January 6-7 Storm Discussion: we’re due?

[North Balti Zen]

6 minutes ago, WxUSAF said:

Under my new “I’ll take anything measurable” criteria for storm success, IMBY, I’ll take the gfs in a hit second. Far N/W folks probably like it a lot less though as it trims precip totals for the mountains.

In an absolute second I would take 3-4 inches (of snow)

[SnowGolfBro]

3 minutes ago, konksw said:

I’ll take a snow globe outside my window for a few hours at this point tbh. 

Yes i think for us lowlanders that is the boom scenario. 

[clskinsfan]

CMC still a coastal hugger. But thermals got crushed. Still a 6 inch event out this way. But not as good as it was.

 

[DarkSharkWX]

2 minutes ago, psuhoffman said:

This feels related to what I was getting at yesterday, if you just look at the features we usually rely on to get a feel for the event, SLP, sfc high, confluence, heights, and ignore the specific thermals, everything has actually been trending BETTER over the last 72 hours.  You have to pull back to see it, ignore individual run random bounces, but if you look over the last 3 days and just look at the average of all those features its better now than it was.  Yet our snowfall has been slowly slipping away across all guidance over that same period.  Because regardless of all those features its been trending warmer.  A run would trend southeast with the track and better with the high...and the rain snow line still moved 10 miles NW, and this was happening across guidance, worse on the euro which is another bad sign since it's the best with thermals among the globals.  

So seeing the GFS trend warmer, even if just 1-2 degrees, I think everyone got that feeling like...here we go.  The only thing making the GFS better than the Euro was it was simply slightly colder, but everyone knows which one is more likely correct on that one thing.  The annoying thing is there is no trend we need with the amplitude or the high, or the confluence, or the upper low, that stuff is all fine, we just need it to be colder than it is.  

On the positive side things might stabilize now and salvage some frozen for the NW parts of this forum.  I could see a path to a quick thump snow still NW of 95 on Saturday.  Also, maybe this is like the storm in early 1987 that gave my area like 6" of slop and was a big interior snowstorm for central PA up into interior New England.  Then there were a few more interior storms before the snow hit the coast.  Maybe we are on a similar progression here.  

If there was a true block there might be a pathway for something like this to have worked for DC.  The path would have been a phased system that was blocked from tracking too far NW.  That would have provided the colder profile needed without an inside track.  But without a block...we were left with a really really narrow path here.  No phase (or a late phase with the trailing SW which is what this is trending towards) wont work for us, congrats New England.  It's too warm without any NS interaction.  But a phase would have likely lead to an inside track anyways.  I don't think those runs 3 days ago that had a 988 low tracking half way up the Chesapeake bay would have actually been snow in DC come game time, that track was way inside what we needed.  And it was likely to adjust further inside if that early phased idea was correct anyways.  

Once we have better blocking and a 50/50 locked in that's when I will get really upset if a setup like this fails.  

6z euro was quite decent thankfully, hopefully it continues in 12z

[mattie g]

I mentioned this in the banter thread because I really don't know anything, but I'll throw it out here.

If you check the last couple days of runs, you'll that the low pops up to the north of Lake Superior. As that thing has deepened and shifted ever so slightly, our thermals have worsened. Not saying that's the only thing that's going wrong, but it can't be coincidental.

[nj2va]

6 minutes ago, mattie g said:

I mentioned this in the banter thread because I really don't know anything, but I'll throw it out here.

If you check the last couple days of runs, you'll that the low pops up to the north of Lake Superior. As that thing has deepened and shifted ever so slightly, our thermals have worsened. Not saying that's the only thing that's going wrong, but it can't be coincidental.

Yeah, that hasn’t helped us at all.  It started showing up on ensembles the other day and clearly hurting us on the OP runs as this has gotten closer.

[TSSN+]

Anyone know what’s up with sterlings radar? Been down for like 3hrs 

[LeesburgWx]

Just now, TSSN+ said:

Anyone know what’s up with sterlings radar? Been down for like 3hrs 

I hope it stays out so I don't have to see the rain line move in

[psuhoffman]

4 hours ago, EstorilM said:

Wow this seemed like a lock for Northern VA, then again people always say you never want to be in the bullseye ~5 days out - all it can do is “trend” away from you lol. 

Skip to the end if you want the TLDR version

We weren't really "in the bullseye".  From 8+ days out guidance showed the potential but was all over the place with the track, as it will be from that range.  Once it started to lock in on the SW for a few runs around day 8 it was south of us.  Then as it caught onto the details it shifted north.  There were a couple random runs as that happened that might have jacked DC, but if you pulled back and looked at the average across all guidance over a whole day's of runs...NEVER was DC the bullseye for snow.  It shifted within one day from being south to north.  Then it settled down for a couple days where it showed DC dangerously on the south edge of snowfall with a WInchester to central PA jack.  That is NOT where we want to be 5-6 days out.  These things tend to trend north the last 100 hours 80% of the time.  Several red taggers said that the last few days.  The warning sings were there.  These are just basic model trend things.

Additionally there is the synoptic setup here.  There was no true block.  There is a 50/50 but everything is shifted east of ideal because the -NAO is very very east based.  We want that ridge centered closer to Greenland to Baffin not where it is.   The confluence is pretty far north here.  This isn't the right setup to stop the typical trends.  There are things that could prevent a storm from trending north the final 100 hours.  A crazy block like 2010.  Those storms didnt' budge the final 100 hours because they couldnt move north at all there was a wall of confluence over PA.  Another option would be a NS feature coming across the top suppressing the wave.  Not sure that's even what we wanted here, but the NS is pretty far north and there is no TPV in quebec for a lobe to rotate around like happened in 2014 and 2015 a few times to help suppress a wave without blocking.  

Not every snow event here follows the standard.  Flukes happen.  There is always a chance.  Even now maybe it trends a few degrees colder and places closer to the city get a thump snow Saturday.  Weirder things have happened.  But thinking this was a lock day 6 was crazy.  I was LOL at some of the posts making declarative statements from places well southeast of me when I was not even comfortable expecting snow up here frankly, knowing the setup and the typical correction in guidance from that range.  

TLDR version below

If you want to feel good about snow in the DC area from 5 days out you need a few things.  

1) Truly cold and deep antecedent airmass where the thermal boundary is well south of us as the wave gets its act together in the TN valley

2)A well placed 1030 or greater high

3) A STJ wave tracking at us from the SW, not the NW or not needing some crazy negative tilt system to bomb straight up the coast.  Something into the TN valley then transferring to the NC coast is the highest probability snow event here

4) Strong confluence where the flow turns somewhere just to our north, like in central or northern PA, not up in northern New England or Canada

5) a true blocking situation with a 50/50 locked in by a ridge to its north.

If you have all 5 of those features then I think its safe to feel optimistic about snow chances in DC from longer leads.  Absent those...I would NEVER feel good about snow until it was within like 48 hours because the more of those factors we lack the more we need lots and lots of other variables to go perfectly to compensate.  It won't be simple or easy.  

We really only had 1 of those this time...we had an ideal STJ wave and track.  And that does put is at least in the game for a fluke to work out absent other things.  But we didn't have all the other things needed to make this an "easy" win for DC.  

[aldie 22]

55 minutes ago, NorthArlington101 said:

sold

[WinterWxLuvr]

The difference with the Can models, and to an extent the UKIE, is that they are much wetter. I guess that’s ok, but at least here, the last few systems have been drier in the actual than they were when modeled. The euro and gfs are really dry here. The NAM moistened up a bit over the 0z.

[winter_warlock]

Gfs a lil colder, a touch more snow .   Hope that trend continues!

[TSSN+]

Uk not bad for the nw crew 

[Warm Nose]

Current mood ITT:

 

[Wonderdog]

Gotta have the block.

[Weather Junkie]

6 minutes ago, TSSN+ said:

Uk not bad for the nw crew 

I’ll take my .2 and call it a winter.

[Miss Pixee]

1 hour ago, nj2va said:

18z Saturday sounding at DCA.  Super close but did get a tick colder than 6z at the same time.  

My neighborhood has volunteered to put bags of ice on the streets if that will help!

[Paleocene]

2 minutes ago, Pixee said:

My neighborhood has volunteered to put bags of ice on the streets to cool them!

I'm gonna turn on my hose to add some cold water to sligo creek; should cool off the anacostia for you to get some river effect snow

[umdterps29]

19 minutes ago, TSSN+ said:

Uk not bad for the nw crew 

What time frame is this through? Can you add through end of day Sunday if not already included? I'm curious as I'll be out at the mountain house. Thanks!

[nj2va]

8 minutes ago, umdterps29 said:

What time frame is this through? Can you add through end of day Sunday if not already included? I'm curious as I'll be out at the mountain house. Thanks!

It’s free on pivotalweather. Deep Creek gets about 6” on the UK, after taking into account the stuff this morning. 

[jayyy]

Imagine after all of this tracking and boom / bust concern it ends up being an areawide 2-5” storm for many what’s kuchera have to say? 10:1 is generous.

[JenkinsJinkies]

8 minutes ago, jayyy said:

Imagine after all of this tracking and boom / bust concern it ends up being an areawide 2-5” storm for many what’s kuchera have to say? 10:1 is generous.

If this verifies BWI will get double the snow as DCA.

Usually if one busts the other busts too.

[WinterWxLuvr]

Euro is better, closer to the GGM and UKIE 

More precip, little stronger, closer

[jayyy]

Pretty interesting to see all of the snowfall accumulation changes from run to run. Track remains mostly the same as Clskins alluded to, but the thermals are all over the place. We may really need to wait until Friday night to know what’s going on, once the airmass / high is actually in place and models aren’t just predicting what it’ll be like.

[nj2va]

12z Euro

[jaydreb]

[TSSN+]

3 minutes ago, WinterWxLuvr said:

Euro is better, closer to the GGM and UKIE 

More precip, little stronger, closer

Doesn’t look that great to me. I’ll take any model but the euro 

[Warm Nose]

1 minute ago, nj2va said:

12z Euro

[jayyy]

Congrats NYC suburbs and SNE

[WinterWxLuvr]

2 minutes ago, jayyy said:

Pretty interesting to see all of the snowfall accumulation changes from run to run. Track remains mostly the same as Clskins alluded to, but the thermals are all over the place. We may really need to wait until Friday night to know what’s going on, once the airmass / high is actually in place and models aren’t just predicting what it’ll be like.

One thing is certain. It’s cold Sat morning. The dews are low. No sun, steady even heavy precip into that makes the cold hard to erode and warm.