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Pattern The Great December Dump

CADEffect said:
Really beginning to get nervous for the end of the month into January. Just looking at the GEFS and the separation from the PV to the stretch of the SSW into our side of the world makes me think January will be warm. However, the GEFS has done this before in November and completely flopped days later.

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Stratospheric warming over out part of the world definitely doesn't mean it's going to be warm at the surface.
 
112Z Euro gives a whopping 2-4" of rain over most of SC, GA, AL, and N FL. Other aspect of this storm on 12Z Euro is winds up to 40 knots parts of N GOM and just off SE US coast! Lowest SLP gets to below 1,000 mb at times. This is shaping up to be a big dog per this run even if no wintry.
 
GaWx said:
112Z Euro gives a whopping 2-4" of rain over most of SC, GA, AL, and N FL. Other aspect of this storm on 12Z Euro is winds up to 40 knots parts of N GOM and just off SE US coast! Lowest SLP gets to below 1,000 mb at times. This is shaping up to be a big dog per this run even if no wintry.
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Crucial December rainstorm BF5ED4E2-337A-4D64-80ED-F29DD4F0F600.jpeg
 
GaWx said:
112Z Euro gives a whopping 2-4" of rain over most of SC, GA, AL, and N FL. Other aspect of this storm on 12Z Euro is winds up to 40 knots parts of N GOM and just off SE US coast! Lowest SLP gets to below 1,000 mb at times. This is shaping up to be a big dog per this run even if no wintry.
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If we only had some cold air to put all that moisture to use with then we could get a good snowstorm the SE hasn't seen in a long time. Just gotta get that high further west and we may be in business.
 
Jimmy Hypocracy said:
Cool zonal flow? yeah that lakes low has me chomping at the bit! No, it’s not that bad. As long as we can keep some of the colder air on our side of the globe we might have a shot
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True....It's a couple of tweaks away from being cold, as opposed to a monumental, herculean effort to situate the PV on our side of the globe.
 
Jimmy Hypocracy said:
I feel like this is what it looked like during the blizzard of 73’ except it wasn’t hot like 2019
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I've found only 3 Gulf lows since late 1800s with pressure under 1,000 mb giving KATL a major winter sorm:

1. 976 mb: Storm of Century 3/13/1993 ~4" snow
2. 997 mb: 2/12/2010 ~4" snow
3. 998 mb: 1/22/1987 ~4" snow

So, of the 32 major KATL snow or sleetstorms since the 1870s, only ~10% had sub 1,000 mb. The median was way up at 1,008 mb. So, fairly weak Gulf lows tend to be more conducive to giving ATL big winter events.

Edit: note that all 3 have been since 1993, perhaps due to a warmer Gulf due to GW but may just be random since only 3.
 
GaWx said:
I've found only 3 Gulf lows since late 1800s with pressure under 1,000 mb giving KATL a major winter sorm:

1. 976 mb: Storm of Century 3/13/1993 ~4" snow
2. 997 mb: 2/12/2010 ~4" snow
3. 998 mb: 1/22/1987 ~4" snow

So, of the 32 major KATL snow or sleetstorms since the 1870s, only ~10% had sub 1,000 mb. The median was way up at 1,008 mb. So, fairly weak Gulf lows tend to be more conducive to giving ATL big winter events.
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What about 93? Thought that was a low mb.


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The turn of the new year might be one of those rare instances where we get a simultaneous -EPO/-NAO where +SCAND is trying to assert itself in concert w/ a deeper Sea of Okhotsk/eastern Russia vortex that's enforcing a -EPO.

This Alaskan + Scandinavian ridging creates a wavenumber 2 "squeeze play" that ultimately could split the polar vortex. It's nice to have the primary TPV lobe on our side of the pond and this sort of pattern will typically force it to descend southward into North America. We may have to contend w/ at least some transient southeast US ridging on the front end of this, but this particular planetary-scale pattern is certainly capable of unloading absurdly cold air masses into the CONUS in early January. Whether or not those actually impact us in the SE US (& if so when) are questions that will remain unanswered for the immediate foreseeable future

gfs-ens_z500a_nhem_51.png
 
NoSnowATL said:
What about 93? Thought that was a low mb.


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You’re correct that that was low (lowest by far), but I already do have that in my list as #1 strongest. That’s why it was named “Storm of Century”. You just missed it.
 
GaWx said:
You’re correct that that was low (lowest by far), but I already do have that in my list as #1 strongest. That’s why it was named “Storm of Century”. You just missed it.
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Haha my bad, shouldn’t be on my phone and drive at the same time.


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Pretty obvious why the CMC is colder. CMC does have a cold bias though

You can see the CMC low is actually aiding our CAD regions here. Verses the euro where the low is working against the CAD. You can see the CAD fighting back in NC on euro.

for anyone to see frozen we have to get help from the Low pressure. Whether that’s created cold or wind funneling cold into the CAD.1753B8DC-FEF8-44E5-8CA2-E59A186CA62F.jpegFFF83112-6073-44C6-BDAE-2689F55677D0.jpeg
 
WxBlue said:
There's nothing more frustrating having a nice cyclone with the moisture... only to lack the d*** cold.
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True! That's why my number one rule is always COLD FIRST. I know others have different preferences, but getting cold in place is always THE priority for me.
 
CMC I noticed actually brings accumulating snow down to I85 in upstate SC not likely. But I’m curious as to how the trends will go this week.


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