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Hurricane Sandy - LIVE - Meteorological Discussion


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102 Knot FL winds now.

URNT15 KNHC 290109

AF308 2218A SANDY HDOB 24 20121029

005930 3244N 07247W 6967 02888 9798 +061 -015 287095 098 046 003 00

010000 3242N 07247W 6960 02900 9798 +066 -016 287093 095 046 003 00

010030 3241N 07248W 6970 02888 9801 +065 -020 287094 096 046 003 00

010100 3239N 07248W 6967 02892 9802 +067 -019 287092 093 047 004 00

010130 3237N 07248W 6969 02894 9800 +070 -014 285090 092 044 003 00

010200 3236N 07249W 6971 02897 9805 +068 -014 282092 094 044 005 00

010230 3234N 07249W 6962 02905 9818 +057 -007 282097 098 044 006 00

010300 3233N 07249W 6963 02909 9818 +059 -020 283100 102 045 006 00

010330 3231N 07250W 6971 02902 9819 +062 -029 285098 102 045 006 00

010400 3229N 07250W 6968 02907 9830 +055 -016 286091 095 047 006 00

010430 3228N 07250W 6965 02914 9827 +059 -021 286096 097 046 008 00

010500 3226N 07251W 6965 02916 9827 +062 -018 287090 096 047 005 00

010530 3224N 07251W 6967 02912 9833 +059 -023 284089 090 047 006 00

010600 3223N 07252W 6968 02916 9838 +055 -016 282089 091 047 006 00

010630 3221N 07252W 6965 02920 9828 +064 -001 280085 086 046 006 00

010700 3220N 07252W 6962 02925 9821 +073 -014 279082 085 043 005 00

010730 3218N 07253W 6961 02927 9812 +082 -035 284086 088 044 006 00

010800 3216N 07253W 6978 02906 9803 +094 -063 287085 089 045 004 03

010830 3216N 07254W 6963 02929 9809 +091 -063 291082 085 /// /// 03

010900 3218N 07254W 6970 02922 9815 +083 -059 288078 081 042 006 03

$$

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102 Knot FL winds now.

URNT15 KNHC 290109

AF308 2218A SANDY HDOB 24 20121029

005930 3244N 07247W 6967 02888 9798 +061 -015 287095 098 046 003 00

010000 3242N 07247W 6960 02900 9798 +066 -016 287093 095 046 003 00

010030 3241N 07248W 6970 02888 9801 +065 -020 287094 096 046 003 00

010100 3239N 07248W 6967 02892 9802 +067 -019 287092 093 047 004 00

010130 3237N 07248W 6969 02894 9800 +070 -014 285090 092 044 003 00

010200 3236N 07249W 6971 02897 9805 +068 -014 282092 094 044 005 00

010230 3234N 07249W 6962 02905 9818 +057 -007 282097 098 044 006 00

010300 3233N 07249W 6963 02909 9818 +059 -020 283100 102 045 006 00

010330 3231N 07250W 6971 02902 9819 +062 -029 285098 102 045 006 00

010400 3229N 07250W 6968 02907 9830 +055 -016 286091 095 047 006 00

010430 3228N 07250W 6965 02914 9827 +059 -021 286096 097 046 008 00

010500 3226N 07251W 6965 02916 9827 +062 -018 287090 096 047 005 00

010530 3224N 07251W 6967 02912 9833 +059 -023 284089 090 047 006 00

010600 3223N 07252W 6968 02916 9838 +055 -016 282089 091 047 006 00

010630 3221N 07252W 6965 02920 9828 +064 -001 280085 086 046 006 00

010700 3220N 07252W 6962 02925 9821 +073 -014 279082 085 043 005 00

010730 3218N 07253W 6961 02927 9812 +082 -035 284086 088 044 006 00

010800 3216N 07253W 6978 02906 9803 +094 -063 287085 089 045 004 03

010830 3216N 07254W 6963 02929 9809 +091 -063 291082 085 /// /// 03

010900 3218N 07254W 6970 02922 9815 +083 -059 288078 081 042 006 03

$$

So about what is that at the surface?

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What? That's really low. Wow.

This buoy is 150 miles east of Hatteras so its pretty close maybe 75-100 miles away from the center gusting to 30-40 knts last few obs

http://www.ndbc.noaa...p?station=41001

the east side is better it appears this buoy is 125-150 miles east of the center and has winds gusting to 60 knts

http://www.ndbc.noaa...p?station=41048

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Recon is finding a FL-SFC reduction factor near 50% #lifesaver

Yep. That doesn't surprise me at all. The 90% value that we often apply pretty-much applies only to strengthening cyclones, deep in or near the tropics, with solid convection. In most 'canes-- especially higher-latitude ones with weak convection-- the value is much lower.

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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):

GJfiD.gif

v1piI.gif

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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):

is this inversion going to weaken or dissapate to help get these winds to the surface more efficiently? kind of thought thats what it was

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The inversion makes it tough to know how much wind gusts to play for various cities.

we were chatting about this in the philly thread. A lot of the high res models and nowcasting models show that inversion coming into southern jersey and into se pa reducing the winds. you can see it here on the 925 wind map off the RAP

RAP_255_2012102900_F18_WSPD_925_MB.png

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we were chatting about this in the philly thread. A lot of the high res models and nowcasting models show that inversion coming into southern jersey and into se pa reducing the winds. you can see it here on the 925 wind map off the RAP

925 is still well off the ground making it hard to know how much of those winds will get to the surface.

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we were chatting about this in the philly thread. A lot of the high res models and nowcasting models show that inversion coming into southern jersey and into se pa reducing the winds. you can see it here on the 925 wind map off the RAP

It's called an eye...come on man.

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Lake Erie Buoy 45005, north of Sandusky, Ohio, reporting sustained winds of 29 knots (33 mph) and gusts to 35 knots (40 mph) at 5 m agl. Sustained winds at 10 m agl were reported to be 31 knots (36 mph) and 33 knots (38 mph) at 20 m agl. So Sandy is nearly producing tropical storm force winds all the way over Lake Erie now. Obviously, there are no tropical storm force winds over the land areas between Sandy's center of circulation and Lake Erie but there are near tropical storm force winds over the open waters of the lake.

http://www.ndbc.noaa...p?station=45005

That's a very good point, and one I'm going to be keenly interested in over the next 24-48 hours. Model soundings (WRF, GFS) over the interior portions of the mid Atlantic show quite a bit of warm mid and even upper tropospheric air, to the degree where the lapse rates are even weaker than moist adiabatic through 500 mb or so. It will be tough to effectively mix down these higher winds aloft on the west side of this system, given such a deep warm, moist profile aloft. At least with Isabel and Irene, there was some dryer air entrainment aloft on the backside, which made for fairly impressive "gust factors" at the surface (i.e. on the order of 2 or so, with obs like "28G57KT"). In this event I'm not so sure the gust factor over land will be there, especially given the time of year with the warm profile aloft and a cool northerly low level flow (i.e. stable environment). At least that's what the forecast soundings are suggesting, though the worst winds for many mid-Atlantic areas south of Sandy's track, and east of the mountains, may be when Sandy makes it far enough inland to allow more of a NW-W surface wind, with the ensuing downsloping component perhaps providing enough (certainly better) low level mixing to allow some of those stronger winds to transport downward.

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I am betting that reduction factor changes pretty fast once cold air really begins to wrap around the center. Bufkit profiles show a rapid steepening of the low-level lapse rates in response.

The nam shows a steeper lapse rate up to the stronger winds at 925 on a couple of 3 hourly soundings at DCA so it doesn't look to bad to me for those two periods. I suspect that the gfs will show strongly winds at 925 than the nam.

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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):

My guess are those are from the outer band of intense flight winds (correct me if I'm wrong). Do you have any charts from sondes nearer the center of circulation? I ask because it seems the reduction factor is actually higher than 0.90 near the center, based on sonde and SFMR data.

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The vort over the deep south is just now beginning to phase with Sandy. That should start to strengthen her overnight and allow the turn west. Still interesting how a system behaving in this manner can be classified as a hurricane. All further strengthening is going to be based on polar jet phasing/interaction. Not SSTs or "improved structure", in the tropical sense.

http://www.aviationw...ltiple&itype=wv

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Wind shear over the cyclone's central circulation has dropped to about 15kt and it appears to be responding.

The IR depiction has improved quite a bit over the last few hours. Relatively cold tops now surrounding the eye with an expanding area of rather cold tops (coldest in quite some time) over the western semicircle.

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My guess are those are from the outer band of intense flight winds (correct me if I'm wrong). Do you have any charts from sondes nearer the center of circulation? I ask because it seems the reduction factor is actually higher than 0.90 near the center, based on sonde and SFMR data.

You are correct, they are from the outer wind maximum. There haven't been any sondes in the eyewall, but as you note the winds seems to be translating much better down to the surface based on SFMR data.

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