January Pattern and Storm Discussion

[strongwxnc]

Yup.. Just what I was thinking about also

Thanks, great read and just to get it out of the way now...

First note that this winter storm was preceded by a few mild days with temperatures reaching the 50s and 60s on January 24th and 25th and again on January 28th when max temperatures reached the upper 50s to lower 60s across central North Carolina. During this warm period the 0.1m (4 inch) soil temperatures reached the mid 40s to around 50 during the late afternoon hours. The amount of diurnal and spatial variability in the data is impressive with diurnal spreads of nearly 10 degrees F during the sunny milder days.

Past experience has shown that when max soil temperatures during the day preceding a snow fall are in the lower 40s or colder and given modest snow rates with surface temperatures at or near freezing, the snow can be expected to accumulate. Max soil temperatures in most of central North Carolina were in the lower to mid 40s with the mid 40 temperatures confined to the southern Coastal Plain (GOLD) and location near the South Carolina border (HAML and LILE).

[griteater]

Funny all the talk of positive tilt trough/suppression/dry/meat grinder sheared waves...timing and supply of the cold air with the short waves rolling through the Great Lakes in the northern stream has and will continue to be the bigger concern IMO.

[griteater]

I'll ask this and anyone can answer, but why would there be more IP/ZR than snow with this type of setup? I would expect that more out of a Miller B-type setup. I'm guessing that the cold air dome being wedged down is modeled pretty shallow?

In a setup with warm air advection in the low levels overriding cold air to the north, you need a huge supply of cold air to keep it cold enough for all/mostly snow (examples - Jan 1988, Jan 2011). The other way to get all/mostly snow is typically with a closed 850mb low tracking to your south, and with the 500mb vort max also tracking to your south (example - Feb 2004)...this prevents the warm nose and keeps the mid levels cold.

[Cold Rain]

In a setup with warm air advection in the low levels overriding cold air to the north, you need a huge supply of cold air to keep it cold enough for all/mostly snow (examples - Jan 1988, Jan 2011). The other way to get all/mostly snow is typically with a closed 850mb low tracking to your south, and with the 500mb vort max also tracking to your south...this prevents the warm nose and keeps the mid levels cold.

Got it. Thanks man. I wasn't able to look at the models when I posted earlier and was speculating that the cold might not be deep enough on the GFS.

All that makes sense.

[Cold Rain]

Funny all the talk of positive tilt trough/suppression/dry/meat grinder sheared waves...timing and supply of the cold air with the short waves rolling through the Great Lakes in the northern stream has and will continue to be the bigger concern IMO.

I agree. That has always been my biggest concern...having a good high to the north. I feel/felt like the system would be there. As long as those highs keep showing up/trending stronger, I'm very optimistic about this one.

[packbacker]

Several amped up members...

http://www.meteo.psu.edu/ewall/ENSPRS_12z/f132.html

[BrierCreekWx]

I'm definitely feeling a lot better about the trends this morning, and I hope I eat crow on what I said previously! FWIW, the 12z GFS looks like it would have probably been all snow just to the north of RDU for most of the event, before ending as a little IP/FZRA. As we've all noted, the cold air is there just to our north so if we can just get it delivered like the morning runs are showing we're going to be in business considering the wetter trends of the ensembles.

[packbacker]

In a setup with warm air advection in the low levels overriding cold air to the north, you need a huge supply of cold air to keep it cold enough for all/mostly snow (examples - Jan 1988, Jan 2011). The other way to get all/mostly snow is typically with a closed 850mb low tracking to your south, and with the 500mb vort max also tracking to your south (example - Feb 2004)...this prevents the warm nose and keeps the mid levels cold.

I see yours and BrierCreeks point, the amped up ones are problematic for our area, the OP run was almost perfect.

[packbacker]

I'm definitely feeling a lot better about the trends this morning, and I hope I eat crow on what I said previously! FWIW, the 12z GFS looks like it would have probably been all snow for most of the event, before ending as a little IP/FZRA. As we've all noted, the cold air is there just to our north so if we can just get it delivered like the morning runs are showing we're going to be in business considering the wetter trends of the ensembles.

You convinced me now, looking at the amped up ones are warm, although its hard to see on the PSU site.

[BrierCreekWx]

You convinced me now, looking at the amped up ones are warm, although its hard to see on the PSU site.

Well hopefully this will continue to trend colder so we can withstand a little more WAA, the trends are definitely in our favor this morning.

[WhiteoutWX]

Let's see what the euro shows. This is its most accurate timeframe usually so it would be nice to have it on board before getting too excited.

[buckeyefan1]

The 12z gfs says CAE stays rain with temps at 40 dropping to 35, and it puts down 1.70 of much needed drought busting rains. I'll take that

[burgertime]

On the SFC Euro doesn't look too different from the GFS out to 90. Temps are alittle colder for my area. We'll see where she goes.

[burgertime]

@96 low looks to be brewing just off of Houston in the GOM. Temps slightly colder than GFS.

[BrierCreekWx]

The evolution at H5 is kind of a mess and I don't think the 12z GFS has it correct. The main take home from this run for me is that we likely have a decent/major precipitation event coming while the parent high in the favored CAD region is trending stronger, and the cold air source is very cold.

[HKY_WX]

looks like the models are trending stronger w/ the northern vort. at 96hrs's it is very strong on the euro and diving pretty far south. if that phases w/ the stj, it would probably produce a big cutoff over the tennsee valley. that would be more of a snow solution.

[burgertime]

@108 our low is kind of a weak mess...it's got that crazy look with a bunch of ULL out west.

[burgertime]

@114 it's gaining strength in LA and looks to be heading for us

[Marion_NC_WX]

I'm not seeing any good parent high pressure systems on the Euro...that's the biggest difference I see between it and the GFS.

[burgertime]

@120 temps are coming down in NC with the low off the panhandle of FL and moisture heading towards NC.

[BrierCreekWx]

looks like the models are trending stronger w/ the northern vort. at 96hrs's it is very strong on the euro and diving pretty far south. if that phases w/ the stj, it would probably produce a big cutoff over the tennsee valley. that would be more of a snow solution.

I'm seeing that also. Looks like the 12z GFS still squashes the southern stream wave instead of phasing it, and then it all just gets kind of wonky. I agree though, if we see phasing with this setup, we're probably looking at a significant snowstorm.

[HKY_WX]

Euro is close to a bomb on this run. Almost a full phase into a cutoff solution.

[Tacoma]

how far north does the precip get. are any trends to the north? looks possibly the nc va border.

[packbacker]

I'm not seeing any good parent high pressure systems on the Euro...that's the biggest difference I see between it and the GFS.

Yeah, we need the 1030 high to slide east, it also appears to be a little vort by the lakes. This is actually cold chasing rain.

[burgertime]

This run of the Euro isn't going to cut it looks like for anyone outside of the mountains @126 moisture is moving in with 850 line along the VA border and SFC temps and sfc freezing line around PA.

[HKY_WX]

I'm seeing that also. Looks like the 12z GFS still squashes the southern stream wave instead of phasing it, and then it all just gets kind of wonky. I agree though, if we see phasing with this setup, we're probably looking at a significant snowstorm.

This soultion makes sense too given the +PNA and 50/50 low. It favors more of a northern stream system digging. With so much activity in the STJ, there is likely to be a phase. This a huge step towards a major SECS.

[BullCityWx]

It's so hard to say what the euro is saying without the full sounding. Does such a thing exist?

[Poimen]

120 EURO 850 temps...also noticed that the EURO tracks LP through the Lakes which delays/prohibits HP from building into NY like the GFS

[burgertime]

Euro has nothing frozen for anyone outside of the mountains but all and all it followed the GFS compared to 00z's run.

[Jon]

Euro is close to a bomb on this run. Almost a full phase into a cutoff solution.

Where are you getting your vort maps? Just wondering... I'm guessing that's what you're looking at here