Bob Chill

4.1" Rockville. Might top 5" before sleet. Going to be close...

No doubt in my mind. At least for my yard. 3"+ in under 3 hours is impressive with any storm around here.

3" as of 8:40 in NE Rockville. Best thump since Jan 2016.

Euro already busted

The only thing you need to worry about is the flip to sleet timing. Stop trying to extrapolate something that isn't going to happen.

You're worried about the wrong thing. Lift is oriented W-E as is the moisture flow. Look to your west and not south.

What's better than 1 MoCo deathband before 9am? Answer: 2 deathbands before 9am Should top 2" here shortly

Radar hallucinations have begun early it seems. The dynamics and lift are overhead and will remain there until well after a flip to sleet and zr. Enjoy the snow while it lasts and stop worrying about things that shouldn't be worried about in the dc/balt/burbs areas.

Straight dumping in Rockville. Close to or over 1" already.

Euro is the dryest model through 18z tomorrow. .2-.4qpf until you get west of the blue ridge.

This storm should also put us both above climo. This has been the most disastrous climo+ year in history though.

You'll like the ukie. Gfs/ukie blend is money

After double checking all the differential equations on the gfs through hr18 I've comfirmed that the 0z run is dead balls accurate.

Sub freezing at 31 now. Nice to have a multi hour stretch sub freezing before onset. Can make a big difference if rates are light at the beginning. Also, stop looking at the hrrr until precip is overhead or at least close. It uses radar data at initialization and generally does really bad or is very inconsistent when onset is still a number of hours away. Honestly, I've never found the hrrr that useful with winter storms. Globals do far better in general.

Radar looks solid but there is no way all the guidance is wrong about when meaninful precip breaks out over each of our yards. Even if onset ends up being 3 hours early or whatever it won't change the outcome for many. The good lift/frontogen is likely very well modeled. Even if onset comes early it will prob be inconsequential until things get more dynamic later overnight for you and around dawn for my yard. This will be a fun event. Sleet is more disruptive on the roads than snowfall. An inch or 2 of frozen ball bearing on the roads can wreak havoc worse than snowfall.

Storm thread was excellent. I was always catching up and wasn't watching daytime model runs until well after they ran. Enjoyed the clean/concise rundown. I applaud the sub posters and mods keeping things clean, concise, and very readable. The one thing I want to add that I don't think was discussed much last few days are ratios. Yes, we have a really nice column at onset but it changes very quickly in regards to DSG and what type of snow will be falling. This won't be pretty fluffy dendrites and even with all snow falling (prob heavy at times) it will resemble sand and oatmeal falling at times. There is a sig WAA pump going on up above 850mb. Losing 800-700mb levels while everything below is important to understand. Could be all snow but still only 8:1 (or lower) ratios. If anyone remembers Feb 2014 or March 2013 onset it will likely resemble that type of snowfall. Not pretty 10 or 12:1 stuff. More of a pounding white meteor or sand or oatmeal or whatever you want to call it. Snow will be dense and will go through a progression of worsening ratios until sleet takes over.

34 and ready for my fully stocked winter wx buffet Just to clear the air and not derail this thread... I took a break for 2 reasons. 1) was burned out and not enjoying myself at all around here and 2) have some important stuff (all good) going on in my personal life. I said I'd be back for obs and here I am. Let's do this man.

I never bought the disaster that was showing up a few days ago. All the ensembles showed the same tpv drop and drift into eastern Canada + the -nao. I've never seen that type of progression just evaporate and flip to warm in the east. It didn't make sense. All we can do now is keep fingers crossed and hope incremental improvements continue. My gut instincts are telling me we're in good shape.

Truth. Last March looks great on the composites but too little too late. It can be maddening at times. When a great longwave pattern sets up 2-3 weeks too late it feels like such a ripoff. We haven't had a legit -ao/nao combo during prime snow climo since 2011. It's been a long time to put it lightly. Maybe this year will mark the reversal of blockless winters. Time will tell. It's still Jan so we're not racing the clock...yet

Very nice trends on the ensembles showing the fabled west based -nao may move in during Feb. Looks like the Davis Strait block builds next week over top of the TPV. Unfortunatlely the tpv is really strong so it bullies the block this go around. However, I'm starting to believe it's a warning shot that it might become a stable feature down the road a little. Always very difficult to feel confident that a real -nao is going to happen until its happening but you have to like the direction the gefs, eps, and geps are going. Even the pac is showing signs of getting right. Fingers crossed for now. I'm as sick of rug pulls as anyone...

We need a -ao/nao combo for a broad conus trough. 77-78 had that iirc. It's not all that uncommon. 95-96, 09-10, and 10-11 all had periods of a -pna coinciding with a trough and winter wx in the east. It's been a while though. Not all -pna's are terrible. Having a -epo is key for cold in the east with a -pna because it deflects the pac jet poleward and away from the north american coast. The -ao/nao suppresses heights in the east so cold continental air can stretch coast to coast in the US. One of the snowiest winters on record in my region happened back in the 60s and basically had a door to door -pna. You guys in the SE probably need a +pna more than my region though. Maybe someone can look back at years where there was a -pna but good snow in your area amd figure out what other features made it work. We may not even need to worry about it as the -pna on ensemble guidance may just be transient or never materialize.

Lol- i wouldnt jump to any quick conclusions. The next 10-12 days will feature several sig below normal airmasses and flow remains active from what we can tell. The neg pna (if it happens at all) looks to coincide with a very negative epo and modestly negative AO. While guidance has backed off on a stout -nao, there is no indication of a +nao. If anything the nao looks like it will still go negative or at worst neutral. One huge difference between a bad pac in Dec and what is progged in early feb is Canada is likely going to be an icebox. As long as the -epo holds (looks very negative in the long range) there will be very cold air across all of Canada. Any intrusions into the conus with be quite cold. In Dec the pac jet blasted every last molecule of cold air off the face of the continent. There's no comparison to late Dec/early Jan from what I'm seeing. Lastly, this new twist with the PNA could end up not happening at all or be brief. We'll just have to see how it goes. In a simpleton view there are only 2 kinds of winter patterns... a shutout pattern or one that could potentially produce frozen precip. After thursday it looks like a decent pattern for some snowfall in both our regions. Not amazing but far better than what most of winter has been like. It should also feature some pretty cold air. Before we worry about d14+ we have to see if we can score before the month is out or in early Feb. Final thought... We can still score with this type of -pna. Arctic air will be abundent in our source region. High pressures will move across to the north. This can set up CAD events or gradient overrunning events. There's no way to know specifics. Let's focus on the period in front of us because the ingredients will be available for winter wx. By the time we get through the next 10 days or so there will be brand new reasons to worry in the long range. Lol

The inverse JB model has near perfect verification scores. Backtested for decades.

Here's the eps d10-15 h5 and 850 means. I don't like fishing or golf when it's cold so maybe in March or we can meet in Phoenix in Feb?

Snow is always subject to luck and chaos so you never know until you are shoveling. However, I'm very confident on an extended period of BN temps. It's going to feel like winter and it's not going to hit and run either. If anything changes I'll come back and delete all my posts here. lol