MAG5035

Man those TT maps that combine all the frozen/freezing precip make me cringe haha. I bet those folks in eastern KY wish they were actually getting 16" of snow.

Some other short range model guidance data to consider. 18z NBM (National Blend of Models). Only goes to 36hr on WB and is still mid event at the end: 18z WPC guidance 50th percentile 24hr snowfall, aka CTP's current expected snowfall:

SPC's 12z HREF guidance (24hr mean snowfall at 48hr). Only goes out to 48hrs so probably isn't covering the entire first wave in eastern PA.

This above post was from back on Saturday. I've been saying the last few days that this week isn't about getting the big storm...as we don't have the amplification in the pattern for it (late weekend into next week appears like that could be another story). We have a gradient pattern with overrunning waves running the gradient and the key was to locate where these swaths were going to go. Things have trended south the last few days, favoring the northern Mid-Atlantic region with best snows but still a good chance of a half decent snowfall south of I-80 and I'm not going to rule out some snow north of I-80 yet. Still looks like a two pronged event, with a surge of precip tomorrow night into Thurs and then late Thurs night into Fri. Just a matter of how far north we can get this overrunning precip. To me this still looks like a good chance of a solid advisory event for the southern two tiers of counties in PA as is with best chances of 6"+ residing in the western MD counties and potentially getting up into the Laurel's counties on the southern tier. One fortunate thing about this trending south as it took the icing swath south, which was one of my concerns outlined on that post over the weekend and that definitely looks like that's coming to fruition. Most of those winter storm watches running the Ohio River across KY into WV are ice related or some kind of snow/ice combo.

0.8" was the total here this morning. Looked like downsloping killed things here as those nice totals and rates over in SW PA def didn't translate over the Laurel's very well locally.

Yea same, looks like I have about an inch at best. I think some downsloping probably isn't helping my cause here. Def a good event over in western PA, looks like a solid 3-5" over in Pittsburgh.

Hard to say yet. Comparing where this seems to be setting up in western PA on radar vs what the 0z 3k and 12k NAM have.. it does appear it's coming in lower. So we'll see how that translates across the state. Some of this might get as low as the turnpike in the Sus Valley but the best probably still goes north of MDT.

Yea I'd say. The 511 cams around the city look pretty snowy already. Flurries just starting here and 23ºF.

Should be seeing snow start here within the next hour or two by looks of the radar. Hoping that this precip swath finds it's way a tad south of where the 0z short range guidance like the NAM takes it. Could be a fluff bomb for whoever gets the best rates.

I know JB has been musing on some of his posts lately about this current Feb pattern looking like Feb '94, which was a gradient pattern not all that dissimilar to what we're looking at right now. Feb '94 ( as well as Jan during the major arctic air intrusions) was a neutral at best but generally positive NAO/AO. I'd imagine his angle in having this similar gradient pattern with the established -NAO in place is that the waves running the gradient would target the DC region/Mid Atlantic more favorably than 1994 did. 93/94 was either the snowiest or 2nd snowiest on record in places like UNV/IPT/MDT but a lot of those events (esp in Feb) were primarily ice down there and also in the southern LSV too.

Yea lol, everyone all worried about stuff getting suppressed this week. Look at where tonight's swath of snow is going. Plus, should throw out the friendly reminder of where guidance had yesterday's storm during that 72-84hrs lead time.

This week really hasn't been about getting the big storm, but chances at more moderate snow events. We're running a pattern on a gradient between alot of arctic air and some attempted eastern ridging.. pretty much a zonal pattern alignment. We don't have the amplification for a big storm (yet), but we have an active storm track with multiple waves tracking the gradient. I made a more detailed post about this last night at the top of the previous page.

I'm not too concerned about suppression currently. It's become apparent that the storm track this upcoming week is going to keep us near or in the crosshairs of several waves rather than a complete overwhelming of arctic air via dumping the PV into the east. We have an eastern ridge trying to pop up against this blocking pattern and hyper negative NAO/AO...elongating the PV and providing this gradient pattern with alot of cold air availability. Could be the MJO trying to influence some as it has and will continue to be mired in Phase 6 and now 7. Usually those phases strongly correlate to eastern ridging JFM (especially 6 but 7 reflects it too). Other than the PNA starting fairly negative, MJO is really the only teleconnection flying in the face of the majority of them being pretty supportive this week (-EPO/-WPO). We have such an established blocking pattern up top that instead of what could have been a period of warm weather, we instead have a battleground for delivering potentially more decent snow events. The exchange in all that appears to be not having straight up frigid weather. So god forbid it might not be -15 to -20ºF lol, but we're going to have multiple chances for wintry weather. Just have to nail down the swaths, and it's probably going to vary favoring different parts of the region and perhaps introducing p-type issues in some instances. I would be surprised if that PV doesn't directly get swung through at some point within the next couple weeks though. I feel like when this overall pattern does start to break down/change/etc (and it will eventually) that all this cold that has gotten to our side of the pole is going to get moved around. And typically, such a thing likes to happen on the heels of a major amplification and storm system.

Tuesday's potential light event seems like it may target central and/or northern PA more than the southern tier by the looks of most of this afternoon's guidance. That's looking like a 1-3" stripe of snow wherever it decides to throw down. Good to see the Euro backing down on bringing the ice into PA with that Thurs/Fri event for now. Seems like it could be a couple different surges of precip with that and a bit of an extended WAA precip phase before the eventual low comes up toward PA. Doesn't look like something that would deliver excessive snows but could be a real nice snowpack builder (moderate with a stripe of heavier totals). I"m not going to rule out potential mixing issues in parts of the region with this eventual system but the setup should favor mainly frozen. Lot's of cold available and an established snowpack lends some support to the PA favorable storm track. And we're not winding up a big storm with this so any WAA surge aloft would likely be limited.

About a half inch fell early this morning, as expected petty much so no complaints.

Woke up to a dusting and some steady snow indeed falling around these parts this morning. 24°F

Here was the CTP update a couple hours ago. Def more leery of the NAM's optimism by the sounds of it. HRRR has looked like garbage in terms of any decent snows, with the latest full run (03z) not even having advisory snows in CTP or pretty much the northern half of LWX's CWA... where there's warnings up. I think HRRR is underestimating precip shield.. it definitely did during the latter stages of last weeks winter storm with the roving bands of snow. How much so is debatable. DC's problem with the lack of accums being presented is the HRRR has half the event as rain. LSV shouldn't have to worry about that. Speaking of temps.. sure wish I had direct incoming with the nice crisp 21ºF and overcast conditions here currently.

Possibly some kind of a light event Tuesday, with some light snow streaking across PA (perhaps light mix southern tier depending on the model). It seems the bigger trouble brewing will be late week in the Thur/Fri timeframe. This is looking like a drawn out warm advection type event at first with an eventual wave(s) of low pressure coming up towards PA. My concern with this setup is given the gradient pattern and the arctic air nearby is it looks like quite a favorable setup for having a significant icing swath. Not necessarily here, but somewhere. 18z GFS for instance mainly snow with this while the afternoon Euro run had alot of ice into PA. Those details are impossible to nail down at this point, but that Thur-Fri timeframe looks to be where the next more significant precip event materializes. Also the question of cold air, as the big time arctic air is on the playing field but trying to figure out how much eventually releases into the eastern US. Models have literally been all over the temperature spectrum, from the mixing events and temps near somewhat above freezing at times to throwing the whole polar vortex over the Great Lakes/NE and what would likely be record cold. Still going to be pretty cold immediately behind tomorrow's system but the significant arctic cold that was looking to happen earlier this coming week now looks to hold off to perhaps D6-7 or so. Guidance is having alot of trouble handling location of the gradient/storm track and the longwave pattern in general.

Lol, you guys have been reading the Mid-Atlantic thread haven't you? I know this isn't looking as great as it was but it still should be a general advisory type event for the LSV. The NAM and company had been the guidance in particular leading the way with that widespread 6"+ and we should all know the NAM can giveth.. but it most certainly can taketh away. Most other guidance has generally been less of a widespread 6"+ threat and more of a debate of how expansive the precip extent is going to be. I thought the coastal low had a chance to run up right on the coastline but it's looking like it will track offshore some, pulling the axis of best snowfall associated with that back southeast some. Basically back to my original SE of I-81 thinking with the best accums. Jury still somewhat out on that NW extent of the precip shield between blossoming coastal and also the area of precip back out over MO/IL/etc. I like a general T-2" NW of I-81 covering back to the I-99 (AOO,UNV,IPT) corridor and perhaps even western PA as we certainly can't rule out a period of mostly light snow anywhere in those areas. Obviously the best chance of 2" or perhaps a bit more is closer to I-81 or perhaps some southern Laurels locations. 2-3" (advisory event) for places like MDT and more of a 3-5" York/Lancaster with an outside chance at some scattered higher amounts near the MD border.. but mostly this is looking to top out at 4-5" by the looks of it.

Here was last night's 0z HREF 24hr snowfall, which is short range ensemble guidance that NWS factors pretty heavily into their snow maps, and you can see why CTP opted for watches in Adams, York, Lancaster. Thought this was the 12z run but good thing I double checked bc it hasn't run 12z yet on the SPC site. Would imagine whatever the 12z shows will factor into whether they opt for warnings in the watch area. Considering the full suite of guidance, they're pretty locked down on the general location of the best swath of snow but there does still seem to be quite a divide in guidance though when it comes to amounts of said swath . Looking at the 12z GFS and GEFS, it's barely an advisory event in the watch counties and a general 1-2 in the rest of the Sus Valley, RGEM same way although that particular model has generally been SE the whole time on the lead up. 06z Euro/EPS supports Sus Valley wide advisory event but borderline at best on upgrading the watches to warnings. It's the short range guidance like the NAM/SREF/HREF that have been robust on warning totals and the 09z SREFs are most robust on NW extent with solid advisory amounts all the way back past I-99. So all things considered, I think what CTP currently has out snow-map wise is pretty good representation right now with location of the swath of best snows and perhaps tempered expectations on the top end accumulation wise.

0z GFS again with the broad coverage but not much in the way of 6"+.

I said earlier I'd consider it a win if I saw 1-2" back this way and that it just had to suck me back in haha. I'm thinking the central counties' (NW of I-81) chance at seeing anything notable hinges on any interaction between the two shortwaves that can generate an area of snowfall further back.. something to the tune of what the 18z GFS tried to do.

Thermal gradient could argue for that closer surface low track ala the NAM.. which has the low into the southern Delmarva vs the GFS/EURO staying notably off the coast. Not like we're stuffing this system down with a significant arctic air intrusion that can push the baroclinic zone offshore. (actual cold air comes in behind this sytem). DC's coming off a day where it's 50ish tomorrow and temps during the event aren't overly cold even in the LSV. Ugh, this system just had to suck me back in lol.

Measured 0.5" of new snow at daybreak, which easily melted off non-snow surfaces this morning. Just did some measuring to get the state of the snowpack in the yard. Mostly ranges 6-9" with an area of shallow snow <3" on the one corner and an area of 14-17" on the downwind side of the house and between the house and the shed. Before the snowpack softened yesterday, that last 3.5" Tuesday evening was windblown and the wind continued Wednesday with some significant blowing and drifting.

The Euro's take: Not focused like the NAM with the big amounts but a broader precip shield. Euro and esp GFS illustrate what I was suggesting in last night's post with getting the northern and southern shortwaves close enough to interact and cause a more expansive shield back NW of I-81. Wouldn't be heavy but I'd consider 1-2" a win back this way if it happened. This is starting to look like an advisory type event roughly I-81 east and I-78 south.