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Wintry April Fools? (1-2) Surprise Storm

Webberweather53 said:
I just don't think we'll have an issue getting precipitation far enough NW in this instance.

The 3km NAM struggles to push the precipitation further inland due to convective feedback issues in the model that lead to spurious deepening of the low off the SC/NC coast that ultimately deters inland moisture transport vs the 12z NAM whose large-scale depiction of the coastal low is likely more realistic & in line w/ other models.

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I'm skeptical still, it's not just the 3km NAM. The RGEM I referenced has a sharp gradient with the qpf and drops 1" of snow max with most areas seeing nothing more than a dusting at best. The RGEM also has quite a few ensembles that confine the qpf more to the eastern areas due to a weaker/east LP track. Boundary layer temps will be an issue especially after 8-9am. These temps by 15Z combined with the warm ground and April sun will likely prevent any additional accumulations and melt anything on the ground, IMO, unless rates are quite heavy.
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snowlover91 said:
I'm skeptical still, it's not just the 3km NAM. The RGEM I referenced has a sharp gradient with the qpf and drops 1" of snow max with most areas seeing nothing more than a dusting at best. The RGEM also has quite a few ensembles that confine the qpf more to the eastern areas due to a weaker/east LP track. Boundary layer temps will be an issue especially after 8-9am. These temps by 15Z combined with the warm ground and April sun will likely prevent any additional accumulations and melt anything on the ground, IMO, unless rates are quite heavy.
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Cases like this w/ modest mid-level WAA, CVA aloft in conjunction with a coastal cyclone almost always end up w/ more expansive & intense precipitation further north & west from the parent cyclone (& is related to overperforming warm noses) and most guidance are evolving as you expect them to in that regard. There are many other issues that will deter snow accumulations but precipitation actually making it far enough inland to roughly the I-85 corridor is likely not going to be one of them, even if "x" model says ______. Boundary layer & ground temps are clearly more of a problem. Places that experience heavy precipitation in upstate SC & lower NC will cool roughly to near or just above 32F due to melting hydrometeors aloft and near the surface, once the precipitation rates dwindle & solar insolation increases, the temps will rise.
 
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Webberweather53 said:
Cases like this w/ modest mid-level WAA, CVA aloft in conjunction with a coastal cyclone almost always end up w/ more expansive & intense precipitation further north & west from the parent cyclone (& is related to overperforming warm noses) and most guidance are evolving as you expect them to in that regard. There are many other issues that will deter snow accumulations but precipitation actually making it far enough inland to roughly the I-85 corridor is likely not going to be one of them, even if "x" model says ______. Boundary layer & ground temps are clearly more of a problem. Places that experience heavy precipitation in upstate SC & lower NC will cool roughly to near or just above 32F due to melting hydrometeors aloft and near the surface, once the precipitation rates dwindle & solar insolation increases, the temps will rise.
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We'll see what ends up happening. I'm skeptical of meaningful precip making it that far inland, the RGEM has more precip in SC but a warmer temp profile so a cold rain in these areas. The places cold enough for snow struggle to cool with temps in the 34-36 range. Combined with warm ground temps it will make it quite difficult to see much accumulation IMO. Most of it will melt either as it hits the ground or soon after. I'm expecting most areas that see snow to get a nice 1-3 hour burst of snow with a dusting in some areas and MAYBE an inch of snow if someone gets under a heavy band.

rgem qpf.jpg
 
snowlover91 said:
We'll see what ends up happening. I'm skeptical of meaningful precip making it that far inland, the RGEM has more precip in SC but a warmer temp profile so a cold rain in these areas. The places cold enough for snow struggle to cool with temps in the 34-36 range. Combined with warm ground temps it will make it quite difficult to see much accumulation IMO. Most of it will melt either as it hits the ground or soon after. I'm expecting most areas that see snow to get a nice 1-3 hour burst of snow with a dusting in some areas and MAYBE an inch of snow if someone gets under a heavy band.

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Feel free to believe what you want and hug your favorite suite of models, but I think you'll end up being wrong in this regard & "meaningful" precipitation will in fact make it to or even past the I-85 corridor (which is what the professional forecasters at NWS GSP are hedging towards as well).

Warm ground temps play a role in snow accumulation but its usually overstated and that doesn't make it necessarily very difficult or anywhere near impossible to get accumulation (even significant accum) if precipitation rates are heavy. There are innumerable examples of this and this case won't be any different if precip rates are heavy.
 
Webberweather53 said:
Feel free to believe what you want and hug your favorite suite of models, but I think you'll end up being wrong in this regard & "meaningful" precipitation will in fact make it to or even past the I-85 corridor (which is what the professional forecasters at NWS GSP are hedging towards as well).

Warm ground temps play a role in snow accumulation but its usually overstated and that doesn't make it necessarily very difficult or anywhere near impossible to get accumulation (even significant accum) if precipitation rates are heavy.
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We will see what happens. I think the best shot at accumulating snow is going to be in upstate SC similar to what the 3km NAM is showing, they have the best timing with the bulk of it moving through in the early morning hours before solar insolation becomes a factor. The 3km NAM and RGEM generally have .1 to .3" of qpf along the 85 corridor. That's not much to work with considering the other unfavorable factors in play here.

I think the 12z 3km NAM is fairly reasonable but a bit high. A general dusting to an inch in the heavier bands. Once we get past 11am it will be tough to get snow anywhere in NC due to BL temps in the 35-37 range.
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It's a terrible model in the long range, I don't like it outside of 8-10 hours, but here's the 12z HRRR.

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Tarheel1 said:
Jimmy, look!!? from the other board!View attachment 18299View attachment 18300
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LMAOOO. Looks a lot like that Euro/Ukie combo for mby in early December? ? I hope this one pans out a little better than that one. I think areas south of 85 in SC are favored here. If this thing holds, we’re going to see some heavy heavy snow. I’m putting my snow meter at 2% right now
 
If this works out, weather forums will be sifting through analogs in 50 years saying “Niño winters are usually bookend loaded. For example look at 2019.” and they won’t be able to grasp how eternernally ------ this winter really was
 
Myfrotho704_ said:
NAM 3km snow holed CLT, lol
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Ugh hopefully that dry slot goes away, I definitely remember getting badly burned by the Jan 3-4 2018 event that had a strong coastal low and the NAM was the only model that consistently showed a dry slot near rdu which ended up verifying to my dismay. Let’s not do that again
 
Some guidelines to consider:
- NAM often has double the amount of liquid equivalent that verifies when it is by far the wettest model.
- Regarding EPS cold bias from Radiant this morning:
“As referenced in Friday’s report, models have shown a bias to be too cold and significantly so even in their near term projections. These biases continued this past weekend, when the 0z Friday Euro EN missed by 4.5 GWHDDs for the Friday to Sunday period. The other model ensembles also missed significantly to the cold side of observation, while the Radiant forecast and GFS OP models where nearest to actual.”

So, some of the NAM runs may be overdoing snow due to qpf while the EPS could easily be doing so due to cold bias. My recommendation is to keep accumulation expectations very low and hope for the best. I assume most would be satisfied to just be able to see the rare and exciting event of big wet flakes falling in April regardless of accumulation. Even if it sticks, it will most likely melt very quickly, regardless. No matter what, I’m excited just to have something like this to track in April!
Edit: I’m educatedly guessing that a good portion of even N GA will see big wet flakes flying, perhaps back to ForsythWx’s location.
 
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12z RGEM hot off the press... qpf is limited in areas cold enough for snow... very limited, and boundary layer temps are 34-36 and quickly warm once the sun comes up. Coming from a model that is sometimes too cold biased this is NOT a good sign IMO.

12z rgem qpf.jpg

12z RGEM.jpg
 
12Z ICON maintains: I know the TT FV3 is almost always way overdone but does anyone know about the TT algo for the ICON?
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Webberweather53 said:
Ugh hopefully that dry slot goes away, I definitely remember getting badly burned by the Jan 3-4 2018 event that had a strong coastal low and the NAM was the only model that consistently showed a dry slot near rdu which ended up verifying to my dismay. Let’s not do that again
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The good thing is that usually the 3km is too dry until it gets in the short range at least that’s what I’ve come to notice in events this winter. It’s a strange dry slot why would this be happening Webber?
 
snowlover91 said:
12z RGEM hot off the press... qpf is limited in areas cold enough for snow... very limited, and boundary layer temps are 34-36 and quickly warm once the sun comes up. Coming from a model that is sometimes too cold biased this is NOT a good sign IMO.

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1 model run doesn’t mean much at all .. if consistently the RGEM keeps this up then we have a problem but wouldn’t look much past this
 
Plus other models are keeping this threat strong and that’s what I’m banking on. Plus if the north west quadrant has more precip and is more expansive (as they usually are with these events) that precip will hit earlier and we won’t have to deal much with the surface temps being too warm
 
Nick_boynton_ said:
The good thing is that usually the 3km is too dry until it gets in the short range at least that’s what I’ve come to notice in events this winter. It’s a strange dry slot why would this be happening Webber?
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Really strong dry layer aloft and descent present from 700 hPa to the sfc
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Nick_boynton_ said:
1 model run doesn’t mean much at all .. if consistently the RGEM keeps this up then we have a problem but wouldn’t look much past this
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None of this will be a “problem” if folks would assume there will probably be little accumulation in most areas at best. Then maybe they will be surprised or maybe not. But little chance for disappointment this way. Hopefully at least there will be some beautiful flakes flying, which I expect.
 
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