Fall/Winter 2020-21 Weather thread

bryguy

Old Mossy Horns
No offense to any of the weather ‘gurus’ here but I have been hearing about this supposed return of the polar vortex since the first of the year. Then it was suppose to be middle of January(and here we are) now it has moved to late January through mid February. Just because some huge atmospheric event happens does not mean it’s effects will be felt like they predict. Is it just as likely that we have just some plain ole ‘normal’ winter weather instead of this hyped arctic blast around here?


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SnowMaker

Eight Pointer
No offense to any of the weather ‘gurus’ here but I have been hearing about this supposed return of the polar vortex since the first of the year. Then it was suppose to be middle of January(and here we are) now it has moved to late January through mid February. Just because some huge atmospheric event happens does not mean it’s effects will be felt like they predict. Is it just as likely that we have just some plain ole ‘normal’ winter weather instead of this hyped arctic blast around here?


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Well is sure as heck hope for that normal winter. I hate when polar air arrives. Just plain sucks
 

shaggy

Old Mossy Horns
No offense to any of the weather ‘gurus’ here but I have been hearing about this supposed return of the polar vortex since the first of the year. Then it was suppose to be middle of January(and here we are) now it has moved to late January through mid February. Just because some huge atmospheric event happens does not mean it’s effects will be felt like they predict. Is it just as likely that we have just some plain ole ‘normal’ winter weather instead of this hyped arctic blast around here?


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Models are kind flipping all around right now. The euro went from cold to warm back to a snow storm on today's run. I still think the 23rd to the 25th is a good look to shift to the colder pattern.
 

downeastnc

Old Mossy Horns
As always with larger scale pattern changes the models flip flop around till we get about a week out, starting to see good agreement on a arctic high dominated pattern regime for the US by middle of next week....so about 7-10 later than originally modeled.....models also hint at another SSW event early Feb which could reinforce the cold pattern.....that said the models are not showing dramatically cold temps invading the US yet, this could simply be the lag models have with catching up to the pattern change again if there is a large 1040mb+ high complex over the Great Lakes we would be pretty cold here and the chances of a ice storm/snow storm would be pretty high.

This high position below is perfect for CAD type events.....CAD ( cold air damming ) is when the dense cold air at the surface pools up east of the mts, then a storm comes up out of the south and over runs the cold at the surface.....with the strong high constantly flowing cold in at the surface we typically see this as a ice storm setup.....you can see the high pressure riding in east of the mts below and that is a cold polar vortex high which is the source of our airmass so interesting to say the least though while I love snow I have little use for ice so hopefully the high is further south and able to give us deep enough cold that any system would be all snow....

GFS model
cold high .png

Euro model
euro .png
 

downeastnc

Old Mossy Horns
Starting to see some decent agreement with a storm around Jan 28th.....been there several runs on several models now and getting inside 7 dayish which is the window where it goes from fantasy to legit chance of happening...decent thump for the whole state......below are the last 2 GFS runs

18Z ( most recent)
gfs_asnow_seus_33.png

12Z ( noon today)

gfs_asnow_seus_35.png
 

downeastnc

Old Mossy Horns
Models still holding onto the storm next week.....this run had the storm a little more north, but again in this range I would not focus on the exact location of the heaviest snow but rather that there is a storm in general, all the snowfall totals on these maps do at this point is give us the potential impact the storm has and this one looks to be high impact for the areas that do get the heaviest snow where ever that ends up being....that said this was a doozy a solid footer plus for the north half of NC from the Triangle to darn near the OBX....

snku_acc.us_ma.png
 

ScottyB

Old Mossy Horns
Contributor
Still there? I heard weather channel dude mention it..... next weekend still looking snowy?? Give us an update please
 

nchunter

Twelve Pointer
Still there? I heard weather channel dude mention it..... next weekend still looking snowy?? Give us an update please

Weather app says a chance Thursday morning. Temps looking a little high. Moisture and cold would have to come together different than current forecast.


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shaggy

Old Mossy Horns
Still there? I heard weather channel dude mention it..... next weekend still looking snowy?? Give us an update please

Models shifted north to mostly a Virginia system. They are slowly trending back towards getting us back in the game.

Roght now NE NC looks to stand the best chance as it stands right now.
 

downeastnc

Old Mossy Horns
the models are slowly sharpening up this system which would result in a southern shift so there is still a pretty good chance this snows for NC, at this point to closer to VA the better your chances.....we also have a saying in the weather world which is you never want to be in the bullseye in this time frame as it almost always shifts some as the storm system gets sampled better.....so overall as it stands if the changes the models are doing continue over the next few days it would probably mean more of NC gets some kind of snowstorm, the actual energy that creates this storm is off the grid so to speak and not being sampled. Once it moves ashore over western Canada and the SW US where the NWS sends up balloons there will be a better grasp of how this will unfold....that should start tonight into tomorrow.

for now...

 

shaggy

Old Mossy Horns
I think it's out to lunch but man the gfs is coming in strong even for you Piedmont fellas. Doesnt have a ton of support so I'm not buying it just yet. If it's right we have a bigger storm on our hands.
 

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45/70 hunter

Old Mossy Horns
Contributor
I think it's out to lunch but man the gfs is coming in strong even for you Piedmont fellas. Doesnt have a ton of support so I'm not buying it just yet. If it's right we have a bigger storm on our hands.
Now yer talkin !! Bring it on!!
 

shaggy

Old Mossy Horns
Now yer talkin !! Bring it on!!

I have no idea what the gfs is seeing or why it just jumped up totals statewide but its ensembles are unanimous and probabilities of 1 inch of snow are at 100%.

I'm not sold on it but its beefing it up. We have to see what the other models do today.
 

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downeastnc

Old Mossy Horns
As usual marginal temp profiles make this a tricky forecast and a few degrees either way could mean cold rain or 4-6" of snow......probably will snow for a good bit of NC tomorrow night but if the surface temps dont crash to 30 or so it will be hard to get much to accumulate at 32-33 degrees. These setups are always fun though since the "bust" potential is pretty high, this setup is not far from something that could end up being a big boy for eastern NC...if the low phases better or the air is just a little colder etc then somewhere down east of I 95 could end up with a good thump out of this if things go perfectly.
 

Fishhunt-365

Eight Pointer
Not sure about all that model and map stuff but where I live around the Lincoln Gaston county line it stormed for an hour , big lighting and big thunder. So I guess we will see if the old saying holds true or not
 

downeastnc

Old Mossy Horns
So is that last graph a prbability may or an accumulation?

Its the probability of a area to get 1" or greater of snowfall....the latest Euro run has a general 1-2" event for a lot of the area in the map above shaded red....it just misses the phase so its a weaker strung out low so lower QPF means lighter snow and accumulations.....if the GFS is closer to correct then the storm phases better and we see more QPF and heavier rates thus more accumulation.
 

downeastnc

Old Mossy Horns
The issue ( as almost always in NC ) is what we call the boundary layer....the last lowest 1000-2000ft of air.....above that its gonna be all snow all the time....if its 36 at the surface though then we get sloppy wet flakes that melt on contact, the Euro is has a weaker system and marginal temps 31-33ish .....the GFS has a stronger storm this means heavier snow, the heavier snow would allow for the snow to literally drag the cold down with it to the surface allowing the column to go isothermal and if that plays out then we get better totals because we have heavier snow and colder temps 29-30 at the surface good for accumulation....so the overall chance of flakes flying is high, what impact that has though still a bit of a question.....

Here is the ens panel from the latest GFS if its correct then its gonna snow in NC.....there are none that really have no snow and a bunch that have a big storm....but temps only need to be a few degrees warmer for this to be all rain at the surface.

gfs-ensemble-all-avg-ma-snow_total_multimember_panel-1835200.png
 

OpticalFox70840

Four Pointer
Its the probability of a area to get 1" or greater of snowfall....the latest Euro run has a general 1-2" event for a lot of the area in the map above shaded red....it just misses the phase so its a weaker strung out low so lower QPF means lighter snow and accumulations.....if the GFS is closer to correct then the storm phases better and we see more QPF and heavier rates thus more accumulation.
Haven't seen any forecasts for snow. I've just seen forecasts continuing to be in the 50s and rainy. Where do you get these maps?
 

Homebrewale

Old Mossy Horns
Our work mets don't have enough confidence one way or another to say what any accumulation will be on Thursday. They will provide an update tomorrow.
 

downeastnc

Old Mossy Horns
Haven't seen any forecasts for snow. I've just seen forecasts continuing to be in the 50s and rainy. Where do you get these maps?

Lots of places have the operational and ens model runs....

I prefer



 
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