WxUSAF

Which is kind of the point. They had a forecast. Why stop using it for that garbage? P.S. Go RPM!!

I made a long FB post today as I've been getting lots of questions from family and friends. Here it is for anyone who cares: Major winter storm for Maryland Wednesday into Thursday Snow will start late morning Wednesday from south to north across the state. It will mix with sleet, and possibly rain, for much of Maryland outside of northern Baltimore county to Frederick and points north. Sleet will eventually turn back to snow later in the evening Wednesday before tapering off early Thursday morning. The gradient between a little slush and snow to a LOT of snow is really sharp. Could be as little as ~20-30 miles in places. Picking that exact boundary is very difficult in advance. Elevation and latitude is critical. Higher elevation locations and locations farther north will get more snow, all else being equal. Numbers below include sleet, and there could be a lot of sleet in places. Howard county: 9-15" in Mt. Airy, 6-12" west Ellicott City, 4-8" Columbia, 2-5" eastern Elkridge. Harford county: 10-18" northwest, 6-12" Bel Air, 4-8" Abingdon, 3-6" Aberdeen and Havre de Grace. Baltimore city: 3-6" 495 beltway: 3-6" north side near Bethesda, 2-5" most elsewhere, 1-3" south side. DC: 2-5" north DC, 1-3" downtown.

I've been telling my kids 1-15". Feeling good about it.

WBAL had a pretty good map earlier, at least prior to any 12z/18z changes. I don't get just ripping the RPM snow map as a forecast. WJZ has this pretty terrible looking maps, but I guess 4-6" around Baltimore is reasonable.

WBAL riding RPM which says 10”+ for areas north of DC-BWI...

Not sure about that. It is progressive, particularly at range.

It’s hard to figure out when a model is just playing into its bias and when it’s on to something. NAM bias is over amplified.

Gfs has a stronger WAA onset than before with good dendritic growth. I’m right in the R/S line during the evening as depicted with an isothermal profile right at freezing below like 900mb. The snow side of that line cashes in.

I’ll apologize Wednesday evening as needed and not before

For those who forecast by ensemble snow maps...just saw the 12z Eps probability of 6”+. I think MBY has been in the 50% contour on almost every run, maybe occasionally bumping up or down one contour. And today’s run? In the 60% contour. Biggest difference is the gradient has tightened which is what almost always happens as you get closer to start time. Howard county has just under 50% to over 90% across it.

NWS forecast looks a lot like 12z euro. More N-S gradient in MD due to how much snow falls after the flip back to snow. I like the NWS map although it’s maybe a little bullish on the 12-18” area size.

Yup confirmed.

Thanks for that tidbit, that’s excellent news. Solid advisory criteria even before the flip, even for the beltway.

Spoke to @Bob Chill via email. He and his family are healthy and well. He’s been busy with work and it’s covid impacts and changes. He doesn’t expect to post anymore but may in the future. He still lurks a bit.

Nice! Still rain here. Your new house paying off!

Ha same thought. 3” of snow, 1” of sleet, and 2-3” of snow on top? All in.

I would need hourly output to see how long the mix period is. But seems like we’d probably get a few inches on the front? Then lots of sleet, then a couple inches at the end. Sign me up.

Track is west but it’s also colder. If you’re forecasting by 10:1 snow maps you’ll like the euro. 925 stays below freezing west of 95. 850 freezing gets up toward the M-D line so sleet for much of us for a time. I’d take the euro in a hot second.

Same at 54. A bit colder than 0z

CC line has wobbled back north. Probably losing some of the best lift as the storm pulls away?

CC line has jumped south so that fits.

It can be hard to interpret. Definitely helps to orient yourself with direct surface obs for reference. The CC product will be very useful Wednesday.

Snow line showing up very well on correlation coefficient radar product. Looks like the line is along Harpers Ferry-Frederick-just west of mappy's house.

The 12K NAM was replaced by the 3k NAM several years ago for a reason. The 3k is probably worth looking at starting with tomorrow's 12z run.

Repeat this week in prime climo season and it's the best week since Feb 2010 for most places. Just sayin'.