Feb 8-9th Miller Boom or Bust Disco

[SomeguyfromTakomaPark]

I think they are leaning more toward the higher end for their official forecast.

 

What are your thoughts on temps for this event?  I'm assuming you guys are thinking the immediate DC area can cool dynamically enough if we get some rates based on the 3-4 nosing into DC.

[Fozz]

You would expect the high res models to be the ones to go nuts with qpf in this type of thing but oddly it's been the globals, first the euro then recently the gfs that show better qpf. The nam rgem and Sref remain unimpressed.

 

I think the high-res models are really amping that OTS storm, which explains the less impressive totals here.

[mitchnick]

6z para gfs looks pretty solid. 2 waves of enhanced precip move through with two pieces of upper level energy. N MD gets 1" qpf. Color me shocked.

paraprecip.JPG

Wow. Starting to get consistency with both gfs and para gfs. That qpf total is almost identical to the 0z run totals.

[Scarlet Pimpernel]

You would expect the high res models to be the ones to go nuts with qpf in this type of thing but oddly it's been the globals, first the euro then recently the gfs that show better qpf. The nam rgem and Sref remain unimpressed.

 

It does give one pause when the mesoscale models...which are now in range for this...are decidedly more "meh" on the event.  And apparently consistently so.

[Fozz]

I think they are leaning more toward the higher end for their official forecast.

 

It's not all that uncommon I don't think.  You can consider the min/max as their estimate of the extremes of the envelope (or spread), so to speak, with the mean being of course the expected value.  I would interpret that to imply they are hedging toward their higher numbers (more confidence in that).  As I recall, they did the same for the January blizzard...the mean numbers were close to the max.

 

ETA:  Ninja'd by ers-wx above!

 

Thanks, that was helpful!

[mitchnick]

I think they are leaning more toward the higher end for their official forecast.

They usually favor the gfs, so that makes sense.

[ers-wxman1]

You would expect the high res models to be the ones to go nuts with qpf in this type of thing but oddly it's been the globals, first the euro then recently the gfs that show better qpf. The nam rgem and Sref remain unimpressed.

It was funny how the 00z NAM went bonkers last night with widespread 0.5 to 1" liquid. 06z went to nothing.

[clueless]

You would expect the high res models to be the ones to go nuts with qpf in this type of thing but oddly it's been the globals, first the euro then recently the gfs that show better qpf. The nam rgem and Sref remain unimpressed.

 

 

It does give one pause when the mesoscale models...which are now in range for this...are decidedly more "meh" on the event.  And apparently consistently so.

 

 

 

Yes.  When it comes game time we will see. Not optimistic with this one.

[ers-wxman1]

What are your thoughts on temps for this event? I'm assuming you guys are thinking the immediate DC area can cool dynamically enough if we get some rates based on the 3-4 nosing into DC.

I think it's marginal at the lowest levels to start especially I-95. Would need steadier precip to overcome this.

[psuhoffman]

It's not all that uncommon I don't think. You can consider the min/max as their estimate of the extremes of the envelope (or spread), so to speak, with the mean being of course the expected value. I would interpret that to imply they are hedging toward their higher numbers (more confidence in that). As I recall, they did the same for the January blizzard...the mean numbers were close to the max.

ETA: Ninja'd by ers-wx above!

I don't know how they derive those things and don't really care but when one of the major models we rely on is spitting out a foot of snow across parts of the area I just think it's a bit disingenuous to say the Max potential is 7". Are you saying that the gfs is not possible. I don't buy its higher totals either but I wouldn't go so far as to label it physically impossible which is what you do by putting a maximum potential map that's significantly lower then it's last couple runs. Maybe nws means maximum likely result which brings me back to my comment yesterday about the words maximumpotential and perhaps they do not know what that actually means.

[NinjaWarrior2]

FWIW 4K NAM is a good bit better than the last couple runs. Looks like Northern MD/NW VA/ Southern PA is the place to be. Better than 12k this run, for Baltimore North. HRRX is a good tick east of 12z 4K NAM for the first low.

[Wonderdog]

It does give one pause when the mesoscale models...which are now in range for this...are decidedly more "meh" on the event.  And apparently consistently so.

I agree. Not to be a downer but the way it's looking now, it's as perfect a setup with this type of event than we could have (my opinion). So only one way to go from here (my opinion).

[stormtracker]

They usually favor the gfs, so that makes sense.

Might be a mistake at this lead tho?  NAM is mesoscale and should be better at this one would think

[Staged]

Do you guys think there will be any accumulation tomorrow evening around jyo or will the majority come over night into Tuesday? Trying to figure out if I should drive the plow truck into work tomorrow. Thanks guys and appreciate everyones knowledge.

[psuhoffman]

I think the high-res models are really amping that OTS storm, which explains the less impressive totals here.

I was thinking that which means if they are wrong about that perhaps once we get past it they will begin to be useful in seeing the banding with the trough better.

[T. August]

I'm goin' GFS all the way. Different beasts, but it did nail the blizzard, so it has my attention.

[mitchnick]

Might be a mistake at this lead tho? NAM is mesoscale and should be better at this one would think

But the para gfs is almost in lock step with gfs. It remains hard to trust the nam at any lead. But this event is sooo diff than the blizzard in that model mayhem is at its worst in a long time.

EDIT: probably more concerned with the RGEM

[Fozz]

I was thinking that which means if they are wrong about that perhaps once we get past it they will begin to be useful in seeing the banding with the trough better.

 

Yep, we'll have to see how it plays out..... maybe tomorrow morning we'll finally have a clear idea about this.

[Scarlet Pimpernel]

I don't know how they derive those things and don't really care but when one of the major models we rely on is spitting out a foot of snow across parts of the area I just think it's a bit disingenuous to say the Max potential is 7". Are you saying that the gfs is not possible. I don't buy its higher totals either but I wouldn't go so far as to label it physically impossible which is what you do by putting a maximum potential map that's significantly lower then it's last couple runs. Maybe nws means maximum likely result which brings me back to my comment yesterday about the words maximumpotential and perhaps they do not know what that actually means.

 

Whoa...I'm just the messenger interpreting what the product is based upon my knowledge of how it works.  I made no assessment on how good it is or if they're wrong or disingenuous by ignoring the high values in the GFS.  Someone asked a question on why the mean was closer to the max, and a couple of us answered that.

 

But to get more at what you're saying, I'm sure they are toning down what the GFS was showing and also hedging because the NAM and other mesoscale models aren't overly bullish.  That's what the human element of the forecast is supposed to do (whether they're right or wrong in the end remains to be seen).  They aren't supposed to just spit out the highest and lowest values that a model shows.  I don't think they consider it "physically impossible", but why throw out the extreme numbers right now?  Could they (or should they) up the max potential?  Maybe, but for right now I'm not sure it really matters.  They've got the max potential up near the MD/PA border in the range of warning criteria or better (the mean is as well), which should be enough to alert people of a possible significant event there.  For a highly uncertain situation, I would think that's not half bad at this point.  I'm sure it will be updated over time, one way or the other, as confidence increases.

[WxUSAF]

I'm still fairly pessimistic on this event. Wouldnt be surprised if Mt Parkton and ji get 4"+, but I'd go t-2" in the cities and maybe 1-3" for the 95 corridor. 24hr of light snow with above freezing temps don't do well for us.

[Bob Chill]

But the para gfs is almost in lock step with gfs. It remains hard to trust the nam at any lead. But this event is sooo diff than the blizzard in that model mayhem is at its worst in a long time.

EDIT: probably more concerned with the RGEM

A bit of information overload going on right now. The general idea hasn't changed for quite a few runs now. We're stuck parsing small shifts with qpf every 6 hours. I don't think fine details are that important yet. The meso's tomorrow at 12z are probably when they start to fine tune things. They're still dealing with the big storm to the south and how that progresses. Globals are imo still the go to.

[H2O]

I'm still fairly pessimistic on this event. Wouldnt be surprised if Mt Parkton and ji get 4"+, but I'd go t-2" in the cities and maybe 1-3" for the 95 corridor. 24hr of light snow with above freezing temps don't do well for us.

P much my thoughts. I'm cool with whatever falls and not gonna hate on those that get more than me

[psuhoffman]

Whoa...I'm just the messenger interpreting what the product is based upon my knowledge of how it works. I made no assessment on how good it is or if they're wrong or disingenuous by ignoring the high values in the GFS. Someone asked a question on why the mean was closer to the max, and a couple of us answered that.

But to get more at what you're saying, I'm sure they are toning down what the GFS was showing and also hedging because the NAM and other mesoscale models aren't overly bullish. That's what the human element of the forecast is supposed to do (whether they're right or wrong in the end remains to be seen). They aren't supposed to just spit out the highest and lowest values that a model shows. I don't think they consider it "physically impossible", but why throw out the extreme numbers right now? Could they (or should they) up the max potential? Maybe, but for right now I'm not sure it really matters. They've got the max potential up near the MD/PA border in the range of warning criteria or better (the mean is as well), which should be enough to alert people of a possible significant event there. For a highly uncertain situation, I would think that's not half bad at this point. I'm sure it will be updated over time, one way or the other, as confidence increases.

I'm sorry if you thought my comments were directed at you. They were adding to your post about the nws product but I by no means thought you had anything to do with it. And I agree with your reasoning and that they toned down the gfs as an outlier but again back to the words Max potential, that's not when you tone down. Max potential is worst case scenario. Another way of looking at it is the actual outcome should never be greater then the Max potential unless it's a truly historic bust. While it's unlikely I could easily see someone in this forum pick up 8" from getting under meso scale banding and that would then beat the so called Mac potential which makes no sense. I think nws is toning down so as not to scare people but if that's the case maybe you shouldn't put out a Max potential map instead of basterdizing it.

[DDweatherman]

Honestly IMHO by looking at the sat/WV loops I'm having trouble seeing how the first storm doesn't continue to come west a slight bit on models. No significance to us except we want that one as far east as possible.

[ers-wxman1]

Thus far the GFS has been the most consistent...whether it's right or wrong remains to be seen but it's run to run has been decent past 3 runs and GEFS back it up. NAM like Bob said should lock in once the banding of mess features become more certain. My own personal preference is to go with what has been more consistent.

[attml]

I can always tell when there a decent probability of snow by the speed a thread moves here on AWF without having to read a single post.  If I just go to a thread talking about snow and it is says "Last post in under a minute" and the page count is moving quickly each time check, I know there is a better chance of snow than anything the local TV channels or the Weather Channel is going to predict :-)

[dtk]

Might be a mistake at this lead tho?  NAM is mesoscale and should be better at this one would think

Well, perhaps true for the 4km nest, but the 12km NAM parent is approx the same horizontal resolution as the GFS (~13km or so) and ECMWF (currently ~15km with the para at ~9km or so I think).  The NAM does have better vertical resolution in the boundary layer.

 

This is part of the reason that I almost exclusively look at the 4km nest and generally ignore the 12km parent.

[AdamHLG]

I can always tell when there a decent probability of snow by the speed a thread moves here on AWF without having to read a single post. If I just go to a thread talking about snow and it is says "Last post in under a minute" and the page count is moving quickly each time check, I know there is a better chance of snow than anything the local TV channels or the Weather Channel is going to predict :-)

I agree 100%.

Sent from my SM-N920V using Tapatalk

[Kevin Reilly]

I can always tell when there a decent probability of snow by the speed a thread moves here on AWF without having to read a single post.  If I just go to a thread talking about snow and it is says "Last post in under a minute" and the page count is moving quickly each time check, I know there is a better chance of snow than anything the local TV channels or the Weather Channel is going to predict :-)

Word true!!

[Scarlet Pimpernel]

I'm sorry if you thought my comments were directed at you. They were adding to your post about the nws product but I by no means thought you had anything to do with it. And I agree with your reasoning and that they toned down the gfs as an outlier but again back to the words Max potential, that's not when you tone down. Max potential is worst case scenario. Another way of looking at it is the actual outcome should never be greater then the Max potential unless it's a truly historic bust. While it's unlikely I could easily see someone in this forum pick up 8" from getting under meso scale banding and that would then beat the so called Mac potential which makes no sense. I think nws is toning down so as not to scare people but if that's the case maybe you shouldn't put out a Max potential map instead of basterdizing it.

 

No problem...appreciate the comment.  To be honest, I see what you're saying and perhaps that's more of us having a somewhat different interpretation on what LWX should use for the max potential.  I can understand your thoughts that they should put out what the "true" max is according to what the GFS has indicated...and for that matter, that one would not want the actual outcome to be greater than the max.  That said, I think there's a lot to be said for applying their own interpretation and hedge based on their experience, what they're seeing in the models, the uncertainty, the possible impact, etc.  The thing about those graphics is that they will change over time and if there's much more confidence in, say, 12" falling somewhere in north-central MD as the day goes on, I'm pretty certain they will up their max (and mean) accordingly.  So, yes, the outcome could well be greater than their current max, but I'd bet it wouldn't be compared to what max they put up there tomorrow.  The event is still more than 24 hours out, it's quite volatile, so I guess I don't totally blame them not pushing bigger numbers just yet (but enough to alert the possibility of warning-criteria in some areas).  Quite unlike the January blizzard, when every bloody model was screaming at least 18" several days out.