December 16/17 Winter Event

[PhineasC]

9-14” for bel air. We will see. 

[Baltimorewx]

2 minutes ago, poolz1 said:

To add to mappy's post. Total call right now..

Interesting. But I don’t buy that Baltimore area gets 4-6” and Bel Air gets 8-12”. In my experience these two areas usually aren’t that far off, both obviously along the I 95 corridor. Now up towards Jarretsville to Pylesville is a different story 

[clskinsfan]

7 minutes ago, poolz1 said:

To add to mappy's post. Total call right now..

Wow. VA disappeared. Here is one for all of us:

 

Edit. I dont know what the hell is going on with that map. It is showing one hour when I pasted the 24 hour map. FAIL. If you click on the map it takes you to the correct image. 

[PivotPoint]

29 minutes ago, Ellinwood said:

Updated my snow map... cut down on the total on the eastern gradient (mainly DC up I-95 and through southern and central NJ). Increased totals along the Appalachians.

Pretty good imo. One exception is I think it's a little light for Leesburg, Middleburg, etc. That zone I still think verifies 10-12". DC is probably accurate, unfortunately.

[EB89]

[WesternFringe]

37 minutes ago, SnowGolfBro said:

Thanks but I’ll wait for the DGEX

That was the old German model, right?

[JakkelWx]

Classic D.C screw zone

[osfan24]

7 minutes ago, poolz1 said:

To add to mappy's post. Total call right now..

Nice! I'm iguessing I'm right on the border of the 6-8 and 8-12 areas and 12-18 isn't out of reach.

[haudidoody]

Bullish for DC. Also, why is Little River Turnpike treated like a highway on that map. Can't trust it.

[baltosquid]

Setting expectations for 4, hoping the storm scoots along with a minimal tuck and some colder air to get me to that yellow on the NWS maps and 8 inches. Would love to eek out a better result than March 2018 if possible. Fingers crossed. Let's see what 18z has to offer in a few hours!

As always, big thanks to all the more knowledgeable posters helping us weenies along. 

[WxUSAF]

NWS forecast looks a lot like 12z euro. More N-S gradient in MD due to how much snow falls after the flip back to snow. I like the NWS map although it’s maybe a little bullish on the 12-18” area size.

[mappy]

1 minute ago, WxUSAF said:

NWS forecast looks a lot like 12z euro. More N-S gradient in MD due to how much snow falls after the flip back to snow. I like the NWS map although it’s maybe a little bullish on the 12-18” area size.

thats fine, it can stop just to my south  

[nj2va]

Solid first guess but based on QPF trends today, they'll need to increase the mountains.

[Kmlwx]

8 minutes ago, WesternFringe said:

That was the old German model, right?

No. It was the Downscaled GFS with Eta Extension. It was awful. 

[T. August]

11 minutes ago, PhineasC said:

9-14” for bel air. We will see. 

You in bel air now?

[osfan24]

1 minute ago, nj2va said:

Solid first guess but based on QPF trends today, they'll need to increase the mountains.

They will. They always start conservatively for big storms and then slowly up amounts as it gets closer in time. 

[Eskimo Joe]

1 minute ago, poolz1 said:

To add to mappy's post. Total call right now..

Where do I sign?

[40westwx]

I want you all to be prepared for the greatest succession of model runs in Mid Atlantic snow storm history.. over the next 36 hours we are going to see a slow and steady shift to colder temperatures.. all of you all teetering on the brink will see you 1-3 turn in  to 2-4.. then to 6-8 and then.. the ever important 8-14.  

This shit is happening

[Maestrobjwa]

50 minutes ago, RDM said:

Anyone have the soundings for DCA and IAD for noon ET Thursday?   Curious how close it's going to be and comparing the two.  Out of consideration for the MD/DEL folks maybe throw in BWI too.  

Hey! The BWI crew are people too (I've always wondered why more Baltimore folks don't post here...it seems to be either DC or snowbelt, lol) 

[clueless]

Just now, 40westwx said:

I want you all to be prepared for the greatest succession of model runs in Mid Atlantic snow storm history.. over the next 36 hours we are going to see a slow and steady shift to colder temperatures.. all of you all teetering on the brink will see you 1-3 turn in  to 2-4.. then to 6-8 and then.. the ever important 8-14.  

This shit is happening

It’s a little early, no?  Only 3pm here.  

[Scarlet Pimpernel]

1 minute ago, 40westwx said:

I want you all to be prepared for the greatest succession of model runs in Mid Atlantic snow storm history.. over the next 36 hours we are going to see a slow and steady shift to colder temperatures.. all of you all teetering on the brink will see you 1-3 turn in  to 2-4.. then to 6-8 and then.. the ever important 8-14.  

This shit is happening

@Jebman, is that you?? 

[WxUSAF]

For those who forecast by ensemble snow maps...just saw the 12z Eps probability of 6”+. I think MBY has been in the 50% contour on almost every run, maybe occasionally bumping up or down one contour. And today’s run? In the 60% contour. Biggest difference is the gradient has tightened which is what almost always happens as you get closer to start time. Howard county has just under 50% to over 90% across it.

[clskinsfan]

1 minute ago, Clueless said:

It’s a little early, no?  Only 3pm here.  

NAM is running now. And looks a little colder. 

[SnowGolfBro]

2 minutes ago, 40westwx said:

I want you all to be prepared for the greatest succession of model runs in Mid Atlantic snow storm history.. over the next 36 hours we are going to see a slow and steady shift to colder temperatures.. all of you all teetering on the brink will see you 1-3 turn in  to 2-4.. then to 6-8 and then.. the ever important 8-14.  

This shit is happening

I remember calling the weather hotline every 6 hours or so the 3 days leading up to the Blizzard of 96.  That was essentially the progression lol

[PhineasC]

6 minutes ago, T. August said:

You in bel air now?

I’m everywhere. I’m standing right behind you now. 

[MillvilleWx]

After about 4.5 hrs of sleep, I decided to be a human at 1230 PM CST and get up for a bit to look at models. After gleaning over the runs, here's my quick thoughts.

I mentioned overnight how I thought the NAM12km had overamp bias with the surface and had height rises too high out ahead of the s/w trough along the Atlantic coast. All the while, the GFS still had a flat bias and the storm was escaping to the east too quickly with focus on the eastern LP instead of the western tuck of the double barrel structure. The guidance is coming into alignment now with majority showing a coastal SC to mouth of Chesapeake to a coastal hug of the Delmarva before stacking near Cape May as the 5H trough axis pivots overhead and briefly closes off. Today was the day where we can officially bring the Nam Nest into picture since it's finally at range. I mentioned before the Nest is a great tool for mesoscale and short term synoptic trends as it handles the UL pattern much better than the parent with a limited overamp bias inside 36 hrs. 

One of the positives in comparing the 12z suite was there was a good deal of agreement on the placement of the SLP center at Wed 18z at the mouth of the bay, about 25-50 miles near ORF. Traditionally, this is where the western crew would benefit as it throws moisture plume would be aimed up the 81 corridor with expansion NE as we see a better low-level convergence signature towards the low center with 85H frontogenesis increasing intensity up the 95 corridor. There will be a quick shift from nothing to moderate precip for pretty much everyone and there won't be a wasted QPF time frame as dew point depressions remain within reasoning of column moistening, unlike what we see with a pure arctic airmass. 

Between 18-00z Thu is where there are some differences in guidance. The GFS has come on board with western low developing and becoming the principle SLP component of the double barrel structure, along with the rest of guidance. They all have similar SLP placement near Lewes, DE at 00z Thu, although CMC/RGEM combo is still the most progressive of the bunch with the primary SLP NE of the remainder of guidance, so I would hesitate using verbatim output on the model due to it's progressive bias. In any case, one of the issues we are seeing is the delay in closing off 85H and 7H until somewhere overhead, which leads to a persistent SE fetch off the Atlantic. This would allow for a protrusion of warmer boundary layer air to advect west of the Piedmont and shift ptype from snow at onset, to sleet/rain, especially those east of the fall line. This has been one of the reasons I was hesitant to give higher totals on prediction for the I-95 corridor until you are farther away with elevation as mixing potential was much greater within that area east of Rt15. Rt15 to I-81 has been consistently the sweet spot for this due to multiple facets of the forecast. One is of course further away from the screaming easterlies within the boundary layer, so the warm nose is limited. There's also a benefit of consistent 7H frontogen extension back to I-81 where lift can be maximized for longer periods of time, leading to a QPF max centered in a triangle from Front Royal to Hagerstown to the Pars Ridge line in NW MoCo. There's a secondary QPF max likely within the strongest, most persistent corridor of 85H frontogenesis to the east along the I-95 coastal plain, so when the low finally begins to stack and 850mb temps crash, there will likely be a secondary snow max (Albeit not as hefty as further west due to snow longevity) along and west of the frontogenic forcing. This places an area like Pars Ridge in Carroll and northern Baltimore Co at play for another tick in snow compared to the rest of the sub. The alignment and strength of the frontogenic forcing is still up in the air, but so far the consistent placement on the Euro and now NAM Nest lead me to believe we are starting to see those fine details coming into the picture. 

The strongest mid-level frontogen will lift into PA, but there is a curve back towards the NW tier of the sub as the 5H and 7H trough axis pivots and closes north of our lat. That will be when the deformation axis begins to develop and we see more SW/NE banding alignment take shape. All guidance has a bulk of the CCB into PA now due to the northern close off, so the max snow potential will reside into PA with the central PA corridor as the best spot for lolli's to 2'. I still think a general 8-14" with local to 16" is possible from Emmitsburg to Mappy with the highest totals further west. 10-16" with local to 20" is possible along the 81 corridor out into WV and SoPA from the Rt99 to US15 extension (Ala @Ellinwood map). The I-95 coastal plain will unfortunately take the brunt of this shift with lowest totals around 1-3" to the east of the corridor, but incremental increases further to the NW, especially once west of the fall line. From there, 3-6" at the beginning of the fall line, with 5-10" 20 miles after that down thru western HoCo, western MoCo, and Loudon in VA. The Catoctins are probably the odd ball in the bunch given elevation, so I would place them in the 10-16" range for this one. Precip should come to an end between 06-12z everywhere with snow lasting the longest over the northern tier of the sub. 

It sucks not being able to be back home to enjoy it, but I love forecasting and this was fun to track and look at the meteorology unfolding from afar with no skin in the game. I hope it trends a bit further SE and everyone can cash a bit more. There's still time for a small tick, but I think the markings are set right now. 

[Yeoman]

4 minutes ago, 40westwx said:

I want you all to be prepared for the greatest succession of model runs in Mid Atlantic snow storm history.. over the next 36 hours we are going to see a slow and steady shift to colder temperatures.. all of you all teetering on the brink will see you 1-3 turn in  to 2-4.. then to 6-8 and then.. the ever important 8-14.  

This shit is happening

You got some khalifa Kush in that pipe?

[baltosquid]

HRRR with its first digital snow for Baltimore for this one. Looks very cold overall. But it's also at 48 hours so... just fun for now.

[Yeoman]

1 minute ago, PhineasC said:

I’m everywhere. I’m standing right behind you now. 

Hopefully with your mask on

[Deer Whisperer]

6 minutes ago, 40westwx said:

I want you all to be prepared for the greatest succession of model runs in Mid Atlantic snow storm history.. over the next 36 hours we are going to see a slow and steady shift to colder temperatures.. all of you all teetering on the brink will see you 1-3 turn in  to 2-4.. then to 6-8 and then.. the ever important 8-14.  

This shit is happening

This science seems solid