Thursday, 02/18: The Next One

Ciao!

Another messy storm is likely to bring snow, ice and rain this Thursday into Friday morning. After today's storm departs to our north and east, High Pressure moves in and replenishes our area with fresh arctic air. Here is the 1033mb High valid for Wednesday morning.



Once we get to Thursday, a brand new low pressure system coming out of Texas (can you believe they will get ANOTHER winter storm later this week??) will move east-northeast toward our area. The reason why Texas and areas much further west than us are seeing snow is because that's where the trough axis has set-up. Anomalous cold is dropping dead center into the U.S. which allows these low pressure storms to mature in the SW CONUS. Whereas earlier this month, the trough axis was over the eastern part of this country and storms were developing a lot closer to the coastline.

Here's our new storm valid Thursday evening. Notice how - once again - the primary low pressure is 'cutting' west into Ohio. As you all know by now, when these storms cut it allows warmer air to infiltrate the boundary layers of our atmosphere and turn precipitation over from snow to ice/rain. Keep in mind however that we're under pretty cold temperatures BEFORE this happens, and we're already getting snow by this point of time. Then we see snow changeover to mix and then to rain as temperatures gradually rise as a result of this primary low cutting into OH.



What happens thereafter is a little tricky. Last night's EURO Ensembles show a secondary low pressure developing off the coast. This is called a 'transfer' which is exactly what happened with the February 1st Roidzilla. In essence, this would keep some parts of our area below freezing and not see a changeover to rain. However, the issue is at the 500mb level.



If we look at the Thursday evening time stamp again but this time at the 500mb level, you can see how heights along the east coast are rising ahead of the mid-level trough. Notice how we are on the east side of this trough, and all the PvA (upper level energy denoted by the yellows/oranges) is elongated along the eastern side of the trough. Look at how far south this trough gets. It practically is in the Gulf of Mexico. The problem is, when the upper level energy is elongated like that and not consolidated at the base of the trough, it means at the surface we're seeing early maturation of the low and a path that leads it more north than east. What's working in our favor is the High Pressure I talked about in the last image, and the fact there is a very pseudo-like 50/50 low which you can see I circled on here. The combination of HP and 50/50 low to the north is what's helping our temperatures stay colder a little longer than normal to promote wintry precipitation instead of just plain rain.



Despite a potential transfer to the coast, we're seeing too much activity happening west of here. The dynamics do not really favor our area for this one. That said, I think the front-end 'thump' of snow could be significant for some. I'm talking a nice 4-8" in spots before changing over. Some models are less bullish with the front-end thump and show very minor snowfall. As we go through this week let's keep an eye on the HP, our temperatures and trends that may involve areas N&W of NYC staying all snow, though I doubt it at this moment.

Thanks Frank! I guess I'll pin my hopes on that front end of thump...if it times out right, a front end thump can amount to a nice snowstorm experience. In that respect, good trends overnight for our area I think in expanding the scope and the amounts of the snowfall in general. Let's see how the 12z runs go...

What I see on the 12Z GFS/GFSv16 is 500 mb heights continuing to be beaten down by TPV lobe that is getting pinned by a 50/50 ish low. This allows for a good cold air pump right into the area. Is it just GFS? Nope it's all the major models. Are they full of dog poop within 3 days range? Certainly possible but to this point they haven't went in a bad direction for this. If anything the cold air holds on longer with each run as the heights are more suppressed and the High gets pinned.

Bottom line is so far so good.

This trend of a slower SE Canada vortex flattens/suppresses the height field over the E US, shifting the track of the next storm later this week SEward w/ a relatively narrower rain-snow transition zone/less ice overall as mid-upper level forcing for descent weakens. https://t.co/rkMKzj8jq8 pic.twitter.com/ntVYmcMLpc

— Eric Webb (@webberweather) February 15, 2021

The 12Z Euro squashed the 500 mb heights like a pancake. If this modelling is accurate I assure you this will be much more frozen than not. The mid-levels may eventually give way to IP, but not before a nice snowfall. Who gets what is TBD, but synoptically I like what I see.

What I was just checking is what the SE trend might mean for the change to rain along the coast, and we can see really good trends in that regard. That primary low I don't think is forecast to hit Ohio anymore. Of course, the flip side is that LHV and NEPA in particular see lower totals, but the snowfall distribution on the 12z GFS is quite equitable...lol.

Based on the trends and what all Frank and heehaw have said so far and and just taking the 12z verbatim, I'm wondering if Eastern Nassau and into Suffolk counties are  maybe the best spot to stay all snow and still get decent rates?

SENJsnowman wrote:What I was just checking is what the SE trend might mean for the change to rain along the coast, and we can see really good trends in that regard. That primary low I don't think is forecast to hit Ohio anymore. Of course, the flip side is that LHV and NEPA in particular see lower totals, but the snowfall distribution on the 12z GFS is quite equitable...lol.

Based on the trends and what all Frank and heehaw have said so far and and just taking the 12z verbatim, I'm wondering if Eastern Nassau and into Suffolk counties are  maybe the best spot to stay all snow and still get decent rates?

IMO the 500 mb trough is too far back to prevent this as all snow event for just about everyone in this forum. It's a question of how suppressed the the heights are at this point to keep the mid-level redevelopment as far east as possible. Without those heights being suppressed the 700-800 mb would just flood the area with warmth and taint the snow to IP.

I've been hearing a lot of chatter about winter being done once we reach the last week of February. Now we have a +NAM state and that probably brings AN temps for last week of February which I have no reason to doubt, but there is evidence to suggest -EPO/-AO/-NAO returns in the end of February into March. If that happens expect more chances for snow regardless of the Pacific PNA and any WAR Atlantic ridge. Actually with the blocking pattern that we've had most of the winter I'd be surprised if it didn't return.

I'm liking the Thursday storm for some decent snow at this point, even if it is limited to the "front end thump." I want to get rid of tonight and tomorrows mess before I invest too much energy in Thursday though. Let's see where the models take us tomorrow afternoon into Wednesday.

Here's your 12Z EURO - let's see if this holds - Banana HP's high over the top would make all layers of the atmosphere cold. For how long remains to be seen. Again this storm sets the stage for Thursday/Friday

18z GFS and RGEM are colder for Thursday’s storm. Starting to get interesting.

The Euro and GFS runs are both a pretty long duration event. Snow begins at daybreak Thursday, doesn't change to sleet/frz rain until Thursday evening, then sleet and freezing rain continue until late Friday morning (with many areas never going over to plain rain). That allows several inches of snow to fall throughout Thursday, then several hours of sleet and ice on top of that into Friday morning. Quite a disruptive event if it plays out this way.

nutleyblizzard wrote:18z GFS and RGEM are colder for Thursday’s storm. Starting to get interesting.

well lets hope it continues because yet again it introduces prolonged frz for 95 coordidor this time 0.1-0.3 which i would much rather have be snow. to the north looks good and we see several inches. but a quarter inch of ice after snow is not good.

When will we have a better idea of driving conditions on Friday?

EPS is colder.
Need the HP to be more west and then slide over the top which UT is showing at this time. This storm now we are eating as a cutter BUT it will help set up the Thursday Friday storm. The Banana High is going to keep the colder air in.
We'll see how this looks by 12 Z tomorrow.

Driving conditions were on Friday? NNJ could be rough for the morning hours.

wow 00z GFS and 00z NAM (out of range but very similar) gives a area wide mothrazilla with 1/4 frz along I-95. would be much better than this non-event. Though that ice if it happens could be very problematic on top of snow on trees weighing them down even more holding the snow on. Theres a whole scale on ice it incorporates total accretion and then wind speeds to determine the severity, its a kinda cool chart, wind has a big factor.

I was just watching the local Met in my area and he said that this Thursday's storm would probably be mostly snow at least in my location. I really hope so. The Ice this morning is about 1/4" thick. Really treacherous out there.

The 700 mb temperatures (about 10K feet ASL) tell the story of where this headed IMO. Every successive run of the models is showing colder 700 mb temperatures. To the point now where they stay well below freezing for the entire event. The suppressed heights are going to keep the redevelopment of the mid-level storms (700 mb/850 mb) well offshore. This means I will not be at all surprised if NW-I95 remain mostly snow for the entire event.

I guess what I'm try to say is significant snow is looking much more likely with this system. It has not taken steps in the wrong direction synoptically whatsoever.

The NAM is more aggressive in the mid level warming. It's not in its good range but it's coming around to that idea of colder mid-levels. Give it until tonight 0Z to really show this IMO. Don't pay attention to its clown snow maps if your SE of the I-95.

If you look at the 500 mb trough (how far west it is) you'd never think this could have a legit chance of being mostly snow (NW-I95), but it's that vigorous ULL (lowering heights) passing through Quebec in conjunction with 50/50 low (pinning the High) that makes it plausible. Unreal.

heehaw453 wrote:If you look at the 500 mb trough (how far west it is) you'd never think this could have a legit chance of being mostly snow (NW-I95), but it's that vigorous ULL (lowering heights) passing through Quebec in conjunction with 50/50 low (pinning the High) that makes it plausible.  Unreal.

Yup exactly.

5 consecutive runs of the GFS de amplifying heights because the ULL keeps trending slower

Aside from loving the actual substance of the discussion, I LOVE the subtle yet profound changes to the language in your scroll and thread title Frank! If I knew Italian, I'd hit you up with a nice little phrase here to show my appreciation. lol

SENJsnowman wrote:Aside from loving the actual substance of the discussion, I LOVE the subtle yet profound changes to the language in your scroll and thread title Frank!  If I knew Italian, I'd hit you up with a nice little phrase here to show my appreciation. lol

Haha

I'm still thinking NYC and south sees a front-end thump before a changeover, but now I'm thinking N&W may stay all frozen...

Frank_Wx wrote:

SENJsnowman wrote:Aside from loving the actual substance of the discussion, I LOVE the subtle yet profound changes to the language in your scroll and thread title Frank!  If I knew Italian, I'd hit you up with a nice little phrase here to show my appreciation. lol

Haha

I'm still thinking NYC and south sees a front-end thump before a changeover, but now I'm thinking N&W may stay all frozen...

so there will be a sharp cutoff at NYC or are you talking far nw of NYC. Still like to wake to nice scroll but is there any chance us coastal areas stay snow? When you say i95 for nj it goes north to south but when ur talking NY 95 goes super close to NYC in face it crosses in the Bronx I believe. So it's kinda confusing when you say NW of i95 in terms of how far.

The 12Z NAM is starting to tell the story at the 500 mb.  Basically heights are flattened and the cold push gets further south with each of its runs. The ULL above hangs around longer each run.  This probably means weaker primary low that transfers quicker and the new storm is further east.  Just indicative of a colder solution where I'm much less concerned about a fast change over.