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Winter storm 12/8-9 model discussion part II


Ji

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 For sure.

 

Better odds we get something I suppose but spotty precip mainly missing to the west would be only partly shocking. If we do that then I'd probably want to finish off with us not cooling the sfc enough and then warming to 33 before the heavier overnight stuff arrives.  ;)

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Better odds we get something I suppose but spotty precip mainly missing to the west would be only partly shocking. If we do that then I'd probably want to finish off with us not cooling the sfc enough and then warming to 33 before the heavier overnight stuff arrives. ;)

30+dbz returns showing in se KY

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You could be right but that forecast goes against all reliable guidance. If an arctic high wasn't parked jogging distance from our heads I would be more willing to agree but if it wasn't the models would agree as well.

The high rez NAM has a thin east to west band of persistent sleet just south of the Mason-Dixon line in late afternoon.  Central Virginia looks like it warms almost to the surface due to robust south and southeast winds aloft.  So early in the winter, any marine layer (fetch off Ches. Bay and Atlantic Ocean) seems to overcome the pressing high, at least in N-Central VA and at least according to the high rez NAM.

 

The question will be which model is correct at 700 mb to 925 mb.

Even the high rez NAM has a very moist 700 mb chart so the shocking

RAP remains a dry outlier.

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The high rez NAM has a thin east to west band of persistent sleet just south of the Mason-Dixon line in late afternoon. Central Virginia looks like it warms almost to the surface from south and southeast winds aloft. So early in the winter, any marine layer (fetch off Ches. Bay and Atlantic Ocean) seems to overcome the pressing high, at least in N-Central VA and at least according to the high rez NAM.

Agree on all points. I was questioning the 3hr window from sn to zr in the dc-balt westward area. It's definitely possible but I wouldn't hedge that bearish attm.

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You could be right but that forecast goes against all reliable guidance. If an arctic high wasn't parked jogging distance from our heads I would be more willing to agree but if it wasn't the models would agree as well.

 

A big part of forecasting is actually taking model output and interpreting it with your own experience and local knowledge.  Otherwise, why not just have a robot translate the model output literally and make it the forecast?  I've lived through a lot of these scenarios, and I don't remember getting much more than a crust in most of the cases.  I love snow, and I hope I'm wrong, but my experience says not to get excited.  I think zr will be the bigger issue in those areas that are prone to it. 

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A big part of forecasting is actually taking model output and interpreting it with your own experience and local knowledge.  Otherwise, why not just have a robot translate the model output literally and make it the forecast?  I've lived through a lot of these scenarios, and I don't remember getting much more than a crust in most of the cases.  I love snow, and I hope I'm wrong, but my experience says not to get excited.  I think zr will be the bigger issue in those areas that are prone to it. 

This high is pretty anomalous. This is definitely not like the crappy marginal situations of the past two winters. I don't see it being major icing near the cities, but it should be more than a trace of snow and some sleet crust.

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A big part of forecasting is actually taking model output and interpreting it with your own experience and local knowledge.  Otherwise, why not just have a robot translate the model output literally and make it the forecast?  I've lived through a lot of these scenarios, and I don't remember getting much more than a crust in most of the cases.  I love snow, and I hope I'm wrong, but my experience says not to get excited.  I think zr will be the bigger issue in those areas that are prone to it. 

Your explanation is credible but either solution is still on the table if considering soundings.

At coolwx.com, the NAM sounding gives Sterling 7 hours of sleet (0.6 inch) and the GFS gives no sleet.

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This high is pretty anomalous. This is definitely not like the crappy marginal situations of the past two winters. I don't see it being major icing near the cities, but it should be more than a trace of snow and some sleet crust.

 

Yeah, I see that, but I think its strength will manifest itself more at the surface--the warm nose aloft will not be denied, but the low-level cold air will be tough to erode, so I am just thinking the freezing rain will be a bigger deal for us.  I see more "freezing" precipitation than "frozen."

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This high is pretty anomalous. This is definitely not like the crappy marginal situations of the past two winters. I don't see it being major icing near the cities, but it should be more than a trace of snow and some sleet crust.

 

Yes, I wasn't trying to be a hard ass. I re-read my post and it was curt. The window is there. If we get hosed on rates during primetime then yes, the bearish forecast is a good one. Delays of the solid precip shield are full of hurt feelings. But that is a different argument then saying that the window is actually just 3 hours without bringing up timing, qpf, etc. 

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Yes, I wasn't trying to be a hard ass. I re-read my post and it was curt. The window is there. If we get hosed on rates during primetime then yes, the bearish forecast is a good one. Delays of the solid precip shield are full of hurt feelings. But that is a different argument then saying that the window is actually just 3 hours without bringing up timing, qpf, etc. 

There are still a number of ways to bust...and none of us will be surprised if we do and none of us will learn from it and we'll move on to Tuesday

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Yeah, I see that, but I think its strength will manifest itself more at the surface--the warm nose aloft will not be denied, but the low-level cold air will be tough to erode, so I am just thinking the freezing rain will be a bigger deal for us.  I see more "freezing" precipitation than "frozen."

OK, I think I misread your post. I thought you were going for a quick transition to plain cold rain which didn't make a lot of sense.

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There are still a number of ways to bust...and none of us will be surprised if we do and none of us will learn from it and we'll move on to Tuesday

 

As always. Locks are reserved for the once in an 8 year winter. One trend I noticed in the favorable runs vs the notsogreat ones was the precip max in eastern KY / southern WV. All the good ones seemed to have a pretty robust .4 - .7 qpf for 6 hours overnight into dawn. I'm watching that area closely. For obvious reasons, there's a connection to how that area fares and how we do in our window of hope. Looks ok so far. Filling in in the east half of TN right now. 

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As always. Locks are reserved for the once in an 8 year winter. One trend I noticed in the favorable runs vs the notsogreat ones was the precip max in eastern KY / southern WV. All the good ones seemed to have a pretty robust .4 - .7 qpf for 6 hours overnight into dawn. I'm watching that area closely. For obvious reasons, there's a connection to how that area fares and how we do in our window of hope. Looks ok so far. Filling in in the east half of TN right now. 

yes, it seems to look much like the original "finger" of precip the models had a couple days ago

I think ur correct wrt us doing better if it comes from the west

anything that comes from the s/sw is bring warm air with it while the stuff from the w.wsw naso much

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SPC WRF and HRRR both seem to agree on somewhat later start times now in the DC Metro...maybe as late as 16-17z...was thinking more 13-14Z earlier todat

that may be what the computers say, but do their very short term forecasts from a few hours ago match up with current radars, which look pretty robust?

maybe they did and maybe they didn't, I'm just wondering

as a reference point, the 0Z NAM said the national radar should look like the link below...there are a lot of returns much closer to us than what the NAM thought only 6 hrs ago

http://mag.ncep.noaa.gov/Image.php?fhr=006ℑ=data%2Fnam%2F00%2Fnam_namer_006_sim_radar.gif&model=nam&area=namer&param=sim_radar&group=Model+Guidance&imageSize=M

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that may be what the computers say, but do their very short term forecasts from a few hours ago match up with current radars, which look pretty robust?

maybe they did and maybe they didn't, I'm just wondering

as a reference point, the 0Z NAM said the national radar should look like the link below...there are a lot of returns much closer to us than what the NAM thought only 6 hrs ago

http://mag.ncep.noaa.gov/Image.php?fhr=006ℑ=data%2Fnam%2F00%2Fnam_namer_006_sim_radar.gif&model=nam&area=namer&param=sim_radar&group=Model+Guidance&imageSize=M

 

The SPC WRF was so-so, the HRRR not so great...the best models at 00Z for getting the precip correct right now were probably the RGEM and SPC WRF and even those were not great...the GFS and NAM both are off.

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The lull makes it awful tough to figure out the ice thing. Surface freezing line @ 1AM runs 95 but precip is light. big slug comes during the next 6 hours. I can't tell when the the freezing line moves through compares to when the good precip is overhead. 

 

Still some snow for sure but the jackpot is much further NW and then a lull. 

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Lull is going to make the public think everyone busted

 

Well, here we are less than 12 hrs from onset...and guidance is everywhere. The euro is great but that was a big move in 12 hours. Now short range and latest american models say other things. Yea, it clouds everything IRT to everything. Heh

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