December 2011 General Disc/Obs

[WxUSAF]

Perfect December day (that doesn't have snow).

[Fozz]

Perfect December day (that doesn't have snow).

It was pretty good, but I'd rather have the high below 40.

[Avdave]

Not bad, with my north facing yard, the frost hung on all day long, looked like a dusting of snow

Already down to 25* here now

[Herb@MAWS]

On east side of Columbia, Sunday hi temp was 36 after morning low of 23, coldest yet for season.

Sunday evening 27 at 9:00pm.

Stay vigilant -- that is all.

[Ian]

Perfect December day (that doesn't have snow).

meh

[WVclimo]

First day with highs in the 30's (38) after the first morning in the teens (17.) Glad to finally see some December temperatures.

Back to 21 now. Really nice out.

[EastCoast NPZ]

First day with highs in the 30's (38) after the first morning in the teens (17.) Glad to finally see some December temperatures.

Back to 21 now. Really nice out.

19F already.

[nw baltimore wx]

oops, didnt read his q correctly. at least we got a 2 for one deal last night.. those kinda skew the stats i guess tho they might be quite few.

No problem.

7 in 2007, 1984, 1974,1972

Perhaps more compelling is the 8 in 1923, before they moved it to the airport in the river

Thanks, and yes, the 8 in 1923 is more impressive.

[snownut]

No whining here. Pleased with season IMBY.

October surprise, nice squall in November, and thick stubborn little December elevation snow.

I am in WV which helps with colder temps, but not Jon Jon high country or snow belt.

Some snow on the ground 10 days this season and all with without any bitter cold.

Web cam shot from moments ago.

[BethesdaWX]

Made it to 21.6 this morning, almost 7 degrees colder than Saturday morning, surprisingly.

[Ellinwood]

My boss likes our potential for snow Friday night into Saturday (16th-17th). Been following it's progression over the last couple of days... showing improvement as we go along, with a nice baroclinic zone and vort. max cutting through south of DC and high pressure pushing in cold air to the north. Teleconnections looking favorable around that time, reflecting the pattern we're starting to see evolve on the models.

[H2O]

My boss likes our potential for snow Friday night into Saturday (16th-17th). Been following it's progression over the last couple of days... showing improvement as we go along, with a nice baroclinic zone and vort. max cutting through south of DC and high pressure pushing in cold air to the north. Teleconnections looking favorable around that time, reflecting the pattern we're starting to see evolve on the models.

Then I hope he is right. There does seem to be a chance which is a good thing given how it has been looking from the start of Dec.

Side note: DCA 3 days of sub 32 low?

[mappy]

Did I hear snow?

[nw baltimore wx]

Then I hope he is right. There does seem to be a chance which is a good thing given how it has been looking from the start of Dec.

Side note: DCA 3 days of sub 32 low?

As Ian said, I think it's technically the 4th day because the first freeze came late on the 10th. I could be wrong though.

[NoVaWx]

My boss likes our potential for snow Friday night into Saturday (16th-17th). Been following it's progression over the last couple of days... showing improvement as we go along, with a nice baroclinic zone and vort. max cutting through south of DC and high pressure pushing in cold air to the north. Teleconnections looking favorable around that time, reflecting the pattern we're starting to see evolve on the models.

Euro looks interesting.

[H2O]

As Ian said, I think it's technically the 4th day because the first freeze came late on the 10th. I could be wrong though.

I should have said in a row. My bad. Thanks tho

[mitchnick]

23 this morning at BWI; I thought we were only forecast to go down to upper 20's

anyone have a link to old forecasts?

[TalcottWx]

Pretty awesome weather the last couple days with cold nights and mild days

[WxUSAF]

23 this morning at BWI; I thought we were only forecast to go down to upper 20's

anyone have a link to old forecasts?

That's what I remember as well. Heavy frost this morning almost looked like a dusting of snow...sigh...

Pretty awesome weather the last couple days with cold nights and mild days

Maybe these are mild days for SNE, but this is pretty typical December weather around here.

[TalcottWx]

Maybe these are mild days for SNE, but this is pretty typical December weather around here.

I'm just a cold weather person, my asthma is better in this weather and its easier for me to run... nice plus that there is also a lot less sweating!

[WxUSAF]

6z GFS Op and ensemble mean and 0z Euro Op and ensemble mean all show a pretty decent pattern developing with a +PNA and the PV displaced south toward Hudson Bay. Still looks like transient cold shots since upstream blocking is weak, but certainly more of them and colder air associated with them.

[mappy]

6z GFS Op and ensemble mean and 0z Euro Op and ensemble mean all show a pretty decent pattern developing with a +PNA and the PV displaced south toward Hudson Bay. Still looks like transient cold shots since upstream blocking is weak, but certainly more of them and colder air associated with them.

Can you explain for those of us who don't know all the details of PNA what that means? TIA

[Bob Chill]

6z GFS Op and ensemble mean and 0z Euro Op and ensemble mean all show a pretty decent pattern developing with a +PNA and the PV displaced south toward Hudson Bay. Still looks like transient cold shots since upstream blocking is weak, but certainly more of them and colder air associated with them.

Just got finished looking at the euro and 6z gfs and I agree that the pattern is better. Too bad it's just a different look of the current pattern and not a true change. Not bad though. We stand a much better chance at getting some ridging around greenland with the pv further south. I like that. And the ridge out west looks a heck of alot better.

Correct me if I'm taking out of my ass but one of the problems I've seen with the pattern is no ridging anywhere around AK. Energy keeps sliding under the ridge and closing off in the desert sw. With no block in place, every time this happens pumps up the ridge a bit and we get rain before the trailing cold front.

It wouldn't take much to fix this though.The last 2 panels of the NHEM 500 map on the euro hint at a more favorable setup in the pac. If the pv were to retrograde w just a little the heights could potentially build near greenland.

Considering how long the crappy pac and nao has been holding up I would have to hedge towards a continuance of crap but if things keep looking like this in the next couple days then I'm going to put my weenie glasses back on.

[mitchnick]

12Z NAM

now that's more like it

http://mag.ncep.noaa.gov/NCOMAGWEB/appcontroller?prevPage=Param&MainPage=indexℑ=&page=Param&cycle=12%2F13%2F2011+12UTC&rname=PRECIP+PARMS&pname=precip_ptot&pdesc=&model=NAM&area=NAMER&cat=MODEL+GUIDANCE&fcast=084&areaDesc=North+America+-+US+Canada+and+northern+Mexico&prevArea=NAMER&currKey=model&returnToModel=&imageSize=M

[mitchnick]

Just got finished looking at the euro and 6z gfs and I agree that the pattern is better. Too bad it's just a different look of the current pattern and not a true change. Not bad though. We stand a much better chance at getting some ridging around greenland with the pv further south. I like that. And the ridge out west looks a heck of alot better.

Correct me if I'm taking out of my ass but one of the problems I've seen with the pattern is no ridging anywhere around AK. Energy keeps sliding under the ridge and closing off in the desert sw. With no block in place, every time this happens pumps up the ridge a bit and we get rain before the trailing cold front.

It wouldn't take much to fix this though.The last 2 panels of the NHEM 500 map on the euro hint at a more favorable setup in the pac. If the pv were to retrograde w just a little the heights could potentially build near greenland.

Considering how long the crappy pac and nao has been holding up I would have to hedge towards a continuance of crap but if things keep looking like this in the next couple days then I'm going to put my weenie glasses back on.

this is all you need to know Bob....patience

[Bob Chill]

Can you explain for those of us who don't know all the details of PNA what that means? TIA

I think I can help with a simplistic explanation. It's a teleconnection and can be our friend when + and our enemy when -.

Quick and easy read: http://www.cpc.ncep.noaa.gov/data/teledoc/pna.shtml

Simpleton terms:

+PNA = ridge west and trough east and -PNA = opposite

When we have no blocking to our north near greenland (like right now), a +PNA is going the prominent driver of cold air and favorable track in the east. Long story short, we really need a ridge out west and a trough in the east if we even want to consider snow chances right now. If we have a -nao, we can have a trough out west and survive because the track is supressed. A -pna and -nao (aligned correctly) can pretty much put the entire country in a trough and we all get snow and cold. Without the block to the north, a -PNA almost always = seasonable to above average temps in the eastern third of the US.

Interestingly enough, the 6z gfs suggests a potential +pna and -nao. I doubt it's right but MA weenies love that combo.

[WxUSAF]

Can you explain for those of us who don't know all the details of PNA what that means? TIA

PNA = Pacific-North American

Basically just another index like the NAO or AO, but referring to whether there's ridging or troughing near the West Coast of North America. +PNA means ridging, -PNA means troughing. To get cold weather, we want a +PNA since an upstream (west) ridge means a trough over us, all things being equal.

Just got finished looking at the euro and 6z gfs and I agree that the pattern is better. Too bad it's just a different look of the current pattern and not a true change. Not bad though. We stand a much better chance at getting some ridging around greenland with the pv further south. I like that. And the ridge out west looks a heck of alot better.

Correct me if I'm taking out of my ass but one of the problems I've seen with the pattern is no ridging anywhere around AK. Energy keeps sliding under the ridge and closing off in the desert sw. With no block in place, every time this happens pumps up the ridge a bit and we get rain before the trailing cold front.

It wouldn't take much to fix this though.The last 2 panels of the NHEM 500 map on the euro hint at a more favorable setup in the pac. If the pv were to retrograde w just a little the heights could potentially build near greenland.

Considering how long the crappy pac and nao has been holding up I would have to hedge towards a continuance of crap but if things keep looking like this in the next couple days then I'm going to put my weenie glasses back on.

No, it's not a true pattern change, but it's a better look. On the downside, the models have teased us with this improving look a couple times in the last few weeks and the can keeps getting kicked down the road or the better look turns into a 2-3 day cool/cold shot and then it's back in the crapper.

From a snow perspective, energy sliding under a western ridge can be a very good thing. But, typically closed lows in the southwest don't work out well since they teleconnect to a strengthening SE ridge. We want s/w's to slip under the ridge but keep moving eastward.

6z GFS ensemble mean actually did build heights into Greenland around Day 10 but then loses it afterwards. Euro didn't show this.

I like the setup for this weekend if anything can actually happen, not for a big snow, but for something. Given we can't lock in a cold pattern, what we need is a transitory shot of cold air and then have a wave develop along the stationary front in the SE and give us some overrunning. Given the apparent lack of a potent s/w, that could never really produce a big storm, but could produce a 1-3" type event. That seems to be what a few runs were showing, but they now have anything even weaker and more surpressed.

[Bob Chill]

this is all you need to know Bob....patience

Patience?!? It's nearing mid Dec after a month+ long craptastic pattern with no tangible relief in sight. AND, I live in the MA where our winter window is the size of a cabin on a ship.

I'm probably one of the more relaxed around here but if I need more patience I should probably order some on amazon and stock up.

Eh, just kiddin. I'm not really worked up at all. We shall see what our lovely stratoshpere can whip us and send our way.

[Kmlwx]

12Z NAM

now that's more like it

http://mag.ncep.noaa...el=&imageSize=M

My reaction -

[usedtobe]

PNA = Pacific-North American

Basically just another index like the NAO or AO, but referring to whether there's ridging or troughing near the West Coast of North America. +PNA means ridging, -PNA means troughing. To get cold weather, we want a +PNA since an upstream (west) ridge means a trough over us, all things being equal.

No, it's not a true pattern change, but it's a better look. On the downside, the models have teased us with this improving look a couple times in the last few weeks and the can keeps getting kicked down the road or the better look turns into a 2-3 day cool/cold shot and then it's back in the crapper.

From a snow perspective, energy sliding under a western ridge can be a very good thing. But, typically closed lows in the southwest don't work out well since they teleconnect to a strengthening SE ridge. We want s/w's to slip under the ridge but keep moving eastward.

6z GFS ensemble mean actually did build heights into Greenland around Day 10 but then loses it afterwards. Euro didn't show this.

I like the setup for this weekend if anything can actually happen, not for a big snow, but for something. Given we can't lock in a cold pattern, what we need is a transitory shot of cold air and then have a wave develop along the stationary front in the SE and give us some overrunning. Given the apparent lack of a potent s/w, that could never really produce a big storm, but could produce a 1-3" type event. That seems to be what a few runs were showing, but they now have anything even weaker and more surpressed.

I was just about to post that when I read your post. I also don't think it a real pattern changer though ridging in AK and western Canada would certainly be an improvement.