East Tennessee Weather II

#3,253
#3,253
norrislakevol said:
Question: What makes the HRRR the best? Seems as if you trust that, discounting the GFS, and even the EURO which have been more aggressive. Is there a reason why? Are those models not as good? I would certainly like to know.
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I look at everything, but in the short term just really like taking a look at the HRRR because it's good at showing terrain effects, warm nose, and overall because of its higher resolution. It's been very good the past year or two with many of these events, especially strongly forced systems or orographic forced systems (which this isn't either). Only model I don't really love much during winter events (but I still look at) is the Canadian because it seems to always over predict snowfall. I really like using ensembles, and think highly of the upgraded GFS and the ECMWF. Ensembles such as the SREF and GEFS are indispensable.

I'd still predict 1-3" for most around Knoxville, but if enough sleet and rain mix in, it could definitely bust for those south of I-40. Just historically this type of track usually creates a pretty tight snow gradient from south to north and is usually in the 1-3" or 2-4" range for those near and north of Knoxville. Ensemble and model trends are going lower with totals and hi-res guidance such as the HRRR are showing how it could bust with surface temps being a degree or two warmer near and south of Knoxville. The SREF now has at least half of it's members around 1.5" or less around Knoxville and some of that will probably melt and not really accumulate. Just a minor change in the track of this system will have large implications on snowfall totals. It's far from a slam dunk forecast, but that's most forecasts around here.
 
#3,255
#3,255
All the 0z guidance in now with the ECMWF trending up some. Overall QPF is 0.3-0.5 consistent between models, big difference is precip type. Still looking like 1-3" in the valley near Knoxville, some slight higher amounts on ridgetops, and much lower totals as you head south of Knoxville.
models-2022010600-f036.snodpc_acc.us_ov.gif
 
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#3,256
#3,256
MetVol said:
I look at everything, but in the short term just really like taking a look at the HRRR because it's good at showing terrain effects, warm nose, and overall because of its higher resolution. It's been very good the past year or two with many of these events, especially strongly forced systems or orographic forced systems (which this isn't either). Only model I don't really love much during winter events (but I still look at) is the Canadian because it seems to always over predict snowfall. I really like using ensembles, and think highly of the upgraded GFS and the ECMWF. Ensembles such as the SREF and GEFS are indispensable.

I'd still predict 1-3" for most around Knoxville, but if enough sleet and rain mix in, it could definitely bust for those south of I-40. Just historically this type of track usually creates a pretty tight snow gradient from south to north and is usually in the 1-3" or 2-4" range for those near and north of Knoxville. Ensemble and model trends are going lower with totals and hi-res guidance such as the HRRR are showing how it could bust with surface temps being a degree or two warmer near and south of Knoxville. The SREF now has at least half of it's members around 1.5" or less around Knoxville and some of that will probably melt and not really accumulate. Just a minor change in the track of this system will have large implications on snowfall totals. It's far from a slam dunk forecast, but that's most forecasts around here.
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Good stuff, thanks for the info. I will definitely have to keep in mind the HRRR for the orographic situations. The models have been very aggravating to me this go around. It is very irritating to have the NAM and the GFS so far off from one another this close to an event. At any rate, some of this looks like a timing thing, and The radar and timing look good. I have seen this exact same scenario play out before in the the early 2000's with the quick striking heavy snow burst at the beginning of an event like this. dynamic cooling will certainly come into play for some if the precip keeps up this intensity, and it looks like it will.
 
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#3,258
#3,258
Models have trended toward lower totals. Hopefully we get at least an inch! I’m already in need of another snow day!
 
#3,259
#3,259
Those 850mb temps are looking like they'll inhibit snowfall. I have hope that it'll cool off and snow will break through but I'm not getting my hopes up.

Those of you who live in Middle Tennessee, enjoy the snow!
 
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#3,262
#3,262
norrislakevol said:
Good stuff, thanks for the info. I will definitely have to keep in mind the HRRR for the orographic situations. The models have been very aggravating to me this go around. It is very irritating to have the NAM and the GFS so far off from one another this close to an event. At any rate, some of this looks like a timing thing, and The radar and timing look good. I have seen this exact same scenario play out before in the the early 2000's with the quick striking heavy snow burst at the beginning of an event like this. dynamic cooling will certainly come into play for some if the precip keeps up this intensity, and it looks like it will.
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We'll get some evaporational cooling on the front end here cooling things down, so it'll be important to monitor wet bulbs this morning as it moves in. It's a frustrating forecast for sure. Wet bulbs at 11am are about 34 at TYS and DKX, 33 at OQT, 31 at JAU, 33 at MOR, and 35 at GKT. The GFS seems to be colder than observations, the NAM is too warm, and the HRRR is probably just slightly on the warm side but better than the NAM. 6z ECMWF was also too dry and cold compared to observations this morning at 15z.

Probably see mostly snow around Knoxville but the warmer temperatures will limit accumulation some. Still think about 1-2" with up to 3" will be possible across the Knoxville. Up towards Norris, should be good to go for some snow and could get 2-4" on ridgetops.
 
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#3,263
#3,263
I’m in powell and haven’t seen a drop of anything yet. Surprising since it looks like Crossville is getting hammered.
 
#3,270
#3,270
HRRR and NAM way too warm compared to observations right now. GFS actually handling it the closest. Also SREF plumes at Knoxville had nudged back up near 2" mean. Still looking like 1-3" for most around Knoxville. Could be a bit lower if sleet mixes in this afternoon.

1641491084091.png
 
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#3,272
#3,272
Seems Met and Matt were right about that warm air. It’s all rain now in Hardin Valley and the moisture doesn’t seem to be as strong as what hit Nashville.
 
#3,273
#3,273
MetVol said:
We'll get some evaporational cooling on the front end here cooling things down, so it'll be important to monitor wet bulbs this morning as it moves in. It's a frustrating forecast for sure. Wet bulbs at 11am are about 34 at TYS and DKX, 33 at OQT, 31 at JAU, 33 at MOR, and 35 at GKT. The GFS seems to be colder than observations, the NAM is too warm, and the HRRR is probably just slightly on the warm side but better than the NAM. 6z ECMWF was also too dry and cold compared to observations this morning at 15z.

Probably see mostly snow around Knoxville but the warmer temperatures will limit accumulation some. Still think about 1-2" with up to 3" will be possible across the Knoxville. Up towards Norris, should be good to go for some snow and could get 2-4" on ridgetops.
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Yeah we just had 1 inch accumulate in less than 45 minutes here in northeastern Anderson county. Once you get a good base then it's easier for the rest to pile up. I will need to research wet bulbs. Thanks for yet another tid bit!
 
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#3,274
#3,274
hUTch2002 said:
Seems Met and Matt were right about that warm air. It’s all rain now in Hardin Valley and the moisture doesn’t seem to be as strong as what hit Nashville.
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Your in Hardin Valley and it’s raining? That’s crazy, I’m in Karns and it hasn’t rained once it’s all snow
 
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