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Mid to Long Range Discussion ~ 2024


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# of 6"+ snowstorms RDU moderate or stronger Ninos: 12 of 31

1880s: 1

1890s: 1

1900s: 0

1910s: 3

1920s: 0

1930s: 1

1940s: 1

1950s: 0

1960s: 2

1970s: 1

1980s: 2

1990s-2010s: 0 (six in a row without one, longest on record)

 

 So, RDU is overdue for a 6"+ storm during a moderate or stronger Nino, especially in Feb, although Feb of 1987 was a big month that just missed with two 5" storms. Jan of 2010 also just missed with its 5" storm.

 

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3 hours ago, eyewall said:

Dallas, Texas now has a higher season total on snowfall than Raleigh for this year. The GFS is still trying for the 19th.

Yeah I'm really getting deja vu on this one so that's not a good feeling. But I do think the orientation and Eastward progression of the cold air is better this time.

gfs_mslp_pcpn_frzn_eus_16.png

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12 Z GFS a little closer to coast with Miller B   
and Canadian a little further south.  Temps marginal but higher rates may overcome before dynamics wane.  It’s still a long shot but not impossible.
 

it’s sad but at least we can track something.     It’s our last chance for 2 weeks.  We can only hope that positive PNA can save the day.  The SE ridge may not be as much of a factor and we could possibly cash in.

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22 minutes ago, Leesville Wx Hawk said:

12 Z GFS a little closer to coast with Miller B   
and Canadian a little further south.  Temps marginal but higher rates may overcome before dynamics wane.  It’s still a long shot but not impossible.
 

it’s sad but at least we can track something.     It’s our last chance for 2 weeks.  We can only hope that positive PNA can save the day.  The SE ridge may not be as much of a factor and we could possibly cash in.

Yeah this one is make or break for the morale around here I think.

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27 minutes ago, eyewall said:

Yeah this one is make or break for the morale around here I think.

The low level warm air advection will ruin any chance of snow even if we did have a system to track. Either that or convection along the gulf coast will keep qpf levels way down. It never fails. 

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21 minutes ago, WinstonSalemArlington said:
Could someone explain to me what it takes for Arctic fronts to enter the States in the East instead of the West. It’s clear that’s polar invasion that includes Portland is going to be underwhelming here.


Need ridging in the west via Aleutian low (+PNA) so that cold air from Canada can move SE into our region. This should happen in about 2 weeks hopefully.


image.thumb.png.e11f51b612e245d57c5eb0d4b08c8e11.png
12 Z GEFS ensemble shows a ridge in the west that pushes the SE ridge.  While not perfect, this is a better synoptic pattern for our region and something to follow moving forward.

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1 hour ago, WinstonSalemArlington said:

Could someone explain to me what it takes for Arctic fronts to enter the States in the East instead of the West. It’s clear that’s polar invasion that includes Portland is going to be underwhelming here.

Per met Alan Huffman's surface compilation of major RDU snowstorms (not talking about ice or sleetstorms meaning sig CAD not necessary)

-best bet is for an Arctic high center, preferably strong and sprawling, to come down into the Dakotas as opposed to further west, which allows for cold enough air to soon after reach the SE in advance of potential precip.

-as opposed to waiting longer for more modified/stale cold first coming into the W, which also often has trouble getting over the Apps

-as opposed to a plunge of the high down into TX/AR/LA, which is often the coldest option but is also usually too dry to allow for moisture return into the lower levels prior to a warmup; high plunges like these often result in extreme cold/dry followed by too rapid a warmup due to warming on the backside of the high

-and then for the large Dakotas high to move SE, ESE and then E through the Ohio Valley thus hopefully still keeping it cold enough in the SE at least as high as 850 mb (with or without significant CAD)

-at the same time you want moist WSW to SW 500 mb flow over the top of the lower level cold in the SE US while the Arctic high is still in/near the Ohio Valley. If the 500 mb flow over the SE is instead WNW or even W, it usually is too dry in the SE for a big storm if any storm at all

-timing is obviously crucial being that big SE snows are infrequent

-best bet at 500 mb is for a split flow of the N stream bringing down but not plunging the Arctic high combined with a moist S stream simultaneously bringing in plentiful moisture from the Pacific and especially Gulf over the top of the S extent of the Arctic high

-more specifically, a +PNA with a 500 mb trough centered near the Mississippi River is what I look for

-Most of the memorable major SE snowstorms are associated with a weak to very weak GOM surface low that doesn't go too far inland, if inland at all other than over FL. These are usually Miller As.

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1 hour ago, Leesville Wx Hawk said:


Need ridging in the west via Aleutian low (+PNA) so that cold air from Canada can move SE into our region. This should happen in about 2 weeks hopefully.


image.thumb.png.e11f51b612e245d57c5eb0d4b08c8e11.png
12 Z GEFS ensemble shows a ridge in the west that pushes the SE ridge.  While not perfect, this is a better synoptic pattern for our region and something to follow moving forward.

Thanks for explaining 

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32 minutes ago, GaWx said:

Per met Alan Huffman's surface compilation of major RDU snowstorms (not talking about ice or sleetstorms meaning sig CAD not necessary)

-best bet is for an Arctic high center, preferably strong and sprawling, to come down into the Dakotas as opposed to further west, which allows for cold enough air to soon after reach the SE in advance of potential precip.

-as opposed to waiting longer for more modified/stale cold first coming into the W, which also often has trouble getting over the Apps

-as opposed to a plunge of the high down into TX/AR/LA, which is often the coldest option but is also usually too dry to allow for moisture return into the lower levels prior to a warmup; high plunges like these often result in extreme cold/dry followed by too rapid a warmup due to warming on the backside of the high

-and then for the large Dakotas high to move SE, ESE and then E through the Ohio Valley thus hopefully still keeping it cold enough in the SE at least as high as 850 mb (with or without significant CAD)

-at the same time you want moist WSW to SW 500 mb flow over the top of the lower level cold in the SE US while the Arctic high is still in/near the Ohio Valley. If the 500 mb flow over the SE is instead WNW or even W, it usually is too dry in the SE for a big storm if any storm at all

-timing is obviously crucial being that big SE snows are infrequent

-best bet at 500 mb is for a split flow of the N stream bringing down but not plunging the Arctic high combined with a moist S stream simultaneously bringing in plentiful moisture from the Pacific and especially Gulf over the top of the S extent of the Arctic high

-more specifically, a +PNA with a 500 mb trough centered near the Mississippi River is what I look for

-Most of the memorable major SE snowstorms are associated with a weak to very weak GOM surface low that doesn't go too far inland, if inland at all other than over FL. These are usually Miller As.

Thanks so much 

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Here’s where it looks like we are headed and this is important for our region.  We finally should go positive PNA in about 2 weeks (typical in El Niño).  We won’t have a -NAO but at least we have a better shot than this current gig (generally no bueno) .  A SSW could help eventually turn NAO negative but that’s speculation at this time.  


image.thumb.png.ac05698b81dcc61252265791efd455b6.png

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1 hour ago, Leesville Wx Hawk said:

Here’s where it looks like we are headed and this is important for our region.  We finally should go positive PNA in about 2 weeks (typical in El Niño).  We won’t have a -NAO but at least we have a better shot than this current gig (generally no bueno) .  A SSW could help eventually turn NAO negative but that’s speculation at this time.  


image.thumb.png.ac05698b81dcc61252265791efd455b6.png

 Looking at the daily indices during 6”+ RDU snowstorms since 1950: whereas a +PNA was fairly common (though far from being required), a -NAO actually wasn’t. The average NAO was actually pretty close to zero with a fairly even mix of -NAO, neutral NAO, and +NAO. So, whereas a -NAO helps with SE cold, itself, it doesn’t seem to be associated with big SE (at least RDU) snowstorms. That was a surprise to me when I complied the stats a few years back.

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Well the clock is running that is for sure. It gets much harder after Valentine's Day. Waiting out the next warmup is going to be rough.  Friday still cant be ruled out but it wouldn't be much. The Happy Hour GFS is looking rather paltry.

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23 minutes ago, eyewall said:

Well the clock is running that is for sure. It gets much harder after Valentine's Day. Waiting out the next warmup is going to be rough.  Friday still cant be ruled out but it wouldn't be much. The Happy Hour GFS is looking rather paltry.

Agreed, it is looking like another crap winter.  Now is our opportunity for something significant and not much.

 

 

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4 hours ago, eyewall said:

Well the clock is running that is for sure. It gets much harder after Valentine's Day. Waiting out the next warmup is going to be rough.  Friday still cant be ruled out but it wouldn't be much. The Happy Hour GFS is looking rather paltry.

 If we weren’t in a strong El Niño, I might agree. However, based on the RDU average snow strictly for moderate or stronger El Niños (31 of them…so a large sample), I have to respectfully disagree about Valentine’s Day being a crucial day this year:

Nov: 0.2”

Dec: 0.9”

Jan: 2.0”

Feb 1-14: 1.0”

Feb 15-28(9): 1.4”

Mar: 1.7”

Apr: 0.4”

 

 So, during these winters, the 2nd half of Feb (the month with the most snow on average despite it being the shortest month) actually averaged more than the 1st half. It may even be the most active half month of the entire winter. And then there’s still March, a pretty active month, itself.

 

 

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2 minutes ago, wncsnow said:

That ton of arctic air ended up being 4 or 5 days give or take. 

3 days and only 2 days in the 30’s, allegedly.

Interesting trend to watch for this evening in central NC is some models (led by GFS) have trended towards a later exit for rain today. Combined with an actual arctic surge, if these trends continue, there is a non-zero chance of frozen/freezing precip before the precip moves out. While best case scenario, amounts would be light, but with temps forecast to literally crash into the mid teens, even if it stays rain we will have black ice issues tonight and tomorrow morning. The later the precip moves out the greater the chance of road issues (even for triangle and points east) 

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During the moderation the last 2 weeks of the month (hopefully get some golf in), Canada will be resupplying with cold air.  I actually liked the orientation of the high pressure better on the 0Z for the first week of February.  The 06Z was further west.  Nevertheless, cold should be poised to move south and east.

image.png.43313c0707d152493cfcddc0522f49fc.png

 

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