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Wintry Palm Sunday NC and VA Winter Storm

Don't fret over one model run. Overall, the models have mostly trended better.
 
Getting into la-la land for the HRRRx so take it for what it's worth but the new 23z run looked better (colder and slower) than the 18z upstream over Indiana, Illinois, and Iowa through 18 hours. Will be interesting to see what this model looks like by the 12z runs tomorrow in addition to the entire HREF suite. We should get a first glimpse of the high res model 0z consensus by tonight when the HREF comes in.
 
The 0z NAM and 1z HRRR are worlds apart on surface temperatures even out to 10 hours w/ the 3km NAM way warmer than the HRRR, one of these models is going to bust terribly over the midwest and OH/TN valley but I'm not sure which one yet.
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Looks at 3k NAM...
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Meanwhile, the RGEM is in the corner pointing it's fingers and laughing at the NAM suites.:rolleyes:

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Webberweather53 said:
The 0z NAM and 1z HRRR are worlds apart on surface temperatures even out to 10 hours w/ the 3km NAM way warmer than the HRRR, one of these models is going to bust terribly over the midwest and OH/TN valley but I'm not sure which one yet.
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We'll know by morning which model head its head stuck in the sand. Definitely will be very important to monitor the upstream evolution of this system and the verification vs reality over the midwest and OH valley and how the high res models trend in the short range because some of their errors and in-situ adjustments could quickly propagate downstream and impact our forecast, in addition to monitoring surface observations compared to forecasts as these may potentially provide very subtle hints on which way the forecast will lean Saturday night. Considering all of the above plus the 12z model suite tomorrow, by then I think we should have at least an okay-ish idea on what's going to happen.
 
Hmm this looks strange to me. There's actually more ascent throughout the entire column and especially in the DGZ on this 0z NAM run (which argues for more dynamical cooling) and you'll notice the wind direction and speed in the lower-levels (indicative of veering and warm air advection) is slightly less pronounced & the QPF overall is the same, yet this runs is somehow warmer?
Ok...
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Webberweather53 said:
Hmm this looks strange to me. There's actually more ascent throughout the entire column and especially in the DGZ on this 0z NAM run (which argues for more dynamical cooling) and you'll notice the wind direction and speed in the lower-levels (indicative of veering and warm air advection) is slightly less pronounced & the QPF overall is the same, yet this runs is somehow warmer?
Ok...
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Upon closer inspection it looks like the timing of thick mid-high level clouds tomorrow morning and into the early part of the afternoon is the difference maker on the NAM vs its 18z suite. Less thick clouds later on allows more insolation to come thru and warm the BL before a thicker low-level cloud deck arrives later in the evening ahead of our precipitation. As was the case w/ the comparison between the HRRR & NAM runs through 10 hours we'll know by morning if this is legit or not.
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Well this didn't take long. The 3km NAM is way too warm already over the Carolinas, has temps in the mid-upper 40s for 3z, reality is in the upper 30s-near 40F according to the newest 3z observations. For example it's supposed to be 49F right now in Rockingham, NC it's already 40F there. Other stations like RDU, Clinton, etc. are also running much colder than forecast just 3 hours out. What a dumpster fire this run has turned out to be in the short range thus far

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Webberweather53 said:
Well this didn't take long. The 3km NAM is way too warm already over the Carolinas, has temps in the mid-upper 40s for 3z, reality is in the upper 30s-near 40F according to the newest 3z observations. For example it's supposed to be 49F right now in Rockingham, NC it's already 40F there. Other stations like RDU, Clinton, etc. are also running much colder than forecast just 3 hours out. What a dumpster fire this run has turned out to be in the short range thus far

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The GFS is not even in the same galaxy in the mountains right now, way too cold by nearly 5-10F in some cases, whereas it's not cold enough in the east-central piedmont and coastal plain of NC.
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Already down to 36 at RDU, forecast low is 34F, looks like that's already in jeopardy. None of this may matter if we warm to our heart's content tomorrow because we don't have clouds tomorrow afternoon that's the big unknown right now.
 
Surely this winter storm just didn’t go down the drain at this late hour? But NAM and GFS follows with much warmer temps, something is up and it’s not snow totals!!


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GFS and NAM suites looking a lot like the RGEM now.
 
BIG FROSTY said:
Surely this winter storm just didn’t go down the drain at this late hour? But NAM and GFS follows with much warmer temps, something is up and it’s not snow totals!!

Sun is at same angle we get 1st week of September. We don't have a heavy cloud deck, preferably some override moisture first few hours Saturday, itll be game set match. To much to recover from in my opinion.

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I just can't believe the Euro would be off that bad either? I know it's over done but I thought maybe half that amount 4-6 inches was possible....
The HRRR has precip here in 9 hours!!
Everybody went to bed after the GFS. lol
 
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The Euro is a degree (if that) warmer than its previous run in the areas of concern over NC but it's virtually the same overall. A 1-2F error is well within the understood and acceptable error range even for model initialization (i.e. this run's changes might be just noise) so remain vigilant esp along/north of US 64.

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Webberweather53 said:
The Euro is a degree (if that) warmer than its previous run in the areas of concern over NC but it's virtually the same overall. A 1-2F error is well within the understood and acceptable error range even for model initialization so remain vigilant esp along/north of US 64.

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This is pretty encouraging with the Euro holding on!!
 
37 degrees in Greensboro dark and early this morning.

I looked briefly at the 6z models and they look more like 18z runs than the 0z. Maybe the 0z runs were a bit of an anomaly?
 
It is 38 here with a dp of 22. Still thinking the 3Km Nam will end up correct as far as the p-type for most of us being rn with some ip and maybe brief Sn west of 85 and North of 40. Mountains should get mostly sn with some ip and possibly even some zr mixed in but no accumulations outside of the higher areas. Still amazing we are tracking something at the end of March so it is a win either way
 
The 0z 3km NAM cloud cover forecast from last night is not looking too good this morning, while these scales aren't directly comparable, if you compare the cloud top values on longwave IR from GOES 16 to its forecast we have cloud tops running -30C to -40C across much of central and western NC while it had values of only -10 to -20C (shallower, warmer, and thinner clouds) that burned off later in the day.
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0z HREF snowfall mean (10:1 SLR). Interested to see what this looks like after the 12z run later today. The amounts are overzealous (which makes sense here given the ratios are assumed to be 10:1), but the distribution is pretty realistic imo
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Webberweather53 said:
0z HREF snowfall mean (10:1 SLR). Interested to see what this looks like after the 12z run later today.
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This is just a friendly reminder what the High Resolution Ensemble Forecast (HREF) actually is. It's essentially an ensemble of most of our high resolution, convection allowing models (CAMs) and uses the 2 most recent runs from the HRW NSSL, HRW ARW, HRW NMMB, and the 3km NAM. It can be a pretty useful product in situations like this and its current 0z forecast isn't all that outlandish imo.

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http://www.spc.noaa.gov/exper/href/
 
Glad to see the NAM was out to lunch. I still think I could end up with a couple of inches out of this.
 
Webberweather53 said:
I'm really not buying the latest NWS snowfall forecast, I think they've backed off way too much especially along and north of 40 & I-85.
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It's so close for the 40/64 corridor northward. It'll be interesting to see how things progress when we start seeing heavier bands of precip set up and if they are enough to cool the warmer layers.

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