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Pattern Fail or Fab February 2023 Pattern Thread

griteater said:
18z GFS

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When is the last time we've had a good old fashioned rain, arctic front move throw change to big snow? Seems like a long time. It's usually light snow to rain or zr.
 
When is the last time we've had a good old fashioned rain, arctic front move throw change to big snow? Seems like a long time. It's usually light snow to rain or zr.
I thought it was just a classic cold chasing moisture look earlier but looking at vort maps there was actually a good moisture fetch and while it is moving fast it still tries to go neutral/negative and pop a fast moving coastal. 13ECFAE7-998A-4AB2-9D80-7C8F487D2D4F.png
 
Rain Cold said:
When is the last time we've had a good old fashioned rain, arctic front move throw change to big snow? Seems like a long time. It's usually light snow to rain or zr.
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Back in Feb 2020 we had a rain turn to snow event over eastern NC for a good 3-5" hit, I remember it raining for several hrs before switching over....
 
Downeastnc said:
Back in Feb 2020 we had a rain turn to snow event over eastern NC for a good 3-5" hit, I remember it raining for several hrs before switching over....
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I think this event as currently shown has a lot of parallels to that event. (btw... i think raleigh was slated for 3-5ish and we got 1.5)
 
ILMRoss said:
I think this event as currently shown has a lot of parallels to that event. (btw... i think raleigh was slated for 3-5ish and we got 1.5)
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Had a solid 4-5" in my backyard...seems like it was like 45-50 that morning and by midafternoon it had switched over to snow....we lost a inch or two to getting the ground cold enough etc as well, snowed a good hr or two before it accumulated and the roads etc never really got bad.

 
ILMRoss said:
I think this event as currently shown has a lot of parallels to that event. (btw... i think raleigh was slated for 3-5ish and we got 1.5)
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Remember that. The clouds at night ruined it with the insulation. 850's looks slightly better this time. GFS is about to roll again, probably a completely different run again haha Hopefully not.

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2020
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Rain Cold said:
When is the last time we've had a good old fashioned rain, arctic front move throw change to big snow? Seems like a long time. It's usually light snow to rain or zr.
Click to expand...
Yeah, in absence of a strong, trailing upper low (like Mar 2009), it's quite rare I'd say to see moderate/heavy amounts of rain flip to snow that accumulates moderate to heavily. One big reason is that cold air advection aloft is a subsidence mechanism, while warm air advection aloft is a mechanism for rising motion and precip generation. So you need other mechanisms to offset that cold air advection aloft in order to generate precip. But the Feb 2020 example mentioned is a good one. I distinctly remember pointing out the cold air advection aloft being an issue in precip generation back my way in the western half of NC, but it produced some decent snow in the eastern half.

The other one that has been mentioned that is probably the best comparison to the 18z GFS run is the first of the winter storms in Feb 1989 (02/17/89) shown in the loops below. Long fetch of west to east moisture from New Mexico via west to east moving low amp southern stream wave with cold air pressing south from strong and sprawling high pressure

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Jimmy Hypocracy said:
Just comparing the 12z CMC to the 18z GFS, the CMC really holds that piece of cutoff energy back in the SW and the GFS moves it through a lot faster. Seems in the past the American model had a tendency to hold our southern stream waves back for days on end and was one of the reasons it was so bad. Now it’s the faster of the two. Just an observation
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I tend to view all of these Op and Ensemble model runs as just scatter shot solutions regardless of the model (Euro/GFS/CMC/UKMet). Don't think we will have any clear idea until the weekend. Could completely disappear. Could be a rain event. But it has to hit just right really in order to produce a wintry event
 
griteater said:
Yeah, in absence of a strong, trailing upper low (like Mar 2009), it's quite rare I'd say to see moderate/heavy amounts of rain flip to snow that accumulates moderate to heavily. One big reason is that cold air advection aloft is a subsidence mechanism, while warm air advection aloft is a mechanism for rising motion and precip generation. So you need other mechanisms to offset that cold air advection aloft in order to generate precip. But the Feb 2020 example mentioned is a good one. I distinctly remember pointing out the cold air advection aloft being an issue in precip generation back my way in the western half of NC, but it produced some decent snow in the eastern half.

The other one that has been mentioned that is probably the best comparison to the 18z GFS run is the first of the winter storms in Feb 1989 (02/17/89) shown in the loops below. Long fetch of west to east moisture from New Mexico via west to east moving low amp southern stream wave with cold air pressing south from strong and sprawling high pressure

ii91Zed.gif


nEKcqkj.gif


PmEGGp0.png
Click to expand...

Man I thought you were talking the other Feb 1989 event, a week after this one, a week that saw temps shoot to the mid 60's and tornados followed by probably the second or third biggest snowfall on my life....Feb 89 was a beast for sure.....
 
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Probably not cold enough on this ICON run but then again I’m not sure on how ICON handles CAD.
 
Downeastnc said:
Man I thought you were talking the other Feb 1989 event, a week after this one, a week that saw temps shoot to the mid 60's and tornados followed by probably the second or third biggest snowfall on my life....Feb 89 was a beast for sure.....
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Yeah that was a completely different setup aloft...it was a hardcore Manitoba Mauler upper wave / low that dove in from the NW....really good one
 
LukeBarrette said:
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Probably not cold enough on this ICON run but then again I’m not sure on how ICON handles CAD.
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The reason you're not seeing a pronounced CAD is because the Dominant High is still in Central Canada and the Low is still departing New England. I suspect there might be some in-situ damming still.

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It’s so odd seeing this solution the gfs is printing but then the Euro is printing a full on CAD storm. Lots of differences to work out.
 
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This looks like a child threw up on to our screens
 
CaryWx said:
1026 HP (meso?) sitting over Norfolk????
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NCSNOW said:
We got big picture reeled in. Its the pinpoint, finer details that will take a while.
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The cold just not penetrating far enough south, sliding out very quick. very progressive. IDK, Got many runs before possible game time!
 
Lol interesting that the 240 Canadian and GFS try to give something else a go after this storm. Weird pattern we’re running into. I don’t really hate where we are at right now. The possibility of winter precip is still showing up. While also not giving us explosive weenie runs is also good imo. Sensitive set ups can change in a dime
 
NickyBGuarantee said:
Lol interesting that the 240 Canadian and GFS try to give something else a go after this storm. Weird pattern we’re running into. I don’t really hate where we are at right now. The possibility of winter precip is still showing up. While also not giving us explosive weenie runs is also good imo. Sensitive set ups can change in a dime
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Feb of 89 was as crazy a month of weather as I have ever seen, would love to see how it analogs....that Feb had 2 or 3 snow/ice events including the monster Feb 24/25 but it also had lots of big warmth with one day hitting 83 early in the month.....we also had a significant severe outbreak on the 21st....

That was a heck of a 7 day period, we had snow/ice on the 18th, this event below on the 21st with temps into the 70's, then the big dog snowstorm 2 days later on the 24/25th with legit blizzard type conditions.

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