Feb Long Range Discussion (Day 3 and beyond) - MERGED

[high risk]

29 minutes ago, Always in Zugzwang said:

@high risk can verify this one way or another, but I don't think it's quite right to say the NAM has a cold bias?

          Yeah, it doesn't have a systematic cold bias overall, but it can run a bit cold in terms of trying to cool columns in marginal winter events with strong lift.     It's also worth noting that it can overdo the strength of the warm nose, usually by cranking up and veering the flow too much between 850 and 700.

           I know we're all looking for reasons to toss its solution that really minimizes the front end thump of snow Thursday.     While it's justifiable to note several times this winter when it has sniffed out some important trends, the NAM feels like a bit of synoptic outlier right now, although I would absolutely not put any money on that.  

[Kmlwx]

Just now, EHoffman said:

Yes hence why I said "for DC."  Since I live in DC.  And we do very poorly with these types of scenarios, almost always.  I don't doubt that somewhere north of DC will get a significant winter event from this.

I honestly am inclined to think there could be an icing threat even south of DC. Again, it'll be a narrow stripe as FRZA always is. I'm not confident (yet) that UHI is going to save you from staying frozen for longer than you're expecting. 

We'll see - still several days out - but just because you're in DC doesn't preclude you from a winter wx threat with this one. Even places like Fredericksburg could still be in the game for icing or sleet. 

[clskinsfan]

19 minutes ago, psuhoffman said:

Rgem still looks good.  3-6” before flip to sleet. 

Was just going to post about the RGEM. It is a pretty awesome storm for the NW burbs verbatim. Great snow/sleet bomb with very little zr west of the Blue Ridge. 

[EHoffman]

Just now, Kmlwx said:

I honestly am inclined to think there could be an icing threat even south of DC. Again, it'll be a narrow stripe as FRZA always is. I'm not confident (yet) that UHI is going to save you from staying frozen for longer than you're expecting. 

We'll see - still several days out - but just because you're in DC doesn't preclude you from a winter wx threat with this one. Even places like Fredericksburg could still be in the game for icing or sleet. 

Yes I do think SOME of the precip will fall frozen in DC.  I just don't think there will be a signficant/any impact in the city.  We are always too warm, we always switch over earlier than anticipated in these types of systems, and we're always too cold on the globals at this time frame.  This is how DC weather works in the winter.

[chris21]

2 minutes ago, Kmlwx said:

I honestly am inclined to think there could be an icing threat even south of DC. Again, it'll be a narrow stripe as FRZA always is. I'm not confident (yet) that UHI is going to save you from staying frozen for longer than you're expecting. 

We'll see - still several days out - but just because you're in DC doesn't preclude you from a winter wx threat with this one. Even places like Fredericksburg could still be in the game for icing or sleet. 

Yeah, if you look at the strength and location of the high and arctic air nearby and light northeast flow it’s actually a classic situation for a major ice event in dc. Def doesn’t look like an all snow event in dc, but I would certainly not sleep on the sleet/ice potential with this storm given the synoptic setup. 

[SomeguyfromTakomaPark]

1 minute ago, EHoffman said:

Yes I do think SOME of the precip will fall frozen in DC.  I just don't think there will be a signficant/any impact in the city.  We are always too warm, we always switch over earlier than anticipated in these types of systems, and we're always too cold on the globals at this time frame.  This is how DC weather works in the winter.

This is kind of a garbage post.  You're not considering or analyzing the synoptic evolution or antecedent airmass.  You're just saying "we always fail".  I've lived in the DC area since 2009 and there have been quite a few good storms that don't fit your narrative.  

[clskinsfan]

The cold push is just light years better on the GFS. 540 line is 50 miles south of the NAM at 60.

GFS starts as snow down to RIC this run. 

Beatdown for all. 

[chris21]

4 minutes ago, EHoffman said:

Yes I do think SOME of the precip will fall frozen in DC.  I just don't think there will be a signficant/any impact in the city.  We are always too warm, we always switch over earlier than anticipated in these types of systems, and we're always too cold on the globals at this time frame.  This is how DC weather works in the winter.

Ehhh... happens a lot... but we just had a high impact freezing rain event two days ago that was apparently “impossible in dc” even though I’ve seen it many times.

[Scarlet Pimpernel]

1 minute ago, high risk said:

          Yeah, it doesn't have a systematic cold bias overall, but it can run a bit cold in terms of trying to cool columns in marginal winter events with strong lift.     It's also worth noting that it can overdo the strength of the warm nose, usually by cranking up and veering the flow too much between 850 and 700.

           I know we're all looking for reasons to toss its solution that really minimizes the front end thump of snow Thursday.     While it's justifiable to note several times this winter when it has sniffed out some important trends, the NAM feels like a bit of synoptic outlier right now, although I would absolutely not put any money on that.  

Thanks, that makes sense.  I'm certainly not discounting the NAM solution out-of-hand at this point.  Thing is, as @Bob Chill mentioned, only a couple or so days ago this was looking like all but a straight-up rainstorm for much of the area, and it's now trended better, apparently (for wintry type precip).  In fact, before this initially fell apart a few days ago, I don't even recall the Thursday event being looked at as snow per se anyhow.  The indications were that Tuesday and Thursday could be significant icing events earlier on.  That there's now even a chance for some kind of snow before a flip to sleet/ice (or whatever) is a big change in the past couple of days.

[SomeguyfromTakomaPark]

1 minute ago, clskinsfan said:

The cold push is just light years better on the GFS. 540 line is 50 miles south of the NAM at 60.

GFS starts as snow down to RIC this run. 

Yessir!  Frozen precip all the way into NC. 

[Bob Chill]

At least on the gfs, run over run is better with the upper level eyeball pushing down heights/assisting confluence. Just a little better. Nothing crazy. Should avoid a rug pull this run

[SomeguyfromTakomaPark]

GFS is a front end crush job. 6+ inches for DC by 15z before changeover.

[EHoffman]

1 minute ago, SomeguyfromTakomaPark said:

This is kind of a garbage post.  You're not considering or analyzing the synoptic evolution or antecedent airmass.  You're just saying "we always fail".  I've lived in the DC area since 2009 and there have been quite a few good storms that don't fit your narrative.  

We always fail in borderline scenarios in mid-to-late February like this, yes.  It's very rare we actually cash on a frozen-to-rain scenario like this.

 

Just now, chris21 said:

Ehhh... happens a lot... but we just had a high impact freezing rain event two days ago that was apparently “impossible in dc” even though I’ve seen it many times.

I wouldn't call 2 days ago high-impact in DC at all.  In fact, we avoided high impact by being a huge heat island and not having ZR accumulate anywhere for hours when it was 29 degrees because of the sun angle.  It's a good example of why it's sooooo hard for us to bank in borderline scenarios.

[WesternFringe]

Purple rates of snow approaching from the southwest at 69 on the GFS

[Grothar of Herndon]

3 minutes ago, clskinsfan said:

The cold push is just light years better on the GFS. 540 line is 50 miles south of the NAM at 60.

GFS starts as snow down to RIC this run. 

Beatdown for all. 

So far 12z Globals are holding and sounds like GFS continues to trend even better for us

[ovechkin]

The NAM has scored well this winter. At this point it is a reminder that accumulating snow in the immediate metro is guilty until proven innocent. 

[psuhoffman]

15 minutes ago, leesburg 04 said:

I'm not one who jumps on the snowiest model and ignores the rest, I'm just making an observation...but in the end it's just my observation. You do you man, you know your stuff and I've never disputed that. I will continue to read your analysis

Fair enough. From my perspective what’s annoying is some seem to focus in on the negative I say. In the last 24 hours I bet I’ve made 10x more positive posts.  And sometimes even within a post I’ll make a positive and a negative point. I’m analyzing all the possible permutations. But then the negative thing I said gets all the attention and it comes off like I cancelled storm when that wasn’t my intent. I intended to point out the NAM was bad and it COULD be right and explained why.  But obviously I suck at communicating that because it turned into “I went off the rails and cancelled the storm”.
 

It doesn’t matter what my intent is if that’s what people take from my posts.  One thing I think that’s at play sometimes is some seem to want certainty and a narrative. I view this as chaos and I’m ok with that. I am open to all the variables and outcomes. I don’t need to pretend to know exactly how it’s going to go. I don’t know. No one does. So people try to read certainty from my embrace of the uncertainty.  
 

The NAM is possible. So is the crazy 10” para gfs. I can see reasons for both. I could see the NAM being a little too aggressive with the warm layer and the heavy rates mixing it out. I can also see an argument for the NAM given this setup and history with this kind of SW flow. I’m open to both possibilities. But I think some want to be told how the bad one isn’t likely and placate their fears and so my embrace of both comes off as an embrace of the fail only. 

[Bob Chill]

4 minutes ago, EHoffman said:

We always fail in borderline scenarios in mid-to-late February like this, yes.  It's very rare we actually cash on a frozen-to-rain scenario like this.

 

I wouldn't call 2 days ago high-impact in DC at all.  In fact, we avoided high impact by being a huge heat island and not having ZR accumulate anywhere for hours when it was 29 degrees because of the sun angle.  It's a good example of why it's sooooo hard for us to bank in borderline scenarios.

There's like a dead sea scroll of climo history backing up your statement so I wont disagree much at all. I will add that temps leading in are *potentially* the coldest of the season. DC proper has the highest chance yet at starting off with snow with surface below freezing for hours instead of seconds before onset. That is the fly in the ointment of your definitive statement. Wont know how it breaks for a couple days. Dont completely discount that temps could be friendly for the first time this year. Expecting fail is def where I would put my money if forced to bet tho

[chris21]

5 minutes ago, EHoffman said:

We always fail in borderline scenarios in mid-to-late February like this, yes.  It's very rare we actually cash on a frozen-to-rain scenario like this.

 

I wouldn't call 2 days ago high-impact in DC at all.  In fact, we avoided high impact by being a huge heat island and not having ZR accumulate anywhere for hours when it was 29 degrees because of the sun angle.  It's a good example of why it's sooooo hard for us to bank in borderline scenarios.

Strongly disagree, could barely walk outside my house Saturday and sat night. It didn’t accumulate anywhere? NWS reported a .25 inch ice in adams Morgan.

[Kmlwx]

I will say this - with regards to @EHoffman's comments. 

If the surface is 31-32 I would of course agree with him more. But if we are in the mid 20s at onset that wedge is going to be stubborn. Again, the warm layer is well above the surface. Low 30s probably means a wet event for DC. Mid 20s and there will be at least SOME trouble with ice. Remains to be seen as well how much of the stuff after any snow falls as sleet vs ZR. 

[clskinsfan]

The GFS is a pretty nasty storm for my area. 7 inches of snow/sleet followed by .4 of ZR. Temps finally reach 32 degrees early Friday morning. What a mess. 

Temps then crash back into the mid 20's Friday midday. Concrete incoming. 

[midatlanticweather]

Let's hope the second Ice Storm in a week does not come true for Richmond area! Would be just awful! 

 

 

 

[Weather Will]

WB 12Z 3K at hr 60 v 12Z Para at hr 60 700 MB

[Kmlwx]

5 minutes ago, EHoffman said:

We always fail in borderline scenarios in mid-to-late February like this, yes.  It's very rare we actually cash on a frozen-to-rain scenario like this.

 

I wouldn't call 2 days ago high-impact in DC at all.  In fact, we avoided high impact by being a huge heat island and not having ZR accumulate anywhere for hours when it was 29 degrees because of the sun angle.  It's a good example of why it's sooooo hard for us to bank in borderline scenarios.

IIRC there were more than one or two posters in DC proper reporting icing that was a bit more than what most people would call a snoozer. I get your overall point - and to an extent I do agree with you. Could easily fail in the way you are suggesting - but the "heat island" of DC is smaller than the entire city in most cases. Think about how much better NW does versus near the airport. 

2 minutes ago, ovechkin said:

The NAM has scored well this winter. At this point it is a reminder that accumulating snow in the immediate metro is guilty until proven innocent. 

The NAM is worth looking at for the reasons PSU has pointed out. But you aren't backing up your posts with evidence like he is. Come on...at least add to the discussion...It's not hard to post something other than "NAM has done well"

[EHoffman]

2 minutes ago, Bob Chill said:

There's like a dead sea scroll of climo history backing up your statement so I wont disagree much at all. I will add that temps leading in are *potentially* the coldest of the season. DC proper has the highest chance yet at starting off with snow with surface below freezing for hours instead of seconds before onset. That is the fly in the ointment of your definitive statement. Wont know how it breaks for a couple days. Dont completely discount that temps could be friendly for the first time this year. Expecting fail is def where I would put my money if forced to bet tho

That's all I'm saying though, is that historically these types of storms fail 99% of the time in DC even if we're getting slammed a few days in advance on "all the models."  Of course it's not IMPOSSIBLE we bank significantly on this, but I find it to be a major uphill battle.

1 minute ago, chris21 said:

Strongly disagree, could barely walk outside my house Saturday and sat night. It didn’t accumulate anywhere? NWS reported a .25 inch ice in adams Morgan lol.

Ehhh no power outages and slippery pavement that melted by the next morning.  Pretty? Sure.  High impact? In CVA and Southern VA, absolutely. Here, not so much.

1 minute ago, Kmlwx said:

I will say this - with regards to @EHoffman's comments. 

If the surface is 31-32 I would of course agree with him more. But if we are in the mid 20s at onset that wedge is going to be stubborn. Again, the warm layer is well above the surface. Low 30s probably means a wet event for DC. Mid 20s and there will be at least SOME trouble with ice. Remains to be seen as well how much of the stuff after any snow falls as sleet vs ZR. 

I honestly think the models are too cold and we're always warmer than progged down here.

[clskinsfan]

Just now, midatlanticweather said:

Let's hope the second Ice Storm in a week does not come true for Richmond area! Would be just awful! 

 

 

 

Hate to be rude. But we need them to be ice so we can get snow. If they rain we will get the ice. 

[LeesburgWx]

After reading the last few pages, it is clear we needed to change this picture once again...

[Bob Chill]

6 minutes ago, Grothar of Herndon said:

So far 12z Globals are holding and sounds like GFS continues to trend even better for us

I loved seeing the gfs beef up confluence/surface high thru hr 54. Putting up the good fight at a time where it usually collapses like the WFT's QB hopes and dreams

[Kmlwx]

Just now, EHoffman said:

That's all I'm saying though, is that historically these types of storms fail 99% of the time in DC even if we're getting slammed a few days in advance on "all the models."  Of course it's not IMPOSSIBLE we bank significantly on this, but I find it to be a major uphill battle.

Ehhh no power outages and slippery pavement that melted by the next morning.  Pretty? Sure.  High impact? In CVA and Southern VA, absolutely. Here, not so much.

I honestly think the models are too cold and we're always warmer than progged down here.

Power outages are not the only metric. I heard plenty of reports of accidents that were definitely above the normal background from just wet pavement. Bridges and overpasses can get ugly fast even with marginal temps. But yes - power outages were minimal in Maryland. 

At my place near Arundel Mills (E of the fall line!) I had to clear off like 0.3 inch of ice from my entire car. Sure - the roads weren't terrible - but they were also salted about 4 times during the icing event. 

Nobody is going to argue with you that DC has a UHI and it DOES impact marginal events. We'll have to see what the surface temps actually end up being for the upcoming event. 

[Ji]

PARA is a beatdown