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January 17th-18th Winter Storm Discussion


BullCityWx

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This storm reminds me of one I got when I lived in KC.  Heavy rain lasting a while till the change over.  And then we got a quick 8 inches with thundersnow.  The track and position of the low relative to Raleigh reminds me of that past track.  I'm usually pretty conservative when it comes to predicting snow, but I really think the folks in the deformation band are going to pick up some significant snow.   

 

Hard to spot exactly where that will wind up, but I really like this one as a major snow maker.  

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Would love, love, love 2-4 here in Shelby-town. But I will take the under!

(Concerned some are missing the trend of the 12z GFS -- definitely weaker with upper level features and quicker to move out moisture. I don't have to tell you that the former will inhibit dynamic cooling adn the latter makes it more likely cold never makes it in to change over precip).

Rooting for you, though!

 

My first call map of the year (sorry only have time to address NC):

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Just for kicks...12z NAM extracted data snowfall totals for a few cities...

 

Huntsville, AL - 1.5"

Birmingham, AL - 4.1"

Chattanooga, TN - 3.1"

Crossville, TN - 4.5"

Knoxville, TN - 6.7"

Bristol, TN - 7.1"

Rome, GA  - 3.1"

Gainesville, GA - 0.9"

Asheville, NC - 5.7"

Hickory, NC - 5.5"

Boone, NC - 10.9"

Charlotte, NC - 4.8"

Raleigh, NC - 3.9"

 

 

 

Atlanta GA, Athens GA, Greenville SC - ZIP

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Just for kicks...12z NAM extracted data snowfall totals for a few cities...

 

Huntsville, AL - 1.5"

Birmingham, AL - 4.1"

Chattanooga, TN - 3.1"

Crossville, TN - 4.5"

Knoxville, TN - 6.7"

Bristol, TN - 7.1"

Rome, GA  - 3.1"

Gainesville, GA - 0.9"

Asheville, NC - 5.7"

Hickory, NC - 5.5"

Boone, NC - 10.9"

Charlotte, NC - 4.8"

Raleigh, NC - 3.9"

 

 

 

Atlanta GA, Athens GA, Greenville SC - ZIP

 

Wow thanks man. Those are some impressive totals for everyone. It will be interesting to see if the NAM keeps this trend. After tonight it'll be nowcast time. 

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Just for kicks...12z NAM extracted data snowfall totals for a few cities...

Huntsville, AL - 1.5"

Birmingham, AL - 4.1"

Chattanooga, TN - 3.1"

Crossville, TN - 4.5"

Knoxville, TN - 6.7"

Bristol, TN - 7.1"

Rome, GA - 3.1"

Gainesville, GA - 0.9"

Asheville, NC - 5.7"

Hickory, NC - 5.5"

Boone, NC - 10.9"

Charlotte, NC - 4.8"

Raleigh, NC - 3.9"

Atlanta GA, Athens GA, Greenville SC - ZIP

Is there a meteorological explanation as to why the snow literally disappears as soon as if hits the Atlanta metro ?

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A look at the 36 hour nam reflectiviy forecast, you can see the impressive signature. http://raleighwx.americanwx.com/models/nam4km/12zNAM4kmreflectivity_SE.html

I hope that look verifies as that deformation band in N GA would likely be producing snow at that time frame.

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Is there a meteorological explanation as to why the snow literally disappears as soon as if hits the Atlanta metro ?

 

i think it's purely a function of the orientation of the deformation band as it sets up north of Atlanta.  ATL is actually colder than Dahlonega in the upper levels due to being closer to the center of the ULL but the precip is just too far north.

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I'll add this before we get too many IMBY I'm gonna get screwed posts.  Just a few days ago this was NON-EVENT. I live in the far NW corner of SC and don't excpect anything except maybe some mixing. At this point, outside the mountains, consider yourself luck if you get any snow.  Early this week many said it was a non-event just a cold rain. Now the trend has miraculously went in our favor, at least for NC.  Don't get bent out of shape if you don't get 4" below 2500ft IMHO.  You will cause Buckeye to get stressed out and then she won't enjoy this event. There are tons of us SC and Ga posters on here that have no chance of getting any snow out of this and we would trade with many of you for just a few inches!!

Godd disco thus far and let's keep it that way and enjoy! :pimp:  :snowing:

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Hey guys long time no see!

 

A constant bias that appears in the all modeling regardless of season is subtropical ridging. The reason why we have been a pretty substancial northward shift the last 24-48 hours in the 500 hPa low is mainly due to the intensity of the subtropical ridging. A quick d(prog)/dt (change of a particular forecast time over multiple model cycles) reveals that the most consistent trend in the numerical guidance is actually this amplifying ridge off the southeastern coastline. Again this is a systematic error in our modeling mainly due to the lack of good insitu observations over large subtropical highs over the subtropical oceanic basins of the world. As a result its likely that this ridge growth is likely to continue up to the analysis time.

 

ride_build.gif

 

So what does this mean in terms of the sensible weather across the southeast? Well of course we have our shortwave impulse that will still exist, but may likely end up bending northward as it dampens out. Thats why we are shifting towards more precipitation in NC/VA and why its brought the chances of snow back in the forecast. Of course, if the subtropical high continue to flex its muscles it might cause the upper level low, and the deformation band to continue shifting northward in the forecast, which wouldn't be great for those in NC, but perhaps better for snow lovers in VA. The magnitude of the upper level low is also very much a question mark at this point, although now that the energy has split off from the polar jet, that question should become a lot more clear. 

 

 

 

 

 

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Hey guys long time no see!

 

A constant bias that appears in the all modeling regardless of season is subtropical ridging. The reason why we have been a pretty substancial northward shift the last 24-48 hours in the 500 hPa low is mainly due to the intensity of the subtropical ridging. A quick d(prog)/dt (change of a particular forecast time over multiple model cycles) reveals that the most consistent trend in the numerical guidance is actually this amplifying ridge off the southeastern coastline. Again this is a systematic error in our modeling mainly due to the lack of good insitu observations over large subtropical highs over the subtropical oceanic basins of the world. As a result its likely that this ridge growth is likely to continue up to the analysis time.

 

ride_build.gif

 

So what does this mean in terms of the sensible weather across the southeast? Well of course we have our shortwave impulse that will still exist, but may likely end up bending northward as it dampens out. Thats why we are shifting towards more precipitation in NC/VA and why its brought the chances of snow back in the forecast. Of course, if the subtropical high continue to flex its muscles it might cause the upper level low, and the deformation band to continue shifting northward in the forecast, which wouldn't be great for those in NC, but perhaps better for snow lovers in VA. The magnitude of the upper level low is also very much a question mark at this point, although now that the energy has split off from the polar jet, that question should become a lot more clear. 

Thanks Phil! I was wondering when you would return! If there is a bias toward the ridge, would it be safe to assume that it currently might be modeled too strong and the low takes a track further south than currently modeled?

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Hey guys long time no see!

 

A constant bias that appears in the all modeling regardless of season is subtropical ridging. The reason why we have been a pretty substancial northward shift the last 24-48 hours in the 500 hPa low is mainly due to the intensity of the subtropical ridging. A quick d(prog)/dt (change of a particular forecast time over multiple model cycles) reveals that the most consistent trend in the numerical guidance is actually this amplifying ridge off the southeastern coastline. Again this is a systematic error in our modeling mainly due to the lack of good insitu observations over large subtropical highs over the subtropical oceanic basins of the world. As a result its likely that this ridge growth is likely to continue up to the analysis time.

 

ride_build.gif

 

So what does this mean in terms of the sensible weather across the southeast? Well of course we have our shortwave impulse that will still exist, but may likely end up bending northward as it dampens out. Thats why we are shifting towards more precipitation in NC/VA and why its brought the chances of snow back in the forecast. Of course, if the subtropical high continue to flex its muscles it might cause the upper level low, and the deformation band to continue shifting northward in the forecast, which wouldn't be great for those in NC, but perhaps better for snow lovers in VA. The magnitude of the upper level low is also very much a question mark at this point, although now that the energy has split off from the polar jet, that question should become a lot more clear. 

 

 

It certainly could be the death nail for NC if signs continue to push it north.

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Hey guys long time no see!

 

A constant bias that appears in the all modeling regardless of season is subtropical ridging. The reason why we have been a pretty substancial northward shift the last 24-48 hours in the 500 hPa low is mainly due to the intensity of the subtropical ridging. A quick d(prog)/dt (change of a particular forecast time over multiple model cycles) reveals that the most consistent trend in the numerical guidance is actually this amplifying ridge off the southeastern coastline. Again this is a systematic error in our modeling mainly due to the lack of good insitu observations over large subtropical highs over the subtropical oceanic basins of the world. As a result its likely that this ridge growth is likely to continue up to the analysis time.

 

 

 

So what does this mean in terms of the sensible weather across the southeast? Well of course we have our shortwave impulse that will still exist, but may likely end up bending northward as it dampens out. Thats why we are shifting towards more precipitation in NC/VA and why its brought the chances of snow back in the forecast. Of course, if the subtropical high continue to flex its muscles it might cause the upper level low, and the deformation band to continue shifting northward in the forecast, which wouldn't be great for those in NC, but perhaps better for snow lovers in VA. The magnitude of the upper level low is also very much a question mark at this point, although now that the energy has split off from the polar jet, that question should become a lot more clear. 

 

The SE ridge is going to be a major thorn all winter it seems for NC, I would be surprised if this storm ends up clipping the NE (Boston, NY).

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