October/November 2019 Mid/Long Range

[CAPE]

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.

 

 

 

[psuhoffman]

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 

[psuhoffman]

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.

 

 

 

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. 

[WxUSAF]

How does an ensemble mean calculate P-type?

[dallen7908]

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

 

[Bob Chill]

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

[clskinsfan]

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.

[Chris78]

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.

[midatlanticweather]

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

[psuhoffman]

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. 

[NorthArlington101]

Really weird evolution but 00z GFS gets the job done as far as first flakes go. Would be a nice way to start the season verbatim, and pretty chilly in the immediate aftermath of the snow.

[yoda]

lol Day 9/10 on the 00z CMC... if we could only get that during the winter months with a HP in place...

[jayyy]

Forecasted high of 30 on 11/13 in central md. Sheesh. Seems so pre industrial. 

[CAPE]

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

 

EPS snowfall mean improved nicely.

[midatlanticweather]

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

[CAPE]

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. 

[BristowWx]

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. 

[Rtd208]

No one should be writing anything off at this range. In a few days a different story. But anyone who winds up seeing even a light snow event on November 12th/13th is a win in my eyes.

[H2O]

The only thing we accumulate more than actual snow is mood swings

[Wonderdog]

Looks like different outcomes every 6 hours. Nice GOM lp coming up coast on 6z but cold air retreats. Cold air is pretty close though. hmmm

[showmethesnow]

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.

 

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.***  

 

 

 

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.***

 

 

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. 

 

 

 

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.

 

 

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'

 

 

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.

 

 

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. 

[psuhoffman]

@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.  

[frd]

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. 

 

[Bob Chill]

@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...

[frd]

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  

[aldie 22]

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

[WxUSAF]

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...

The cold shots that we’ve had and are about to have seem to have some strat influence, which is limiting the influence of the MJO as it’s moved through warm phases. Last winter, MJO dominated over the strat influence for most of the winter. MJO will get into the colder phases as we move into the 2nd half of the month and it also seems that the strat will continue to get beat up (see Mike Ventrice’s Twitter). So I think there still should be cold air around for much of the month. But what happens in December? Does the MJO heading back into warm phases have an influence? Does the decadal warm December trend happen? Or does the strat continue to help favor some cold air getting down into the eastern CONUS?

[Bob Chill]

30 minutes ago, WxUSAF said:

The cold shots that we’ve had and are about to have seem to have some strat influence, which is limiting the influence of the MJO as it’s moved through warm phases. Last winter, MJO dominated over the strat influence for most of the winter. MJO will get into the colder phases as we move into the 2nd half of the month and it also seems that the strat will continue to get beat up (see Mike Ventrice’s Twitter). So I think there still should be cold air around for much of the month. But what happens in December? Does the MJO heading back into warm phases have an influence? Does the decadal warm December trend happen? Or does the strat continue to help favor some cold air getting down into the eastern CONUS?

One thing we prob all suspect and agree on is a stout relaxation of the current very anomalous Nov cold is coming. I'm sure either late Nov or early Dec ends up being pretty warm for a time. Which is totally normal and happens like every single year and stuff. lol

Dec 2013 was interesting. Cold early, down right hot, and then the hammer. I don't mind December having a sig warm period but I do mind it when it's all the eye can see for 2, 3, or even 4 weeks. I really have no idea what's in store for Dec but I know what to look for. If Dec goes end up cold or at least has a decent duration period of real winter wx in the east then some of the seasonal forecasts aren't going to look so good. 

[LP08]

12z GFS has snow early Tuesday from the NS.  Front pushed through much quicker.

[psuhoffman]

1 hour 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...

That was my thoughts as reading it.  Granted he includes some factors and influences that are above my pay grade into his calculus BUT he is going with a pacific pattern that is opposite of what it is trending towards right now.  Doesn't mean it is wrong...he gives some very good reasoning as to why the current trends could be a false flag, but the bottom line is it is still a lot of guess work as to which factors and influences will be dominant absent a strong enso signal.