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Cold Rain

So What Did We Learn Here?

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Well, it appears that yet another winter storm has baffled meteorologists, forecasters, models, and snow enthusiasts everywhere.  Personally, I'd put this in the Top Five Busts of All Time category, probably in the top three, behind only the Carolina Crusher and the epic December Debacle in 2000.

I personally want to thank all of the mets and forecasters that do their best to interpret the data and give us useable information so that we can prepare for the conditions ahead.  They shouldn't be the target of anger or hateful rhetoric, as they often are on social media after events like this.

I also want to thank all of you who show up here, post maps, provide analysis, give historical context, and post obs.  This is the very first place I go for weather info.

So, with that said, what have we learned here?  I can think of a few things.  Feel free to add your own:

The NW "trend" is real and almost always occurs.

Model snowfall maps are useless at any lead or range.

Pink areas on a p-type map indicate slightly colder rain than the green areas.

Models usually vastly underestimate both the degree and duration of warm layers.  If the model is even hinting at a warm layer, cut your snowfall forecast by at least 50%.

Models usually overestimate QPF.

Cold air moving in concurrently with the storm will be much slower to do so than indicated by forecast models.

A high pressure located in a near ideal spot is needed for a widespread snowstorm.

Modeled backside snow usually vastly underperforms.

The duration of wintry weather will usually be much shorter than you think.

A Miller A taking a near ideal track in the heart of winter with apparent sufficient supply of cold air can still produce a lot of rain.

The change-over from rain to sleet or sleet to snow usually takes much longer than anticipated.

Even with ideal conditions, forecasted snowfall totals should be trimmed by at least 25%.

Snow and sleet can easily accumulate and remain on a ground that was above freezing ahead of the storm.

Snow and sleet can easily accumulate on a wet ground.

Optimism and hope do not make it snow in the south.

Congrats to all of you to the north and west that saw lots of snow.  Enjoy it, have lots of fun, and take lots of pics.  Everybody else, enjoy your wintry mix and the upcoming mild period before winter hopefully returns later this month or next.

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For us in NE Georgia, I'll add that without cold high pressure wedging down the east side of the appalachians, it's virtually impossible to get snow here, topography, warm noses, you name it.  Cold air coming in from the NW has a next to impossible time getting over the mountains in time for an impending storm.....one of the reasons why I never even pay attention to clippers anymore like I did when I was younger.  That being said, Imwas really surprised at how bad the models failed us over here, especially with the consistency they showed over such a long period of time.  All in all that was pretty much a big cup of fail.  :facepalm:

 

- Buck

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I want to point out a couple of points I agree with you on, Cold Rain.  One, on the model snowfall maps and two, models overestimate QPF.  It seems to me that even within 24 hours or even 12 hours of a snowfall event, predictions and forecasts more so than not always bust on amounts whether it's underestimated or over-estimated.  I really don't get it and would like to know the answer why.  I find it that forecasts are better if we have an all rain (liquid) event than a snow (frozen) event.  I could be wrong.  Just my observations from following weather for many years.

 

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I've learned that no one knows what's going to happen in these situations until it actually happens, even the people who make smugly definitive statements. 

I've learned there is a pretty big "garbage in, garbage out" problem in models for this area, if they cannot be tweaked to account for the "NW trend" that apparently everyone knows about. 

I've learned that no one talks about the "urban heat island effect"--or at least I assume that's what was happening when I saw pink circles in radar over Atlanta, Charlotte and Raleigh, three major areas of disappointment.

I've learned that this is the wrong hobby for me. But I have to re-learn that every year, sadly.

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1 hour ago, thess said:

I've learned that no one knows what's going to happen in these situations until it actually happens, even the people who make smugly definitive statements. 

I've learned there is a pretty big "garbage in, garbage out" problem in models for this area, if they cannot be tweaked to account for the "NW trend" that apparently everyone knows about. 

I've learned that no one talks about the "urban heat island effect"--or at least I assume that's what was happening when I saw pink circles in radar over Atlanta, Charlotte and Raleigh, three major areas of disappointment.

I've learned that this is the wrong hobby for me. But I have to re-learn that every year, sadly.

I wonder if the "urban heat island" had anything to do with the relatively little amount of wind we had - usually I think of cold air coming in with a nice northerly wind, but that didn't happen (compare the wind readings now at ~10:30a EST to the day prior http://w1.weather.gov/obhistory/KRDU.html). 

One thing I noticed (that may not be odd - someone else can chime in here if I'm wrong), but the only sounding data for the RDU area came from the NCSU Sounding Club at about 0z last night - was surprised the NWS didn't seem to have their own data. Perhaps more sounding data prior to the event could have better confirmed what the temperatures were looking like aloft (esp in comparison to how the models were predicting soundings to look like)? QPF wasn't the big question mark in the rough forecast, but rather temperature profiles, and those weren't generally well sussed out by models (except the NAM and a few others).  

The question about which model better handles WAA - is there general data about the NAM here? People seem to be arriving at the conclusion to better trust the NAM when it sees a shift/WAA, but is that something NAM-specific or should we be looking more to see if any model is suggesting temperature profile problems? Seems like guesswork that could be verified using historical data and model predictions. 

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Basically all of the models showed a Lee side minimum for this storm with totals in the 1-4" range on nearly every run.....well there was no Lee side minimum, only a Lee side MAXIMUM. Looks like the foothills will wind up the big winners in NC. Family in Hudson and Granite Falls reporting 8-10" and still snowing. Fiancé says 6" in Boone and still snowing.


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models are useless. ensembles are useless. every. single. ens. member. for the euro and gfs 24 HOURS OUT showed a huge hit for RDU.  the morning OF THE STORM the euro showed 12" of all snow for rdu. we track these storms 190+hrs out and even with a 12hr lead time they still are crap.  don't believe any snow forecast until you can see the coorelation coefficient line 100+ miles to your south.

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6 minutes ago, DopplerWx said:

models are useless. ensembles are useless. every. single. ens. member. for the euro and gfs 24 HOURS OUT showed a huge hit for RDU.  the morning OF THE STORM the euro showed 12" of all snow for rdu. we track these storms 190+hrs out and even with a 12hr lead time they still are crap.  don't believe any snow forecast until you can see the coorelation coefficient line 100+ miles to your south.

Yeah I forgot to mention the ensembles.  It's almost pointless to make any sort of accumulation forecasts outside of specific, specialized circumstances (like when we're in an ice age and the temp is at least 20 below up through the entire column).

Instead, the forecast should call for a bit of wintry weather of some type over some portion of the area starting at some point and lasting for a spell.

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1 minute ago, franklin NCwx said:

Don't expect any snow unless you're 50 miles nw of 85.

Yep...climo favored areas always win out.  Only caveat for our region is we need some form of strong block.  We had weak ridge pop, +AO/+NAO.  Unless we have a solid atlantic (50/50-NAO) I won't believe what the models show for Raleigh again.  

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NAM and UK did well on this while the Euro honestly was off.

UK showed the possible mixing 2 days in advance up the CLT/RDU area while pushing better qpf northwest.NAM picked  it up about 12-24 hours out.

Just my opinion.

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8 minutes ago, packbacker said:

Yep...climo favored areas always win out.  Only caveat for our region is we need some form of strong block.  We had weak ridge pop, +AO/+NAO.  Unless we have a solid atlantic (50/50-NAO) I won't believe what the models show for Raleigh again.  

I think a good rule of thumb is when models start showing good totals for the mtns the 85 corridor is in trouble. If you look at previous storms whenever central and eastern nc do well we get fringed.  

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Looks Ike the modeling generally overestimated QPF, as usual.  There was a lot, to be sure, but places like GSO probably didn't break 1" of liquid equivalent.  Not much of a surprise, though.

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One prop to the GFS--It was picking up on this storm at 300+ hours. Had me in/near the bulls eye back then.  

Problem was it just kept betting the streak though and when the SR models came in with ground truth the GFS was too high on itself to admit 'location' errors so to speak.  :P

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If you are in the Upper Savannah River Valley and the NAM is the only one cutting your totals, you better believe it. It sniffed out the warm nose decently well, especially the 4 km and the 3 km Para if I remember correctly.

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1 hour ago, Cold Rain said:

Yeah I forgot to mention the ensembles.  It's almost pointless to make any sort of accumulation forecasts outside of specific, specialized circumstances (like when we're in an ice age and the temp is at least 20 below up through the entire column).

Instead, the forecast should call for a bit of wintry weather of some type over some portion of the area starting at some point and lasting for a spell.

Well said sir.  That last sentence should be every forecaster's motto.  You can't blame them for being wrong.  You just want the magnitude of the uncertainty to be properly communicated.

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1 minute ago, franklin NCwx said:

The euro is a terrible model.

Lol it has gone downhill some since the downgrade they did.

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58 minutes ago, Queencitywx said:

We need more damn balloon launches. 

This!  I really would have loved to have known where that pesky warm nose was situated.  925's were down around -2 and -3 and 850's waffled between -1 and -2 every time I was looking at the SPC maps.  

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2 hours ago, franklin NCwx said:

Don't expect any snow unless you're 50 miles nw of 85.

I live six miles north/northwest of I-85 and got almost five inches of snow. 

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yeah i'm joining  Cold Rain's school of thinking. he tried warning us but I like many hugged the GFS and Euro way too hard. should have known better considering we've gotten burned so many times in the past. lesson learned.  RDU in any "bulls eye" a few days before an event is pretty much screwed.  If any part of the storm involves a warm nose anywhere RDU is pretty much screwed.90% chance of atleast x amount of snow has the same weight as a 0% chance. Sometimes even the best Mets have no idea what's going to happen even if they sound like they do.  The Models are clueless. from now on i'm not believing anything until i see it. 

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2 minutes ago, lilj4425 said:

I live six miles north/northwest of I-85 and got almost five inches of snow. 

Ok. You did good on this one but how many busted in the past?

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5 minutes ago, WxKnurd said:

This!  I really would have loved to have known where that pesky warm nose was situated.  925's were down around -2 and -3 and 850's waffled between -1 and -2 every time I was looking at the SPC maps.  

Usually, you can always count on the warmest layer of the atmosphere during our storms to be in the 750-800 mb layer, it seems.

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6 minutes ago, superjames1992 said:

Usually, you can always count on the warmest layer of the atmosphere during our storms to be in the 750-800 mb layer, it seems.

That was where I was thinking it had to be.  My guess is it was around 800 mb.

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Temps will always be an issue south of 85. If the models are hinting at a warm nose, 9/10 the warm nose will over perform. Tough for us to get a good snow in the southern part of the upstate with a Miller A setup.

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