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Pattern January 2021 - Joyless January

GaWx said:
I don’t know about Raleigh, but I do know of only one pure “bowling ball”/upper low (i.e., with no accompanying cold surface high to the north and no low surface center to the south) that produced major snow (3.5”+) at KATL and that was early March of 2009. By far the best opportunity for ATL has been associated with a Gulf or near Gulf coast surface low that is often weak in combo with a well timed cold enough surface high that is still leading to cold air advection. So, often that surface high is then still located in the Midwest rather than the NE US. When the high is already in the NE, that’s when ATL is more likely to face a CAD based mainly IP/ZR. For either of these, the 500 mb flow is usually WSW or SW.
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How often does Atlanta get snow from a surface low that forms in the Atlantic ?
 
GaWx said:
I don’t know about Raleigh, but I do know of only one pure “bowling ball”/upper low (i.e., with no accompanying cold surface high to the north and no low surface center to the south) that produced major snow (3.5”+) at KATL and that was early March of 2009. By far the best opportunity for ATL has been associated with a Gulf or near Gulf coast surface low that is often weak in combo with a well timed cold enough surface high that is still leading to cold air advection. So, often that surface high is then still located in the Midwest rather than the NE US. When the high is already in the NE, that’s when ATL is more likely to face a CAD based mainly IP/ZR. For either of these, the 500 mb flow is usually WSW or SW.
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I can think of a few but they were mainly trailing an initial system so I'm not sure they would qualify as a pure ull
 
Day 10 Canadian. Cold air would be in place (dew points teens and low 20s). 850 zero line in N. NC (moving northward). Maybe a ice to snow setup for many? You would think the cold to the NW would eventually catch up as the storm deepens off the coast (or at least that's what I'm dreaming):
aaadd.JPG
 
FallsLake said:
Day 10 Canadian. Cold air would be in place (dew points teens and low 20s). 850 zero line in N. NC (moving northward). Maybe a ice to snow setup for many? You would think the cold to the NW would eventually catch up as the storm deepens off the coast (or at least that's what I'm dreaming):
View attachment 61744
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Well, if we miss that one, here comes another...

1609609183243.png
 
Dewpoint Dan said:
How often does Atlanta get snow from a surface low that forms in the Atlantic ?
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For major ATL snow, I’m not aware of a single instance going back to the late 1800s where the surface low only starts forming in the Atlantic. The reason is that the airflow by then is too dry (cold but dry coming off the mountains.) Great examples: late Dec of 1989 and early Jan of 2018, for which ATL was not hit. The very rare major SE coastal snows normally don’t also result in much, if any, snow at ATL.
 
GaWx said:
I don’t know about Raleigh, but I do know of only one pure “bowling ball”/upper low (i.e., with no accompanying cold surface high to the north and no low surface center to the south) that produced major snow (3.5”+) at KATL and that was early March of 2009. By far the best opportunity for ATL has been associated with a Gulf or near Gulf coast surface low that is often weak in combo with a well timed cold enough surface high that is still leading to cold air advection at or higher than 850 mb. So, often that surface high is then still located in the Midwest rather than the NE US. When the high is already in the NE, that’s when ATL is more likely to face a CAD based mainly IP/ZR because by then 850s are already rising above 0C. For either of these, the 500 mb flow is usually WSW or SW.
Click to expand...
Here's the H5 look, I wouldn't compare this really as an analog to this event.
2009-03-01 00z.png2009-03-02 00z.png
 
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