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October/November 2019 Mid/Long Range

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7 minutes ago, WinterWxLuvr said:

From my limited resources it sure looks like the 18z gfs end members are really trying to blow this thing up and cut it right over us or to our west. Doesn’t look like a lot of good snow chances in there.

It is an odd looking evolution, and one I highly doubt ends up being ground truth reality. Seems to have an initial wave along the front, then develops low pressure somewhere along the coast, so snow NW of the metros then rain changing to snow SE, but mostly rain in between.

1573635600-BCcuXonGVq0.png

 

 

 

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7 minutes ago, osfan24 said:

Looking forward to when we can begin NAM extrapolations!

Why not now?  All you have to do is extrapolate it 6 hours....about 14 times 

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3 minutes ago, C.A.P.E. said:

It is an odd looking evolution, and one I highly doubt ends up being ground truth reality. Seems to have an initial wave along the front, then develops low pressure somewhere along the coast, so snow NW of the metros then rain changing to snow SE, but mostly rain in between.

1573635600-BCcuXonGVq0.png

 

 

 

Yea at this moment the models are favoring a split with one wave riding to our nw and one se. yea I know all the typical snow hole jokes but I am not sweating that exact placement being correct from this range. If that type evolution is right then if they are off a bit in either direction we get snow. And the whole evolution might change also. 

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16 minutes ago, psuhoffman said:

Yea at this moment the models are favoring a split with one wave riding to our nw and one se. yea I know all the typical snow hole jokes but I am not sweating that exact placement being correct from this range. If that type evolution is right then if they are off a bit in either direction we get snow. And the whole evolution might change also. 

We've had quite a few of these types of deals over the last 4 winters. There are numerous threads started with d5 waves in a progressive pattern that ended up being no event at all. Lol

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1 hour ago, WinterWxLuvr said:

This looks like waves riding a frontal boundary to me. I could be wrong as I profess no expertise. If that’s the case we would seem to be depending on that front getting far enough south of us but not too far. Depending on the models to not overdo how far south it gets is a problem it would seem as that seems to be consistently over done. Timing of the waves with the boundary in the right place would then come into play.

it could work out great I suppose but not sure I’d hang a hat on this one even if it were later in the season.

I would think it ends up the way we usually get our first flakes out here and that is with the frontal passage itself. Still time to work out the timing details on the waves though.

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38 minutes ago, dallen7908 said:

EPS College Park thru Nov 17

0" 12/51

<1" 16/51

1" 7/51

2" 10/51

3" 3/51

4" 1/51

5" 2/51

 

I think having almost 1/3rd of the members giving atleast 1" is very impressive for the first half of November. It really shows what a winter like pattern we are in.

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We are hearing them all. The caveats, the take it to the bank on a model going bonkers, the sign me up, bus gassing, talks. We live and die by each run. Pattern is progressive, just hoping we get the stall and waves right. I want a 2013/2014 type set up and it just keeps working..but, as usual, too far out. I like the idea of flakes. I would not be surprised to be in the hole of the split. I don't know what is going to happen. Just fun having it all on our plates early. Hopefully we score some snow.. Hopefully this is the start of anther epic season. But we gotta be patient. No help in this post, but happy to see the gang back

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2 hours ago, Bob Chill said:

We've had quite a few of these types of deals over the last 4 winters. There are numerous threads started with d5 waves in a progressive pattern that ended up being no event at all. Lol

Oh I am not confident we get snow. Just confident we won’t fail exactly how the guidance shows right now. 

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13 minutes ago, midatlanticweather said:

I think Lucy picked up the football on the 6z run of gfs. 

I'll give the Euro another run or 2 to really raise expectations with a region wide warning event before crushing everyone's dreams. 

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35 minutes ago, midatlanticweather said:

I think Lucy picked up the football on the 6z run of gfs. 

Ugh.  Still 1st flakes don’t seem impossible now.  Good enough I suppose. 

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1 hour ago, C.A.P.E. said:

0z Euro got it done. A 2-4" deal for the region.

1573689600-O0m8VS6t5NI.png

 

EPS snowfall mean improved nicely.

1573732800-6DX4nswm3QQ.png

I'll take the mean imby:whistle:. If you compare the Euro run from 24 hrs ago its gotten much more progressive which is probably good for our snow chances.  Maby it lessons the boom potential but increases likelyhood of flakes to a few inches . Still oodles of time with this of course. 

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As some have noted the overall look and evolution with our system next Tue/Wed has changed from possible coastal development to more a glorified frontal passage. And here is why we are basically seeing these differences.

Now for those who read my post over the weekend I had noted that what we were seeing was interaction between the PV and NS energy in western Canada which was driving a deep drop of the upper latitude trough southward into the US. We were seeing PAC energy riding underneath unmolested and in front of this trough. It was actually a pretty good setup for possible southern/coastal low development. But what we are now seeing is that there is a partial interaction with the NS energy with PAC energy in the NW. What this is doing is twofold. First it is siphoning off energy from the NS which is weakening its interaction with the pv energy. Thus we are not seeing as vigorous solution between the two (shallower drop of the upper latitude trough). Second the interaction between some of the NS energy and the PAC energy is now creating lower latitude troughing into the SW. So now what we have is a flatter and more progressive flow running in front of these systems. Not a good look for possible coastal development.

euro117500vort.thumb.gif.562076cb3565fea86cabf5441b2ac468.gif

 

Now some may cringe when we start talking seeing snow from a frontal passage, me included. After all those that have followed weather in this region for a few years know how well that normally works out for us with the cold chasing the moisture. Normally not so well. But as depicted now on the Euro it actually is a pretty decent setup. Note the 'As depicted now' though. 

I will run you through some things to show you what I mean. Below we have the 700mb heights and vortice map shortly after precip has begun. Now what I want you to note is where we are seeing the energy situated. This is where we are seeing lift. Also take note of the where we are seeing the 700mb trough setting up. Now lets look at what we are seeing at 500 mbs.

***Just an aside but notice that the 700 mb trough is strongly positive at this stage. Shows the progressive nature of the flow at this point that pretty much shuts off our chances for coastal development.***  

 

euro138hr700vort.thumb.gif.23f132ff89d4a1a18ecf928c240a3ec8.gif

 

 

Quite often with a frontal passage we will see the lift at 500s displace slightly to the west of the lift seen at 700mbs. But this isn't so much the case here. What we are seeing is a pretty decent displacement to the west at 500mbs. 

***Again note the strongly positive tilt of the trough. A very progressive look.***

 

euro138hr500vort.thumb.gif.0f65ab97b0859fade88e22f9be56e99c.gif

 

Now you may be asking yourselves why the displacement of the 700 and 500mb vorticity/lift matters. The diagram below shows why. On the first image we have the general profile of what we generally see at mid levels when it comes lift during a cold front (less displacement between the different levels). As you can see the precip associated with lift shuts off quickly just as the cold air at lower levels starts to enter the picture. We all have seen this, where it rains and rains while we wait for the cold air to bleed in only to watch a couple of water logged flakes plop to the ground just before everything shuts down. Now the second pic shows what we are seeing on the EPS now. This further displacement westward at 500s is allowing the moisture transport to drive deeper into the cold air giving us a much longer period of snow. 

 

moisturetransport.gif.6bec8f5be741c7cfe665ce3ef8e27857.gif

 

 

Now the above diagram (second pic) can be seen when it comes to the cold air. This is the 850's shortly after precip has started to fall. Notice that the 850s have already cleared the metros and we still have a fairly long duration of precip to follow.

euro850.thumb.gif.b321837f7d4f19238065c37736fcfeb3.gif

 

 

Quite often times we get the 850's and yet the surface temps are slow to respond. This doesn't look to be the case here. We are seeing a sharp frontal passage on the surface as well as we see 10-14 degree drops in 3 hours putting us quickly into the low/mid 30's'

 

eurosurfacetemps.thumb.gif.9498de97d5d5f4c18892072f992cd262.gif

 

Some have probably noted on the Euro snow map above that the heavier axis of snow is located to the south. Why we are seeing this is that we have a heavier slug of moisture feeding northward from the deep south/gulf just in time to catch up and enhance the snowfall in southern MD/N Va. This moisture is actually driven northward by the lower latitude trough initiated by the PAC/NS energy from the very first map above.

 

euromoisture.thumb.gif.f92ef49328da7aeefb0edf3c1a8a5d44.gif

 

Now the above is a winning scenario in my mind for seeing our first accumulating snow region wide. But will this general look last until game time? Maybe, maybe not. If I were to place money I would probably put it on us seeing further changes. There is a lot of energy streaming through the PAC and NS flows not to mention the energy flowing around the pv. And this doesn't even bring into account all the energy at different levels. It is a very active pattern and to think the models are handling these parcels of energy correctly is probably asking too much. 

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@showmethesnow

We had a somewhat similar type wave in November 1995 put down a nice early season snowfall across the region.  This looks to have an even colder air-mass to work with than that one did. 

ETA:  on a side not though... while I think this setup has potential to put down some anomalous snowfall somewhere south of typical for this time of year... the specifics of where and how much are likely not to be resolved until late.  This is a somewhat similar setup to many of the progressive waves along the thermal boundary we saw in 2013/14 and 2014/15 and if we think back on that period while it was awesome, a lot of times the "threats" at day 7 turned into nothing and the actual snow we saw wasn't even on the radar until inside 72 hours.  

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Looking like maybe we do not lose the trough in the East later in the month.

I like the signal for the Kara Sea ridge 

Also, the consider the MJO as well for later in the month and then continuation  of the progression would lead to a warm up in early December. 

 

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@frd

That JMA height plot implies favorable conditions to continue pushing the pdo positive. Iso's winter forecast is extremely well thought out and articulated but imho the potential trouble spot is his -pdo influence/forecast. We'll know in a month or 2...

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2 minutes ago, Bob Chill said:

@frd

That JMA height plot implies favorable conditions to continue pushing the pdo positive. Iso's winter forecast is extremely well thought out and articulated but imho the potential trouble spot is his -pdo influence/forecast. We'll know in a month or 2...

I liked your post but then I got it ....... so here you go  :lol:

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17 minutes ago, Bob Chill said:

@frd

That JMA height plot implies favorable conditions to continue pushing the pdo positive. Iso's winter forecast is extremely well thought out and articulated but imho the potential trouble spot is his -pdo influence/forecast. We'll know in a month or 2...

Imho we will know in about 3-4 months for sure

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