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February Mid/Long Range Discussion


George BM

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2 minutes ago, Bob Chill said:

There's a number of euro ens members that get decent precip in here before 18z sunday. Not a bad run honestly considering the setup. Much better than what the 12z gfs/gefs had. 

I'm not done all the numbers yet, might finish tonight, but from what I've seen getting at least some transient nao or ao blocking help at some point might be our best hope to score a respectable event in a Nina. I know duh kind of statement. But it's nice to see some hints of blocking showing up. 

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It is nice to have the Euro on my side for once this winter. It has completely shut me out so far this winter (and been right). Even the GFS isnt horrible out here in all honesty. It would be nice to have a little bit stronger HP and in a better position. But we still dont know all of the details at this point.

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45 minutes ago, psuhoffman said:

There have been examples where a storm just races up in a setup like this and the cooling from heavy precip can hold off the warming just enough...it thumps before the warm air can win. It's rare but I think the first 1987 storm was a unicorn dream example of that. It actually is the rare setup where we might have an advantage over NYC in something like that being south and west. They almost always lose with the fetch off the ocean in these. 

It  had a low over the Great Lakes but also had a strong negative NAO so it was a much different animal. 

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19 hours ago, BristowWx said:

You know we are on that line.  Where we stare at the porch light waiting for that change over.  You know what I mean.

Ha Ha, that sure brings back great memories. But I would stare at the street light where I lived. Plus I would note temperature drops hoping for a changeover. Seemed like there were more of those years ago.

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6 minutes ago, Wonderdog said:

Ha Ha, that sure brings back great memories. But I would stare at the street light where I lived. Plus I would note temperature drops hoping for a changeover. Seemed like there were more of those years ago.

I will be doing that on Sunday..but the other way waiting for it to change to rain...and then wanting to jump off the roof...and cursing the CMC for giving me hope.  Its not easy being a weenie

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On 1/30/2018 at 2:19 PM, usedtobe said:

Lol, or not.  It's a pattern where most events will have issues.  For example the Sunday/Monday issue could easily slip to out south or have the northern stream amplify enough to warm us too much for snow.  This isn't a pattern where you get the old 50 50 low to help lock in the cold air.  All DC systems can fail but those with no negative NAO or 50 50 low fail more often and this is a pattern where it is hard to get a 50 50 low.    That doesn't preclude us getting 2-4 inch or even greater snow but makes it harder.  I'm not overly excited about the next couple of threats which means one of them is probably a lock to come in.

Not sure I said any of that was on the horizon. I've become something of a realist when it comes to winter over time. Or maybe I always was since I used to watch you guys fail repeatedly from a snowy perch up north.  

That said the models since yesterday are a good reminder the time ahead has got its issues. I'd still feel fairly confident we will come out of this stretch with more than we had going in, etc etc. 

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20 minutes ago, Yeoman said:

Does it align with the Farmers Almanac?

In terms of the Sun/Mon storm? Both hinted at a coastal...but the Old Farmer's said "Periods of rain and snow north, rain south" (seems to be going that way, unfortunately...), the regular Farmer's said "Noreaster", lol So they both nailed the fact that there would be a storm, but it looks like only one will be right about what kind!

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1 minute ago, Cobalt said:

If it makes you feel any better the GEFS is better for that time period. Maybe it wins like it won during the potential Christmas torch? We'll see.

yea im not that worried...plus it does contradict the euro weeklies

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4 hours ago, psuhoffman said:

I am starting to remind myself about the NAO thing.  I did some prelim data digging back in the fall for nina winters and snow and I saw a HUGE correlation with monthly snow and NAO.  I kind of allowed myself to "forget" that and look at other ways to win once the NAO became a lost cause again.  But the thing about those EPO snow analogs is I don't think many of them are nina's.  So perhaps using "this is how to snow with a -epo/+nao pattern doesn't work with a nina.  I have been collecting data to either confirm or refute the hypothesis and will post when I have time to finish the analysis.  

A while ago I had looked into winter climo (snowfall) with the following 8 regimes (w/o even considering the epo):

La Niña with predominantly +NAO, -PNA

La Niña with predominantly +NAO, +PNA

La Niña with predominantly -NAO, -PNA

La Niña with predominantly -NAO, +PNA

 

El Niño with predominantly +NAO, -PNA

El Niño with predominantly +NAO, +PNA

El Niño with predominantly -NAO, -PNA

El Niño with predominantly -NAO, +PNA

Needless to say, when you break up climo by these sub-categories, you quickly realize the variability among that 17-ish inch annual snowfall mean for DCA. The data clearly showed that we obviously do best with the +PNA/-NAO combo ("duh!"), but especially when both are tied with an El Niño. 

La Niña coupled with a largely -PNA (protuberant SE ridge) and a +NAO fared worse in terms of snowfall. No surprise there...and no surprise that the El Niño, with +PNA, -NAO and La Niña with -PNA, +NAO represented the "goal posts" with average annual highest and lowest seasonal snowfall respectfully.

What's interesting is the seasonal totals with everything in between. La Niña Winters are okay so long as we get some blocking (-NAO)...which we had in 2013-14. La Niñas with a predominant +NAO tend to give us the dreaded "cold/dry and warm/wet" patterns in the absence of blocking. Generally speaking, +PNA will be more prevalent in La Niña Winters, but not always. Thus for thoroughness, it's best to compartmentalize into the 8 categories. 

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The biggest take away with regards to timing and the strength of the surface low on Sunday/Monday is the timing of the southern stream wave and the interaction with the northern vort as it moves past the Mississippi Valley. The GFS has been hanging back the southern stream piece with the Euro more progressive with the ejection of the piece in the same time frame. The Euro has the upper level disturbance on 12z Sunday rolling through the Lower Mississippi Valley while the GFS still has the disturbance running across Eastern Texas. Because of the Euro being a bit more progressive with the southern wave, there's a bit more stream separation and the diffluent flow out ahead of the southern piece allows for moisture to stream into the region quicker, leading to more time to work with the antecedent airmass before the inevitable flip to rain for many. GFS on the other hand hangs back the disturbance, which allows for more stream interaction early on, creating a stronger low and a better WAA regime into the region, scowerring out the cold quickly, leaving the area void of much wintry precip. If the southern wave can take on a more progressive approach and limit the stream interaction early, we could see a better WAA snowfall before the northern stream catches the southern wave and amps the surface reflection enough to generate a better southerly component to the wind field, and torching out our mid-levels. I think the chance for this to stay all snow is unlikely for the 95 crew and areas located to the west out to Rt 15. There's an outside shot this could stay snow out to 81, or at least stay a mix for most of the storm, but with a developing low, it would be very tough without any pressing high to the north. Will want to keep an eye on that southern stream system on the coming runs. Progressive like the Euro is good and what we want. 

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@MillvilleWx

Great post dude. The super simpleton way to look at it is we have an eroding antecedent airmass to work with and thats it unless something changes (very doubtful). However, there are ways to maximize. Most importantly is to get precip going asap. That alone can prolong the column for snow. I've written off any chance at all snow for my yard. Now I'm focused on how I can maximize before a flip. I have a hunch the gfs will speed things up like the euro. Hopefully all ops can agree on a period of snow over the next 2 days and lock in on it 

We haven't seen many short term trends go the slower/amped direction. I don't think Sunday will be any different in that regard. 

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1 hour ago, Ji said:

LOL...this was the time period we were ALL looking forward too

Well hopefully its wrong, but yeah thats exactly the timeframe when the pattern was supposed to be getting good. Time to readjust maybe. We need a real -AO and a at least some weak ridging in the NAO domain. Maybe these features will magically appear lol.

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1 minute ago, Bob Chill said:

@MillvilleWx

Great post dude. The super simpleton way to look at it is we have an eroding antecedent airmass to work with and thats it unless something changes (very doubtful). However, there are ways to maximize. Most importantly is to get precip going asap. That alone can prolong the column for snow. I've written off any chance at all snow for my yard. Now I'm focused on how I can maximize before a flip. I have a hunch the gfs will speed things up like the euro. Hopefully all ops can agree on a period of snow over the next 2 days and lock in on it 

We haven't seen many short term trends go the slower/amped direction. I don't think Sunday will be any different in that regard. 

do you know the ETA of the snow (or precip) sunday?  would be cool to see flakes flying during the SB.

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2 minutes ago, Bob Chill said:

@MillvilleWx

Great post dude. The super simpleton way to look at it is we have an eroding antecedent airmass to work with and thats it unless something changes (very doubtful). However, there are ways to maximize. Most importantly is to get precip going asap. That alone can prolong the column for snow. I've written off any chance at all snow for my yard. Now I'm focused on how I can maximize before a flip. I have a hunch the gfs will speed things up like the euro. Hopefully all ops can agree on a period of snow over the next 2 days and lock in on it 

We haven't seen many short term trends go the slower/amped direction. I don't think Sunday will be any different in that regard. 

But we haven't seen many southern stream systems either

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