Pattern Jarring January

[Shawn]

Let me remind; that this potential could be coming during another pattern shift of sorts. Lets be happy we are looking at a snowier situation versus ice.

 

[Clayton Reid]

I agree this is not a clipper at this point. Yes origins are around there but it's a piece that pretty much or almost become detached from the main trof. Oh btw, I hope this isn't rude, but since when is the potential for 2-3" of snow NOT a big deal??

I mean it's a big deal I guess especially for Macon. I might be spoiled because I live in the ATL and I haven't seen a 4+ snow in a while since 2011. Really wanna see that again. And I hope for the day when I have 6+ possibly in my backyard. I've researched a couple of storms that were 5-8 inches officially in the ATL. Would love for that to happen again soon in my lifetime and backyard haha.

 

[Stormlover]

I agree this is not a clipper at this point. Yes origins are around there but it's a piece that pretty much or almost become detached from the main trof. Oh btw, I hope this isn't rude, but since when is the potential for 2-3" of snow NOT a big deal??

Hmm, someone posted a video of Brad Travis about it, and it is an Alberta Clipper. Not saying it can't pick up some energy from a wave, but it's origins are as a clipper.

 

[Webberweather53]

I don't see the cold air lagging being an issue nor do I see the coastal low factoring into this at all for anyone other than far eastern Carolinas and northward without the upper trough dramatically digging further southwest. I do agree that the critical element is how soon the trough tilts - there is little to no wiggle room with that. All in all, we have pretty different interpretations of this event, that much is clear, and that's ok. Good to have more than one viewpoint sometimes.

I disagree, the EPS and ECMWF clearly suggest however that cold air could be an issue (even aloft) with RDU sitting on the SE fringe of the heaviest snows arguing that sleet and rain are liable to mix in (while the GFS as usual is probably too flat and too east) and climatolgically cold air is almost always an issue in at least 90% of winter storms here... The coastal low is definitely in play at this juncture even further west, a weak/flat overrunning could sneak in even inland of the coast with impressive broad southwesterly flow ahead of the upper level trough. A localized center of excess diabatic heating in concurrence with convection that will develop along the Gulf Coast could easily evolve and propagate upscale further NW into the Carolinas and GA and result in a weak/flat wave that's inland of the Carolinas and lead to issue with cold air especially in the mid levels where we often need it the most.

 

[Shawn]

Hmm, someone posted a video of Brad Travis about it, and it is an Alberta Clipper

As it swings through from the source region of Alberta, it will be considered that. As it continues to amplify and change "forms" at H5, it will be an entirely separate entity with a likely surface low/coastal becoming dominant.

 

[Alias47]

I've heard that clippers tend to not produce well for Alabama. What will we be looking for that may give us a sign that we could get snow this next week? I live above B'ham in Etowah. We tend to fair well in most snow scenarios. Just curious.

 

[Taylor C]

The 18z GEFS is wetter then the last couple of runs.

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Whoa, this is huge! Very good confidence booster that we will have a good snow storm.

 

[Shawn]

I've heard that clippers tend to not produce well for Alabama. What will we be looking for that may give us a sign that we could get snow this next week? I live above B'ham in Etowah. We tend to fair well in most snow scenarios. Just curious.

A deeper, track with a strong push of the cold. Watch the wind directions and flow. It's not a standard "clipper" when it comes across in the way you are used to seeing them swing through to your North. Usually, even NC struggles with a standard clipper feature, while this time the Southern dive and strength is better for many further into the South.

 

[whatalife]

Like @Storm5 said, I suggest you guys keep a look out on the precipitable water maps from the GFS and other modeling at "pivotal weather". (the ones on tropical tidbits wont show much, as they are anomaly maps). The drier they get, the less chance of appreciable moisture breaking out for all areas.

If they continue to show wetter, that's a good thing!

I agree this is not a clipper at this point. Yes origins are around there but it's a piece that pretty much or almost become detached from the main trof. Oh btw, I hope this isn't rude, but since when is the potential for 2-3" of snow NOT a big deal??

Very good pts on both parts.


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[TheBatman]

A deeper, track with a strong push of the cold. Watch the wind directions and flow. It's not a standard "clipper" when it comes across in the way you are used to seeing them swing through to your North. Usually, even NC struggles with a standard clipper feature, while this time the Southern dive and strength is better for many further into the South.

You can’t explain it no better then that!!!

 

[Alias47]

A deeper, track with a strong push of the cold. Watch the wind directions and flow. It's not a standard "clipper" when it comes across in the way you are used to seeing them swing through to your North. Usually, even NC struggles with a standard clipper feature, while this time the Southern dive and strength is better for many further into the South.

Awesome explanation! Thanks!

 

[Stormlover]

As it swings through from the source region of Alberta, it will be considered that. As it continues to amplify and change "forms" at H5, it will be an entirely separate entity with a likely surface low/coastal becoming dominant.

I'm all for that!

 

[Webberweather53]

I disagree, the EPS and ECMWF clearly suggest however that cold air could be an issue (even aloft) with RDU sitting on the SE fringe of the heaviest snows arguing that sleet and rain are liable to mix in (while the GFS as usual is probably too flat and too east) and climatolgically cold air is almost always an issue in at least 90% of winter storms here... The coastal low is definitely in play at this juncture even further west, a weak/flat overrunning could sneak in even inland of the coast with impressive broad southwesterly flow ahead of the upper level trough. A localized center of excess diabatic heating in concurrence with convection that will develop along the Gulf Coast could easily evolve and propagate upscale further NW into the Carolinas and GA and result in a weak/flat wave that's inland of the Carolinas and lead to issue with cold air especially in the mid levels where we often need it the most.

Even in the Feb 1984 case where our s/w came out of ND and dove SE practically all the way to the apps and central Carolinas and GA the R-S line was as far west as eastern Wake County...

 

[RollTide18]

From NWS Mobile:

A strong surface cold front will continue moving south across the
Gulf of Mexico, allowing very cold temperatures to advect into the
forecast area from the north through Tuesday night. Sub-freezing
temperatures are expected to push all the way to the gulf coast by
late Tuesday night, allowing the light rain to change over to all
snow as far south as the northern gulf.

Snow accumulations will be determined at a late time, but a blend
of the GFS and ECMWF currently have up to one inch snow north of
I-10. Snow accumulations may end up being even higher as the
thermal profiles may still be a bit a underdone. Dynamic cooling
in the lower levels due to evaporative cooling and the "dragging"
of cold air aloft closer to surface is sometimes not accounted for
in the models, and additional moisture may be drawn in ahead of
the system. This system is pushing through rather fast, so the
entire event will be less then 24 hours. Dry conditions will
follow Wednesday and Thursday behind the cold front. Much below
normal temperatures will persist through the long term. /22

 

[Webberweather53]

That's fine, but that is not what the EPS and ECMWF are indicating at this juncture with this system. The only reason for the sharp cutoff is due to the heaviest QPF axis being further west, not warm air.

Actually, the ECMWF is in fact showing mixing over RDU like I said & surface temps are above freezing for some of the event

 

[Clayton Reid]

From NWS Mobile:

From NWS Mobile:

Thanks for sharing this! Very valuable info to consider regarding possibly of models underdoing things, etc.

 

[Arcc]

What's the catalyst for a NW trend ??? The Pacific is driving the pattern , it's extremely progressive . The typical NW trend worry is far less in this setup . I'm far more worried about squash city

It can easily trend north, the models love to over do the northern stream all the time. It can still "squash" it and move the trough farther NW.

 

[SCweather]

NWS CAE mentioning a possibility of snow Tuesday night into Wednesday. A local met around these parts (WIS) is sorta honking the horn a bit to early though.

 

[Arcc]

there is nothing to trend northwest, this is clipper

Sure there is, you weaken the trough and the wave axis is farther north. The models overdo the cold push all the time. Is it gonna trend long distances, no but it can definitely end up farther north that modeled.

 

[Webberweather53]

Nice try. RDU is below freezing from 925 up and surface temp is at 35F. You think that would be a mix? Get real.
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Lol idk why you're getting angry about this it's actually warmer in earlier frames at the surface. We need enough time to push the isothermal melting layer to the ground with surface temps in the mid 30s, light QPF won't cut it. Taking the surface output from the models verbatim this far out isn't a good idea even if it's warmer by a degree or two than advertised that will lead to more mixing