Newman

Haha you're not wrong! 18" would be pretty incredible and be a top 10 all time storm for Philly

That GFS run is a classic NYC -> Boston HECS verbatim. Although there's a southern stream component to it, the TPV lobe in the northern stream does the heavy lifting and bombs it out justttt too late for Philly and SE PA latitudes. I wonder how strong the NAO block gets to push that just a bit further south? It'll be fun to track this one and see how the morphology changes as we get closer.

I would venture to guess 90%+ of the posters here in our subforum don't take the long range models as gospel. This is in fact a weather forum: we post long range weather maps, track storms, and analyze ensemble guidance. When someone posts a 5+ day out map, it's assumed by most that it's exactly that... A weather-prediction model output with an attempt to simulate a chaotic, non-linear, dynamic fluid that we call the atmosphere. When the local Philly news outlets share long range guidance to the uninformed public? That's a problem and a whole other topic of discussion. Improving the communication of probabilities to the public, emergency managers, stakeholders, etc. is currently a huge area being tackled by the NWS. It's why there's been a big shift away from individual deterministic model evaluation and emphasis on in-house statistical ensemble products (NBM for example). In short, on a weather board like this I know most don't just take the models as gospel. The people on here are well-informed and knowledgeable about their stuff. We look at the long range models and scrutinize them because that's what we do and love. Speaking of long-range guidance... I believe this winter has been quite favorable at the 500mb level for mid-Atlantic snowstorms. Parts of SE PA have not been impacted as much due to small nuances in the flow that don't show up until close to game time. Compared to last winters, this has been quite an improvement.

Made it to -11 this morning in Laramie, would think we get even lower tonight

HRRR shows some light snows getting into SE PA around 6-7pm dropping a C-1" in the NW burbs, consistent with the winter weather headlines currently up

1.25" in Fleetwood

Just to highlight the differences and what I'm talking about, here's a comparison between the 18z RGEM vs 0z NAM. These small differences make a difference with getting precip into NYC and northern Jersey

The NAM allows for a more expansive precip shield with a 180-190kt upper level jet screaming over northern New England, putting Eastern PA, NJ, and NYC in a favorable right entrance region. The flatter models aren't really all that different with MSLP placement, it's the jet and SER flex that's different

Upper level jet streak has been trending towards a better position with the 11/12 storm on the NAM. Better upper-level divergence in the right entrance region of the jet bringing a more expansive precip shield north. NAM gets 0.6" of QPF to Philly!

Even with the favorable regional models coming in at 18z, I'm not sold on the magnitude of QPF depicted yet. Still think accumulating snow gets into much of SE PA, but a 1-3 or 2-4 ordeal is the way to go right now

RGEM is a really solid hit. Low end WSW for much of SE PA

The GFS and CMC have it too, Euro is just a bit warmer. Question will be if we can get a HP to anchor in SE Canada and how much CAD holds on.

NAM also shows the thump of sleet/snow Wednesday night less than 24 hours after the Tuesday night storm pulls away

First call from NWS. Seems reasonable and what my call would be right now. I told my folk yesterday in Fleetwood my first call is 1-3"

Long-range 18z HRRR shifted quite a bit cooler compared to its earlier 12z run. I took a sounding from near KABE at 02 UTC and you can see the warm nose between 700-850mb creeping close to freezing. The next hour mark it switches over to sleet, but at this time we're going to town with deep lift and saturation in the DGZ. The HRRR indicates ~0.1-0.2" of QPF during this hour, so you could thump a quick 1-3" if that's correct. Really depends on how intrusive that warm layer is. We saw with the storm earlier this week the HRRR was way too cold, which is it's typical bias. Either way, I don't foresee much ZR in the Lehigh Valley and Berks, it'll be mostly sleet IMO with a glaze of ZR. Down in Montgomery, Bucks, Chester I see the higher ZR accretion. SW of 95 is probably mostly rain or a light glaze of ice on cold surfaces. As a side note, look at that hodograph and low-level WAA/veering lol

And another storm after Valentine's on the GFS, tries for a triple phase. Insanity

That 12z HRRR run is really snowy for much of Berks and the Lehigh Valley. I think it's out to lunch, it's the only model that mutes the WAA and keeps it at bay. The entire profile stays below freezing for most of the storm. I guess it's hard to know whether the warmer (NAM) or colder (HRRR) models will win out as of now. The typical model biases are being shown...

Final total of 7/8" in Fleetwood, season total is just under 16"

My folk in Fleetwood have about 0.5-0.75"

That 12 GFS run is hit after hit of snow and/or ice for PA

The low in Laramie last night was -25

My folk in Fleetwood measured between 7.5-8 inches around the yard and on the snow board.

KRDG has been reporting mod or heavy snow for 3 hours straight now.

Brother in Lititz just measured a bit over 4" in grass

18z HRRR looks solid for most across the CWA, WSW criteria met for Berks and the Lehigh valley. Upper Bucks, Chesco, Montgomery as well. Philly itself flirts with the snow/mix line for much of the game tomorrow, but ultimately remains on the "snow" side of the line. Worst conditions in Philly are probably when the storm is pulling through with the last hour or two as temps crash and ratios/rates are enhanced a bit. So, I would expect a snow or snow/mix during the entire game tomorrow with the 4th quarter possibly being the worst.