I think most of us are starving for a winter storm and have been scouring various sources for any information that might lend support to the notion that this weekend may bring a wintry event to the metro region. Monday's 18z GFS run was a tease as it had a near perfect scenario and track for a widespread moderate to heavy snow event for virtually our entire region. Unfortunately, that scenario lasted all of 6 hours until the 00z run came out and started a succession of northward shifts of the midwest low, running it well to the northwest of us to the Great Lakes and Canada. The last gfs run, today's 18z, shifted the low track slightly further east, but still well west of us. While there will be a reinforcing shot of cold air on Saturday, if Sunday's track stays west of here, southeast winds will erode the cold air for most of us before any significant precip can occur. The models do have a  secondary forming on the coast, but the 18z GFS has the coastal developing off Boston, too far north to be of any help here. Under the latest GFS run, IMO most of us would see some kind of frozen precip at the onset, but with a quick change to rain. It is only Wednesday, and a number of posters on the board today correctly indicated there's still time for the model tracks to shift to something more favorable, not to mention that we're not even within the NAM's range for Sunday yet. Not looking great right now but, as many posted today, too early to shut it down.

Thanks for summing that up robbbs, indeed it is too early to tell but we should have a some what better handle of this storm by Friday evening/night with many I presume pulling an all-night-er watching the models..  :smile:

haha not me ill be in baltimore all weekend for the army/navy game


go army beat navy!  :biggrin:

Great summary Sat!  I think you got everything  :laugh:
Now can someone please give us some good news about this weekend storm?

Good summary, Robbs. Let's keep our fingers crossed.

Great summary Robbbs. Outlines the scenario quite nicely.

I would agree that it's not yet time to write the storm off; however, there's more bad than good in terms of the overall synoptic-scale set-up. Three main aspects of this pattern through Day 7 are unfavorable: 1) Placement of the Polar Vortex, 2) No 50-50 low near Newfoundland, 3) Lack of a neg NAO block in the north atlantic.

The strength of the late week clipper is, IMO, our only hope for widespread snow this far south. If the system can intensify enough to temporarily raise heights over SE Canada, forcing the polar front further south, thereby resulting in a storm track further south -- then there's a chance for some winter weather. Current depictions on virtually all guidance, including the NAM, aren't too pretty. Yes, the NAM is a bit better but not much.

I'm going to attempt to break this down in visual format - with my hideous drawings. Below is the 18z GFS 500mb depiction for Sunday:

[img width=600 height=419]http://i7.tinypic.com/6s8m9hl.jpg[/img]

Things to note:

1) Lack of blocking near greenland, in fact, the NAO is solidly positive with a powerful low to the east of Canada. What this means is any high pressure over SE Canada is going to have a difficult time holding its ground as there's nothing downstream to block its movement. If a BLOCK was in place near greenland, that HP in southern Canada would have NOWHERE to go, thereby preventing a low cutting thru the Great lakes. However, we don't have that.

2) Polar vortex position is in SW Canada, thus a SWLY upper flow across the Mid-west. Not favorable for east coast snow -- it teleconnects to ridging over the southeast US as one can see on the map posted above.

3) Trough is negatively tilted in the Mid-west already - bad sign. We want a neg tilted trough on the east coast as that promotes cyclogenesis/bombogenesis. However, seeing this in the center of the country is often a precursor to rains along the coastal plain.

Hopefully this helps as to why it's not a good set up right now.

I'm not saying it can't change -- as the 18z GFS is a bit south. Our only shot is my first point from above -- we NEED a STRONG CLIPPPER, to pull down the cold air and force a more southern track, or we're done.

good writeup

this stom is basically done for now for us a few flakes to rain

i hope not  >:(

Where's your Christmas spirit snowfreak? Miracles are possible.  :biggrin:


Would be foolish to write something off 5 days in advance, even if it doesn't look too great now.

after what i just saw on the nam maybe im speaking to soon am i rite?

This storm looks like even as fat west as buffalo might have rain...

so without a block, that means that the storm could easily be carried up into Canada, correct?

sorry - as "far" west as buffalo
has anyone seen more of an easterly - southerly tract?

00z NAM is a good bit cooler than the GFS. If extrapolated, it would probably be a good front-end dump of snow/ice, especially for inland areas. Notice the NAM is more bullish on the late week clipper thus a colder foundation for the precip. Not to mention a 1036MB high in a perfect position. I'm fairly confident some parts of New England will get hammered with this system (snow/ice). It's a question of how far southeast.

Brett,

Yes, and that's what the GFS, Euro, UKMET are depicting at this time. However, the NAM is sensing a stronger late week clipper, which would allow a colder airmass into the Northeast prior to the arrival of the storm. We don't need a -NAO for snowstorms in the NE, that's one of the reasons why I haven't written this off. High pressure placement is good - only improvements I'd like to see is a Polar vortex further east in Canada (would aid in forcing the low south).

All in all I think this is far from resolved.

oh boy do i hate that PV lol :wacko:

EDIT: just checked the 00z and seems like its a whole 10-20miles east lets keep the trend lol

nick gregory - 10:05am "is there snow in store for this weekend?"  total sell job to get us to come back - snow sells and this is why when the mets call for rain - take it... if there was a sniff of a big snow they would shout it from the rooftops and all the bread and milk would be gone

Great job! Even I get it now. :biggrin: I do have a question. Where and what causes this SE ridge we always hear about? Is it that big H near south Fl

992MB low in the west already on the gfs :ohmy:

Storm,

The Dec 3rd 2003 blizzard was a rainy lake cutter 3 days before the event on just about every model.

i remember that storm,we got hit hard on the east coast with snow

i dont remeber but did we see snow then atleast?lol

Thanks for that boost of hope about 2003 storm.  I am probably just wishing that it was true but I still think that there is hope.  I have a gut feeling that the models may start holding on to that cold air and that we may see a trend toward a more southern route for the storm.  We have seen some models waffling back towards that trend.  Perhaps not the 00Z gfs, but the 18Z did show a bit more of a southern trend.  Okay I admit it I am wishcasting LOL.  If we actually see outside the window that the clipper is not bringing in too much cold air by Friday night then I will give up, but until then I am holding out for a miracle.  :biggrin:

Thanks for the write-ups Robbbs & Storm - NICE JOB!!!

I am holding on to little hope that this weekends storm turns into a decent winter event where I live in Central Jersey...

It looks to be like until the NAO goes negative we need a miracle to get a good snow storm in our area.  What are the chances of this happening any time soon.  From all the threads I've read - sounds like December and March are the months we stands a prayers chance at some good winter weather.  Not for nothing but by time March rolls around, I am ready for spring - especially in a warm/snowless winter that I would just like  to forget.

Unless there is an enormous shift in the models, the weekend event is an inland runner, which never bodes well for a snow event in our area, especially along the coast. This is shaping up to be a snow to sleet to rain scenario. A bit of a wild card is that an arctic air mass will settle in to our region by Saturday. This may keep the cold in place somewhat longer than usual before the change-over. For now, the most likely outcome IMO is snow to start for most/all of our area, then a fairly fast change to rain along the coast, gradually working north and inland with a change to rain there as well.

Are there any signs of NAO going negative later in December?

The signals are still for a shift to a mild pattern on/about mid December. I haven't seen much about the NAO but that's an element that's always difficult to forecast in advance.

I think one thing some of us are not taking into account is how early in the season it still is. Especially at the coast, you need almost a perfect scenerio to get accumulating snow at this time of year. The ocean is just to warm.

Robbbs,

6Z GFS shows a very cold map and an active east coast storm track at mid month. Yesterday's Euro was showing blowtorch possibilities though. Clearly models are having a very hard time deciphering this La Nina pattern at this point in the season..

Weatherbowl,

You are 100% right but a few days back that perfect scenario was being played out. The features of the map then, and even now showed a 50-50 low, an arctic airmass in Quebec and a clipper (fairly strong at that time) headed SE looking like it would pull the PV east and shoot the cold deep into the east. All this was happening just as a storm emerged in the SW. That is a perfect lead in recipe and those 3 features are what made everyone get excited about snow. If you had a neg Nao the storm would almost certainly have stayed well south and would have been either a major east cooast threat in a perfect set-up scenario or the PV would have overwhelmed it and suppressed it far south and out to sea. The latter is what happens in seasons where places like Norfolk get snow before places like us and the catskills. Thinking back didn't Myrtle Beach and Wilmington NC see snow about this time a year ago - well before us or the catskills ever saw it.

The problem is many (myself included) read that map anf forgot that we are in strong La Nina mode. The stronger La Nina is the more likely you'll get lake cutter storms even in lead-in set-ups that look great for the east coast. They all die off and are constantly reforming SE but usually the damage is done for us as the last reformation is often east or NE of Boston. If this La nina plays out in normal fashion this will be a great year for the midwest and far northern New England (mainly central and northern Maine) as that latter area sits far enough north to take advantage of the re-developing storms.

Are we in what is actually considered a strong La Nina or is it still moderate?

Last time I checked two weeks ago we were on the low end of a moderate La Nina. We have not been above that level since this La Nina started and some believe it may have peaked or leveled off already.

Thanks Robbbs!

So than what is all the talk of a strong La Nina that I am reading about lately?

noaa,weather channel and nws all  lowered my temps on sunday,its now 35 in bk for the high

I still don't think this is game-set-match, at least for inland areas. NAM depicts a weaker primary storm - if extrapolated would transfer energy to a secondary low near Long Island. Although the track of the storm is west of us - which doesn't bode well for all snow - this can still be a significant snow changing to sleet and ice event for the interior Northeast. We've got a low running directly into a fresh 1036mb Canadian high positioned over SE Canada. Without the upstream -NAO block, the hope for wintry precip lies in the extent of the polar airmass prior to the arrival of precipitation. That HP is going to knock the heck out of the primary low, to the point where folks Boston-Albany northward may see decent snows/ice out of it.

Coast looks like mainly rain, snow/sleet at the onset -- right now -- however, I haven't ruled out the possibility of a shift south in later runs. Keep in mind we're out at 80-84 hours on the NAM -- the time frame to watch is once we get within 48-50 hours of the storm. Mesoscale models may begin to detect a more intense low-level cold airmass, thereby increasing the probability of a snow/ice event, particularly inland. Still some bugs to be ironed out with this one folks.

Upon closer examination of the NAM 700mb charts -- it actually depicts an energy transfer to a secondary low SE of the Jersey Shore. I believe this is a trend towards holding the low-level cold in place longer for all areas. Soundings shouldn't be looked at this far in advance - but just FYI - sussex is all frozen through 84 hours.

[img width=600 height=450]http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/nam/18/images/nam_700_084s.gif[/img]

It's funny Storm. We knew the Canadian map features never supported some of the GFS maps two days ago and now finally there's some shift south and with quicker coastal development. If we had only had a neg nao.

Ice, you're telling me.

If we had a neg NAO this would've easily been an all snow event for NYC, probably Philly and Baltimore too. Whereas in this case, we're hoping for a last-minute transfer as the primary low is cutting through the Lakes.

What concerns me most about this storm is that I may be driving back from Brookville Pa. on Sunday.  That would be over 200 miles on route 80, not exactly fun if it is snowing.

This looks like central and northern New England's snowstorm. Weathergeek & Nittany should do quite well in Lyndonville VT with this one.

hey robbbs, how should high point do?  Mostly Snow?

Probably snow to mix to rain even there. Most likely a mess before the change-over.

I think so also but the 18Z GFS is awfully warm and real late with the coastal.

That same GFS at 144 hours is looking interesting with a potent clipper that is far south. We'll see how that one plays out. The 12Z run was horrendous for us from start to finish.

Bullseye for downeast Maine thru Augusta. Bangor probably gets walloped. Central New England and upstate NY somewhat screwed by the energy transfer. It happens with all transfer systems somewhere. Look at that precip in the pac NW!

http://www.nco.ncep.noaa.gov/pmb/nwprod/an...fs_p60_120l.gif

nam and gfs is different

ice that clipper at 144hr upton says that looks to be a quick hit of snow and rain. so far this early part of winter seems like its going to be one of those years were its cold and dry then warms up just enough for rain for the city on east then gets cold behind it again.

We'll just have to watch it on the Caribou cam. :smile:

Caribou may be too far north for the real big stuff - at least per this GFS run. Find some Bangor, Ellsworth, Bar Harbor, Augusta and maybe Portland cams.

This first storm is so typical La Nina that it's scary already.

That's the case in early-mid December even in good conditions. I'd like to say it's early, give it time but a La nina pattern is like a cancer to winter the further out you go. We're going to need a break and a reasonably long neg nao for us to get a month of straight winter weather this year.

The clipper is 2-5" of all snow on that run.