January Medium/Long Range Discussion

[Chris78]

1 minute ago, Bob Chill said:

Flash freeze verbatim. lol. Lows in the single digits as the storm departs. Might not be a pretty snowstorm or big icestorm but still disruptive on the euro. 

ETA: lows below zero... lol. I'll take the over

Is the backend snow plausible or unrealistic like backend snow normally is lol.

[Amped]

I can't look at that euro 168 500 map and not laugh. 

[Scarlet Pimpernel]

6 minutes ago, DCTeacherman said:

Euro has us dropping from 55 to 25 in 6 hours Sunday afternoon...talk about a cold front. 

Probably overly extreme, I'm sure.  But wow, that would be unreal and I'd have to imagine that comes in on a blast of wind.  The fastest temperature drop I experienced was the 1978 blizzard in Ohio, 30 degrees in two hours (mid 40s to mid teens)...along with 70+ MPH gusts.

[ryanconway63]

Anybody else taken a look at the Jan 24th time frame for a storm....I've been watching the 24th/25th for a few days now and I think there are ingredients on the table for a decent threat.   Thoughts??

[AfewUniversesBelowNormal]

21 minutes ago, JakkelWx said:

Yikes

 

The trends are correlating exactly with snowcover/melt. 

[Casualbrain]

21 minutes ago, JakkelWx said:

Yikes

Looking like an epic ice storm in the Apps....

 

[Sparky]

21 minutes ago, DCTeacherman said:

Euro has us dropping from 55 to 25 in 6 hours Sunday afternoon...talk about a cold front. 

Hopefully like that Feb '15 cold front.

[Ji]

wow another cutter on the euro at 240...what kind of pattern change is this?

[SomeguyfromTakomaPark]

17 minutes ago, WxUSAF said:

How much snow on the backend for the euro?

It has northern burbs 4-6, DC 6-8, and south and east 8-10, all in 6 hours. 

[yoda]

2 minutes ago, DCTeacherman said:

It has northern burbs 4-6, DC 6-8, and south and east 8-10, all in 6 hours. 

I don't see that on WB?

[Scarlet Pimpernel]

Just now, DCTeacherman said:

It has northern burbs 4-6, DC 6-8, and south and east 8-10, all in 6 hours. 

Thanks for the info.  Probably not likely at this point, but man that would be cool at the same time a flash freeze is going on!

[SomeguyfromTakomaPark]

Just now, yoda said:

I don't see that on WB?

It’s on stormvista, could be a messed up snow algorithm with the changeover. 

[midatlanticweather]

5 minutes ago, Sparky said:

Hopefully like that Feb '15 cold front.

That was a wild one! I was in Fairfax and drove through the front with the blinding snow home - warm when I git in the car, freezing on the other side in about 40 mins.

[Eskimo Joe]

5 minutes ago, DCTeacherman said:

It has northern burbs 4-6, DC 6-8, and south and east 8-10, all in 6 hours. 

That changeover and snow amount would rival Jan 27, 2011.  Paste bomb in about 9 hours that crippled DC and Baltimore. 

[yoda]

7 minutes ago, DCTeacherman said:

It’s on stormvista, could be a messed up snow algorithm with the changeover. 

I would guess so... DCA barely gets an inch of snow the entire run on WB... so someone's is wrong lol

[Scarlet Pimpernel]

1 minute ago, Eskimo Joe said:

That changeover and snow amount would rival Jan 27, 2011.  Paste bomb in about 9 hours that crippled DC and Baltimore. 

That storm was more like 8" in about 5 hours (where I'm at), but yeah it was pretty incredible!

[NorthArlington101]

Just now, yoda said:

I would guess so... DCA barely gets an inch if snow the entire run on WB... so someone's is wrong lol

for whatever reason it shows up better on this map.

[Bob Chill]

10 minutes ago, Ji said:

wow another cutter on the euro at 240...what kind of pattern change is this?

MJO dude. It's over. 

[paulythegun]

ECMWF holds onto the snow pack for the fall-line and areas NW through the arrival of Saturday's storm. One thing we don't get often in this area is snow on snow so it'll be interesting to see how that impacts the initial CAD front end event as well as the ultimate trajectory of the low. 

There have been quite a few studies on the southern edge of snow cover extent influencing the placement of the baroclinic zone:  Here's one:

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.688.9620&rep=rep1&type=pdf

Quote

"Large-scale modeling studies have hinted that areas near the edge of the snow extent support enhanced baroclinicity due to differences in surface albedo and moisture fluxes. In this study, we investigated the relationship between snow cover extent and MLC trajectories across North America using objectively analyzed mid-latitude storm trajectories and snow cover extent from the North American Regional Reanalysis (NARR) for 1979 to 2010. We developed a high-resolution MLC database from sealevel pressure minima that are tracked through subsequent three hour time steps and we developed a simple algorithm that identified the southern edge of the snow cover extent. We find a robust enhanced frequency of MLCs in a region 50-350 km south of the snow cover extent"

The extent to which models can deal with marginal snowpack is unknown to me. I do know that ECMWF currently has a bias toward holding on to snowpack too long...see here:

https://confluence.ecmwf.int/display/FCST/Known+IFS+forecasting+issues

 

[yoda]

3 minutes ago, NorthArlington101 said:

for whatever reason it shows up better on this map.

I mean this shows it too... 32 and 35 degree lines are in the far SE corner of the map

[Bob Chill]

12 minutes ago, Ji said:

wow another cutter on the euro at 240...what kind of pattern change is this?

It actually fits last night's ens run very well. D10:

 

D10 Op:

 

D15 EPS:

 

Everything is going as advertised. Cutters and west tracks will continue until the WAR becomes a -NAO. 

[Ralph Wiggum]

14 minutes ago, Ji said:

wow another cutter on the euro at 240...what kind of pattern change is this?

But these cutters are setting the stage for the real pattern change coming in Feb. Delayed but not denied.  Besides the ens and weeklies say hold tight and we know even with agreement that those are never wrong. 

[Bob Chill]

@yoda

Euro op is cold chasing precip. Temps are the timestamp and QPF covers the previous 6 hours. 12z run will be completely irrelevant in 12 hours so I'm not going to spend any time parsing details. If it is cold chasing precip then I'll go with 9 out of 10 don't work in my yard. 

[psuhoffman]

15 minutes ago, Ji said:

wow another cutter on the euro at 240...what kind of pattern change is this?

That one might be even more likely to truly cut.  The pna gets temporarily beat down on all guidance and the trough is amplifying unto the central US with the war not yet into NAO territory. That’s a strong cutter signal.  The next 2 weeks has potential for some frozen but if your expecting a blitz and snowpack building you are likely going to be frustrated.  Once the NAO goes negative then frozen will be favored over rain every threat and given the stj keeps throwing waves at us every few days that should end well. 

[yoda]

2 minutes ago, Bob Chill said:

@yoda

Euro op is cold chasing precip. Temps are the timestamp and QPF covers the previous 6 hours. 12z run will be completely irrelevant in 12 hours so I'm not going to spend any time parsing details. If it is cold chasing precip then I'll go with 9 out of 10 don't work in my yard. 

I understand that... was just trying to figure out the huge diff between WB and SV... DCTeacherman was saying 6 to 8 in DC so was trying to find where it showed that

[mikeg0305]

That storm was more like 8" in about 5 hours (where I'm at), but yeah it was pretty incredible!

This brings back bad memories. My normal 40 min commute home took over 5 hours. 83 north shutdown above Hunt Valley. Lucky for me I had prepared with a full tank of gas, drinks snacks and when i was finished drinking a port-a-potty

[Ralph Wiggum]

Just now, psuhoffman said:

That one might be even more likely to truly cut.  The pna gets temporarily beat down on all guidance and the trough is amplifying unto the central US with the war not yet into NAO territory. That’s a strong cutter signal.  The next 2 weeks has potential for some frozen but if your expecting a blitz and snowpack building you are likely going to be frustrated.  Once the NAO goes negative then frozen will be favored over rain every threat and given the stj keeps throwing waves at us every few days that should end well. 

The WAR has been a feature since Sept. I noted it in my winter outlook and didnt like seeing it continually show up right when the nao was supposed to dip. What makes it different now that several people are expecting the WAR seasonal tendency to change on a dime? 

[Snowstorm5921]

The 12z EPS are even worse than 6z.  Going in the wrong direction.

[Roger Smith]

I think that the relationship between snow cover and cyclone tracks is largely a manifestation of persistence rather than forcing. The southerly extent of snow cover is likely to be similar to the track of previous cyclones. So if persistence is the best forecasting random element then the next cyclone should run along the snow boundary too, except that a snowfall event is more likely than not to be followed by cold air which would be statistically linked to falling heights, so therefore at random the next cyclone should run further south than the first snow-producer did. 

In actual fact I think there is almost no forcing mechanism from event to event. If other factors realign the upper level flow, then a low will just charge into the snow cover zone and rain on it, and the only feedback will be in terms of slight downward pressure on air mass temperatures in the warm sector. 

Also in this case, you have two distinct snow boundaries so the next major system could choose either one to verify the theory (one being south of your region and one being around upstate NY into south-central ON). 

In this particular case, I have a hunch that there will be a last-minute trend south on the main event after the leading wave is followed by a sagging frontal boundary and the strong high clamps down on the energy. Not 100% confident that you'll be in the sweet spot, perhaps more like s PA, but in with a chance for 5-10" anyway. The harsh temperature drop seems realistic for any who do get into the warm sector. 

[nj2va]

6 minutes ago, Ralph Wiggum said:

The WAR has been a feature since Sept. I noted it in my winter outlook and didnt like seeing it continually show up right when the nao was supposed to dip. What makes it different now that several people are expecting the WAR seasonal tendency to change on a dime? 

Two different features I know, but the same can be said about the Pacific.  10 days ago, people here were ready to write off winter because it had shown its hand (PAC puke) and we shouldn't expect it to change on a dime.  Welp, the pattern changed quite quickly in the Pacific and here we are.  Weeklies have been honking a -NAO for the last several weeks to take hold in late January and now the ensembles are showing in the LR.