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January 6-8 2014 arctic attack obs thread...


Marion_NC_WX

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I am curious as to what is keeping it so warm in the Sandhills region of NC? I just find it so strange that Macon and Atl are going to be colder than Fayetteville. It is pretty frustrating though, TWC has our high Tuesday at 35 and a low of 18. Cold, but not record breaking or even all that uncommon.

 

If this belonged in banter I am sorry please letme know!!

 

I was curious about this too.  It isn't elevation, because 3-500 ft doesn't justify that type of temperature difference(it is less than the difference between Greenville and Asheville which is 1200' difference), it isn't necessarily the mountains, because Greenville, Charlotte, and Winston Salem are all east of the mountains and in the same temperature range as Atlanta and points north and west.  I have asked meteorologist this same question, and I never get a direct answer.  With the way the map looks sometimes it would appear as if there were a mountain range somewhere south of Greenville that runs up to Rockingham then turns direction east and heads straight for the Atlantic, because the cold air jets straight over the mountains to the triad and points east.  It boggles the mind. 

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Not sure where to post on the Sunday-Monday AM precip event so I'll just throw it here.

 

 

Pretty cool graphic for N GA snow chances from 4 different 12Z models. Pic is from @MiloneFOX5 's twitter:

 

the wpc maps are showing some snow chances (mostly atl north and west) and also even though less than .10", a fairly large area has possible frzn rain quite a few hours sun/mon from 6z sun to 6z mon

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Didn't know that. Thanks.

 

But I did notice that GEFS was wetter than the operational run. Sort of resembled the wetness of the nam.

 

Seems like it would be really tough to get precip over here in a dry air mass of this magnitude on this side of the mountains without some pretty decent moisture transport.

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I'd say all bets are off with this kind of arctic airmass coming in...wouldn't be surprised if there are snow showers east of the mountains.

me either, especially after the surprise flakes here last night.  steady flurries for a couple of hours (dont know how long exactly, had to go to bed finally) with last nights blast moving in.  if we can get another one, and after more moisture this weekend, maybe a chance again.

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Again, the core at least in the deep south, are smack dab right over the Atlanta Metro.  amazing.  It looks like a glacier...

Interesting to note the 12z gfs valid 0z tuesday is about 5 degrees colder in/around atlanta and athens than the prior runs at the same time. It has atlanta for example at 9 degrees at 0z....where before it was "only" around 15. It has a low in atlanta of 4

 

Gainesville is already 6 (SIX!) by 0z. However it only drops gainesville to 3 by 12z tue. hard to believe there is only a 3 degree drop the entire night. I think many areas at this point will probably crack zero from atlanta to athens north, unless the models reverse the trend. fwiw, the 12z euro is further south with the -20c 850mb temps too..now reaching atlanta and athens too.

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Interesting to note the 12z gfs valid 0z tuesday is about 5 degrees colder in/around atlanta and athens than the prior runs at the same time. It has atlanta for example at 9 degrees at 0z....where before it was "only" around 15. It has a low in atlanta of 4

 

Gainesville is already 6 (SIX!) by 0z. However it only drops gainesville to 3 by 12z tue. hard to believe there is only a 3 degree drop the entire night. I think many areas at this point will probably crack zero.

Wouldn't high winds slow the cooling? The 3 degree drop you mention would make sense if the winds stay at or above 20 mph.

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It looks like Little Critter put together that map if you've seen those books...I like it. The morning superensemble was ugly for Days 6-10. +EPO/+NAO and warm in the east.

I have. :) Love reading those books with my kid. You have to think we'll see the NAO turn around. It can't keep being predominately positive every winter indefinitely.

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I'd say all bets are off with this kind of arctic airmass coming in...wouldn't be surprised if there are snow showers east of the mountains.

 

 

Seems like it would be really tough to get precip over here in a dry air mass of this magnitude on this side of the mountains without some pretty decent moisture transport.

 

Its still 70+ hours out. Something to watch but generally looking the whole long wave pattern on the trough is Neutral to slightly negative. With one LP in the NE along with one trying to form along the front rounding the base of the trough. There should be a very tight and powerful baroclinic zone along the coast. So it maybe possible for a weak area of LP to form along the front and strengthen as it tracks N/NE.

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Wouldn't high winds slow the cooling? The 3 degree drop you mention would make sense if the winds stay at or above 20 mph.

Of course winds prevent radiational cooling and keep things mixed up but Given the nature of the airmass involved, I don't think it's reasonable to expect a 3 degree temperature drop all night.  Take last night/this morning  for example..winds were 35 to 40mph and temps still dropped below yesterdays/last evenings model runs  by a few degrees. Also CAA will continue all night in the lowest 100mb. As we go through the night, the core of the coldest temps will actually be centered from 900mb to 950mb. 950mb temps in gainesville for example will be -18.4c by 12z tue.

 

And if you compare actual temps/lows this morning with what the gfs was showing 3 days ago for this morning, it was about 5 degrees colder than what it was showing. So I would be bit surprised if temps only drop by that small of an amount.

 

Regardless, you won't be able to tell the difference because it's going to be colder than a witch's......hat. ;)

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I'd say all bets are off with this kind of arctic airmass coming in...wouldn't be surprised if there are snow showers east of the mountains.

 

 

Totally agree, this isn't something we see every winter.  Not saying someone gets a crippling snowstorm, but I think some will out perform the models outside of the mountains.  

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Of course winds prevent radiational cooling and keep things mixed up but Given the nature of the airmass involved, I don't think it's reasonable to expect a 3 degree temperature drop all night.  Take last night/this morning  for example..winds were 35 to 40mph and temps still dropped below yesterdays/last evenings model runs  by a few degrees. Also CAA will continue all night in the lowest 100mb. As we go through the night, the core of the coldest temps will actually be centered from 900mb to 950mb. 950mb temps in gainesville for example will be -18.4c by 12z tue.

 

And if you compare actual temps/lows this morning with what the gfs was showing 3 days ago for this morning, it was about 5 degrees colder than what it was showing. So I would be bit surprised if temps only drop by that small of an amount.

 

Regardless, you won't be able to tell the difference because it's going to be colder than a witch's......hat. ;)

 

Makes sense. Going to be fun to watch for sure.

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Seems like it would be really tough to get precip over here in a dry air mass of this magnitude on this side of the mountains without some pretty decent moisture transport.

I think this would be primarily driven by strong mid-level frontogenesis like what happened this past November. However, this time the winds are more northwesterly vs northerly, so my concern is that down sloping will dry the column further east in GA and the Carolinas. The other side to that argument is that the temperature gradient is going to be ridiculous, so there almost has to be some secondary circulation development along the front. Would not surprise me to see a narrow band of decent snow immediately behind the front. And even if it's just a dusting that falls, it's going to be around for a few days!

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Lookout,

 I'm 95% sure you're talking about early Feb. of 1996.

A while back, i was looking through the ewall maps and I think at one point I wondered if that was it too. But those maps aren't exactly high resolution. The reason I want to find it is because I want to figure out the circumstances behind what caused it and if it could ever happen again.

 

Of course I'm no where near as good as you and others at past storms, in part because i lose patience trying to find info. Any good sites to look at whole atmosphere maps, surface observations, etc for a storm that long ago?

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Its still 70+ hours out. Something to watch but generally looking the whole long wave pattern on the trough is Neutral to slightly negative. With one LP in the NE along with one trying to form along the front rounding the base of the trough. There should be a very tight and powerful baroclinic zone along the coast. So it maybe possible for a weak area of LP to form along the front and strengthen as it tracks N/NE.

Yeah, that makes sense. I just always worry about downslope drying over here. This is an unusual setup, though. But an inch seems a bit high. Anyway, it'll be fun to watch unfold, especially if there are flakes flying!

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A while back, i was looking through the ewall maps and I think at one point I wondered if that was it too. But those maps aren't exactly high resolution. The reason I want to find it is because I want to figure out the circumstances behind what caused it and if it could ever happen again.

 

Of course I'm no where near as good as you and others at past storms, in part because i lose patience trying to find info. Any good sites to look at whole atmosphere maps, surface observations, etc for a storm that long ago?

 

WxUnderground is good for historical surface obs: http://classic.wunderground.com/history/airport/KATL/2014/1/3/DailyHistory.html?req_city=NA&req_state=NA&req_statename=NA

 

Iowa Mesonet has Nexrad Radar back to 1995: http://mesonet.agron.iastate.edu/current/mcview.phtml?prod=usrad&java=script&mode=archive&frames=70&interval=60&year=2010&month=2&day=4&hour=13&minute=35

 

NOAA Reanalysis Maps for sfc and upper air: http://www.esrl.noaa.gov/psd/data/composites/hour/

 

Plymouth Reanalysis Maps for sfc and upper air:

http://vortex.plymouth.edu/reanal-u.html

 

http://vortex.plymouth.edu/ua-r.html

 

http://vortex.plymouth.edu/u-make.html

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A while back, i was looking through the ewall maps and I think at one point I wondered if that was it too. But those maps aren't exactly high resolution. The reason I want to find it is because I want to figure out the circumstances behind what caused it and if it could ever happen again.

 

Of course I'm no where near as good as you and others at past storms, in part because i lose patience trying to find info. Any good sites to look at whole atmosphere maps, surface observations, etc for a storm that long ago?

 

1. Daily wx maps up to 2004:

 

http://www.lib.noaa.gov/collections/imgdocmaps/daily_weather_maps.html

 

 

2. Unisys back to 1/1996:

 

http://weather.unisys.com/archive/index.html

 

 

3. NOAA four maps on one reanalysis back to 1950:

 

http://www.hpc.ncep.noaa.gov/ncepreanal/

 

 

4. Every six hours of reanalysis back to 1948:

 

http://www.cdc.noaa.gov/Composites/Hour/

 

 

5. Plymouth State upper air 1957-98:

 

http://vortex.plymouth.edu/ua-r.html

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Is it me or is the 18z trending even colder.

I dunno, but it wouldn't surprise me to see things trend a bit colder as we work closer. It looks maybe a tick wetter behind the front for central NC...but maybe that's just an illusion or me not correctly interpreting the eWall graphics.

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I dunno, but it wouldn't surprise me to see things trend a bit colder as we work closer. It looks maybe a tick wetter behind the front for central NC...but maybe that's just an illusion or me not correctly interpreting the eWall graphics.

Ya I noticed that as well. The NAM seemed to trend wetter also. Might be just a tick colder but shoot 3-5 degrees colder in this airmass is significant.

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