December Mid/Long Range Discussion

[clskinsfan]

7 minutes ago, Eskimo Joe said:

Look at the sharp west coast ridge though. It counteracts the Alaska low temporarily and the ridge crests over Idaho as the trough goes negative over Missouri.

Honestly it looks like a pretty similar setup next week to me. We just dont have any energy on the southern stream.

[Roger Smith]

Applying some research into energy peaks and feeding that into projected patterns, it looks like GFS is on track for first ten days, so I will just comment past that interval. 

Large energy peak Dec 11-12 is already showing up on model runs and I believe the depiction today is about how this one plays out, a coastal secondary acting a bit like an Apps runner and so 40s to low 50s, windy and turning very cold afterwards (briefly), 1-3" snow potential for higher portions of region west and north. 

A more moderate energy peak around Dec 18-20 would likely be a Colorado to Ohio to Vermont storm track, so could produce some warm advection snows in e PA and n md. In a best case scenario, blocking begins to establish to north and forces this one to redevelop around Delmarva, then it could be a 4-6 inch snowfall event. For now I will go with low 40s, rain in I-95 corridor and mixed precip north.

A better chance for a winter storm exists in period Dec 25-27 for a more classic nor'easter and as this is a very large energy peak, it could be a significant storm. If blocking fails to develop by then it would more likely be a cutter. But if there is going to be one big storm in December, I would say Dec 25-26 (26-27 timing more for New England). 

This approximately seven-day energy peak cycle will probably maintain into January and I look for very large amplitude upper patterns that could produce all sorts of anomalous conditions across eastern NA. February may return to more of a classic coastal storm track and I am more optimistic about Feb than Jan. A key transitional period will be around Jan 24-25. If a blockbuster Feb is on tap, signs of its arrival will be either a fast change from mild to cold around those dates, or the onset of a storm track similar to Jan 30 to early Feb 2010. 

I believe it will be a very active winter and not very similar to last winter, or 2015-16 in terms of only two wintry events of note. From snowfall contest I can see this is a fairly widespread viewpoint. 

[Stormchaserchuck1]

1 hour ago, psuhoffman said:

I lowered the criteria to 3" at BWI in order to get a larger sample size.  These are all Nov/Dec 3" snows in Nino years since 1957. 

That's not that far off what we have going for Dec 5-6.. northern Greenland ridging going into the Arctic circle.. check. main problem is that -PNA tries to take over the GOA/+pna trough too soon, It becomes an Aleutian island ridge when the trough is hitting the east coast. better chances earlier, it's weird that the earlier wave goes negative so far west. 

[stormy]

1 hour ago, psuhoffman said:

This is a composite of every 8" snowstorm at BWI in a Nino year since 1957-58.  There were 20 such storms.  As you pointed out... the trough in the north Pac is there on the mean, and there on almost every one of those storms in the set.  Most of those storms are January to March but a few were in December.  

Thanks PSU, this composite graphic gives great support to my earlier posted preference to a Cincinnati/ Nashville trough axis.

[WesternFringe]

2 hours ago, stormtracker said:

I’m a bit worried about the 850 line at Day 27 tho. Warm nose?

Exactly.  What are the verification scores for the Euro weeklies on temps 1-4 weeks out? How about those DJF temp maps?  I honestly don’t know, but I would be surprised if they were high.

1 hour ago, Weather Will said:

I have been watching the weeklies every day because I look for trends.  The trends are delaying the sustained cold until late December.  Could something pop up in a sea of warm.  Sure!  But that is not going to get picked up outside a couple days at best.  

What sea of warm?  Last I saw, all these long range temp predictions were saying about an average December, which is cold enough to snow where I live at least.  Forecast has 7 of the first 13 nights of December below freezing here.

[ldub23]

The first step to getting winter to take  up camp in the east  is for  California to dry up like a  prune, opposite  of  last  year. Lets hope this  is the  pattern now-Feb

 

[frd]

Still thinking late month has potential.

 

 

 

 

 

 

 

 

[poolz1]

3 hours ago, WxUSAF said:

“usually” what happens is that all those features (NPac trough and western ridge) are west of those positions leading into the storm and then they roll east with the big storm. 

And is why we usually drip drip drip a few days after a big storm.  Just like the h5 post from PSU yesterday about the mid-nov storm in 87.  The plot was the day(s) of the storm.  But leading into that storm had a great pattern....the day of not so much.

Early in the winter season so far but the varying pattern makes me thing we shouldn't be surprised about a surprise.

 

[CAPE]

Somewhat disparate looks between the latest run of the GEFS and GEPS in the AO/NAO space at D15. Probably in part related to uncertainty with the MJO progression. Can still see hints of an h5 ridge building towards GL on the GEFS. Anyway, go Canada!

[brooklynwx99]

2 hours ago, CAPE said:

Somewhat disparate looks between the latest run of the GEFS and GEPS in the AO/NAO space at D15. Probably in part related to uncertainty with the MJO progression. Can still see hints of an h5 ridge building towards GL on the GEFS. Anyway, go Canada!

that Scandi ridging on the GEFS is nice, could be a precursor to a -NAO event especially given SPV weakening. the EPS is similar in that regard

[CAPE]

0z Euro with the clipper action. Verbatim an inch or 2 for the northern tier and flakes in the air for many.

[jayyy]

0z Euro with the clipper action. Verbatim an inch or 2 for the northern tier and flakes in the air for many.

Hoping for a nice little 1-2” event up this way if it does materialize. Elevation will be key

[CAPE]

Euro has a distinct sharp shortwave embedded in the flow with the trough neutral/slightly negative. GFS has the shortwave, but the trough is positively tilted as it approaches the coast. Results in some nice upslope snow for the western ridge then pops a low well off the coast as the trough goes neutral. Mostly dry for the rest of the region with downslope flow. GEM similar to the GFS.

[yoda]

Morning AFD from LWX sounds good re Sunday on for some snow 

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Showers seem likely Sunday-Sunday evening as heights fall across the
region ahead of a negatively-tilted s/w trough moving across the OH
River Valley and the northern mid-Atlantic and sfc low pressure
develops overhead. Colder air begins to filter in Sunday night as NW
flow strengthens as low pressure deepens offshore. Snow showers late
Sunday night into Monday may accumulate several inches of snow
across the higher terrain before shortwave ridging builds in briefly
on Tuesday.

A second shortwave trough diving from the Central Plains into the OH
River Valley Tue into Wed will reinforce the trough pattern across
the East bringing temperatures back to slightly cooler than normal
and a second and more significant round of snow showers/squalls
across the Appalachian region Wednesday. This could also bring the
first measurable snow, albeit light to locations east of the
mountains. Conditions should begin to improve Wed night and the
second half of next week as trough axis shifts east.

&&

[yoda]

06z GFS has a big storm in distance (Dec 12)... wasn't too far off from being good for us

[nj2va]

1 hour ago, yoda said:

06z GFS has a big storm in distance (Dec 12)... wasn't too far off from being good for us

300 hours so lots will change yadda yadda but nice to see fantasy land chances. I don’t even think we saw many of those last year. 

[Weather Will]

MJO gets toward 7 by the 14th...  hopefully laying the foundation for a more favorable pattern as we head toward the holidays.

[CAPE]

The general look in the LR as the longwave pattern reshuffles features a TPV lobe dropping down towards Hudson Bay and the EPO going negative. This would pretty quickly replenish cold air in western/central Canada.  Also continuing to see indications of a ridge building into Greenland from Scandinavia.

[Ralph Wiggum]

37 minutes ago, CAPE said:

The general look in the LR as the longwave pattern reshuffles features a TPV lobe dropping down towards Hudson Bay and the EPO going negative. This would pretty quickly replenish cold air in western/central Canada.  Also continuing to see indications of a ridge building into Greenland from Scandinavia.

The trof N of the Hawaiian Islands is a nice feature that had been lacking in recent years. Hints of an Aleutian low showing up. 

[frd]

43 minutes ago, Weather Will said:

MJO gets toward 7 by the 14th...  hopefully laying the foundation for a more favorable pattern as we head toward the holidays.

Amplitude might be trender higher in recent MJO forecasts. Late month continues to look interesting. 

[CAPE]

1 minute ago, Ralph Wiggum said:

The trof N of the Hawaiian Islands is a nice feature that had been lacking in recent years. Hints of an Aleutian low showing up. 

Yeah roll that look forward a few days and we might just have a pretty favorable pattern with some chances for the last 10 days of the month.

[WxUSAF]

1 hour ago, Weather Will said:

MJO gets toward 7 by the 14th...  hopefully laying the foundation for a more favorable pattern as we head toward the holidays.

 

57 minutes ago, CAPE said:

The general look in the LR as the longwave pattern reshuffles features a TPV lobe dropping down towards Hudson Bay and the EPO going negative. This would pretty quickly replenish cold air in western/central Canada.  Also continuing to see indications of a ridge building into Greenland from Scandinavia.

 

17 minutes ago, frd said:

Amplitude might be trender higher in recent MJO forecasts. Late month continues to look interesting. 

This is all connected of course. Models always bias MJO waves to dissipate too quickly. Moving through 7-8-1-2 from mid-December to early January with the cold air on our side of the globe and a very weak strat PV is an enticing combination. And throw in a Nino STJ.

[NorthArlington101]

GFS again coming in with a medium range opportunity early Wednesday morning. Looks kinda like the EURO Something trackable at a reasonable timeframe. Let’s do it.

[mattie g]

Just now, NorthArlington101 said:

GFS coming in with a medium range opportunity early Wednesday morning. Something trackable at a reasonable timeframe. Let’s do it.

I was about to post this. Trough digs nicely and is trying to get that low under us. If temps can cooperate, we might be onto something.

[NorthArlington101]

GFS again coming in with a medium range opportunity early Wednesday morning. Looks kinda like the EURO Something trackable at a reasonable timeframe. Let’s do it.

Lol, it’s a sweet run. Very close to a solid storm.

[ldub23]

[stormtracker]

lol.  Well, it's something to look at.   But keep in mind, the H5 map has been changing with every run.  12" for Charles County.  100% believable.  

Shut up stormtracker. 

[WxUSAF]

Icon is a slightly weaker version of the GFS. GGEM trough stays too progressive and positively tilted, maybe show showers for some.

[TSSN+]

Screw it. Lock it in. Let’s get the party started already. 

[Stormchaserchuck1]

2m temps are approaching +6c in DC. It might be hard to get accumulations south of 40N.