BTRWx's Thanks Giving

10 minutes ago, GATECH said:

DT refuses to cave….LOL, guess he didn’t see the gfs

He never does.

Can we please stop posting 10:1 maps.

GFS is a disaster for I-95.

Maybe this is a season of overpreformers?

53 minutes ago, psuhoffman said:

I would love for some others to contribute... I will open the zoom tonight at 10:OO and stay on until the GFS is out.  

Calling BobChill!

Is the 18z euro running?

7 hours ago, mattie g said:

I know PSU has mentioned this, but I would love to hear some other folks' takes on things, as well. If I knew anything, I'd chime in, but I don't so I won't. 

Besides, I'm sure most folks here can listen to a Philly accent for only so long...

One way to do that is PSU can ask the audience questions to test us.

1 minute ago, jayyy said:

Very true. One thing is for sure, ill be up through the 00z euro run tonight as we enter it’s wheelhouse. Feeling very good about our chances of a warning event 

That could happen region wide due to the ice threat.

3 minutes ago, Snowfan96 said:

My only point is the NAM doesn’t get enough credit, esp. in these types of scenarios/set-ups. It tends to be more reliable and accurate than many have come to believe.

It's unreliable near the end of its run.

This snow is really heavy to shovel!

Around 10" in Alexandria.

2 minutes ago, Its a Breeze said:

12" of happiness 

 

Location?

0z euro

3 minutes ago, CntrTim85 said:

 

My sister teaches in Loudon County. They are currently in a 2 hour delay. She has asked me to keep her apprised of the situation. She is anticipating a day off but would like as much notice as possible. This leaves me invested. Why can't you people just engage in conversation about the current weather and not attack people based on their locale? AGAIN, is anyone concerned about dry air eroding the precipitation field? 

You can do that without invading.

4 minutes ago, CntrTim85 said:

Again, I am not trolling and have done nothing to violate the rules of this forum. Please stick to the weather and topic at hand. Are you concerned about dry air on the back side? Or current temps and mixing? I've seen it many times with these setups. 

You're posting way too frequently in a region you don't live in.

Would the current radar depiction be a good indication of the northern edge tomorrow?

6 minutes ago, MillvilleWx said:

Well, I finally got to look at things for the storm and man, it's a pretty dynamic setup that should drop the hammer SOMEWHERE in this sub-forum, but the question is....where?

Let's take a look at the 500mb setup

There's a prolific 500mb shortwave (s/w) currently rotating around the base of a mean trough with closed reflection over northern AL. Historically, this is a great position for the sub-forum to cash in, so long as the ULL doesn't mess itself on the trek eastward. As you can see, it is forecasted to not only hold, but actually strengthen as it crosses the App front with a negative tilt of the shortwave trough. This provides a textbook level divergent signature downstream ahead of the ULL and attendant s/w. What happens is an explosion of the precip field with convective prevalence due to maxed ascent on the left exit region of the 500mb jet max. Also, here's another piece to tickle the fancy....

 

Here is the 700mb presentation on Monday morning. A closed 700mb low cuts across the NC/VA line which is a fantastic track for areas near Rt 50 and south as VV's will be off the charts on the northern periphery of the 7H low. This puts the NoVA area from Fairfax to the east in the core of the ascent within the mid-level profile. 

 

Looking at the 7H frontogen picture using the NAM Nest, you can see a distinct signature over NoVA into SoMD and the lower Eastern Shore with a convergent pattern within and just north of the main frontogenic forcing. This is where the most prolific banding would occur for those with winter precip. Another maximum will occur on the lead side of the low due to the moisture fetch off the Atlantic from SE flow (This is actually important for the snow lovers on the Lower Eastern Shore). 

Now, go back and look at the 500mb gif I posted above, There's a s/w zipping eastward out of the northern Midwest that will put a straight edge to the northern side of the precip field. It's a developing confluent signature that will create a sharp cutoff on the northern side of the mid-level moisture field, which means someone will get hung out to dry, literally where this ends up developing. I will say there is a distinct northern mini max potential about 30-50 miles south of the main convergent area created by the confluence. This area typically maxes with the localized ascent, plus the favorable thermodynamics at play. Don't be surprised of some interesting totals coming out of areas within that zone to the north of where the main area gets slammed. 

So, when it comes to the dynamic nature of the mid and upper-levels, there will be no shortage of ascent to work off, and that in turn will help establish a healthy area of precip for the event, especially those within the perfect setting of the mid and upper closed lows. 

Now, lets talk about the caveat to the setup, thermal profiles. Right now, we have modest cold air advection (CAA) areawide with drier boundary layer air working behind the front that slid through earlier. This is important as wet-bulbing at both the lowest 100m of the boundary layer AND the layer b/w 600-800mb will generate the ptype separation a few hrs after the precip begins. Right now, thermals are borderline for the first 3-6 hrs of the event as sleet will likely mix or be the predominant ptype for the very beginning. As the mid and upper levels traverse eastward, you'll see a considerable cooling aloft that will mix into the boundary layer and change everything to snow from northwest to southeast. Areas on the very northern edge might only see a brief period of liquid and/or sleet before completely changing to snow. I think the area from Rt 50 south to the AKQ area will be the sleet zone for the first stage of the event. This area is also in the benefit of being within the "crush zone" for precipitation due to the expected ascent from the mid-level frontogen. There will probably be a period where sleet/snow mixes with massive flakes before shifting to all snow and then raging with continuous large aggregates. Boundary layer will be improving through the AM, so ratios will start pretty meager, but quickly shift to a climo norm, perhaps final 3 hrs ending around an avg of 12:1 with some places seeing 15-20:1 pending local banding. 

As I see it, there will be a line about 30-50 miles wide of pretty decent snowfall with the northern edge tapering back in a gradient caused by the confluent area to the north. Here's my current thoughts on snow totals. This is all from everything I've looked at and adjusted based on current ground temps needing some time to recover from the warmth earlier today.

 

Hope everyone here gets some snow. Enjoy y'all!! 

Best post I have ever read on these forums!

1 minute ago, nw baltimore wx said:

Bullseye for precip.

and snowfall accumulation

4 minutes ago, WxMan1 said:

I always thought, when ptype would be an issue, that the 3KM NAM Ferrier SLR would be a good sanity check. Even in this case, when the warm layer is mainly (entirely) surface based instead of aloft. 

I would look at these totals as the lower percentiles or "expect at least this much". I know this map isn't comforting for most of us, including me with MBY in central AA County. But we are going to need those rippin' rates.

Crazy how low that map is for Southern Maryland! Most forecasts has them as the bullseye.

2 minutes ago, SnowDreamer said:

SREF mean over last 4 runs @ DCA. The pink line is most recent (21Z).

1 minute ago, SnowLover22 said:

My brother who lives in Alexandria wants to know how much snow he can expect. It would be reasonable to tell him at least 5 inches?

I would expect right around that amount.

7 minutes ago, Snowchaser said:

WeatherNation has the most bullish forecast I've seen. A zone of 12''-24''. Madness.

 

 

I have no idea how they have their own network!

1 minute ago, CntrTim85 said:

I'm sure I'll catch a lot of grief for this post BUT the bust potential is extremely high on this one. Good luck to everyone up north! 

True, it can bust high or low.

You there PSU?

I can't believe Washington gave up a touchdown on 4th and goal twice in one game!