Terpeast

Still not seeing anything falling. Ashburn, 28/13

Hard to tell if anything is falling, but my grill top has a little dusting

Anyone under the radar returns just east of 81? Snowing or virga?

You got a taste of that this week.

Let's see if the afternoon's LWX AFD mentions the possibility of expanding advisories west.

SPS for Loudoun County (and any county not in the WWA), specifically mentions higher amounts east of rt 15: ...LIGHT ACCUMULATING SNOW AND HAZARDOUS TRAVEL LATE TONIGHT THROUGH EARLY SATURDAY AM... Light to locally moderate snow will move across eastern West Virginia, northern and central Virginia, and western and central Maryland, late tonight into early Saturday morning. Snow will move into the southern Shenandoah Valley and central Virginia between 7 to 9pm before advancing north and east toward northern Virginia and central Maryland between 9 to 11pm. Hazardous travel conditions are expected with air temperatures in the low to mid 20s and snowfall rates of 0.25 to 0.50 inches per hour. Visibility may drop to one mile at times with light winds expected. It is recommended to delay any travel that is not necessary between midnight and 6am Saturday. Snowfall moves out of the area between 5 to 8am Saturday with improving conditions Saturday afternoon as high temperatures climb back above freezing. Storm total snow accumulations of a coating to 1 inch are possible with locally heavier amounts up to 2 inches along and east of US-15.

Cirrus rolling in with temps at 30. May just keep me below freezing

Yeah it was a big miss, and it wasn’t the only model.

look upstairs, could be a follow up wave that does it. EPS shows something similar

15z RAP shows 0.2+ qpf for both IAD and DCA by tomorrow. That's double from 03z. HRRR smaller uptick but noise-ish

0z eps has a threat window around jan 20

I think there is less risk of cold suppression the next round with a lower PNA and the trough axis shifted further west of us instead of right over us or to the east. But it won't take much to push the boundary far enough south for us to snow and get the northern folks in the game, too.

It will be interesting to see how it interacts with the fast NS. Models at longer leads tend to underestimate the NS/pac jet. So while this is now showing a massive cutter, I'm curious if the NS wave will start coming out a little ahead to flatten out the flow and bring us more colder air before the wave ejects from the SW. That would give us snowier outcomes than the current runs are showing.

My station snuck above 30 each day this week, which kinda surprised me a bit with all this snow cover. Tbf the wind stayed up and we didn’t have that high pressure overhead. Could also have been a downslope component.

Looks good. 4-6 hours of light snow.

Can’t believe it was 24 years ago. I remember it like yesterday. Yelling at the TV when the weatherman was saying “out to sea” while the radar right next to him was spreading due north.

This one's yours, Bob. Enjoy!

Still insistent on an inch around here.

There were a lot of overrunning events, right? That's what the maps above look like to me

I didn't see the movie. Carry on, guys

I'm not even a dog owner, and this is a bit too much

The smoothing is probably from averaging across analog matches above a certain confidence interval. Like taking rollforward maps of 10 different analog matches (for example) and then averaging them all together. Probably an oversimplification, but you get the idea.

I checked the EPS weekly clusters for Jan 23-Feb 7 (sorry, can't share or I'll get in trouble), and 60% does have a pacific ridge, but with some extension northward into western AK, and some troughiness into the midwest and east. It's not as bad a look as we might expect. 40% is SE ridge.

Let's close that little snow hole over my house, and we'll call it a deal.

For those here who don't know or aren't sure (or need a reminder)... AIFS is deterministic AI model that uses the operational ECMWF as initial conditions. It is not an ensemble model, nor an ensemble member, which is pretty amazing since ensembles tend to perform better at long leads. AIFS might be picking out good "analogs" and extrapolating what happens after each analog as a composite, and doing an excellent job at that.