December Medium/Long Range Discussion

[BTRWx's Thanks Giving]

9 minutes ago, Winter Wizard said:

Lots of west leaning members here, tread carefully. 

That's a lot of uncertainty still.

[BTRWx's Thanks Giving]

1 minute ago, WxWatcher007 said:

12z EPS probs. Contains both events. 

 

 

That looks much more realistic than other models have shown imo.

[Maestrobjwa]

So I guess the only "rug getting pulled out" scenario would be a further west track at this point?...

[jaydreb]

11 minutes ago, DCTeacherman said:

Let’s hope you’re right.  A lot of those EPS lows would be a lot of rain for the majority of the sub forum.  

Well, in case we were wondering about our most likely fail scenario, this is it.  

[Weather Will]

WB 12Z EPS snow maps

[jaydreb]

Just now, Maestrobjwa said:

So I guess the only "rug getting pulled out" scenario would be a further west track at this point?...

Yeah, I’m much more worried about west/warm than I am about weak/progressive/OTS.  

[psuhoffman]

1 hour ago, stormtracker said:

It’s actually not too bad. SV maps have dc n and w 18-20+.  Not gonna happen. But still. Not a complete disaster 

I’m late to the party and probably 150 posts behind...but it hits the wall of confluence and turns due east just in time to save DC north.  Keep in mind euro is typically the most amplified model (sometimes a little too amplified) so seeing it slightly north of other guidance (initially) isn’t shocking.

[baltosquid]

EPS a bit worse but it’s also easy to see how battered we’ve been for a while now  

We’ve got the CMC, GFS and Euro Ops with some pretty great results for the usual suspects and the I95 corridor; the UKMET is less bullish but still a good result for a lot of us in Dec. Yet you’d think from the discussion on the EPS we’re set up for a soul crushing bust even though it still gives some of us more snow than all last year lol. One run at a time, best models for us in a long long time!

[WxUSAF]

Just now, psuhoffman said:

I’m late to the party and probably 150 posts behind...but it hits the wall of confluence and turns due east just in time to save DC north.  Keep in mind euro is typically the most amplified model (sometimes a little too amplified) so seeing it slightly north of other guidance (initially) isn’t shocking.

Hopefully the over amplified bias is playing by with the EPS as well.

[AmericanWxFreak]

EPS mean jackpots BOS while the OP whiffs on them. At that latitude, the OP is further E then basically every ens member 

[IronTy]

12Z EPS shows Calvert County a litte love, I'll take it and pray to the wraparound Gods as well. 

[MD Snow]

FWIW the ICON has consistently been the warmest and furthest West with the LP track of all the globals. Is it on to something?

[Snowchaser]

It's been awhile.  

LEVEL 4 OUT 5 and five days out

 

 

[BTRWx's Thanks Giving]

4 minutes ago, Snowchaser said:

It's been awhile.  

LEVEL 4 OUT 5 and five days out

 

 

4 days out

[Maestrobjwa]

10 minutes ago, MD Snow said:

FWIW the ICON has consistently been the warmest and furthest West with the LP track of all the globals. Is it on to something?

Wouldn't let my mind go there if I were you...and just remember it's the ICON, lol Let's just see what happens in the next suite...then we can discuss blip or trend

[Wonderdog]

Why isn't there an enhanced area on that map?

[BristowWx]

4 minutes ago, Wonderdog said:

Why isn't there an enhanced area on that map?

They did it by county...if they did it by east/west we are good.  

[Chase]

4 minutes ago, Wonderdog said:

Why isn't there an enhanced area on that map?

Confidence isn't high enough/impact isn't high enough to be at Enhanced for the 95 corridor.  

[PhineasC]

5 minutes ago, Wonderdog said:

Why isn't there an enhanced area on that map?

Rain/snow line. I would assume LWX is predicting a sharp cutoff between good snows and mostly rain, and the models do basically show that.

[Snowchaser]

I'm shocked Cville is in the Red. Clearly they know more than me lol.

[Amped]

11 minutes ago, Wonderdog said:

Why isn't there an enhanced area on that map?

Wondering the same thing.

[Chase]

Just now, Snowchaser said:

I'm shocked Cville is in the Red. Clearly they know more than me lol.

There are three regions on the map.  Charlottesville is lumped in with Hagerstown, just like Fairfax is lumped in with St. Mary's. 

Could be area for improvement in the future if it ultimately presents a problem, but I love the product! 

[Chris78]

Attached are the 6z and 12z eps. Very subtle changes.  I know snow maps aren't the end all be all but very good consistency imho.

[Eskimo Joe]

So far it appears as though the Euro EPS is the "worst" case scenario for snow lovers, the op Euro/UKMET/ICON/GFS/GEFS in the middle, the CMC/GGEM is the best.

[psuhoffman]

43 minutes ago, WxUSAF said:

Hopefully the over amplified bias is playing by with the EPS as well.

Since the Eps is based on the op and typically supports it it makes sense it would have the same bias but I can’t say for sure.  But Imo the reaction to the 12z Eps is overblown.  It’s not as bad as it looks.  It’s sort of an illusion imo.  There are several factors that make that 108 hr panel look awful.  There was always a camp in the EPS going back 48 hours that has a too far inside track v the cluster of tracks that would support a decent amount of frozen.  
 

From my analysis I don’t think the % in each cluster changed that much. Several factors made that 108 panel look worse. First a few if the inside runners are way inside this run. But it matters not to us if the track is up the fall line vs up the bay. Both are rain. Matters for Harrisburg I guess.  The inside runners are deeper too skewing the mean.

Second the timing tightened up.  There is way less timing differences on the 12z v 0z so now there is one panel where you can see all the inside runners at one time.  
 

Third the timing changed by 3 hours so now that 108 panel catches the storm at its closest inland pass in VA where before most of the lows we’re still down in NC then off the MD coast.  We didn’t have one panel on the EPS that caught all the lows at their ugliest look before.

By my count if you look at all the panels and estimate (hard to do with some but this is close) there were 21 members out of 50 that were inside of a “frozen supporting track” at 0z. That doesn’t mean the others were all huge hits but tracks that should support a decent bit of snow into 95.  At 12z I count 23 inside runners.  So maybe 2 more in the camp we don’t want.  But that seems like noise to me.  
 

 

 

 

[Doorman]

OPC 96hr surface prog

https://ocean.weather.gov/Atl_tab.php

 

 

[jaydreb]

11 minutes ago, psuhoffman said:

Since the Eps is based on the op and typically supports it it makes sense it would have the same bias but I can’t say for sure.  But Imo the reaction to the 12z Eps is overblown.  It’s not as bad as it looks.  It’s sort of an illusion imo.  There are several factors that make that 108 hr panel look awful.  There was always a camp in the EPS going back 48 hours that has a too far inside track v the cluster of tracks that would support a decent amount of frozen.  
 

From my analysis I don’t think the % in each cluster changed that much. Several factors made that 108 panel look worse. First a few if the inside runners are way inside this run. But it matters not to us if the track is up the fall line vs up the bay. Both are rain. Matters for Harrisburg I guess.  The inside runners are deeper too skewing the mean.

Second the timing tightened up.  There is way less timing differences on the 12z v 0z so now there is one panel where you can see all the inside runners at one time.  
 

Third the timing changed by 3 hours so now that 108 panel catches the storm at its closest inland pass in VA where before most of the lows we’re still down in NC then off the MD coast.  We didn’t have one panel on the EPS that caught all the lows at their ugliest look before.

By my count if you look at all the panels and estimate (hard to do with some but this is close) there were 21 members out of 50 that were inside of a “frozen supporting track” at 0z. That doesn’t mean the others were all huge hits but tracks that should support a decent bit of snow into 95.  At 12z I count 23 inside runners.  So maybe 2 more in the camp we don’t want.  But that seems like noise to me.  
 

 

 

 

Thanks for walking me back from the ledge.  

[psuhoffman]

@WxUSAF I’m not saying an inside runner isn’t a legit fear here.  Even up here that’s my fear. I don’t see any way this gets suppressed south. The trough goes neutral and starts to lift pretty far west. The whole flow is amplified. The block/50-50 are anchored a little north of the examples where we see something squashed to our south. Imo this is going to be a hit or too far north and rain. I feel pretty good about this ATT but still a long ways to go.  But you know me if there is an “oh no it’s all falling apart” moment I will be the first on here warning about it. The 12z EPS wasn’t that imo. 

[MillvilleWx]

Night crew check in after 6 hrs of sleep (Will be heading back to bed shortly)

Few thoughts gazing through things:

1. Initial thoughts holding with regards to ptype and where the best spots look to be. Fall line and west should remain majority snow unless we see a more amplified surface reflection. EPS showed more mixing out to even I-81, but if you look closely at the low clusters, everything that was inland was sub 990 with some at the low to mid 980’s. Remember the ptype algorithm is a smoothed mean that takes into account ALL members of the ensemble package. Even a few over amped members can skew the mean warm and could correct later in time as we get closer and filters the noise.

2. The confluence signature is becoming a positive feedback here with a classically aligned height pattern to our north that will pay dividends. High pressure over Quebec is consistently modeled around 1036-1038, which is solid for a snow event west of the fall line, so long as the low doesn’t over amplify.

3. Snow maps are fun, but best to look at QPF charts and base soundings. One of the bog things to look for in this storm is the CCB action on the final half of the system. Primary 8-10:1 caveats aside for areas along and west of the fall line for the first half of the storm, but this will have 15-20:1 potential within the deformation axis as 7H frontogenic progs have been off the charts across central MD, NoVa, Panhandle WV, into SoPA. There will be a nose of + theta-E advection when this begins to wrap as it crosses OCMD latitude. Where that points will be key in determining who gets the love on the back half. Even so, it’ll slowly gain latitude and sweep through to the east, so the ending of the system could be epic for many. It’s very classic in a Mid Atlantic MECS.

4. All that said, the typical Rt15 on west crew is in the best shape with elevated areas along Pars Ridge to Mappy sitting in a solid area due to elevation and mesoscale tendencies with bombing surface reflections. The lack of dry NW winds on the back half of the storm signify an expansive qpf shield is likely with this event, so even out to the mountains should see some love. Hancock on east is the best areas with some upslope component likely out near Garrett.

5. Sleet will undoubtedly occur for areas in the Blue Ridge in VA once south of Front Royal, but they could get smacked before a change over as southerlies scream out with the low reflection moving north.

6. Anyone who knows their climo should weight it in the result. You know your tendencies and nothing in this storm suggests a sway from the norm. A stronger high around 1040 would be what causes the mentality to shift, but it’ll likely fall short.

Now if you’ll excuse me, I’m gonna go back to sleep and I’ll be back on the night shift tonight to add more tired thoughts to this event. Be happy y’all. There’s a storm brewing!


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[H2O]

Millville ftmfw