CT Rain Posted August 13, 2012 Share Posted August 13, 2012 Also don't forget that in the era of super res data, that gate to gate doesn't technically apply anymore. Some tornadic velocity couplets can now be resolved at better than a true gate to gate sense. In other words, "gate to gate" isn't necessarily immediately adjacent radials. What do you mean by this? Resolution is high enough now that couplet can be separated by a radial? Link to comment Share on other sites More sharing options...
CT Rain Posted August 13, 2012 Share Posted August 13, 2012 The best I see it via KBOX is around 70 kts, separated by a radial. This is also about the time that BOX went with the TOR (2040z volume scan). Before and after that it was mostly broad in the BOX CWA, definitely more impressive near the OKX border as well. If you look at this trace from HFD, you can see that the strongest winds occur with the pressure rise as the meso-low passed. Very much like our isallobaric wind events in the cool season. Compare it to HYA on December 9, 2005. The strongest winds occur as the pressure rises immediately following the closest approach of low pressure. Obviously, the case from a couple days ago occurred on a much smaller scale, in both time and space. Equally strong winds though. I saw a barograph trace from Glastonbury... 6 1/2 mb drop in 40 mins from that thing. Pretty impressive little mesolow. Link to comment Share on other sites More sharing options...
CT Rain Posted August 13, 2012 Share Posted August 13, 2012 The GTG was pretty high at one point, like 60kts plus if I recall, but it wasnt a classic tornadic signature by any means. But the wind numbers in general in it were up there. There certainly was rotation, but you could at some points argue it was broad. They made the decision, and I think it was right since it got the attention of people at least. Also keep in mind this is preliminary. There may be some kind of tornado path out in the woods that will be found over the coming weeks. That has happened before as well. Just because there's a system with strong/damaging winds doesn't mean we need a tornado warning for it. A strongly worded severe thunderstorm warning is fine too. Saying "well there was a lot of damage in Glastonbury... the tor was warranted" is sort of a lame argument IMO. I didn't disagree with the warning call... it was quite marginal though... definitely not a slam dunk. There were several times in the storm's path in CT (particularly down in Guilford) where I would have been close to pulling the trigger. Link to comment Share on other sites More sharing options...
Damage In Tolland Posted August 13, 2012 Share Posted August 13, 2012 Wed could be fun Link to comment Share on other sites More sharing options...
Collinsville Posted August 13, 2012 Share Posted August 13, 2012 Fixed Link to comment Share on other sites More sharing options...
CoastalWx Posted August 13, 2012 Share Posted August 13, 2012 Wednesday is a Sultan day if anything. Link to comment Share on other sites More sharing options...
Ginx snewx Posted August 13, 2012 Share Posted August 13, 2012 The best I see it via KBOX is around 70 kts, separated by a radial. This is also about the time that BOX went with the TOR (2040z volume scan). Before and after that it was mostly broad in the BOX CWA, definitely more impressive near the OKX border as well. If you look at this trace from HFD, you can see that the strongest winds occur with the pressure rise as the meso-low passed. Very much like our isallobaric wind events in the cool season. Compare it to HYA on December 9, 2005. The strongest winds occur as the pressure rises immediately following the closest approach of low pressure. Obviously, the case from a couple days ago occurred on a much smaller scale, in both time and space. Equally strong winds though. Glastonbury Link to comment Share on other sites More sharing options...
CT Rain Posted August 13, 2012 Share Posted August 13, 2012 Glastonbury Yeah... that's wild. You know what else I was thinking about the other day was we basically had a MCV develop within an MCV. Within that we had the mesocyclone. Pretty cool stuff. Link to comment Share on other sites More sharing options...
radarman Posted August 13, 2012 Share Posted August 13, 2012 So much to look at from Friday and Saturday. Good times. Here were two shots from the storm that moved through this area on Saturday evening. There was no low level rotation visible, but no doubt a pretty strong mid-level meso. The photos are from the WWLP website, taken within minutes of the first radar image. The second shot is as this passes less than a kilometer from the radar. This appeared in the sky as a dangling scud cloud. Link to comment Share on other sites More sharing options...
HoarfrostHubb Posted August 13, 2012 Share Posted August 13, 2012 That is wild looking. Link to comment Share on other sites More sharing options...
HM Posted August 13, 2012 Share Posted August 13, 2012 Just an incredible MCV and severe weather day for CT. As for the forecasting end of things, I am happy about how things went on a nowcasting note and the day before to some extent. While predicting MCV-genesis is difficult at best, we were hinting at the possibility of something getting organized in the morning the day before. A lot of forecasts down my way were talking about showers and thunderstorms later in the day which I thought was wrong. There was clearly CVA and a relative max in the wind fields coming through 15-18z with notable CAPE (very clear CAPE decrease on the NWP between this time frame down in the coastal northern Mid Atlantic) and high moisture content. I thought it was pretty clear that the models were signaling this wave in the morning and the potential for heavy rain with embedded severe. I am pleased about mentioning the potential for rotation but I was way too IMBY with that event. It didn't occur to me until nowcasting time what this would mean further upstream (embedded weaker mesocyclones becoming something more). Link to comment Share on other sites More sharing options...
N. OF PIKE Posted August 13, 2012 Share Posted August 13, 2012 HM you see any EML potential days for the NE on the horizon Link to comment Share on other sites More sharing options...
SnowMan Posted August 13, 2012 Share Posted August 13, 2012 Nice clouds today..pics taken from Danvers, Andover and Nashua. Was one of those pics taken at Avalon Danvers apartment complex? Link to comment Share on other sites More sharing options...
OceanStWx Posted August 13, 2012 Share Posted August 13, 2012 What do you mean by this? Resolution is high enough now that couplet can be separated by a radial? For the lowest 3 or 4 slices (depending on the VCP) we get super res data which is on the order of 0.25 km. So some of the larger tornadic circulations may not appear to be gate to gate. Obviously, this is not a major problem in New England, but it does happen. Extreme example alert, but for Springfield the strongest strongest couplet at this time was about 75 inbound and 75 out (150 kts), but it was not gate to gate. It was separated by a radial with around 60 kts. The super res is also more noticeable the closer to the radar, as the beam hasn't widened to the point it has out by Springfield. Link to comment Share on other sites More sharing options...
Ginx snewx Posted August 13, 2012 Share Posted August 13, 2012 Yeah... that's wild. You know what else I was thinking about the other day was we basically had a MCV develop within an MCV. Within that we had the mesocyclone. Pretty cool stuff. Absolutely, if you look at the entire radar complex you can see inflow in the main LP, if you will, then inflow into the MCV then inflow into the micro destructive MCV. This was a very uncommon MCV. Link to comment Share on other sites More sharing options...
Ginx snewx Posted August 13, 2012 Share Posted August 13, 2012 I would like to ask HM if that Glastonbury trace is indicative of a Gravity wave. Great couplet. Much bigger Baro drop then anything else I could find, what made it significant is that a nearby Meso station recorded the same. Link to comment Share on other sites More sharing options...
CT Rain Posted August 13, 2012 Share Posted August 13, 2012 For the lowest 3 or 4 slices (depending on the VCP) we get super res data which is on the order of 0.25 km. So some of the larger tornadic circulations may not appear to be gate to gate. Obviously, this is not a major problem in New England, but it does happen. Extreme example alert, but for Springfield the strongest strongest couplet at this time was about 75 inbound and 75 out (150 kts), but it was not gate to gate. It was separated by a radial with around 60 kts. The super res is also more noticeable the closer to the radar, as the beam hasn't widened to the point it has out by Springfield. Oh OK, I see what you're saying. I love the level 2 nexrad data... it's phenomenal. Even in that case even though you had 135 knots g2g - not too shabby lol. I'm guessing 1 or 2 radials between inbound and outbound velocities would still classify as a couplet for a tornadic circulation close to the radar with the hires data? Link to comment Share on other sites More sharing options...
CT Rain Posted August 13, 2012 Share Posted August 13, 2012 I would like to ask HM if that Glastonbury trace is indicative of a Gravity wave. Great couplet. Much bigger Baro drop then anything else I could find, what made it significant is that a nearby Meso station recorded the same. I'm not sure why you're thinking gwave... seems like a classic barograph trace for a strong mesolow moving through. The intensification of it over CT probably lead to a strong isallobaric component of the wind that helped intensify the velocities. Link to comment Share on other sites More sharing options...
CT Rain Posted August 13, 2012 Share Posted August 13, 2012 Just an incredible MCV and severe weather day for CT. As for the forecasting end of things, I am happy about how things went on a nowcasting note and the day before to some extent. While predicting MCV-genesis is difficult at best, we were hinting at the possibility of something getting organized in the morning the day before. A lot of forecasts down my way were talking about showers and thunderstorms later in the day which I thought was wrong. There was clearly CVA and a relative max in the wind fields coming through 15-18z with notable CAPE (very clear CAPE decrease on the NWP between this time frame down in the coastal northern Mid Atlantic) and high moisture content. I thought it was pretty clear that the models were signaling this wave in the morning and the potential for heavy rain with embedded severe. I am pleased about mentioning the potential for rotation but I was way too IMBY with that event. It didn't occur to me until nowcasting time what this would mean further upstream (embedded weaker mesocyclones becoming something more). I was reading through some MCV literature over the weekend (a lot of the BAMEX stuff is great) but I'm still not sure of the physical process that caused us to develop a tight MCV within a broader MCV. Was what spun up that we watched on radar over CT partially a reflection of a strong meso low developing in the boundary layer that tightened up once it moved inland (frictional effects)? If you know any good papers shoot me a link. Link to comment Share on other sites More sharing options...
OceanStWx Posted August 13, 2012 Share Posted August 13, 2012 Oh OK, I see what you're saying. I love the level 2 nexrad data... it's phenomenal. Even in that case even though you had 135 knots g2g - not too shabby lol. I'm guessing 1 or 2 radials between inbound and outbound velocities would still classify as a couplet for a tornadic circulation close to the radar with the hires data? I'm not sure there would be many mets who wouldn't pull the trigger in that case of a radial or two separation. I would have to dig into the algorithms more in depth, but I could conceive of a situation where a 30 in 30 out couplet was separated by a radial with very low velocity and the traditional tornadic vortex signature detection algorithm may not recognize it and alarm the forecaster via SCAN. But again, the forecaster would already be looking at the base data and see the circulation anyway (hopefully). Link to comment Share on other sites More sharing options...
CT Rain Posted August 13, 2012 Share Posted August 13, 2012 I'm not sure there would be many mets who wouldn't pull the trigger in that case of a radial or two separation. I would have to dig into the algorithms more in depth, but I could conceive of a situation where a 30 in 30 out couplet was separated by a radial with very low velocity and the traditional tornadic vortex signature detection algorithm may not recognize it and alarm the forecaster via SCAN. But again, the forecaster would already be looking at the base data and see the circulation anyway (hopefully). I went back and looked at the Friday storm on OKX again... and there was one area in Guilford with 60 knots of g2g when that thing came ashore but once it moved inland the couplet broadened into more of a broad mesocylone than tight meso. Link to comment Share on other sites More sharing options...
CT Rain Posted August 13, 2012 Share Posted August 13, 2012 For the record here is the SRV signature for the EF0 on Long Island around the time of tornadogenesis. The radar beam is about 1kft AGL here. Not terribly impressive (outbounds only 10-15 knots in the circulation) but it was enough. Link to comment Share on other sites More sharing options...
OceanStWx Posted August 13, 2012 Share Posted August 13, 2012 For the record here is the SRV signature for the EF0 on Long Island around the time of tornadogenesis. The radar beam is about 1kft AGL here. Not terribly impressive (outbounds only 10-15 knots in the circulation) but it was enough. That's a pretty common Northeast thing, the asymmetric couplet. The two "halves" of the couplet don't need to be equally strong or even significant to be tornadic. That is a great example there. And considering how tight that couplet is (small area of enhanced inbound) that points more towards tornadic. Link to comment Share on other sites More sharing options...
CoastalWx Posted August 13, 2012 Share Posted August 13, 2012 I was reading through some MCV literature over the weekend (a lot of the BAMEX stuff is great) but I'm still not sure of the physical process that caused us to develop a tight MCV within a broader MCV. Was what spun up that we watched on radar over CT partially a reflection of a strong meso low developing in the boundary layer that tightened up once it moved inland (frictional effects)? If you know any good papers shoot me a link. When you go back and look at radar, the cell really went to town and developed its own characteristics well west of that original MCV type feature. I was thinking something similar in your last sentence. It may have been originally a weak meso low or perhaps started to develop a meso low as the low seemed to develop in a way not to dissimilar from tropical type lows. I think there was very little lightning IIRC with that cell as well. It's not the first time I've seen these little spin up feature embedded in an arm of convection extending east from the primary low...but I've never seen it spin up over land like it did. Link to comment Share on other sites More sharing options...
CT Rain Posted August 13, 2012 Share Posted August 13, 2012 That's a pretty common Northeast thing, the asymmetric couplet. The two "halves" of the couplet don't need to be equally strong or even significant to be tornadic. That is a great example there. And considering how tight that couplet is (small area of enhanced inbound) that points more towards tornadic. Yeah there were several cases like that over the Atlantic south of OKX on Friday. You'd see a huge/quick spike in inbounds and relatively meh outbounds. Link to comment Share on other sites More sharing options...
CT Rain Posted August 13, 2012 Share Posted August 13, 2012 When you go back and look at radar, the cell really went to town and developed its own characteristics well west of that original MCV type feature. I was thinking something similar in your last sentence. It may have been originally a weak meso low or perhaps started to develop a meso low as the low seemed to develop in a way not to dissimilar from tropical type lows. I think there was very little lightning IIRC with that cell as well. It's not the first time I've seen these little spin up feature embedded in an arm of convection extending east from the primary low...but I've never seen it spin up over land like it did. I don't seem to remember the initial MCV (the one we were tracking over the Delmarva?) being east though. I could totally be remembering incorrectly though lol It seemed to me the initial MCV was fairly broad but the center seemed to track over central LI and central CT. It appears the mesolow that went to town may have been enough to force low topped convection and that's what gave you the impressive radar appearance. Link to comment Share on other sites More sharing options...
Quincy Posted August 13, 2012 Share Posted August 13, 2012 I don't seem to remember the initial MCV (the one we were tracking over the Delmarva?) being east though. I could totally be remembering incorrectly though lol It seemed to me the initial MCV was fairly broad but the center seemed to track over central LI and central CT. It appears the mesolow that went to town may have been enough to force low topped convection and that's what gave you the impressive radar appearance. I looked back and we had what I believe was the initial MCV track into the PHL area and then up through western NJ. The cluster that really amped up just south of LI seemed to first form off the SE NJ coast. Link to comment Share on other sites More sharing options...
CoastalWx Posted August 13, 2012 Share Posted August 13, 2012 I don't seem to remember the initial MCV (the one we were tracking over the Delmarva?) being east though. I could totally be remembering incorrectly though lol It seemed to me the initial MCV was fairly broad but the center seemed to track over central LI and central CT. It appears the mesolow that went to town may have been enough to force low topped convection and that's what gave you the impressive radar appearance. I guess what I'm describing is what the radar loop show. To me, the original circlulation went very near or just SE of the OKX radar site. I think at the time we were surmising that is may be part of that weak surface low trying to develop, but it began looking like a much more defined circulation. However notice by 1839Z, we have a blob of very high DBZ now NW of the radar site. Keep following this and notice the evolution of it. It even started to leave an outflow boundary looking feature to its SE by 1918Z. It was this cell that started to go to town, but to me..it looked like it branched off or developed on the NW side of the original circulation. I don't have archive GR analyst like you and OceanSt have so maybe you can take a more detailed look. http://weather.rap.u...e=21&duration=3 Link to comment Share on other sites More sharing options...
Damage In Tolland Posted August 13, 2012 Share Posted August 13, 2012 Will dews get 70 or higher Tues nite/ Wed? Link to comment Share on other sites More sharing options...
CoastalWx Posted August 13, 2012 Share Posted August 13, 2012 Will dews get 70 or higher Tues nite/ Wed? Probably. Link to comment Share on other sites More sharing options...
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