WxMan1

What irks me about all of this is here we are, 2025, and the global models still struggle consistently locking in with a system for 5+ days out during the winter. At least, one that's going to involve snow for the DMV. Rain storms April through November? No problem. It always seems that the models are generally in better agreement. Whether It's split flow, northern and southern stream contributions, amplified waves or not. Same sampling issues, or lack thereof, that we have with winter storm tracks here in the East. Can't figure it out, unless it's just anecdotal on my part. This is where I thought AI would help, and maybe to some extent it is. But even the EC AIFS has bounced around with solutions between days 4-7.

Remember that well. It was on the heels of the Thursday, January 22 1987 storm. It was also Super Bowl Sunday, Sunday, Jan 26th. Broncos vs the Giants, SB21. Started snowing late in the AM and was heaviest during the evening.

While there's no doubt reason to doubt, just remember what so many of you said, including PSU Hoffman... In terms of the pattern, in terms of the teleconnections, it was all about Feb 20th-ish for a long time now. Nothing has changed. That was talked about even before this past snow event. THIS was potentially the bigger prize because of the phasing and tucked in low track off the coast. Nothing has changed in that regard. Enjoy the ride!

Not sure if anyone has seen this yet. Tomer's got an experimental site going, which includes p-type for the EC AIFS. Pretty cool! https://polarwx.com/models/?model=aifs&base=ptype_estimate&background=plain&state=states_brown&country=countries_brown&proj=conus&archive=false&run=2025020818

Yeah it could be a real nice hour, maybe 2 for us in AA east of 95.

36/33 with rain and some mangled snowflakes mixed in. I know we were given the Canadian runs some crap (including the high res), But it had the right idea with rain or a mix for a while to start here in the immediate DC metro. My bar is 2". If we can get that, terrific. Wouldn't be surprised for 1-1.5" though.

2" is my bar here in central AA County. Again, I want a least a decent coating of fresh insulating snow before the deep freeze during the week. A snowpack can mitigate deep frost depths and frozen water lines, and as a homeowner, yes to this please!

Yeah, my bar for mid AA (Crofton area) is 2-3" as well. Feel like the boom around here is now more than 4", which is fine with me since I'll be shoveling it. The key however is to get at least some snow. Before we get highs in the teens and lows in the single digits (or lower), I would like at least a fresh blanket of insulating snow to mitigate deepening frost depths and the potential problems therein. Don't need any frozen pipes, thank you very much!

Quite a N-S gradient in AA County per the GFS (2-9"). More typical (climo like) that what we've seen this winter, but still, everyone in the immediate DC metro region will be on the lookout for pingers.

Fatties falling now in Crofton underneath that band.

Just a little less than 6" in Crofton MD as of 9 am. Large aggregate flakes now, so I know the pingers are near.

I can't believe I'm following two simultaneous threads about 2 significant snow events that would affect our area, all within a week. Pinch me. It would potentially be the most snow in a week over the metros since February 5-11 2010.

If that were to happen, it would be the best one week in terms of total snow accumulation for us here in Anne Arundel County since Feb 5-10 2010.

Hints of W-E banding in those 10+ inch stripes...within one band in a historically favored area (along I-70). Me thinks the disparity will be a little more in reality. As in, 7-8" vs. 10-11"+ within those bands. Good to see the latest NAM Nest depict what I think could be reality; we all just hope in our back yards we're not in between bands. Then again, that's being greedy, no?

Latest from the NWS' experimental Probabilistic Precipitation Portal (https://www.wpc.ncep.noaa.gov/Prob_Precip/). Granted, there will undoubtedly be a sharper gradient with the higher amounts, with lesser amounts on either side of the best FGEN banding, but it does look like most of the forum will get at least 6". That's what I'm hoping for -- and I'm glad to see those 6" probs went up near the M/D line (to 65-70%). 8"+ probs are 45-50% now near the M/D line (also up from previous model cycle), while IMBY here in central AA County up to around 67%. Meanwhile, 12" probs went up IMBY towards Annapolis as well (now 35-40%), no doubt given the robust 12Z high-res CAM guidance. Still thinking 7-9" as a 'mode' for a large chunk of the immediate metro region. Some areas maybe less (farther north), obviously those underneath the best bands have a better chance of hitting 10-11+ inches given the better (deeper) ascent within the dendritic growth layer. More about the membership in this ensemble, which uses the NDFD snow forecast as the 'mode' of the distribution: Welcome to the Probabilistic Precipitation Portal, a resource provided by the National Weather Service to communicate the range and probability of possible precipitation amounts over the next 72 hours (3 days). Data on this page come from the Probabilistic Quantitative Precipitation Forecast (PQPF) and the Probabilistic Winter Precipitation Forecast (PWPF), which are updated twice daily at the Weather Prediction Center. These probabilistic forecasts are derived from a blend of the following: 10 members from the NCEP GEFS ensemble 25 members from the ECMWF ensemble 10 members from the Canadian ensemble 1 member from the NCEP SREF NMMB 2 most recent runs of the NCEP HRRR model 2 most recent runs of the Canadian Regional Model 2 most recent runs of the NCEP NAM 3km CONUS Nest model 4 NCEP Hi-res WRF-ARW model runs NCEP Hi-res FV3LAM model NCEP GFS model ECMWF deterministic model NCEP GEFS ensemble mean NDFD forecast This page updates each hour, typically at 25 minutes past the hour.

32°F in Crofton MD right now, high clouds moving in. Over the years I've come to trust the ASOS/AWOS dewpoints over anything else, so I'm gonna go with the 5°F Td at both BWI and Annapolis.

Well, I thank you. There really are some excellent mets on this board, and it has been great following and keeping in touch with them and all the weather enthusiasts for well over a decade now. Heck even during the Eastern US Wx board days. Let me just add... collectively we are essentially a ML/AI model. So much experience in this room, we've seen it all, or just about, in the last couple of decades. That really helps forecasting events like this. Think the mean and mode for the immediate metro region will be 6-8", maybe 7-9". That's what the probabilistic maps are suggesting. Certainly 10-11" will be possible wherever that FGEN band sets up later Monday. Maybe along Rte 50, though probably south. Either way, some cold smoke coming, at the right perfect time of year climatically speaking. Enjoy it everyone!

Yeah the ICON is rarely part of any of our blends (especially QPF) at WPC. Verification numbers just don't justify it. Including the NAM12 outside of 48-60 hours, and the NAM Nest outside of 24-36 hours. UKMet is one that cannot be totally discounted (it did nail the Binghamton NY 40"+ snow event a few years back), but I really wish we (at NCEP) could get a hold of their ensemble suite. Obviously, the op ECMWF cannot be discounted (never can), but at least until tonight's runs, I'd still put more credence in the EC ensemble mean. I'm thinking (hoping?) the 12Z ECMWF is the 'low end' for those of us in the metro region north. Still think 6" is a good bar for DC and immediate metro. Interesting that DCA could very well make out better than BWI (how often does that happen?)

Scott -- It seems our last 3 events (both last year, and the one in 2022) were these similar W-E cutters with strong frontogenetic support. Areas along and south of the beltway seemed to do very well, especially South Anne Arundel into Calvert County and I believe (for the '22 event) even Fredericksburg. Last year we did quite well in Crofton -Bowie -- 4.1" for the first event, and another 4-5" with the second. All in one week. Our one week of winter, lol.

Lots of dark blues on the 3km NAM on TT, almost from the get-go. All that snow falls within a 4-5 hour period. Definitely some near zero to negative theta lapse rates.

00Z Euro, 10-1

Latest CPC 3-4 week progs..

Getting more clumping flakes now here in Crofton, def a sign of nearing 0C somewhere along. Oh WAA, you were good today, so it's okay if you want to mix now..

Just got done with shoveling (round 1). Just a little less than 3.5" here in Crofton, still snowing.

Very happy to work with these guys at WPC. And to you Scott and Pete: Perfect timing for 3 days off! Yeah baby!