December and a Hint of January Pattern Discussion

[Ian]

Looks like we lose 850's and surface between 192-198. Bulk of precip is done for the most part but definitely a period of rain from FDK/JYO on eastward.

Pretty narrow stripe of snow all things considered. Should be some heartbreak later today and some joy tomorrow followed by suicides and then back to joy.

The WD index must have been assimilated into this run.

[Bob Chill]

Euro want's to push in another very impressive cold airmass d11 and beyond. -15 to -20 850'knocking on the door. What a fun start to the month.

[Bob Chill]

The WD index must have been assimilated into this run.

This one has our number. It's a lock. Book it. All in.

[Heisy]

Euro want's to push in another very impressive cold airmass d11 and beyond. -15 to -20 850'knocking on the door. What a fun start to the month.

 

It seems like a +PNA is trying to form on 10-day EURO, but there's no blocking showing up at all, so could be transient. 

[Bob Chill]

It seems like a +PNA is trying to form on 10-day EURO, but there's no blocking showing up at all, so could be transient.

No reason to doubt a continuation of variability for the foreseeable future. Euro d10 also has a closed low off the socal coast with split flow and active northern stream. It's really a great look that we haven't seen much of the last couple years. Without a block any type of phased system will likely go west but with so much cold around it keeps front end possibilities around as well. All lala speculation but I can't find any reason to hit the panic button this year.

[yoda]

I just hope that we don't lose all this potential... WD index is climbing rapidly. I would like at least one good event (like 2 to 3 inches of snow) out of this pattern. However, as we all know, each run will bring the highs and lows. And the day 10 EURO looks nice one again.. it always looks nice at Day 10

[stormtracker]

The WD index must have been assimilated into this run.

WD Index =

 

Number of months since last 5” snowstorm + (previous month warm departure)

 

0 - 14  Not Due

1-20  A little due

21 - 30 Due

30+ Due like a m***********r

[mitchnick]

WUnderground maps show snow falling when the cold front passes late Fri night in Western MD by 141 hrs. and it moves east after that, though there is no accumulation indicated along I95. So we really have 2 events to follow on this 10 day run.

I came in late and didn't see anyone mention this 1st threat specifically so if it is, never mind.

[WinterWxLuvr]

I agree with Randy. The euro, from what little I can see of it, seems to vary quite a bit run to run while the gfs stays steady on this. As Bob said, euro may trend toward gfs (which doesn't look bad at all).

Do I have a flawed memory or are the models getting cold air back in a little earlier than they were a few days ago?

[CAPE]

I agree with Randy. The euro, from what little I can see of it, seems to vary quite a bit run to run while the gfs stays steady on this. As Bob said, euro may trend toward gfs (which doesn't look bad at all).

Do I have a flawed memory or are the models getting cold air back in a little earlier than they were a few days ago?

No flaw in your memory. Was looking like after the 10th a few days ago.

[CAPE]

There's just a wall of 1040+hp all across the eastern half of Canada. Keeps the storm from cutting and we are in the win zone all things considered.

The euro is quite different @ h5 compares to the gfs. In some ways I think the euro will end up trending more towards the gfs in coming days. The gfs is much more N/S oriented with the boundary compared to the euro's more E/W orientation.

I wonder if the Euro might end up more correct with the E-W orientation, given initially the arctic air is dumping in the west, and overall lack of high pressure to our N/NE in this pattern. Would rather see the GFS be more correct here.

[CAPE]

12z GEFS implies more of a light to moderate snow scenario for N.VA, MD, DE. for the 9th.

[usedtobe]

The Euro ens mean takes the low towards the lakes like the operational did but also has a monster high to provide damming.  One caveat about the damming and snow.  The 850 temps can be below freezing and you might still get sleet or freezing rain.  Remember 1994 when the 850mb temps were around minus 8 when it started sleeting.  When we get into the time ranges when the models have a better handle on the surface, we'll need to see the temps from 850 to 700 mb for a possible warm layer.

[CAPE]

The Euro ens mean takes the low towards the lakes like the operational did but also has a monster high to provide damming.  One caveat about the damming and snow.  The 850 temps can be below freezing and you might still get sleet or freezing rain.  Remember 1994 when the 850mb temps were around minus 8 when it started sleeting.  When we get into the time ranges when the models have a better handle on the surface, we'll need to see the temps from 850 to 700 mb for a possible warm layer.

Very good point. I remember leading up to the 1994 event, when there were calls for 4-8 inches of snow, that it looked more like a sleet-fest changing to zr. And for most of the area thats exactly what ended up occurring.

[Bob Chill]

Euro ens take the whole coutry pac zonal d11-15. Kinda ironic because heights are up around gl and the pv is still in canada but we lose our delivery mech. Par for the course. Very cold stuff rebuilds in western canada. Probably some sort of repeat after relaxation. So far out there that it's not worth worrying about and much can change but pac zonal has been hinted at more than once mid-month. 

[snow.]

The Euro ens mean takes the low towards the lakes like the operational did but also has a monster high to provide damming.  One caveat about the damming and snow.  The 850 temps can be below freezing and you might still get sleet or freezing rain.  Remember 1994 when the 850mb temps were around minus 8 when it started sleeting.  When we get into the time ranges when the models have a better handle on the surface, we'll need to see the temps from 850 to 700 mb for a possible warm layer.

 

yes...which is why I am not sure the snow panel on the euro is all snow even for the western burbs

[CAPE]

Euro ens take the whole coutry pac zonal d11-15. Kinda ironic because heights are up around gl and the pv is still in canada but we lose our delivery mech. Par for the course. Very cold stuff rebuilds in western canada. Probably some sort of repeat after relaxation. So far out there that it's not worth worrying about and much can change but pac zonal has been hinted at more than once mid-month. 

Delivery mechanism has been the -EPO. Does that relax? Without that, and a strongly +AO, cant help but go zonal.

[Bob Chill]

Matt, signs of your late month block are definitely showing up. Euro ens d11-15 build a scandanavian ridge and ridge over the bering sea is pushing poleward to some extent. PV looks to get locked into canada and the +AO is gone. Even though the conus is zonal on the run these types of changes are noteworthy. 

[mitchnick]

The Euro ens mean takes the low towards the lakes like the operational did but also has a monster high to provide damming.  One caveat about the damming and snow.  The 850 temps can be below freezing and you might still get sleet or freezing rain.  Remember 1994 when the 850mb temps were around minus 8 when it started sleeting.  When we get into the time ranges when the models have a better handle on the surface, we'll need to see the temps from 850 to 700 mb for a possible warm layer.

which is why, even though some scoff at me, I like to look at the 1000-500 thickness when soundings unavailable

if it is at or below 5400, you (OK, not "you", but the average snow weenie!) can be pretty confident it's snow

[Bob Chill]

Delivery mechanism has been the -EPO. Does that relax? Without that, and a strongly +AO, cant help but go zonal.

 

The epo ridge is more westward with lower heights over the GOA. This allows the flow into the conus to flatten over the goa taking us zonal. IMO- I wouldn't jump in and say this is a new stable feature. Way too far out there to worry about. A period of zonal flow in the US is almost expected at some point this month but a long duration pattern isn't likely imo. 

 

I do find the scandanavian ridge poking towards greenland intriguing to say the least. As long as the source of our cold air doesn't go poof we will likely continue the roller coaster. 

[Amped]

The Euro ens mean takes the low towards the lakes like the operational did but also has a monster high to provide damming.  One caveat about the damming and snow.  The 850 temps can be below freezing and you might still get sleet or freezing rain.  Remember 1994 when the 850mb temps were around minus 8 when it started sleeting.  When we get into the time ranges when the models have a better handle on the surface, we'll need to see the temps from 850 to 700 mb for a possible warm layer.

You talking about the MLK day one?  That was one of my favorite freakish setups of all time. Was living in CT, Got snow to heavy rain then back to snow.   Would be interesting to see what kind of ice storm a similar setup can produce here.

[mitchnick]

The epo ridge is more westward with lower heights over the GOA. This allows the flow into the conus to flatten over the goa taking us zonal. IMO- I wouldn't jump in and say this is a new stable feature. Way too far out there to worry about. A period of zonal flow in the US is almost expected at some point this month but a long duration pattern isn't likely imo. 

 

I do find the scandanavian ridge poking towards greenland intriguing to say the least. As long as the source of our cold air doesn't go poof we will likely continue the roller coaster. 

well if it does, I'm gunna' start randomly calling up chicks in eastern Canada and asking them for a date....won't be too long before it turns frigid up there!

[PhineasC]

I'd be OK with a nice sleet and ZR storm. It has been a long time. Snow is preferable, of course.

[CAPE]

The epo ridge is more westward with lower heights over the GOA. This allows the flow into the conus to flatten over the goa taking us zonal. IMO- I wouldn't jump in and say this is a new stable feature. Way too far out there to worry about. A period of zonal flow in the US is almost expected at some point this month but a long duration pattern isn't likely imo. 

 

I do find the scandanavian ridge poking towards greenland intriguing to say the least. As long as the source of our cold air doesn't go poof we will likely continue the roller coaster. 

Some breakdown or retrogression of that ridge is inevitable. What we need is some semblance of a block setting up, as well as some weakening of the PV.

[Bob Chill]

Some breakdown or retrogression of that ridge is inevitable. What we need is some semblance of a block setting up, as well as some weakening of the PV.

 

There's a lot of spread but both the gefs and euro ens relax the -epo but at the same time move towards a more favorable ao/nao. The means on the ao are dead neutral at the end of the runs but the spread is wide. These are new developments with the ens. Looking at the previous handful of runs, the 12z suite is a large shift. Are we in for a large scale reshuffle with circulation? Who knows but signs just started emerging today and are noteworthy. Hopefully the trends remain over the next week or 2. It would really suck to lose the -epo and not get help elsewhere. 

[mitchnick]

There's a lot of spread but both the gefs and euro ens relax the -epo but at the same time move towards a more favorable ao/nao. The means on the ao are dead neutral at the end of the runs but the spread is wide. These are new developments with the ens. Looking at the previous handful of runs, the 12z suite is a large shift. Are we in for a large scale reshuffle with circulation? Who knows but signs just started emerging today and are noteworthy. Hopefully the trends remain over the next week or 2. It would really suck to lose the -epo and not get help elsewhere. 

personally, I think the changing or warming of forecasts by some based on the breakdown of the -EPO ridging come across somewhat as being made in a vacuum

if the -EPO does break down, there will have to be changes elsewhere in the NH which could also keep us from torching

[yoda]

Nice 1040+ H easing into the Northern Plains at 126 on the 18z GFS

[Amped]

Nice 1040+ H easing into the Northern Plains at 126 on the 18z GFS

Doesn't look good though. Troff is less strung out and further west. Should there be an actual decent shortwave with this we will change to rain. It may show a nice thump first.

[yoda]

Doesn't look good though. Troff is less strung out and further west. Should there be an actual decent shortwave with this we will change to rain. It may show a nice thump first.

 

I think more ice than anything else with the CAD in place... though if the s/w is strong enough it could be rain

 

As we can see at 171, decent moisture influx from the SW moving NE and CAD locked in

[Amped]

I think more ice than anything else with the CAD in place... though if the s/w is strong enough it could be rain

 

As we can see at 171, decent moisture influx from the SW moving NE and CAD locked in

 

 

We quickly go above 0c at 850. Cad still locked in judging buy the surface high.