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Potential Thanksgiving Event

strongwxnc

By strongwxnc,
in Southeastern States

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GaWx

GaWx

Posted
Posted

"On January 7 and 8, 1973, Atlanta and areas of north Georgia were hard hit by one to four inches of ice that closed schools and left 300,000 people without power for up to a week. Over 2.25 inches of liquid equivalent in the form of freezing rain, sleet, and snow fell on Atlanta between 7:00pm and 9:00 a.m. on January 8, while temperatures remained at 32°F. "

  That, among the obvious things is what stuck out to me....32 the whole event on the porch thermometer in Buckhead.  Granted it wasn't a great one, so it could have fluctuated some, but in the trees where the money shot was, it was cold enough to dissipate the heat as it fell.  My front steps rail had over three inches on it, and up top the limbs had more.  And it was zmonster in my yard...no sn or ip.

  Don't get cozy thinking the heat will save you if every thing lines up right, but we had reinforcing winds too, fighting the waa step for step. I don't see this being that, lol. I doubt that comes along very often.

 

Tony,

 A big thank you for setting the record straight for Atlanta major icestorm climo. What the poster "1300m" may not realize is that the Atlanta and nearby areas of N GA, which we know much better historywise/climowise through our own experience and extensive research, do not have the same climo as his area of NC. In ATL, strong wedges can really put the stop on the thermometer due to our geography. That was considered one of the worst Atlanta icestorms in recorded history (>2.25: liquid). Yet, the temperatures stayed right at 32 F for 14 hours with ZR!!

 

 That is just one significant ATL icestorm with 30+ for the coldest. I just checked the 28 significant ATL icestorms since 1879 for which I have temperature data. (I'm missing all temp. data for only one.) A very respectable 10 of these 28 had the coldest at 30-32, including both icestorms of Jan. 2000 (lowest 31 and 30, respectively..2nd one hit during Super Bowl) and the 12/14-15/2005 storm (lowest 31). Others with lowest of 30-32: 2/6/1979, 1/7-8/1973 (Tony's storm), 3/25/1971, 12/24-25/1962, 1/23/1923, 1/8/1912, and 1/30/1882. Of these 10, one low was 32, four were at 31, and five were at 30.

 

 Compilation of lowest temp. for all 28 ATL sig. icestorms since 1879 for which temp. data available:

 

32: one storm

31: four storms

30: five storms

29: five storms

28: six storms

27: two storms

26: three storms

25: no storms

24: one storm

23: one storm

 

Edit: When there is ZR/steady E to NE winds, Hartsfield airport is actually quite representative of the surrounding area.

 

Edit #2: Case closed. When one has the facts/hard data to back up his side, it is hard to lose.

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1300m

1300m

Posted
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Tony,

 A big thank you for setting the record straight for Atlanta major icestorm climo. What the poster "1300m" may not realize is that the Atlanta and nearby areas of N GA, which we know much better historywise/climowise through our own experience and extensive research, do not have the same climo as his area of NC. In ATL, strong wedges can really put the stop on the thermometer due to our geography. That was considered one of the worst Atlanta icestorms in recorded history (>2.25: liquid). Yet, the temperatures stayed right at 32 F for 14 hours with ZR!!

 

 That is just one significant ATL icestorm with 30+ for the coldest. I just checked the 28 significant ATL icestorms since 1879 for which I have temperature data. (I'm missing all temp. data for only one.) A very respectable 10 of these 28 had the coldest at 30-32, including both icestorms of Jan. 2000 (lowest 31 and 30, respectively..2nd one hit during Super Bowl) and the 12/14-15/2005 storm (lowest 31). Others with lowest of 30-32: 2/6/1979, 1/7-8/1973 (Tony's storm), 3/25/1971, 12/24-25/1962, 1/23/1923, 1/8/1912, and 1/30/1882. Of these 10, one low was 32, four were at 31, and five were at 30.

 

 Compilation of lowest temp. for all 28 ATL sig. icestorms since 1879 for which temp. data available:

 

32: one storm

31: four storms

30: five storms

29: five storms

28: six storms

27: two storms

26: three storms

25: no storms

24: one storm

23: one storm

 

Edit: 3. When there is ZR/steady E to NE winds, Hartsfield airport is actually quite representative of the surrounding area.

 

So, based on your own statistics, 23/28 of ATL's most significant ice storms occurred with a temperature that had been at or below 30F which is exactly what I said to begin with. 

 

The other thing that I mentioned which I'm not sure you saw was that just because ATL is showing 32 does not mean that other locations are at that temperature. It would likely be a degree or two colder in those areas. At 32, latent heat will limit ice accrual and that is a scientific fact.

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NCCatawba

NCCatawba

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Reports tonight will be interesting. I think the further norther locations will pick up on a little bit more snow and sleet than expected. My best guess would be from Surry County down to perhaps to here in north-west Catawba. But definetly the areas in between with maybe a sweet spot near Taylorsville. We will see.

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GaWx

GaWx

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Posted

So, based on your own statistics, 23/28 of ATL's most significant ice storms occurred with a temperature that had been at or below 30F which is exactly what I said to begin with. 

 

The other thing that I mentioned which I'm not sure you saw was that just because ATL is showing 32 does not mean that other locations are at that temperature. It would likely be a degree or two colder in those areas. At 32, latent heat will limit ice accrual and that is a scientific fact.

 

 

Your original post was this:

 

"Just a general statement on freezing rain but in my opinion/experience freezing rain with a temperature at or above 30F is typically a self-limiting process because the latent heat of freezing results in melting and warming of the near-surface layer, limiting ice accrual.

 

Rarely have I ever seen a significant icing event occur when the surface temp wasn't colder than 30F during the event, although granted the antecedent cold conditions are helping to keep the ground (and other surfaces) cold before this one."

-------------------------------------------------------------------------------------------------------------------------------------------------------

 

 1) So, you originally referred to at or above 30, not above 30. Why are you now changing it to above 30? So, there have been 10 of 28 ATL icestorms not colder than 30. What's so rare about 10 of 28? That's 36% of the storms for a range of just three temperatures!

 

2) Also, only 28-31 each had the coldest for as many as 4-6 storms. So, I'd say that 30 and 31 are certainly well represented. Only right at 32 isn't well represented since there was only one. Looking at the overall distribution, 30-31 was well within the mix.

 

3) I never said that the most/majority of ATL icestorms had a coldest of 30+. I said this: "Atlanta has had a good number of major and lengthy ZR's with the lowest near or even slightly above 30." Your use of the word "rare" is not appropriate when one considers 36% had 30+! I think you're trying to weasel out of a losing argument.

 

4) I already said this (I know local climo..I've been following it closely for over 30 years)

 

"When there is ZR/steady E to NE winds, Hartsfield airport is actually quite representative of the surrounding area."

 

Example: 1/28-30/2000 icestorm (Super Bowl weekend): KATL low was 30. So was Marietta, NE ATL, and Peachtree City (FFC). West Atlanta was actually warmer at 31.

 

 So, I totally disagree with your statement. I think it is another attempt at weaseling out of your losing argument.

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Amos83

Amos83

Posted
Posted

just to report in.... it's been snowing here in Nashville for the past hour and half.... nothing heavy but it has been all snow now rain or sleet mix. Temp has dropped from 43 to 35 degrees during the time as we get some evap cooling. Should switch over to rain as the upper levels warm but wanted to give all my fellow southers east of me an update.

 

Oh and I'm in Nashville because my adopted son was just born! So not only am I getting to see it snow I'm a dad now :santa:

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HurricaneTracker

HurricaneTracker

Posted
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Here's the latest iteration of GSP's forecasted ice accretion totals. The Hickory "metroplex" circle of death has evaporated! But, still little accretion expected for my direct area.

This is also more than GSP had in their forecast this morning, especially for Asheville and points west, which are usually quite safe from ZR events as they are further from the cooling effects of the escarpment.

Sent from my steam-powered printing press.

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Snow Wisher

Snow Wisher

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Posted

just to report in.... it's been snowing here in Nashville for the past hour and half.... nothing heavy but it has been all snow now rain or sleet mix. Temp has dropped from 43 to 35 degrees during the time as we get some evap cooling. Should switch over to rain as the upper levels warm but wanted to give all my fellow southers east of me an update.

 

Oh and I'm in Nashville because my adopted son was just born! So not only am I getting to see it snow I'm a dad now :santa:

Congratulations!!!! 

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dsaur

dsaur

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"Only right at 32 isn't well represented since there was only one."     Oh, it represented!  That was the most representingest storm I ever saw until the Blizzard, lol.   There was a thermometer on the bank at the head of my street, next to Lenox. and it read 32 the whole storm too, so I have back up :)  It poured and poured, and was zrain right from the start.  The trees were creaking by 8 or 9 with the build up.  By 2  I never wanted anything to stop more...well, except for those times I drank too much :)   Only a few times have I ever wanted to see the temp go up from 32.   But I don't think that would have stopped it.   That storm wanted Atlanta to die!   T

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HKY_WX

HKY_WX

Posted
Posted

Good luck to those out west. I will be back in hky for thanksgiving wednesday, hoping to catch some back end snow showers on the drive wed even/night. I think tomorrow morning looks like a good .1 to .15 over the foothills with some areas near a quarter inch in the escarpment/mountain valleys. Will be slick in the early morning hours.

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jburns

jburns

Posted
Posted

just to report in.... it's been snowing here in Nashville for the past hour and half.... nothing heavy but it has been all snow now rain or sleet mix. Temp has dropped from 43 to 35 degrees during the time as we get some evap cooling. Should switch over to rain as the upper levels warm but wanted to give all my fellow southers east of me an update.

 

Oh and I'm in Nashville because my adopted son was just born! So not only am I getting to see it snow I'm a dad now :santa:

 

Snow is nice, but this is awesome.  Congratulations!

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NavarreDon

NavarreDon

Posted
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Can't remember who posted the link for the wind map but a big thanks! I realize it not real time but it is a amazing look at a cad in action! Here is the link for anyone who doesn't have it. Click on a area several times to enlarge it. Really neat to see the "CAD funnel" & the interaction the Mnts provide.

 

http://hint.fm/wind/

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GaWx

GaWx

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Posted

"Only right at 32 isn't well represented since there was only one."     Oh, it represented!  That was the most representingest storm I ever saw until the Blizzard, lol.   There was a thermometer on the bank at the head of my street, next to Lenox. and it read 32 the whole storm too, so I have back up :)  It poured and poured, and was zrain right from the start.  The trees were creaking by 8 or 9 with the build up.  By 2  I never wanted anything to stop more...well, except for those times I drank too much :)   Only a few times have I ever wanted to see the temp go up from 32.   But I don't think that would have stopped it.   That storm wanted Atlanta to die!   T

 

 T,

 I'm going by Hartsield which was actually colder (30 for the lowest during the precip.) So, I'm counting that as a 30 F storm for coldest. So, here's another example of Hartsfield not being warmer. It was apparently slightly colder. Measurable rainfall started there at 1 PM on 1/7 and it continued through 7 AM on 1/8: 18 straight hours!

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NEGa

NEGa

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Can't remember who posted the link for the wind map but a big thanks! I realize it not real time but it is a amazing look at a cad in action! Here is the link for anyone who doesn't have it. Click on a area several times to enlarge it. Really neat to see the "CAD funnel" & the interaction the Mnts provide.

 

http://hint.fm/wind/

wow! how did you come across that graphic?  that is amazing, and you are right, it really shows the cad.  looks good at this point. 

 

what i wouldnt give for the precip to be here now haha.  wetbulb has dropped a little and it closing in on 28 :shiver:

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strongwxnc

strongwxnc

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wow. That would be very bad for the area. I have been through a .25"+ storm before..

Go call with that county school system going with a 3 hour delay tomorrow.

 

Here's the meteogram for Hickory regarding freezing rain potential.  The average of the past two GFS runs puts KHKY at over 0.25 inch of ice accretion.  Hmmm...

 

attachicon.gifZR.png

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