Hoosier Posted July 16, 2013 Share Posted July 16, 2013 We've been talking about it in other threads but what's going on now can be considered historic even though the sensible weather really isn't. The 00z July 15 Pittsburgh sounding and now the 00z July 16 Wilmington OH sounding have come in with a 500 mb height of 600 dm, with a rare 600 dm contour on tonight's analysis. I came across this list of 600 dm height occurrences. It covers the period from 1957-2006. http://www.weathergraphics.com/tim/above600.txt I don't recognize some of the stations on that list, and some of them probably don't exist anymore, so the only ones I recongize in this subforum are: 12z 6/15/78 KDAY12z 7/17/03 KDVN I checked some dates from 2007-present and couldn't find any additional ones but certainly possible I could've missed something. Perhaps as unusual as the values themselves is the way that this has happened. This isn't a ridge that has built eastward from the Plains, which is what you would normally expect this time of year...it's just the opposite with the ridge building in from the east and strengthening. There may be a chance at another 600 dm reading tomorrow before the ridge weakens a bit. We'll see. Link to comment Share on other sites More sharing options...
Chicago Storm Posted July 16, 2013 Share Posted July 16, 2013 The aforementioned DVN sounding is erroneous. Link to comment Share on other sites More sharing options...
Hoosier Posted July 16, 2013 Author Share Posted July 16, 2013 The aforementioned DVN sounding is erroneous. Thought it seemed weird but wasn't sure. Link to comment Share on other sites More sharing options...
Chicago Storm Posted July 16, 2013 Share Posted July 16, 2013 Thought it seemed weird but wasn't sure. Actually, it looks like the DAY sounding is too. Link to comment Share on other sites More sharing options...
Hoosier Posted July 16, 2013 Author Share Posted July 16, 2013 Actually, it looks like the DAY sounding is too. I think you're right. Other obs from that day don't really support it. Well then, it might be even more unusual than what it seemed. Of course we are at the mercy of fairly widely spaced observation sites so it's possible that marginal cases slip through. Link to comment Share on other sites More sharing options...
Roger Smith Posted July 16, 2013 Share Posted July 16, 2013 The highest I can recall seeing on a map (in N America) was 603 dm, think it was in July 1995. You have to wonder what the max was in July 1936 before measurements began. Link to comment Share on other sites More sharing options...
andyhb Posted July 16, 2013 Share Posted July 16, 2013 I believe that death ridge in July 2011 reached 600 dm at least once. Link to comment Share on other sites More sharing options...
mnweather Posted July 16, 2013 Share Posted July 16, 2013 I believe that death ridge in July 2011 reached 600 dm at least once. I think Omaha had that. Link to comment Share on other sites More sharing options...
Powerball Posted July 16, 2013 Share Posted July 16, 2013 Link to comment Share on other sites More sharing options...
TimChgo9 Posted July 16, 2013 Share Posted July 16, 2013 A: what is the significance? B: what does "dm" stand for, or what does it measure? Link to comment Share on other sites More sharing options...
Chicago Storm Posted July 16, 2013 Share Posted July 16, 2013 I believe that death ridge in July 2011 reached 600 dm at least once. I think Omaha had that. Correct... Link to comment Share on other sites More sharing options...
Hoosier Posted July 16, 2013 Author Share Posted July 16, 2013 A: what is the significance? B: what does "dm" stand for, or what does it measure? dm is decameters which is a unit of measurement (1 decameter=10 meters). 600 dm is difficult to achieve at least in this part of the country. We've seen countless summer ridges with peak heights in the mid/upper 590's but getting that last little bit to get to 600 is tough. It is an indicator of a deeply warm airmass that is in place. A red tagger could explain this better but a simple way to think of it is that the heat bubble is pushing the 500 millibar pressure level to a height that is higher (in this case, ~600 dm) than normal. Link to comment Share on other sites More sharing options...
TimChgo9 Posted July 16, 2013 Share Posted July 16, 2013 dm is decameters which is a unit of measurement (1 decameter=10 meters). 600 dm is difficult to achieve at least in this part of the country. We've seen countless summer ridges with peak heights in the mid/upper 590's but getting that last little bit to get to 600 is tough. It is an indicator of a deeply warm airmass that is in place. A red tagger could explain this better but a simple way to think of it is that the heat bubble is pushing the 500 millibar pressure level to a height that is higher (in this case, ~600 dm) than normal. Thanks Hoosier! So, then. 600dm= 6,000m or 19,685 ft? Or do I have that wrong? Thanks for the explanation. Makes things easier for a weather noob like me to understand Link to comment Share on other sites More sharing options...
Hoosier Posted July 16, 2013 Author Share Posted July 16, 2013 Thanks Hoosier! So, then. 600dm= 6,000m or 19,685 ft? Or do I have that wrong? Thanks for the explanation. Makes things easier for a weather noob like me to understand right Link to comment Share on other sites More sharing options...
Hoosier Posted July 16, 2013 Author Share Posted July 16, 2013 Current mesoanalysis has a 600 dm contour over N IN and nearby areas. It's in between all the sounding sites (ILX/DVN/ILN/DTX) so I don't know if any of the 00z RAOBS will pick it up. Link to comment Share on other sites More sharing options...
nwohweather Posted July 17, 2013 Share Posted July 17, 2013 Current mesoanalysis has a 600 dm contour over N IN and nearby areas. It's in between all the sounding sites (ILX/DVN/ILN/DTX) so I don't know if any of the 00z RAOBS will pick it up. Maybe DFI in Defiance will Link to comment Share on other sites More sharing options...
Chicago Storm Posted July 17, 2013 Share Posted July 17, 2013 Four ( ) locations in the region had 600DM at 0z...DVN, ILX, ILN and DTX... Link to comment Share on other sites More sharing options...
Hoosier Posted July 17, 2013 Author Share Posted July 17, 2013 Four ( ) locations in the region had 600DM at 0z...DVN, ILX, ILN and DTX... Wow. Don't think it would be a stretch to say it may be a once in a lifetime occurrence. Link to comment Share on other sites More sharing options...
Stebo Posted July 17, 2013 Share Posted July 17, 2013 Four ( ) locations in the region had 600DM at 0z...DVN, ILX, ILN and DTX... I am hoping for something >600 in the morning, ILX or DVN probably have the best shot at it. Link to comment Share on other sites More sharing options...
Hoosier Posted July 17, 2013 Author Share Posted July 17, 2013 Link to comment Share on other sites More sharing options...
Chicago Storm Posted July 17, 2013 Share Posted July 17, 2013 Here is the contoured map version... Link to comment Share on other sites More sharing options...
Chicago Storm Posted July 17, 2013 Share Posted July 17, 2013 I am hoping for something >600 in the morning, ILX or DVN probably have the best shot at it. A time when a N. IN sounding would have been nice to have... Link to comment Share on other sites More sharing options...
Hoosier Posted July 17, 2013 Author Share Posted July 17, 2013 In the past 13 months, ILX has recorded an 850 mb temp of 30C and 500 mb height of 600 dm. They might be the only station east of the MS to reach both of those levels in the entire RAOB era let alone a little over a year apart. Link to comment Share on other sites More sharing options...
cyclone77 Posted July 17, 2013 Share Posted July 17, 2013 Thicknesses are very impressive, but the heat wave is rather meager for July. Still cool though. Link to comment Share on other sites More sharing options...
Jonger Posted July 18, 2013 Share Posted July 18, 2013 Thanks Hoosier! So, then. 600dm= 6,000m or 19,685 ft? Or do I have that wrong? Thanks for the explanation. Makes things easier for a weather noob like me to understand I'm a newb when it comes to heights, would this provide a efficient transport of lower level moisture further up in the column? Like I said, newb. Link to comment Share on other sites More sharing options...
michsnowfreak Posted July 18, 2013 Share Posted July 18, 2013 Thicknesses are very impressive, but the heat wave is rather meager for July. Still cool though.I don't even fully understand this thickness stuff in the summer lol...but I do know that from a sensible weather aspect (as unbearable as it is) this heatwave is NOTHING. Why are the temps not more impressive if the 600dm heights are so epic? Link to comment Share on other sites More sharing options...
Hoosier Posted July 18, 2013 Author Share Posted July 18, 2013 I don't even fully understand this thickness stuff in the summer lol...but I do know that from a sensible weather aspect (as unbearable as it is) this heatwave is NOTHING. Why are the temps not more impressive if the 600dm heights are so epic? The 600 dm heights were more of a result of an unusually deeply warm airmass. During the peak height period, freezing levels were really high (like 17-18k feet) and the 500-600 mb layer was quite warm. Deeply warm doesn't always equate to blowtorch/record warmth, and 850 mb temps were not terribly impressive. Link to comment Share on other sites More sharing options...
Mallow Posted July 18, 2013 Share Posted July 18, 2013 Not that this is in the region, but I noticed the thread and remember this one well... Link to comment Share on other sites More sharing options...
Chinook Posted July 18, 2013 Share Posted July 18, 2013 I don't even fully understand this thickness stuff in the summer lol...but I do know that from a sensible weather aspect (as unbearable as it is) this heatwave is NOTHING. Why are the temps not more impressive if the 600dm heights are so epic? Sometimes the extreme 100F situations in the Midwest and Great Lakes have more of a dry airmass that develops in the south central (or even the desert) that moves to the Midwest, with drought-type soil moisture, like last year. Right now, we have a high-moisture, high-PW airmass that developed on top of us, along with medium or high soil moisture. Link to comment Share on other sites More sharing options...
michsnowfreak Posted July 18, 2013 Share Posted July 18, 2013 The 600 dm heights were more of a result of an unusually deeply warm airmass. During the peak height period, freezing levels were really high (like 17-18k feet) and the 500-600 mb layer was quite warm. Deeply warm doesn't always equate to blowtorch/record warmth, and 850 mb temps were not terribly impressive..Thanks for the explanation! Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.