stormskeptic Posted October 29, 2012 Share Posted October 29, 2012 An interesting, well-defined inversion is evident in some of the dropsondes, which is helping to prevent some of the higher winds aloft from mixing down to the surface. A couple examples (images from tropicalatlantic.com): The other interesting thing about this dropsonde sounding is how the strongest winds are at flight level (I think about 700mb) and go down from there. In a purely tropical system isn't the vortex and thus the winds usually strongest around 950 mb? I wonder if they are just measuring some of the energy from the trough rotating around the bottom of the circulation. Link to comment Share on other sites More sharing options...
allgame830 Posted October 29, 2012 Share Posted October 29, 2012 Wondering since the 11pm update has Sandy at 950 MB, but the dropsonde had 949MB. I know its only 1 MB but how come they did not put that in the advisory. Link to comment Share on other sites More sharing options...
Ed Lizard Posted October 29, 2012 Share Posted October 29, 2012 Facebook: Nicole Mitchell Only the hard-core weather geeks will probably understand this. The short version is that Sandy still has some very tropical characteristics! From a former military colleague (Rich Henning) who now does the NOAA side of the hurricane missions: For my tropical friends....a pretty amazing G-IV research mission across Hurricane Sandy is just concluding. The jet bombed the center from 150 mb and found 951 mb with a dropsonde. A P-3 fixing the center from 12,000 feet dropped a sonde two minutes earlier and found the same 951 central surface pressure. The G-IV showed how intact the warm core remains all the way up to 300mb and how surprisingl y light the shear is over the core up at 200mb (with both directional diffluence and speed divergence making things amazingly favorable to keep Sandy remaining tropical for the moment). On my P-3 mission earlier this morning there was enough core convection to briefly form an elliptical eyewall for one of our center fixes. Link to comment Share on other sites More sharing options...
Mallow Posted October 29, 2012 Share Posted October 29, 2012 It's interesting that the BAM suite would take Sandy way north... suggesting the more tropical Sandy is, the further north she goes. The reason I bring it up is that, per a wunderground comparison of Satellite to modeled data, Sandy is currently east of every model's forecast at 03z (NAM, GFS, Euro, even RUC and RPM). Unless the "eye" is misleading and the actual mslp center is located under the middle of the convective burst that appears to be the western eyewall. EDIT: Though that may not be related at all to it being "more tropical" than expected. Most of the GFS ensembles were further east and ended up bringing Sandy in to the same area the operational did. Link to comment Share on other sites More sharing options...
HurricaneJosh Posted October 29, 2012 Share Posted October 29, 2012 One important thing to point out: that little eyewall/core thing looks awesome, but that's not where the highest winds are occurring. They're occurring more than 100 n mi from the center-- and that's just not a very tropical-style wind field. Link to comment Share on other sites More sharing options...
newtownwx Posted October 29, 2012 Share Posted October 29, 2012 It's interesting that the BAM suite would take Sandy way north... suggesting the more tropical Sandy is, the further north she goes. The reason I bring it up is that, per a wunderground comparison of Satellite to modeled data, Sandy is currently east of every model's forecast at 03z (NAM, GFS, Euro, even RUC and RPM). Unless the "eye" is misleading and the actual mslp center is located under the middle of the convective burst that appears to be the western eyewall. EDIT: Though that may not be related at all to it being "more tropical" than expected. Most of the GFS ensembles were further east and ended up bringing Sandy in to the same area the operational did. Interesting point there Mallow. Is it possible to infer that the blow-up in convection could be due to upper-level divergence and therefore large values of negative omega? This could tell us the direction in which the low is moving (west). We just went over this lesson in my Synoptic class, wasn't sure if I could apply Dine's Compensation here. Link to comment Share on other sites More sharing options...
NaoPos Posted October 29, 2012 Share Posted October 29, 2012 One important thing to point out: that little eyewall/core thing looks awesome, but that's not where the highest winds are occurring. They're occurring more than 100 n mi from the center-- and that's just not a very tropical-style wind field. Absolutely. All that is doing is just expanding the wind field further and further. Link to comment Share on other sites More sharing options...
BlizzardWx Posted October 29, 2012 Share Posted October 29, 2012 Great analysis guys. Sandy is looking much healthier this evening with the convection wrapping around the eye again. Looks prime for strengthening to start occuring. Link to comment Share on other sites More sharing options...
Cheeznado Posted October 29, 2012 Share Posted October 29, 2012 NHC still looks to be too slow and too far south as all guidance has landfall at 0Z or maybe a hour or two later. Also, this may come closer to central or northern NJ than southern. Link to comment Share on other sites More sharing options...
CT Rain Posted October 29, 2012 Share Posted October 29, 2012 NHC still looks to be too slow and too far south as all guidance has landfall at 0Z or maybe a hour or two later. Also, this may come closer to central or northern NJ than southern. I did see the GFS tick south a bit from its 18z run toward more S NJ. Do agree about too slow. Link to comment Share on other sites More sharing options...
billgwx Posted October 29, 2012 Share Posted October 29, 2012 925 is still well off the ground making it hard to know how much of those winds will get to the surface. Only about 1200 ft with this intense storm, and forecast soundings continue to show a mixed layer reaching to that level. Also worried it could happen in a burst late this afternoon especially across coastal CT and Long Island via gravity wave ducting accompanying the intense 100-kt 850 mb LLJ NE of the center. Steepening lapse rates after the center makes landfall will probably do the job more efficiently. Think both will yield 75-85 mph gusts. Link to comment Share on other sites More sharing options...
downeastnc Posted October 29, 2012 Share Posted October 29, 2012 41001 B 0250 34.56 -72.63 105 273 360 19.4 25.3 21.7 13 9.8 62 28.66 +0.03 77.4 79.5 Buoy 41001 105 nm west of the center showing the winds are not mixing down very well right now peak gust last hr was 29.1 knt http://www.ndbc.noaa.gov/station_page.php?station=41001 However buoy 41048 250 west of Bermuda is getting hammered pretty good well east of the center peak gust last hr was 60.2 knts http://www.ndbc.noaa.gov/station_page.php?station=41048 Same with 41002 225 miles south of Hatteras its been gusting 40-50 every hr for most of the day http://www.ndbc.noaa.gov/station_page.php?station=41002 so maybe this is a bit of good news for the coastal areas as the NW quad seems to be the weakest at least at this time. Link to comment Share on other sites More sharing options...
billgwx Posted October 29, 2012 Share Posted October 29, 2012 41001 B 0250 34.56 -72.63 105 273 360 19.4 25.3 21.7 13 9.8 62 28.66 +0.03 77.4 79.5 Buoy 41001 105 nm west of the center showing the winds are not mixing down very well right now peak gust last hr was 29.1 knt http://www.ndbc.noaa...p?station=41001 Buoy 41001 is in a relative lull right now compared to much stronger 925 mb winds to both the north and south of the center. Next few hours will be telling as the GFS forecasts 70-75 kt 925 mb winds to pass over. Link to comment Share on other sites More sharing options...
Floydbuster Posted October 29, 2012 Share Posted October 29, 2012 Late night video update on Sandy. Wind howling on Statue of Liberty webcam. Link to comment Share on other sites More sharing options...
Ed Lizard Posted October 29, 2012 Share Posted October 29, 2012 Only about 1200 ft with this intense storm, and forecast soundings continue to show a mixed layer reaching to that level. Also worried it could happen in a burst late this afternoon especially across coastal CT and Long Island via gravity wave ducting accompanying the intense 100-kt 850 mb LLJ NE of the center. Steepening lapse rates after the center makes landfall will probably do the job more efficiently. Think both will yield 75-85 mph gusts. You get LL lapse rates in Suffolk County well after Sandy is inland, and in an generally onshore direction. Link to comment Share on other sites More sharing options...
yoda Posted October 29, 2012 Share Posted October 29, 2012 948.8 mb extrap at 34.883 N 70.600 W Link to comment Share on other sites More sharing options...
Kaner587 Posted October 29, 2012 Share Posted October 29, 2012 948.8 mb extrap at 34.883 N 70.600 W was just going to post that...lowest so far. Definitely impressive. Link to comment Share on other sites More sharing options...
turtlehurricane Posted October 29, 2012 Share Posted October 29, 2012 Convection has become more impressive in the past several hours. I think Sandy will have a decent shot to intensify as it turns to the west under the ridge, that's usually a favorable configuration for tropical cyclone intensification since shear decreases, even though this is a hybrid I think that rule of thumb still holds. Link to comment Share on other sites More sharing options...
yoda Posted October 29, 2012 Share Posted October 29, 2012 Totally lost on reading the Air Force dropsonde obs... but looks like 35.0N 70.6 W is the eye Link to comment Share on other sites More sharing options...
nyblizz44 Posted October 29, 2012 Share Posted October 29, 2012 Totally lost on reading the Air Force dropsonde obs... but looks like 35.0N 70.6 W is the eye u have the link by chance? Link to comment Share on other sites More sharing options...
yoda Posted October 29, 2012 Share Posted October 29, 2012 u have the link by chance? http://tropicalatlantic.com/recon/UZNT13/KNHC/ Link to comment Share on other sites More sharing options...
mike2010 Posted October 29, 2012 Share Posted October 29, 2012 10/29 05:19:32Z 948.8 MB Link to comment Share on other sites More sharing options...
gulfcane Posted October 29, 2012 Share Posted October 29, 2012 000 URNT15 KNHC 290539 AF308 2218A SANDY HDOB 51 20121029 052930 3422N 07125W 6967 02808 9663 +095 +059 284047 048 022 003 00 053000 3420N 07127W 6964 02812 9663 +099 +056 282048 048 022 003 00 053030 3419N 07128W 6965 02813 9665 +099 +063 284044 048 023 005 00 053100 3418N 07129W 6968 02807 9690 +080 +080 280039 041 025 005 01 053130 3417N 07131W 6963 02816 9690 +080 +080 282040 043 029 007 01 053200 3416N 07132W 6981 02798 9688 +080 +080 281046 048 032 011 00 053230 3415N 07133W 6970 02814 9681 +090 +066 283046 047 031 007 00 053300 3414N 07134W 6959 02826 9696 +070 +070 288041 045 047 009 01 053330 3413N 07136W 6962 02828 9694 +080 +072 291045 047 071 010 00 053400 3412N 07137W 6969 02813 9697 +074 +073 296045 046 072 015 00 053430 3410N 07138W 6962 02820 9704 +070 +070 292044 045 069 017 01 053500 3409N 07139W 6963 02818 9706 +070 +070 292048 050 071 012 01 053530 3408N 07141W 6977 02807 9699 +070 +070 288049 052 071 012 01 053600 3407N 07142W 6966 02821 9705 +070 +070 283045 049 070 012 01 053630 3406N 07143W 6967 02825 9711 +070 +070 279043 045 078 010 01 053700 3405N 07144W 6963 02832 9706 +077 +070 283045 046 077 010 00 053730 3404N 07146W 6965 02834 9710 +076 +071 286049 051 075 010 00 053800 3403N 07147W 6966 02831 9721 +060 +060 290045 051 073 010 01 053830 3402N 07148W 6961 02843 9714 +076 +070 295046 048 071 006 00 053900 3400N 07150W 6965 02838 9703 +089 +072 296050 050 069 002 00 The 71kt SFMR was uncontaminated....some higher values were with high rain rates though. So about 70kts it appears. The 78kts was contaminated. Link to comment Share on other sites More sharing options...
yoda Posted October 29, 2012 Share Posted October 29, 2012 000 URNT15 KNHC 290539 AF308 2218A SANDY HDOB 51 20121029 052930 3422N 07125W 6967 02808 9663 +095 +059 284047 048 022 003 00 053000 3420N 07127W 6964 02812 9663 +099 +056 282048 048 022 003 00 053030 3419N 07128W 6965 02813 9665 +099 +063 284044 048 023 005 00 053100 3418N 07129W 6968 02807 9690 +080 +080 280039 041 025 005 01 053130 3417N 07131W 6963 02816 9690 +080 +080 282040 043 029 007 01 053200 3416N 07132W 6981 02798 9688 +080 +080 281046 048 032 011 00 053230 3415N 07133W 6970 02814 9681 +090 +066 283046 047 031 007 00 053300 3414N 07134W 6959 02826 9696 +070 +070 288041 045 047 009 01 053330 3413N 07136W 6962 02828 9694 +080 +072 291045 047 071 010 00 053400 3412N 07137W 6969 02813 9697 +074 +073 296045 046 072 015 00 053430 3410N 07138W 6962 02820 9704 +070 +070 292044 045 069 017 01 053500 3409N 07139W 6963 02818 9706 +070 +070 292048 050 071 012 01 053530 3408N 07141W 6977 02807 9699 +070 +070 288049 052 071 012 01 053600 3407N 07142W 6966 02821 9705 +070 +070 283045 049 070 012 01 053630 3406N 07143W 6967 02825 9711 +070 +070 279043 045 078 010 01 053700 3405N 07144W 6963 02832 9706 +077 +070 283045 046 077 010 00 053730 3404N 07146W 6965 02834 9710 +076 +071 286049 051 075 010 00 053800 3403N 07147W 6966 02831 9721 +060 +060 290045 051 073 010 01 053830 3402N 07148W 6961 02843 9714 +076 +070 295046 048 071 006 00 053900 3400N 07150W 6965 02838 9703 +089 +072 296050 050 069 002 00 The 71kt SFMR was uncontaminated....some higher values were with high rain rates though. So about 70kts it appears. The 78kts was contaminated. What about the 77 one right below the contaminated 78? Link to comment Share on other sites More sharing options...
allgame830 Posted October 29, 2012 Share Posted October 29, 2012 000 URNT15 KNHC 290539 AF308 2218A SANDY HDOB 51 20121029 052930 3422N 07125W 6967 02808 9663 +095 +059 284047 048 022 003 00 053000 3420N 07127W 6964 02812 9663 +099 +056 282048 048 022 003 00 053030 3419N 07128W 6965 02813 9665 +099 +063 284044 048 023 005 00 053100 3418N 07129W 6968 02807 9690 +080 +080 280039 041 025 005 01 053130 3417N 07131W 6963 02816 9690 +080 +080 282040 043 029 007 01 053200 3416N 07132W 6981 02798 9688 +080 +080 281046 048 032 011 00 053230 3415N 07133W 6970 02814 9681 +090 +066 283046 047 031 007 00 053300 3414N 07134W 6959 02826 9696 +070 +070 288041 045 047 009 01 053330 3413N 07136W 6962 02828 9694 +080 +072 291045 047 071 010 00 053400 3412N 07137W 6969 02813 9697 +074 +073 296045 046 072 015 00 053430 3410N 07138W 6962 02820 9704 +070 +070 292044 045 069 017 01 053500 3409N 07139W 6963 02818 9706 +070 +070 292048 050 071 012 01 053530 3408N 07141W 6977 02807 9699 +070 +070 288049 052 071 012 01 053600 3407N 07142W 6966 02821 9705 +070 +070 283045 049 070 012 01 053630 3406N 07143W 6967 02825 9711 +070 +070 279043 045 078 010 01 053700 3405N 07144W 6963 02832 9706 +077 +070 283045 046 077 010 00 053730 3404N 07146W 6965 02834 9710 +076 +071 286049 051 075 010 00 053800 3403N 07147W 6966 02831 9721 +060 +060 290045 051 073 010 01 053830 3402N 07148W 6961 02843 9714 +076 +070 295046 048 071 006 00 053900 3400N 07150W 6965 02838 9703 +089 +072 296050 050 069 002 00 The 71kt SFMR was uncontaminated....some higher values were with high rain rates though. So about 70kts it appears. The 78kts was contaminated. So does this mean, Sandy's winds will be upped sometimes over the night? Link to comment Share on other sites More sharing options...
gulfcane Posted October 29, 2012 Share Posted October 29, 2012 What about the 77 one right below the contaminated 78? 2nd to last column is the rain rate, not the last column. 10 would be 10 mm/hr rain rate. I think NHC will typically discount the SFMR at 10 and above but it just depends. The last column where several ended in 01 just means the temp is questionable not the winds. 053700 3405N 07144W 6963 02832 9706 +077 +070 283045 046 077 010 00 Link to comment Share on other sites More sharing options...
phil882 Posted October 29, 2012 Share Posted October 29, 2012 A rain rate of 10 mm is not that significant in the grand scheme of things. The more eyebrow raising observation is that this took place in an area of relatively light flight level winds, which could provide a clue that these winds might not be accurate. still though, thats a widespread swath of 70+ knot surface winds. That could be justification alone for a slight bump up in the winds as long as the data is accurate. EDIT: The winds have been verified by a dropsonde that measured 72 knots at 969 hPa (~10-20m before splashdown) in roughly the same area. It is also interesting to note that while the 700 hPa winds were only 50 knots, the same region was 104 knots at 850 hPa. There is definitely some lower toped convection that is making things more interesting in the SW quadrant. Link to comment Share on other sites More sharing options...
turtlehurricane Posted October 29, 2012 Share Posted October 29, 2012 Light snow being observed in the Appalachians, mostly upslope but there are some bands associated with Sandy in West Virginia (albeit primarily jet forced) collocated with sub 0 °C 850 temperatures. Link to comment Share on other sites More sharing options...
gulfcane Posted October 29, 2012 Share Posted October 29, 2012 A rain rate of 10 mm is not that significant in the grand scheme of things. The more eyebrow raising observation is that this took place in an area of relatively light flight level winds, which could provide a clue that these winds might not be accurate. still though, thats a widespread swath of 70+ knot surface winds. That could be justification alone for a slight bump up in the winds as long as the data is accurate. SFMR readings were not flagged as questionable as the last column did not include "3". Plus the next data set has a lot of FL winds in the 80's. Seems reasonable. 70kts. Link to comment Share on other sites More sharing options...
battlebrick Posted October 29, 2012 Share Posted October 29, 2012 dropsonde found 83 mph winds just above the surface (969 mb).. for some reason didn't record at surface (972 mb).. the ~120 mph winds in the upper levels are pretty frightening. Link to comment Share on other sites More sharing options...
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