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Holidays 2017-18 Mid-Long Range Disco


WxUSAF

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Loving this CAD look/cold air source on the EPS......sprawling HP over much of N Alaska, Western Canada, extending into SE Canada BUT look at that flow around this HP......all the way directly from Siberia clockwise around HP with the NW flow extending over the globe across thru E Canada and Nova Scotia then NNE flow around that along the Piedmont. Nice! Talk about a Siberian connection.f2f7c079c3b1f84ecf00f36d31a43cff.jpg

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More tidbits for you from LWX... (bolding mine)

(snip)

Sunday will feature drier conditions for most of the day, with
skies remaining mostly cloudy and near normal temperatures. A
weak area of low pressure will approach from the west Sunday
evening accompanied by strong short wave energy, bringing the
chance for light snowfall Sunday evening, mainly across our
western zones. At the same time, but further east than previous
model cycles, low pressure will develop and strengthen off the
Mid Atlantic coast, rapidly moving northeastward. Because of the
further eastward track and faster motion, this system looks to
be moisture limited with minor accumulations possible along the
Allegheny Front, western Maryland, and the Blue Ridge
mountains, while a mix of rain/snow showers will be possible
east of these locations
. For those traveling this holiday
weekend, continue to monitor our latest forecast for any
changes.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Arctic high pressure will build over the region Mon through Wed
night. Daytime temperatures will be a good 10F to as much as 15F
colder than normal under this Arctic high. Attention then turns to
potential coastal low during the second half of next week with a
large area of precip overrunning Arctic air with a significant
snow threat especially for the big cities along the I-95 corridor.
Global model trends past 24 hrs have shown a more developed
system along the coast raising confidence on potentially
significant wintry precip giving strong cold air damming signature
supported by strong 1040+ mb high over Quebec. Trends in the
ECMWF/EPS have also shown faster/earlier coastal development with
sig wintry precip developing over the area by 12Z Fri.

(snip)

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On 12/21/2017 at 6:26 AM, showmethesnow said:

****Just saw the 06z GFS. WOW!!! Tell you what, if my thoughts below are wrong I sure hope they are wrong in this direction. 30+ inches (12" plus a whole bunch of ice), would take that in a heartbeat. And here I was trying to bolster peoples moral. Guess the GFS already did that.  :) ***

_________________________________

Been following the models for the last couple of days but have been so busy I really haven't had time to post. Anyway I thought I would get my thoughts out there while I had a chance.

*Now remember 'I am a half glass full' sort of guy so take that into account when reading.*

Now as far as everything in general. I stick by my statement from last week that this stretch we are heading into has the potential to rival some of the better stretches of cold and snow we have seen in recent memory. But as we all know by now timing and luck play a big part for snow in our region so keep that in mind. Now what I am seeing is an actively moving pv located in a favorable location in Canada for our local, a mean trough that we are continuously on the base or front side of, cross polar flow continuously pumping cold into central and eastern US, an active southern jet not to mention what looks to be 3 jets running through the CONUS at most times, and an active pattern with energy flowing everywhere (all three jets and around the pv itself) from Christmas through the end of the runs. To make it even sweeter it looks as if this general overall pattern I mentioned above will extend beyond the end of the runs, probably by a good bit, as everything for the most part looks very stable. Now barring a major breakdown of the models, I could probably put good money on us doing well over the coming several weeks and feel very comfortable with that bet.

As far as Christmas. Except for the fact the cold is coming in quicker we are seeing pretty much what I had expected and somewhat hoped for. And I still would not be surprised if the cold is delayed somewhat from what is currently depicted. Thought the odds of snow (besides some flurries or snow showers) were of low odds because of the progressive nature of the cold and the issues with timing low development to coincide with the cold push. The cold is somewhat muted and we are not seeing the deep southward push into the central part of the country from runs several days ago. We are also seeing the cold pushing in from the northwest vs. previous runs of from the west. These are all good things because it means we will not have the cold overwhelming everything and actually sets up any potential boundary in a much more favorable SW to NE tilt for the days following Christmas.

Now as far as the period following Christmas. I am starting to have high hopes for the period from late Wed/Thursday through the weekend. Not going into the nitty gritty but from what I have been seeing from the models suggest we may be possibly looking at a one, two punch. For late Wed/Thursday I would not be surprised in the coming days that the models start keying on a possible storm running from the mid-west and underneath us (there is a possibility that it could be somewhat suppressed). This storm, if it exists, would have a capped upside for our region (2-4 type deal?) because of its progressive nature but the ramifications for the weekend would possibly be huge. At this point everyone has been keying on a possible event over the weekend. Models have been showing just about every solution available (not sure I really buy the solutions showing the huge ridging developing in the central potion of the country nor the northward push into the Mid-west by the low). Now at this point I look at the models and to me they suggest any storm during this time frame would probably be somewhat suppressed. This is where our potential Thur. storm comes into play. At this point the setup shows a suppressive flat flow heading off the east coast even though we see the pv and surface lows located just west of the 50/50 region which would typically back up flow. But in this case the PV is elongated in nature which does nothing to back up the flow. But insert the possible Thursday storm into the equation and what we see is the pv lobe out south and west to accommodate this low moving through the 50/50. This would create backing which would in turn mean that the weekend storm instead of being suppressed and heading out sea would now probably run up the coast from the deep south with tropical jet moisture embedded within it. A possible big ticket item.

Now I will mention that the above scenario actually has some support within the ensembles which have an uptick through the Wed/Thur time period and a much more substantial uptick for the weekend. At this point I am not going to parse through the individual members but would not be surprised if some of better looking members have some version of this playing out. 

 

 

Wanted to revisit the bolded in a post I made yesterday. Though I really don't like to key on the Euro op at range I thought both yesterday's 12Z and the overnight run made a move towards my thoughts on how this could possibly play out.

Below we have yesterdays overnight run (Dec 21) of the Euro op. Ignore to the west and just focus on the PV and the flow around it. All lows in the 50/50 region are not created equal and this is a pretty good example. What we see at 500 mb is a long elongated pv. Follow the flow around that feature and you see that it is basically flat with no buckling. This means that we are seeing very little in the way of the flow backing. This is really not a good look for a potential coastal storm. One other thing, notice that there is a Low x'ed out off the coast. We see no low develop in the previous day or two before this time frame.

5a3ce3650667e_500mbDec21.gif.57f82c3725174773449aab7eb73b3890.gif

Now below is the overnight run of the op. Again focus on the PV and the flow. Notice the pv is rounded and is lobing out to the east. Now notice the flow is not flat like the previous example but instead has a rounded look. This look will create some backing of the flow. The response of this backing is we now see the beginnings of ridging between the pv and the trough dropping down through the central part of the country. Now also notice the low. Unlike the previous example we see a low the previous day or two form off the coast and move up into the 50/50 region. This low is what is causing the improved pv look. Now this look is a much better look for a possible coastal and in fact we do see a somewhat decent storm pop up. But it isn't quite there yet for a big ticket item. One other ingredient may come into play. As that pv reinforcing low is forming and then moving up the coast we are also seeing energy streaming underneath us. At this point it is late to the party with very little in the way of a short wave reflection. But I think as we near in time on the models that feature will start showing a distinct shortwave where we start seeing a strip of snow (1-2", 2-4" type deal) running from the lower Midwest through or underneath our region. And the models have hinted at this on and off to boot. Now the one other thing we want to see is there actually be some interaction between this energy running underneath us and the pv reinforcing low. Whether through a slower developing low or a quicker solution with the energy. We see this and what we have is a stronger low running up into the 50/50 region and the response from the pv would turn what is a good look now into an excellent look as we would see even better backing of flow. I will show you what I mean below.

 

5a3ce573944b3_500mbDec22.thumb.gif.708bf32103e3175651fb0fd3b0c20831.gif

Now this is the setup  from the overnight run as we have the storm off the coast. I am not sure how many are aware, but this setup just misses a big ticket storm. The trough is excellent, with the negative tilt and a closed low about to run through our region. But the timing is just off as our coastal is already making an exit to our north. We see the trough finally catch up to the low up around New England where it bombs the pressures out. Now this is where a stronger pv reinforcing low (wed/Thur) comes into play. You inject an even stronger low northward and what will result is a stronger more rounded pv with all likelihood of lobeing out even farther south and east. What this would do is back up the flow even more where we see the ridging marked below even more pronounced. This improvement with the ridge would have a major impact in regards to the coastal low and the trough dropping down behind it. It would slow the coastal down drawing it closer to the coast and give a deeper and sharper drop to the trough giving it the ability to capture the low much quicker in the process. So in a nutshell we would hopefully see a low track closer to the coast from our south, quicker intensification and/or bombing out and a track up the coast more NNW as opposed to NNE. 

 

5a3ce59666b8c_Stormsetup2.gif.454772d40cd4bdca89a4d3969a471179.gif

 

 

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IMO as showme has indicated with his posts, it seems to me that this storm will totally depend on the PV moving into a 50/50 location and how it sets up.  that will tell if its an apps runner that gets too far N before transfer or gets to TN before jumping to the coast.  Models have bee all over the place wrt SE ridge and SW trof so next 7 days will continue to see shifts.  

I always get tainted in most big storms so my goal is to limit how long i stay there.  

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5 minutes ago, H2O said:

IMO as showme has indicated with his posts, it seems to me that this storm will totally depend on the PV moving into a 50/50 location and how it sets up.  that will tell if its an apps runner that gets too far N before transfer or gets to TN before jumping to the coast.  Models have bee all over the place wrt SE ridge and SW trof so next 7 days will continue to see shifts.  

I always get tainted in most big storms so my goal is to limit how long i stay there.  

For whatever it's worth I am not buying into the models attempts for the far northward intrusion of the low and warmth to our west. At this time I am leaning towards very little movement northward of the primary before we see a transfer off the SE coast (N Car/S Car).

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6 minutes ago, showmethesnow said:

For whatever it's worth I am not buying into the models attempts for the far northward intrusion of the low and warmth to our west. At this time I am leaning towards very little movement northward of the primary before we see a transfer off the SE coast (N Car/S Car).

I'm not buying anything atm.  If you do a trend back on the GFS there isn't any consistency other than taking a big SE ridge and western trough and slowly flipping it.  but that pattern repeats itself if you keep going back.  Its hard to know how it will be in 3/4 days to know if we will see the E ridge/W trough pop again only to beat it back down the closer things come in.

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6 hours ago, SteveVa said:

DT needs some lessons in coherent writing, his twitter feed looks like it's been written by a 10 year old with extensive weather knowledge. 

DT is dyslexic, so please by all means continue to make fun of someone with a reading/writing disability. 

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27 minutes ago, H2O said:

IMO as showme has indicated with his posts, it seems to me that this storm will totally depend on the PV moving into a 50/50 location and how it sets up.  that will tell if its an apps runner that gets too far N before transfer or gets to TN before jumping to the coast.  Models have bee all over the place wrt SE ridge and SW trof so next 7 days will continue to see shifts.  

I always get tainted in most big storms so my goal is to limit how long i stay there.  

pffft you love the taint

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42 minutes ago, Jebman said:

There is, I would venture to say, some slight interest in this pattern the next 2-3 weeks.

Yeah, just a little bit....

Glad see things looking consistently better out west with the ridging (well until the end of the runs)...but there's lots to chat about before that.  

Trend for something sizable continues to grow.

 

 

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