Jump to content
  • Member Statistics

    17,604
    Total Members
    7,904
    Most Online
    ArlyDude
    Newest Member
    ArlyDude
    Joined

December Med/Long Range Discussion Part 2


WinterWxLuvr

Recommended Posts

  • Replies 1.1k
  • Created
  • Last Reply

Splitting off next week through xmas, the ensemble mean is a little misleading in terms of what the sensible weather will be.  A glance at the mean would say "torch" city.  Reality is there will be ridging along the east coast in general, but the leftover cold air that has flooded North America will be pushing behind waves as they ride along the boundary and so the period will be more transient with some warm days and some cool ones with a storm track that may keep us in the game for at least tracking something.  The key will be how much the cold can press.  Last night the data was pretty grim.  The Euro from 0z and the GEFS from 6z pretty much shifted the boundary just far enough to the northwest to put us on the warm side for most of the waves.  Both had a mean for the period of only about 1.5-3" depending on location.  That is a false signal.  Remember from years past the default mean during any not totally awful hostile pattern is a couple inches.  That is because a small cluster of members are going to show a fluke hit in any patter that isnt awful.  That skews the mean to a few inches even if nothing is likely to happen.  When the mean starts geting up above 5" that is when there is an actual signal for something.  That is just in general, the specifics of how you get to the mean matter but as a general rule a mean for a week or more period that is more then a few days out of less then a few inches is usually just a false signal.  Of course then the 12z GEFS comes in much more bullish on next week.  Seems to have shifted the boundary back south enough to put us in the battle zone.  Every member except 4 clips us with something decent during the week.  I will be very interested to see the EPS in a couple hours.  My take right now...root for the cold to get in.  NOTHING is dry for the week.  The runs that are snowless are just very wet.  The STJ seems to want to come alive for a bit and there are also several northern systems digging down, get the cold boundary south and we will be ok.  I have no idea if the cold can do it though, the models have been generally over estimating the south push of the cold air masses so far this year.  Also, none of the threats on the gefs is a high percentage.  Even with its mean around 8.5" in DC it gets there by scattering hits all week.  A few monday, a few wed, some on xmas.  So each wave is a low probability.  Historically that skews the mean up because in reality each threat is likely to fail.  But throw the hail mary enough times and you might complete one so its worth watching just dont get your hopes up. 

Link to comment
Share on other sites

Could be another case of the models not seeing the cold air until it gets here.  Could be that they can see it retreating faster due to no HP above us.  I think it will still be something to watch once the cold air gets in here and how fast does it modify.

 

 

Link to comment
Share on other sites

5 minutes ago, Bob Chill said:

Just noise between the two to be honest. They both have 850's >0 north of the potomac before 12z. That's the ugly part. 

Euro has been shifting its boundary and thus the battle zone with the qpf north each run overall for a while now.  its now up in central PA.  Its still hanging close enough with the GFS closer to keep us in the game but any more bleeding the wrong way and were in trouble. 

Link to comment
Share on other sites

Op euro does the whole "stuck in the southwest" upper low thing next week and that will kill any chance for snow here.  With no blocking and a tendency for ridging anyways thats going to pump the heights even more in front and blast the ridging way up in the east before anything can organize out of the gulf.  Anything from the northern branch is going to encounter warm air in front of it.  Either way were screwed if thats right.  Hopefully its the euro up to its old tricks. 

Link to comment
Share on other sites

Long range I am less pessimistic then the day 15 means might indicate I should be.  The GEFS in the long range has been slowly coming around to a look that is evolving towards a better pattern.  Its way out and far from a lock but it hints the hostile patter were entering is transient not a long term stable feature.  Also on our side, january 2000 has been showing up on day 10 analogs a lot.  Its the only one that actually matches this years analogs pretty good and that pattern rolled forward into a really good 2 week period later that month.  I think we could all live with something similar.  The euro looks awful but the weeklies at least imply towards later january it gets to the same place just much slower.  Obviously I would rather the faster evolution but at least even it offers hope.  My gut says we don't stay in the +epo +nao pattern for long.  With some luck we get a fluke snow next week, mute the warm up, then transition out before things get too ugly. 

Link to comment
Share on other sites

It's a NINA...OK, not officially, but ENSO temps qualify as a NINA. BWI's average snowfall for the month of DEC during all ENSO states is 3", and most of that average is made up of NINO years I'm willing to bet. If I can scrape out half of DEC's average Friday/Saturday, I'll consider it a win and pray the other 1.5" falls during next week. That's the only way to look at it around here.

Link to comment
Share on other sites

20 minutes ago, mitchnick said:

It's a NINA...OK, not officially, but ENSO temps qualify as a NINA. BWI's average snowfall for the month of DEC during all ENSO states is 3", and most of that average is made up of NINO years I'm willing to bet. If I can scrape out half of DEC's average Friday/Saturday, I'll consider it a win and pray the other 1.5" falls during next week. That's the only way to look at it around here.

Except there is no such thing as average snow. The mean is just a bunch of non average years averaged together. In reality we go several years with barely anything in December then once in a while get a decent one like 2002 and 2009. Rooting to hit average kind of misses our climo of feast or famine. 

Link to comment
Share on other sites

1 minute ago, psuhoffman said:

Except there is no such thing as average snow. The mean is just a bunch of non average years averaged together. In reality we go several years with barely anything in December then once in a while get a decent one like 2002 and 2009. Rooting to hit average kind of misses our climo of feast or famine. 

Median is a much better descriptor of snowfall IMO.

Link to comment
Share on other sites

8 minutes ago, WinterWxLuvr said:

Median is a much better descriptor of snowfall IMO.

Since 2000 BWI has had 1.4" or less 11 times.  basicaly exactly average twice 2.9" and 3"  And 4 times significantly above average, 9.7, 9.6, 4.8 and 20.1.  The way I see it is we are basically rooting for that 4/17 year every year.  The rest are usually nothing or pretty darn close to nothing. 

Link to comment
Share on other sites

35 minutes ago, psuhoffman said:

Except there is no such thing as average snow. The mean is just a bunch of non average years averaged together. In reality we go several years with barely anything in December then once in a while get a decent one like 2002 and 2009. Rooting to hit average kind of misses our climo of feast or famine. 

Well, an average is used to derive what the NWS calls "normal" as stated by the U.S. Climate site here: https://www.ncdc.noaa.gov/data-access/land-based-station-data/land-based-datasets/climate-normals/1981-2010-normals-data, although I don't necessarily disagree with you that using the mean or median  may be better. But since the average is close enough for my purposes and is listed on LWX's site for easy reference, I'll go with that as my measuring stick. In any event, give me my 3" opf snow in DEC and I'll be relatively satisfied.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Guest
This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...