February Mid/Long Range Discussion 2

[psuhoffman]

57 minutes ago, Ji said:

@psuhoffmanthe EPS snowfall map is still as bad as Ive seen this winter and now its taking us to March 7th. First week of march is a disaster?

Not in range yet. If by Friday we don't see some response then I'll worry some. 

[frd]

4 minutes ago, psuhoffman said:

Not in range yet. If by Friday we don't see some response then I'll worry some. 

@psuhoffmanI read that models do poorly with retrograding blocks. Have you heard the same ?

 

 

[Superstorm]

Could be a prequel next Tuesday.


.

[psuhoffman]

Just now, frd said:

@psuhoffmanI read that models do poorly with retrograding blocks. Have you heard the same ?

 

 

Models do poorly with anything that's 10+ days away. 

[frd]

12 minutes ago, C.A.P.E. said:

Ensemble snowfall maps are pretty useless at 10 day leads, especially with a major pattern change ongoing. Not sure why some people pay so much attention to them. And yes, realistically we are probably looking at around the 3rd for a legit threat. Could be sooner, but expecting it is probably going to result in disappointment. This is going to be a slow process.

Seems the moisture may not really be an issue as we have a somewhat split flow developing and the MJO looks to be favorable, plus wow the SOI is still negative.  

[frd]

3 minutes ago, psuhoffman said:

Models do poorly with anything that's 10+ days away. 

I respect that :-)    This winter has been a challenging one and it is only going to get more challenging from a weather dynamics point of view , total chaos soon 

[Ralph Wiggum]

Ensemble snowfall maps are pretty useless at 10 day leads, especially with a major pattern change ongoing. Not sure why some people pay so much attention to them. And yes, realistically we are probably looking at around the 3rd for a legit threat. Could be sooner, but expecting it is probably going to result in disappointment. This is going to be a slow process.

This. The eps from what I recall showed nothing at range for the past Saturday event and for some it was the biggest event of the season. I know that isnt saying much but just goes to show things can sneak in shorter range....we dont need a massive snow signal 10+ days out.

[AfewUniversesBelowNormal]

The jump in blocking from 168-240 just doesn't seem possible this year. Models are possibly trying to balance out the anomalous 500mb vortex that has been in northeast Canada all winter 

[psuhoffman]

3 hours ago, Ji said:

@psuhoffmanthe EPS snowfall map is still as bad as Ive seen this winter and now its taking us to March 7th. First week of march is a disaster?

Regarding the snowfall mean after taking a closer look... both the GEFS and EPS have meager snowfall reactions due to a scattershot look in the long range.  They are generally unfocused in where they want to place any feature and since in a blocking regime like this waves will not be coming as quickly there is really only room/time for one threat yet in the window that they can see as of now.  And given they are all over the place with that one threat there is no real signal for anywhere.  

The EPS has a few suppressed southeast storms, only a couple show up on the snowfall map because on a few boundary level temps are an issue and the EPS snow algorithm is more conservative than the GEFS one so they don't show those as snow.  Then they show a few hits...then the main way most miss us is by forming a storm out of a northern stream vort that either dives in north of us as a mauler type clipper or by retrograding something back in from the east into New England...  If we had to identify the most likely fail scenario here that would be it...because such a scenario would then suppress anything that tries to come at us for a pretty long period as the system that does develop to our north would get stuck and just spin and in some cases pinwheel around the 50/50 low and squash everything below it.  But are you really that worried about something like that at day 13-15 being dead on accurate?  

Also, we have had several times the last few years where the snowfall maps looked good but we all said "but the pattern doesn't really support that" and sure enough the actual ground truth matched what the pattern supported more then those snowfall maps at range when reality set in.  Just a few weeks ago heading into this latest -epo +nao pattern the snowfall means for both the eps and gefs looked great...but we all knew that historically we end up on the losing side way too often with that.  What ended up?  Central PA loved this...my in-laws up in Pine Grove PA have been getting burried for the last 3 weeks...while we got a LOT of rain and a bit of ice and the southern edge of one snowfall.  Reality matched the analogs more then those snowmaps.  

So I would much rather have the h5 look right then those snowfall maps at day 10-15.  Most of the time, in my experience over the years...if the pattern looks right eventually the snow maps respond.  That doesn't mean a good pattern has to produce...we all know the examples of excellent blocking patterns that were duds for us wrt snowfall... March 2001, Dec 2002, Dec 2010 being some great examples... And there are others where we got some snow but nothing epic because we just got unlucky with close misses like March 2013.  But there are also wins like March 58, March 62, March 65, March 76, March 99 where blocking scored us late snow...and a few of those examples are otherwise blah nina years so....

[CAPE]

Excellent post PSU.

[Bob Chill]

PSU's post saved me keystrokes. Slow flow + long lead = no focus. It's that simple. We're only getting glimpses of the beginning of the pattern anyways. There's no doubt in my mind as the days go by the chances will increase on LR guidance but even that isn't meaningful. We need to be patient. The next 10 days are likely a no go. Just hope within the next 10 days we start to see something discrete emerge. We're in time passing mode for a while. Is what it is. 

[PCT_ATC]

3 hours ago, psuhoffman said:

Models do poorly with anything that's 10+ 5-7 days away. 

Modified.   at least for this screwed up winter! 

[frd]

Hmm, this is a bit confusing.  No one ever said extreme cold, but it seems like he is blowing off any potential during March

 

 

 

[Bob Chill]

9 minutes ago, frd said:

Hmm, this is a bit confusing.  No one ever said extreme cold, but it seems like he is blowing off any potential during March

West based -NAO blocks aren't big cold patterns for anyone in the east (often AN in the NE).  The SE typically has the largest neg departure while our area is generally just slightly below. If you think back to 09-10, it got pretty warm pretty quick after the big storms. That's usually how it goes. However, what a west based -NAO does is give us a good storm track. The kind where the storm itself is usually the coldest day(s) but the general temps surrounding it aren't that cold. If you ignore how storms typically track during a -NAO and just base your thoughts off temp anomalies then it's easy to say "too warm/won't snow". I disagree with Maue's connection with temps and sensible wx. OTOH- if no storm happens then the period can easily look pretty boring and not very cold. 

Everyone is racing each other to make definitive calls right now. Someone is going to be right by default. lol

[rcflyermd68]

i guess it  comes  down  to  who  do  you trust  the  most??

[Bob Chill]

4 minutes ago, rcflyermd68 said:

i guess it  comes  down  to  who  do  you trust  the  most??

I trust me the most. lol. I also won't make any bold claims or definitive calls. We have a chance at a big east coast storm. That's about all you can really say at this point. When the blocking weakens or breaks down is probably the best chance but anything goes once the upper level pattern aligns. We could easily be waiting until mid-march before anything good happens....or we might not...or nothing might happen at all...that's my call. 

[rcflyermd68]

i have no problem with youre specifics,  youre very knowledgable. I do a lot of reading, and very little posting. Have a great day sir.

[Fozz]

1 hour ago, psuhoffman said:

Regarding the snowfall mean after taking a closer look... both the GEFS and EPS have meager snowfall reactions due to a scattershot look in the long range.  They are generally unfocused in where they want to place any feature and since in a blocking regime like this waves will not be coming as quickly there is really only room/time for one threat yet in the window that they can see as of now.  And given they are all over the place with that one threat there is no real signal for anywhere.  

The EPS has a few suppressed southeast storms, only a couple show up on the snowfall map because on a few boundary level temps are an issue and the EPS snow algorithm is more conservative than the GEFS one so they don't show those as snow.  Then they show a few hits...then the main way most miss us is by forming a storm out of a northern stream vort that either dives in north of us as a mauler type clipper or by retrograding something back in from the east into New England...  If we had to identify the most likely fail scenario here that would be it...because such a scenario would then suppress anything that tries to come at us for a pretty long period as the system that does develop to our north would get stuck and just spin and in some cases pinwheel around the 50/50 low and squash everything below it.  But are you really that worried about something like that at day 13-15 being dead on accurate?  

Also, we have had several times the last few years where the snowfall maps looked good but we all said "but the pattern doesn't really support that" and sure enough the actual ground truth matched what the pattern supported more then those snowfall maps at range when reality set in.  Just a few weeks ago heading into this latest -epo +nao pattern the snowfall means for both the eps and gefs looked great...but we all knew that historically we end up on the losing side way too often with that.  What ended up?  Central PA loved this...my in-laws up in Pine Grove PA have been getting burried for the last 3 weeks...while we got a LOT of rain and a bit of ice and the southern edge of one snowfall.  Reality matched the analogs more then those snowmaps.  

So I would much rather have the h5 look right then those snowfall maps at day 10-15.  Most of the time, in my experience over the years...if the pattern looks right eventually the snow maps respond.  That doesn't mean a good pattern has to produce...we all know the examples of excellent blocking patterns that were duds for us wrt snowfall... March 2001, Dec 2002, Dec 2010 being some great examples... And there are others where we got some snow but nothing epic because we just got unlucky with close misses like March 2013.  But there are also wins like March 58, March 62, March 65, March 76, March 99 where blocking scored us late snow...and a few of those examples are otherwise blah nina years so....

Great post, except December 2002 definitely wasn't a dud. Maybe you meant December 2001?

[frd]

32 minutes ago, Bob Chill said:

West based -NAO blocks aren't big cold patterns for anyone in the east (often AN in the NE).  The SE typically has the largest neg departure while our area is generally just slightly below. If you think back to 09-10, it got pretty warm pretty quick after the big storms. That's usually how it goes. However, what a west based -NAO does is give us a good storm track. The kind where the storm itself is usually the coldest day(s) but the general temps surrounding it aren't that cold. If you ignore how storms typically track during a -NAO and just base your thoughts off temp anomalies then it's easy to say "too warm/won't snow". I disagree with Maue's connection with temps and sensible wx. OTOH- if no storm happens then the period can easily look pretty boring and not very cold. 

Everyone is racing each other to make definitive calls right now. Someone is going to be right by default. lol

I agree with your logic. 

And on a related note, I would not be surprised for an interval sometime in March, maybe near mid month,  for a more negative temp departure, as it seems the PNA goes more neutral , and even positve possibly and before that there appears to be a - EPO loading going on. The EPO is forcasted to go negative.   Lastly, a  phase 2 MJO in March has the very highest correlation to cold anomalies in the East.   ( may extend further West as well, source - JB video )  

[mattie g]

39 minutes ago, frd said:

Hmm, this is a bit confusing.  No one ever said extreme cold, but it seems like he is blowing off any potential during March

 

 

 

It doesn't look to me like he's blowing off potential. He's just making a general statement about temperatures in the East. Bob's post sums this up nicely.

[Fozz]

29 minutes ago, Bob Chill said:

West based -NAO blocks aren't big cold patterns for anyone in the east (often AN in the NE).  The SE typically has the largest neg departure while our area is generally just slightly below. If you think back to 09-10, it got pretty warm pretty quick after the big storms. That's usually how it goes. However, what a west based -NAO does is give us a good storm track. The kind where the storm itself is usually the coldest day(s) but the general temps surrounding it aren't that cold. If you ignore how storms typically track during a -NAO and just base your thoughts off temp anomalies then it's easy to say "too warm/won't snow". I disagree with Maue's connection with temps and sensible wx. OTOH- if no storm happens then the period can easily look pretty boring and not very cold. 

Everyone is racing each other to make definitive calls right now. Someone is going to be right by default. lol

Maybe it's just me, but it seems to me that our best patterns for sustained cold seem to come from a very -EPO but an unimpressive (or sometimes +) NAO.

1994, 2014, and 2015 come to mind. I'm also curious about what those setups would've brought if most teleconnections were the same, except the NAO/AO were also very negative. I remember hearing many times during those latter two winters that the lack of a north Atlantic block often kept us from getting even more snow, even though 2014 was a great year for a lot of us.

[BristowWx]

Just looking at the GFS op late range that is one hell of a block near GL.  if nothing else it should keep spring at bay for a while.

[Bob Chill]

13 minutes ago, Fozz said:

Maybe it's just me, but it seems to me that our best patterns for sustained cold seem to come from a very -EPO but an unimpressive (or sometimes +) NAO.

1994, 2014, and 2015 come to mind. I'm also curious about what those setups would've brought if most teleconnections were the same, except the NAO/AO were also very negative. I remember hearing many times during those latter two winters that the lack of a north Atlantic block often kept us from getting even more snow, even though 2014 was a great year for a lot of us.

It's a seesaw of sorts up above. A -ao/nao combo is pretty warm compared to normal around the pole. Our big cold come from cross polar and/or big arctic dumps. A -AO/NAO doesn't typically deliver that. A -AO/NAO just displaces whatever cold there is up in Canada. 

It's hard to get a -EPO/AO/NAO pattern because wavelengths still need to buckle. It's hard to get continuous ridging from AK/Arctic Circle/Eastern Canada/N Atl. A -AO/NAO are often below normal here except for when there's a nasty vortex in AK or GOA flooding our source region with maritime air. Not really seeing that right now. But below normal /= big cold. 

13-14 and 14-15 had a significant displacement of the trop PV and that delivered big cold AND allowed storms to track favorably. That's atypical stuff. A -EPO/+AO/+NAO usually has big cold with bluebird skies but the cold runs away from precip arrives and then repeats. A significant amount of luck went into the 13-15 stretch. We saw a weaker version of that period recently and ended up on the wrong side of every storm. That's more typical and what usually happens during +AO/+NAO/-EPO periods. 

The AO/NAO teleconnections are more correlated with favorable storm tracks and no big neg departures with temps. Big blocks keep us below normal for long stretches of time but not big departures. The real magic of blocking is favorable coastal storm tracks and not frozen lakes and ponds and sub zero temps. 

[cae]

With the discussion recently about temps and March snow, I was curious as to what the historical relationship is.  The below plot shows Jan-Feb-March temps vs. snowfall for Baltimore for all years since 1884.  The vertical lines show the average temps for each month over all years.

(In case you're curious, the month with 50" was February 2010.)

The first thing that comes to mind is that there's clearly a relationship between temps and snow.  In March months when we had above-average temps, Baltimore got an average of 1.9" of snow.  When we had below-average temps, Baltimore got an average of 6.2".  We've never had snow in a March with average temps above 50, and we've always had snow in years when average March temps were below 39.8 (4 degrees below the long-term average).  But there's also a lot of spread.  1942 stands out as a month in which the temps were more than 3 degrees above average but we still got 22" of snow.

The other thing I noticed is that given a February and March with the same average monthly temperature, we'll probably get more snow in March.  It's better to be in the upper 30s in March than in February. 

Of course usual caveats apply.  This is all broad brush analysis, and the particulars of every year are different. 

[psuhoffman]

1 hour ago, Fozz said:

Great post, except December 2002 definitely wasn't a dud. Maybe you meant December 2001?

Yes 2001 sorry 

[mappy]

DT aleet

 

[frd]

Yeah baby..........loving this 

Go Ian !!!!  Great info 

 

 

 

 

[smokeybandit]

What are DC's top one-day March snowfalls?

[WxUSAF]

41 minutes ago, mappy said:

DT aleet

 

So something on the Euro changed?

[AfewUniversesBelowNormal]

Not buying the awesome massive block, patterns don't break like this when the Hemisphere is so rigid. It's feedback from the +NAO left of some medium