Pattern January 2017 Discussion

[sigwx]

[quote author=Stormlover link=topic=60.msg4787#msg4787 date=1483107289]
Spann put this out

That map almost looks like the 6z CMC hour 192

 

[Stormlover]

[quote author=Stormlover link=topic=60.msg4787#msg4787 date=1483107289]
Spann put this out

That map almost looks like the 6z CMC hour 192

CMC doesn't have a a 6Z, just 0Z and 12Z, like the Euro

 

[Metwannabe]

Yesterday the Para had a consolidated lp cutter and last two runs more suppressed weaker overrunning event.....  for NC folks the HP not in a good spot and cold really doesn't make it here like does west of the apps, still possible but just verbatim on those particular model runs.  But the 06z Para almost had an east coast crawler, now if that happens.......  anyway like other's have stated, I'd feel really good about my chances if I was in northern MS/AL and TN, western NC.  Not to say the rest of us don't have a chance still all kinds of options on the table and that's all we can ask for right now imho

 

[sigwx]

I know but I notice that the ECMWF looks just like the CMC. I should have said that to begin with, they are very close, very nice to see models that close

 

[SD]

The models aren't hinting at a strong low because the height gradient in the east tightens which shears the western shortwave thus you get this low amplitude look. There are 2 ways in this look to get a stronger low First is a phased scenario where it's 100% depending on timing of the phase as to who gets rain or snow. The second option is what we saw with the 12z runs yesterday where the heights are more relaxed and there is the ability to have a stronger low pressure and room for amplification. The problem with this is it gives the SER the ability to push back and biases everything north.

You don't need a strong low here to generate a good amount of precipitation. The moist southwest flow aloft over top the air mass already in play will do well at generating precip. The addition of any energy from the west will act to enhance moisture plumes at times.  The good thing about this look is horizontal temperature advection is kept at a minimum so we aren't likely to have a blazing warm nose aloft

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Oh be still my beating heart, the slightest possibility of a winter event without a blazing warm nose..... can it be?  Do those still exist? Lol  Great explanation by the way

Just pulled this from the GFS. As you can see there is a weak warm layer which is to be expected given the WSW flow aloft but its not a honking +5c nose, its pretty close to a snow sounding. There are a few systems that were similar to this one from the past

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[SnowHusky]

Depending on where you are and the setup, the overrunning is horrible for my area (as of right now). That's why I'd rather have a Gulf low or a low that tracks just across the Gulf coast. The 06z GFS has a high just north of the OH river which would set up snow north, NW and western side of the consolidated low. A consolidated low would be better cause everyone would get snow. The SW flow would have more ice and IP rather than snow. The thickness values aren't even cold enough for snow during the SW flow. The best snow growth is -5c at 850mb.

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[Storm5]

Re: January 2017 Discussion

Depending on where you are and the setup, the overrunning is horrible for my area (as of right now). That's why I'd rather have a Gulf low or a low that tracks just across the Gulf coast. The 06z GFS has a high just north of the OH river which would set up snow north, NW and western side of the consolidated low. A consolidated low would be better cause everyone would get snow. The SW flow would have more ice and IP rather than snow. The thickness values aren't even cold enough for snow during the SW flow. The best snow growth is -5c at 850mb.

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saying a consolidated low would give everyone snow is not a correct statement .

you can get big snows with a SW flow .

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[Metwannabe]

[quote author=metwannabe link=topic=60.msg4793#msg4793 date=1483108784]

The models aren't hinting at a strong low because the height gradient in the east tightens which shears the western shortwave thus you get this low amplitude look. There are 2 ways in this look to get a stronger low First is a phased scenario where it's 100% depending on timing of the phase as to who gets rain or snow. The second option is what we saw with the 12z runs yesterday where the heights are more relaxed and there is the ability to have a stronger low pressure and room for amplification. The problem with this is it gives the SER the ability to push back and biases everything north.

You don't need a strong low here to generate a good amount of precipitation. The moist southwest flow aloft over top the air mass already in play will do well at generating precip. The addition of any energy from the west will act to enhance moisture plumes at times.  The good thing about this look is horizontal temperature advection is kept at a minimum so we aren't likely to have a blazing warm nose aloft

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Oh be still my beating heart, the slightest possibility of a winter event without a blazing warm nose..... can it be?  Do those still exist? Lol  Great explanation by the way

Just pulled this from the GFS. As you can see there is a weak warm layer which is to be expected given the WSW flow aloft but its not a honking +5c nose, its pretty close to a snow sounding. There are a few systems that were similar to this one from the past




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[/quote]

The sounding for krzz at the same time shows snow.... man what a thin line.  I have a feeling someone will end up in a sweet spot, just barely cold enough for sn but enough moisture to get a decent thump. 

 

[GaWx]

Depending on where you are and the setup, the overrunning is horrible for my area (as of right now). That's why I'd rather have a Gulf low or a low that tracks just across the Gulf coast. The 06z GFS has a high just north of the OH river which would set up snow north, NW and western side of the consolidated low. A consolidated low would be better cause everyone would get snow. The SW flow would have more ice and IP rather than snow. The thickness values aren't even cold enough for snow during the SW flow. The best snow growth is -5c at 850mb.

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Thanks for your nice contributions! Based on going through the old 850 mb maps of the biggest Atlanta snows since the 1950's, most were when the 850 mb temp was at or within a few degrees colder than 0C. Whereas -5C may offer the best snow growth, most storms were between -3C and 0C for the majority of the storm.

Also, please be careful when saying something like "everyone" would get snow with a consolidated low. There are some who live near the coasts, for example.

 

[SnowHusky]

[quote author=NorthGAWinterWx link=topic=60.msg4803#msg4803 date=1483110641]
Depending on where you are and the setup, the overrunning is horrible for my area (as of right now). That's why I'd rather have a Gulf low or a low that tracks just across the Gulf coast. The 06z GFS has a high just north of the OH river which would set up snow north, NW and western side of the consolidated low. A consolidated low would be better cause everyone would get snow. The SW flow would have more ice and IP rather than snow. The thickness values aren't even cold enough for snow during the SW flow. The best snow growth is -5c at 850mb.

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Thanks for your nice contributions! Based on going through the old 850 mb maps of the biggest Atlanta snows since the 1950's, most were when the 850 mb temp was at or within a few degrees colder than 0C. Whereas -5C may offer the best snow growth, most storms were between -3C and 0C for the majority of the storm.

Also, please be careful when saying something like "everyone" would get snow with a consolidated low. There are some who live near the coasts, for example.
[/quote]
I knew it was a bad idea to say everyone would get snow lol. But the majority of the southeast would get snow (based off of historical Gulf low snow events) coastal Carolina's would get snow on back edge of low and depending on track of low. Heck, the coastal NC can get good snows if the low amplifies and the low would have to be at the right place off shore.

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[SD]

I'm curious about the pattern post 1/15 could get into something decent

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[Metwannabe]

Re: January 2017 Discussion

[quote author=NorthGAWinterWx link=topic=60.msg4803#msg4803 date=1483110641]
Depending on where you are and the setup, the overrunning is horrible for my area (as of right now). That's why I'd rather have a Gulf low or a low that tracks just across the Gulf coast. The 06z GFS has a high just north of the OH river which would set up snow north, NW and western side of the consolidated low. A consolidated low would be better cause everyone would get snow. The SW flow would have more ice and IP rather than snow. The thickness values aren't even cold enough for snow during the SW flow. The best snow growth is -5c at 850mb.

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saying a consolidated low would give everyone snow is not a correct statement .

you can get big snows with a SW flow .

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[/quote]

Agreed.  About the only areas that benefit from a strong lp, are those of us northern southeastern peeps and those on the far nw fringes of the SE but everything has a line up just perfect

 

[WeatherLC]

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[Webberweather53]

As far as gulf lows are concerned, I found only three sub 1000 mb lows since the late 1800's that gave Atlanta 3.5+" of SN/IP. One was the ~977 mb 3/1993 blizzard, which was a very rare storm that gave major snow after a changeover from rain that occurred before it passed. The other two lows were in the high 990's.
For the remaining 30 something major SN/IP, the lowest pressure while in the gulf was 1000+. The average is not too far from 1010 mb and a few were as high as near 1020 mb. So, the best chance is from a weak low/overrunning. Some of the biggest SN/IP in Atlanta were from very weak lows (1015+).
  The track is almost always through either SE GA or north FL though a few went through central FL. Actually, that is also a common track for many of the big well inland AL/NC/SC big snows as well.

Im not sure what the 3rd storm is but I know March 1-3 1942 is definitely one of the other storms that were sub 1000 and produced big snow in ATL. About 6-12" of snow was reported in the Atlanta metro, and the snowfall distributions were very similar to March 1993... 25" was reported on Mount Mitchell in NC and widespread areas of 16-24" were prevalent in the NC mountains, with a foot or more north & west of I-85. This storm in early March 1942 is eerily similar to March 1993 wrt track, intensity, time of the year, and snowfall, just a tad weaker... They're essentially twins lol.

March 3 1942 North America Surface Maps (NOAA 20CRv2)

March 12-14 1993 North America Surface Maps (NCEP NCAR Reanalysis)

March 1-4 1942 snowfall (NCDC RSI)

March 2-3 1942 NC Snow map

 

[VegasEagle]

I'm curious about the pattern post 1/15 could get into something decent

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Is it a good time to start a seperate thread on this?

 

[jgee322]

Hi!  I have just joined from Tunnel Hill, Ga (Catoosa county just south of Chattanooga, TN).  I don't know much about the science of the weather, but I am fascinated with it.  Thanks for providing a place that people can go to learn more about how weather works!

One quick question... what is SER?




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[SD]

[quote author=SD link=topic=60.msg4813#msg4813 date=1483112137]
I'm curious about the pattern post 1/15 could get into something decent

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Is it a good time to start a seperate thread on this?
[/quote]
I don't see why not

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[SD]

Hi!  I have just joined from Tunnel Hill, Ga (Catoosa county just south of Chattanooga, TN).  I don't know much about the science of the weather, but I am fascinated with it.  Thanks for providing a place that people can go to learn more about how weather works!

One quick question... what is SER?




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Southeast ridge

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[Webberweather53]

[quote author=SD link=topic=60.msg4813#msg4813 date=1483112137]
I'm curious about the pattern post 1/15 could get into something decent

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Is it a good time to start a seperate thread on this?
[/quote]

I'm guessing we probably won't until tomorrow or the following day, I think most here generally agreed upon anything inside 144 HR being the cut-off for throwing up another thread

 

[SnowHusky]

Re: January 2017 Discussion

Hi!  I have just joined from Tunnel Hill, Ga (Catoosa county just south of Chattanooga, TN).  I don't know much about the science of the weather, but I am fascinated with it.  Thanks for providing a place that people can go to learn more about how weather works!

One quick question... what is SER?




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SER means southeastern ridge, thanks for joining!

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