MAG5035

There’s been some half decent back building on PBZ radar. Starting to have a more NW-SE component to its movement. Have to see how well that translates over the mountains to the Sus Valley.

At about 4.5” here, with light to moderate rate. Temp down to 28ºF

Wow, it was about 2 hrs ago or so you posted that you were working on your first inch.

The 511 cams on US 322/22 on both sides of the Duncannon bridge look like they’re getting pounded too, as well as the rest of that stretch down to I-81.

Well I dunno where exactly in Harrisburg everyone there lives but it seems like it’s snowing everywhere in/around town there now looking at 511 cams. The 700mb FGEN band is setup overhead as well. This should pile up pretty fast.

Steadier stuff should be working into York/Lancaster here pretty directly by the looks of LWX radar.

Just got home here, was out for the evening. Nice event ongoing with 3.5” down and a nice moderately heavy rate currently. 29/28ºF

3:40 after nooners. 37º/16ºF light wind and cirrus overcast. Max wind gust of 38mph occurred around 4:30 this morning.

My bad haha I didn’t realize they divided up the warnings up that much.

Here’s some of the western part of that, CTP went warnings all southern tier and bumped up the advisories in the next tier to warnings. Western southern tier (Bedord/Fulton/Franklin) is 5-7 and Laurels is 6-8.

Looks pretty reasonable. I wonder why his northern fringe goes to infinity at the PA/NY border.

This is the kind of event our area overachieves on if the good precip and forcing are north enough.

Haha I didn’t know everyone was putting their snow maps out while I was working on my post. The snow map game is strong in here today.

My map for this. Tried to make a compromise in blends but perhaps on the bolder side. I anticipate CTP needing another tier or so of advisories in the central and upping at least the western half of the watches to warnings. 3-5” amounts should be common in the main swath. Big question is in or near the area I hashed. I was going to get cute and try to highlight two distinct areas but I’d probably need a bigger map. Any rate I feel the hashed area has the best chance to see an embedded swath of 5-6”+ and/or local totals of 6+. Best 700mb forcing is in there coupled with 700mb temps in the low minus teens. The fluff bomb potential is high with that. The southern Laurels will have that plus the benefit of some extra upslope forcing and colder surface temps.. hence the distinct 5-8” I anticipate there. The other snowfall max is probably somewhere in the northern Mid-Atl (northern VA/northern MD, where better 850mb forcing will be. That won’t yield the bigger ratios like the 700mb dynamics that should be residing in southern PA.

Yea that is true, and they honestly looked really good by the end of Sunday when things shifted south a bit. They upgraded high confidence counties to warnings and kept the watches that reached into the Sus Valley. The big shift south Monday at <24hrs til go time really sent the forecast sideways. Then they never downgraded the warning they had for here last event either when it was abundantly clear AOO-UNV wasn’t getting 6+. Even JB said just prior to the event they needed to get rid of the warnings for the State College area haha. They just turned it into a 2-4” winter storm warning, which I’ve never seen before. Then of course the high confidence counties above I-80 that were originally warned didn’t even see any snow in the end. What happened with the Tuesday event was brutal, and I don’t know if there was much to be done with that kind of a shift in guidance. I don’t expect anything drastic to happen with this system. Precip shield should have much less of a northern gradient than Tuesday and big thing for our area is determining how much of southern PA to put in advisories IMO. Wagons north seems to be the theme of happy hour so far (need the Euro yet).

To be fair, LWX’s watch statement is for most likely outcome of 2-4” with isolated 6” amounts in heavier bands. That’s a bit of a stretch for a region that needs widespread 5” or more to verify a warning, technically. Both ends of the spectrum between CTP and LWX haha.

Certainly there’s support for the southern Laurel’s to have one. You’d think a coordination with LWX/PBZ having watches in Garrett/Western Alleghany in western MD (LWX) and Eastern Preston in WV (PBZ) would possibly warrant a watch up into Somerset. Those high elevations are probably going to be low-mid 20s during the height of the event. Temps aloft are supportive of a higher ratio event and couple that with some upsloping and I believe some of those short range models are onto something having 6”+ up in those areas. I dunno about watches east of that yet. Like I said a bit ago, probably don’t need to rush the advisories. I’d wait to see 0z and then go from there. I’m surprised there hasn’t been a mention in the HWO about any accumulating snow or prospects of it at all, though. I dunno, I doubt it but maybe getting burned on models bailing south 100 miles in the 24 hr lead up to Tuesday mornings event made for some cold feet.

Weird take, the only thing that represents what CTP is talking about in their AFD was the 12z GFS op. Everything else supports advisories in at least the first tier or two of counties in southern PA currently. No need to jump the gun issuing them just yet but I’m not sure what guidance they’re basing the current take on. Also weird, the snow here has transitioned to graupel

Snowing here now.

Got dark in a hurry down here. Waiting for the precip to reach the ground. At 39 with a 26ºF dewpoint so probably can manage some flakes out of this.

You’ve done it now, I’m using math haha. Trying to see how Pivotal calculates it’s Kuchera vs WB. So, basically it applies an equation that uses the max temp in the lowest 500mb. In this instance the warmest temp is the surface temp.. which according to the NAM holds at 31ºF for the event. Applying that equation using the surface temp (31ºF = 272.594K) yields a 9.13 to 1 ratio via Kuchera. Right around its output and also <10:1. WeatherBell’s output is greater than 10:1 so something different is being calculated, whether they don’t use temps right at the surface or maybe they’re applying the bottom equation for all temps, which technically would be wrong. To simplify, the bottom equation is used for the max temp being less than or equal to -2ºC. Plugging that same temp for MDT (about -0.5ºC) into would give about a 10.5 to 1 ratio. Interesting, maybe the codes cracked on that. That would definitely make a difference in map output with marginal temps.

Hmm that’s interesting, Weatherbell is 3.3” Kuch and 2.8” 10:1 at Harrisburg. Splitting hairs at this point in time really but given colder surface temps and a much colder column ratios should be better than 10:1.

Here’s the 24 hr Kuchera for the NAM for specifically Saturday. It’s a little bit higher than 10:1.

It could also generate a broader area of snows as well without much deviation to the low track but a bump north certainly wouldn’t hurt. Something to hone in when this gets deeper into the short range. This probably won’t have the razor thin margin like yesterday’s event. Other thing is it going to be much colder in front of this wave. 850 temps in southern PA during the event is -8 to -10ºC and 700mb temps in the low minus teens. Great column for big ratios for a change. I think I-80 and south is in play for at least 1-2”. Just a tenth or two of liquid equivalent probably makes a decent advisory event. Could be a narrow swath of borderline warning totals, but right now the prospects of that seem to favor those just south of us (perhaps northern MD).

I don’t personally think any one op model or ensemble has really stood out from the rest this winter for better or worse. They’ve all been generally to sometimes wildly inconsistent at longer leads (beyond D7). That comment might come off like well duh.. it’s beyond D7, but the focus on that time range should be more towards the large scale pattern and not individual features. And typically you can hone in on a general theme at least, but this year has been more difficult. That could be a product of the general pattern this winter, which has been blocky and has an active southern stream/split flow. Where I would direct any ire towards modeling this winter if I were to do so is the extended products… specifically the Euro weeklies. They have been too cold all winter at longer leads and they were a catalyst in the lead-up to expecting the perfect 500mb pattern (to the tune of a 1978, 2010, etc) this month and that led to sky high expectations.. and the associated disappointment when it hasn’t quite worked out that way DESPITE delivering to some degree with yesterday’s and likely Saturday’s system. Doing WeatherBell’s temp forecast contest this winter, I got burned in December leaning towards Euro weeklies with blending. Although most did because no one was expecting the kind of warm December we ended up with. You only have from the 15th to the 20th of the prior month to make these predictions and that’s it. I learned my lesson in January and placed 6/98, anticipating a warm front 10 days or so and a cold second half, with the pattern slower to transition. The cold shot in the middle of the month was so significant that the late month warm-up actually saved my forecast from being way too warm in the central part of the country. They rank the models in that too, basically they calculate the rankings based on the total temp error between the 12 stations you pick temps for. The GEFS extended and Euro Seasonal were ranked within the top 5. The Euro weeklies ranked 57th.