January Med/Long Range Disco Part 2

[Bob Chill]

@cae

I haven't look at all the runs and your post might be completely correct but what I noticed is the enhanced precip coincides with jet support overhead. Pretty strong southwest flow jet running the front. With moisture embedded in the flow the jet could provide additional lift. The event is mostly overruning/isentropic upglide but the euro tossed back in some coastal enhancement potential. 

[bsperlin]

1 hour ago, cae said:

I'm continuing with my attempt to better undertand the levels between surface and 500 mb and where the moisture comes from.  For the overnight runs, I've been trying to figure out what causes the area of relatively heavy precip in VA / NC.  The best explanation I've found is at the 925 mb level.  At this level, but not at levels above or below it, a center of circulation forms with onshore winds.

 

I believe the oneshore winds at this level transport the moisture inland and cause the area of higher precipitation.  If you look at different runs, the precip max ends up wherever this center goes.  It was relatively far north on the 00z GFS, and more south on the 18z and 06z GFS.  Folks near DC and Baltimore want it to be farther north.

There is no corresponding center of circulation at the surface though.  I suspect that it's because it would be hard to form one over land, but if this were to occur over the ocean we'd see one.  E.g. in the old Euro runs, where the trough was less positively tilted, this center of circulation became the coastal.   Now that the trough has become more positively tilted, the 925 mb circulation doesn't always make it to the coast, so we don't always see it reflected on surface maps, but it has a similar effect.  It creates an area of onshore winds that lead to enhanced precip.  In future runs, we might want to keep an eye on the 925 mb level to get a sense of who is going to jackpot.

I'm not sure what causes this center to form where it does, but maybe the mets and other knowledgeable posters have some insight.  I suspect if the trough shifts north it would help.  Maybe a slower trough would help too?  Of course if I got anything wrong here, please let me know.

Thanks, we need more dynamic analyses here, rather than quoting a variety of model runs.  This is the type of thinking I can learn from!

[cae]

19 minutes ago, Bob Chill said:

@cae

I haven't look at all the runs and your post might be completely correct but what I noticed is the enhanced precip coincides with jet support overhead. Pretty strong southwest flow jet running the front. With moisture embedded in the flow the jet could provide additional lift. The event is mostly overruning/isentropic upglide but the euro tossed back in some coastal enhancement potential. 

I see what you mean.  There seem to be two moisture feeds here, from the gulf and Atlantic, and they both probably play a role.  Perhaps the dynamics at the two levels are related?  I.e., could a relatively strong jet flow overhead cause a storm to spin up at the lower levels?

[Bob Chill]

6 minutes ago, cae said:

I see what you mean.  There seem to be two moisture feeds here, from the gulf and Atlantic, and they both probably play a role.  Do you know if the dynamics at the two levels are related?  I.e., can relatively strong jet flow overhead cause a storm to spin up at the lower levels?

I'll defer to the Mets on this one but in my simpleton view I think a slp will require a more neutral tilt trough for low pressure to form out in front. A slp forms but it happens too late and too east. Nam was the best run we've seen lately and event that was going to be too far easy. 

Unless h5 sharpens I think our best shot is rooting for moisture/lift embedded in the flow. Inverted trough type of deal is still possible too if low pressure forms too far east. IVTs are really hard for models to get right until very short leads. We see phantom ones pop up often in the med range but rarely hold in the short range. Now that we're entering the short range maybe some sort of ivt or coastal enhancement starts to show up. 

[BTRWx's Thanks Giving]

The biggest difference appears to be the western Atlantic, but other than that I like these similarities. 

https://www.esrl.noaa.gov/psd/map/clim/sst.shtml

 

https://data.giss.nasa.gov/gistemp/maps/

 

[Ji]

is this accurate...i keep hearing the NAO going negative but this never ever shows it lol

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/new.nao_index_ensm.html

[BTRWx's Thanks Giving]

7 minutes ago, Ji said:

is this accurate...i keep hearing the NAO going negative but this never ever shows it lol

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/new.nao_index_ensm.html

With the PNA negative and the MJO heading to 3 and 4, I don't think we have much time to score. 

[cbmclean]

6 hours ago, Ji said:

is this accurate...i keep hearing the NAO going negative but this never ever shows it lol

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/new.nao_index_ensm.html

Visitor from the SE forum here: I have heard more mention of a -AO on this forum although one or two mentions of a possible -NAO.  -NAO episodes seem pretty difficult to achieve the last few years or so.

[showmethesnow]

Mentioned yesterday that knowing the EPS tendencies this year in holding back the SW energy/trough that the the run yesterday (00Z) probably was showing a pretty good window of opportunity in the long range (day 13-15). The current 00Z run is actually releasing the SW trough a little quicker and we are just beginning to see the potential for that period (day 12-14 now). The one thing we will probably need to see though is some form of a legitimate -NAO during this period of which the current run backed down on some. One thing that could possibly offset a lack of a -NAO is if in fact we see a more southerly pv then currently projected. Thought I would also mention that taking the same thoughts as above that this period of time is now starting to show up on the GEFS as well.

Also I am still seeing indications that the EPS wants to flip the hostile PAC in the longer range (+PNA, -EO). The GEFS has also been hinting at a flip as well. At this point in time my confidence is growing somewhat that we do actually see a flip in the next 2 to 3 weeks.

[frd]

@Bob ChillSome strat stuff  in a series 

 

[frd]

from HM

 

[frd]

Jason is a voice of reason with the srat stuff, and very sensible . If nothing else the PV should weaken , beyond that it's more uncertain. IMHO, better this senario than a powerful consolidated PV. 

 

 

[showmethesnow]

4 minutes ago, frd said:

from HM

 

Won't claim to be an expert whatsoever when it comes to the strat pv but to the best of my knowledge when you see one 3 wave during a winter chances increase quite substantially for follow ups later in the season as well as just general disturbances of the pv.

[frd]

6 minutes ago, showmethesnow said:

Won't claim to be an expert whatsoever when it comes to the strat pv but to the best of my knowledge when you see one 3 wave during a winter chances increase quite substantially for follow ups later in the season as well as just general disturbances of the pv.

Yes, there are studies on the precursor pattern in early Jan and follow up events like what HM is taking about working together to weaken and disturb the SVP 

[Bob Chill]

Once we get past the rain storm in a week, things become a little interesting again. Both the GEFS and EPS are showing more potential for confluence to the north and CAD hp placement. Obviously too far out for specifics but the roller coaster pattern we're in isn't all bad. I have a hunch we'll be tracking something tangible within a week. 

[psuhoffman]

9 minutes ago, Bob Chill said:

Once we get past the rain storm in a week, things become a little interesting again. Both the GEFS and EPS are showing more potential for confluence to the north and CAD hp placement. Obviously too far out for specifics but the roller coaster pattern we're in isn't all bad. I have a hunch we'll be tracking something tangible within a week. 

Agreed I see the same thing. 

[Bob Chill]

5 minutes ago, psuhoffman said:

Agreed I see the same thing. 

You and I and maybe 2-3 others will be the only ones interested I think. LOL

[Ji]

29 minutes ago, Bob Chill said:

You and I and maybe 2-3 others will be the only ones interested I think. LOL

which storm date should i start a thread for?

[Bob Chill]

14 minutes ago, Ji said:

which storm date should i start a thread for?

[Ji]

2 minutes ago, Bob Chill said:

its a winchester winter

[frd]

50 minutes ago, Bob Chill said:

You and I and maybe 2-3 others will be the only ones interested I think. LOL

I'm in !

And,I have high hopes that this hobby will offer a high ROI in Feb. 

I also feel that the warm up has limited staying power. 

If we get the -EPO back in Feb.,  and tap some of that Siberian air mass - 70 F.,  watch out, this time there will be storms I think .

[Cobalt]

1 minute ago, frd said:

I'm in !

And,I have high hopes that this hobby will offer a high ROI in Feb. 

I also feel that the warm up has limited staying power. 

If we get the -EPO back in Feb.,  and tap some of that Siberian air mass - 70 F.,  watch out, this time there will be storms I think .

Yeah, I'm in too. Feb is a game time month. Don't need stars to align, but as long as the pattern is favorable, we could easily make a couple leaps towards climo. 

[psuhoffman]

1 hour ago, Bob Chill said:

You and I and maybe 2-3 others will be the only ones interested I think. LOL

You know me. I track everything to the bitter end. That's just who I am. I get the frustration but I think because it's been cold some are skewing things. Nina climo sucks. We know that. Out average snowfall in a Nina is only 10-20" region wide. And if you remove the 2 good outliers in the last 40 years it gets worse then that.  If we do manage a 1-3" this week we're actually close to climo for the core of our region, and ahead if Nina climo. Way over in the eastern zones. And of course our western brethren are the ones with a legitimate gripe imho. 

I want to be using a yard stick to measure snow like everyone else but I'm also realistic about this and don't feel like we're in the midst of some epic fail att. If we don't score at least one decent event that could change but there is a lot of time left and we haven't even entered peak climo and some signs point to lining up things in feb. all that has me feeling somewhat content right now to let this play out. 

The pattern after the day 8-9 rain looks ok. It's not an "it's happening" pattern but not a shutout either. Something could come if it. And it's acceptable while we wait for things to line up in feb. 

[psuhoffman]

1 hour ago, Bob Chill said:

Fringed 

[North Balti Zen]

2 minutes ago, psuhoffman said:

Fringed 

Heh. I wanted to say that...

[WxUSAF]

26 minutes ago, psuhoffman said:

You know me. I track everything to the bitter end. That's just who I am. I get the frustration but I think because it's been cold some are skewing things. Nina climo sucks. We know that. Out average snowfall in a Nina is only 10-20" region wide. And if you remove the 2 good outliers in the last 40 years it gets worse then that.  If we do manage a 1-3" this week we're actually close to climo for the core of our region, and ahead if Nina climo. Way over in the eastern zones. And of course our western brethren are the ones with a legitimate gripe imho. 

I'm very much of this mindset also.  Most of the Virginian's have a legit gripe about this winter, but for most of MD, we are near (or in some cases much above) climb to this point, Nina or not.  Add an inch or two from this week and we're in pretty solid shape for January 17.  Assuming it's not a wall-to-wall torch through the end of the month after this, which I don't think it will be, then it's quite possible we score a bit more before February starts.  And then hopefully some of these long range tea leaves for February pan out and we end strong.  

[gymengineer]

4 minutes ago, WxUSAF said:

I'm very much of this mindset also.  Most of the Virginian's have a legit gripe about this winter, but for most of MD, we are near (or in some cases much above) climb to this point, Nina or not.  Add an inch or two from this week and we're in pretty solid shape for January 17.  Assuming it's not a wall-to-wall torch through the end of the month after this, which I don't think it will be, then it's quite possible we score a bit more before February starts.  And then hopefully some of these long range tea leaves for February pan out and we end strong.  

I agree too. That first December event was actually a moderate event for many locations-- IAD got 4"-- which is not a guarantee to have in the bank by 1/15 in any season. Since then, I've seen accumulating frozen precipitation every single week except for one. That's pretty active for these parts. Obviously none have been as big as the first snow event, but nothing's ruling out another moderate event or two by the end of the snow season. 

[Bob Chill]

The band is still together. Lol. I'm always good. The only thing that burns me are big events that vanish in under 48 hours. Once inside of that 48 hour range you can almost see the snow piling up out the window and getting it pulled last minute sucks. I never let myself get to the point of no return until really close in. If there are temp problems I don't get hooked until after its happening. Something about those close in rug pulls feels worse than a hangover though. 

 

[Ji]

Wow. Usually for tracking a major storm..if its still there at 96 hours...to me we are in. Problem is we can't seem to break 120 hours on these major storms

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[WxUSAF]

Tweet not focused on us, but you can see the season-to-date snowfall for our subforum on this map.  Most of MD east of FDK is doing reasonably well compared to climo if not much better.  VA is hurting.