Terpeast

LWX AFD if not already posted (from 3:50 am). Their office has been handling this storm better than any of the models i applaud them for their restraint. They also slate the start of the storm during Friday night, which could help us with the temps. A strong southern stream mid/upper-level trough over the Mid-South Friday night quickly moves northeast as it phases into a flat trough over the OH Valley/Mid-Atlantic on Saturday. At the surface, an associated area of low pressure develops along the northern Gulf Coast and very quickly moves across the Southeast states through Saturday morning. The surface low becomes better organized as it crosses eastern NC into far southeast VA, where it moves offshore along the NC/VA border. Precipitation overspreads the area from southwest to northeast starting late Friday night into Saturday. Temperatures Friday night are forecast to be below freezing for most of the area. However, there is considerable uncertainty to the east of US-15 as easterly winds advect in a warmer marine airmass and strong WAA ahead of the surface low help to increase temps along/east of I-95. All that being said, precipitation is likely to start out as snow west of US- 15 and a rain/snow mix along/east of US-15. As the morning progresses, areas east of I-95 are most likely to transition to a cold rain, with steady snow west of US-15, and a mix in between. Having the surface high well to the north and weak onshore flow proceeding the surface low are not generally favorable for accumulating snow along I-95. Any chance to see higher snow totals there will be dependent on higher precip rates and wet bulb effects overcoming the marginal temperature profile. Still, p-type is going to be highly sensitive to the track of the low, with a tight rain-snow gradient likely. Significant snow accumulations are most likely along/west of the Blue Ridge and Catoctins. Where precip is more likely to be in the form of rain, near and east of I-95, there is the potential for instances of flooding. Continue to monitor the progress of this storm as the weekend approaches.

Low of 26.6

The deck has been reshuffled. Totally different evolution from 12 hours ago and 24 hours ago

Beat down DC and NW at 96

Big shift west in sfc high

Move back to Ashburn and maybe you’ll change our luck

Same. I just moved back here a year and half ago. Even if it’s just 3” imby as depicted by the NBM, that’ll be my first good event as well.

From 12/29. Let’s see how they update this map though

Was hoping to see some sort of update from LWX in tonight's AFD, but not much changes there. I don't envy their jobs right now, but I do admire their restraint. They haven't blinked.

@psuhoffman called it. Said the GEFS was wrong, and here we are. Still 300 hours away, but all the majors are in agreement on the LR pattern

Same. The high looks to be in a better position

No, I was seeing the same

Yes, a bigger phased system would only have worked with a block that holds the 50/50 low down and keeps cold air close by. But for marginal in situ airmasses without a block, a weaker slider is what we usually want. Sure, a very dynamic storm can and has dropped heavy snow with big rates in a marginal airmass but that tends to be the exception

Could just be the thing that helps us keep “just” cold enough air west of i95

Just by looking at this, it seems like the 18z gfs is depicting a completely different synoptic setup than any of the previous runs.

Looks like I’m gonna have another model analysis session tonight after this 18z gfs run. Am with the kiddos for now, but I’ll be popping in here to check on things

Maybe. If the trailing wave merges with the one we’re looking at… holds it back a bit. I guess it’s possible if the NS wave strengthens more and gets us a refresh of cold air. But can it be done in 4 days? If we had 6-7 days to make it happen, it’s possible.

While I'm really disappointed in the Jan 6-7 system (I started seeing the red flags yesterday with weakening confluence), this upcoming pattern - if it pans out - will have stronger confluence up top and a slower pac jet. We won't have trailing shortwaves mucking things up if/when we have a good one on the way.

I don't think it matters at this point anymore. Maybe root for it to start at night after temps drop

Back to where we were on the 31st, but still better than on the 30th. Do you have the same charts for IAD?

I noticed a trend where strorms look stronger at longer leads and then become weaker

More like, its the end of the first quarter and we’re down 14-3. We did get a field goal on Dec 11. Still plenty of game left

The r/s line was too close that any north trend would kill it

In the h5 charts I posted earlier, there were huge 500 mile swings in the western trough behind this system's wave. There's no way that detail has been nailed down yet.

Even a 20 mile shift in the right direction would change everything, and we won't see it until close to game time. That's if the r/s line stays where it is and doesn't continue trending north.