner air ahead of it. Had the smoke not been there, the lake breeze would likely have been the focus a little farther NW.
  17. The supercell that's been NW of OSH has evolved into a classic book-end vortex over the past 30 min or so. GRB is sampling 90+ mph outbound winds around 3000'. This feature looks to directly affect the Milwaukee metro area and may at least clip portions of Chicagoland. It has yet to encounter the most favorable instability, unfortunately. Likely to be a threat for rain-wrapped tornadoes with it off and on, as well.
  18. The overnight MCV is being sheared apart due to the strong winds aloft - def can see those remnants aloft w/ the feature over IA. The only implication I can see related to that is the min in instability caused by the warm front being driven S/W by an outflow boundary. Recovery can happen quickly in this setup during the late PM hours, but it's not totally clear where the instability gradient will be as TS ride the ridge SE and then S tonight. The latest HRRR does capture current instability fields relatively well. Hate to say this, but the 12Z GFS actually looks more reasonable than a lot of the CAMs from what I'm seeing so far. First warning up by Lake of the Woods now. Will be very interesting to see if that's the start of the main show (probably so).
  19. somewhere inland from duluth will probably have the relatively higher discreet sup potential, but north woods is def not chaser country. don't recommend chasing qlcs tornadoes at night, especially given the terrain and how fast these'll be moving.
  20. Toss most of the overnight CAMs that have little to none of the ongoing WAA activity captured. Orientation of the severe threat looks more N-S oriented than the initial day 1 outlook and may end up father W given the instability axis will have trouble building east as long as the MN TS continue.
  21. Eh, what happens here is conditional on the AM MCS and whether things recover over IA/MN. If those areas don’t recover, we are likely to be in the enhanced risk for winds tomorrow night, along with a pretty sig risk for flash flooding given the lingering boundaries that may be nearby.
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