Tuesday, December 31, 2013

Active Start To 2014... That's An Understatement


5 PM Tuesday Update... I just want to clear something up with the post below.  No matter what model you look it, it's going to be cold next week.  There are no guarantees in weather until after it happens, but the confidence level is quite high.  I just thought it was interesting how the European model keeps plunging temperatures the way it does whenever it sees snowpack.  The last time it tried to do this, Dec. 5th and 6th, it was wrong.  If the snow does fall, ! IF !, then we'll see if it hits it this time.  But for right now, it does look like some of the coldest air of the winter thus far is on the table for next week.  We'll see and I'll keep you updated.

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1:30 PM Tuesday Update...  I just wanted to show you something interesting I have noticed lately with the European model.  This is NOT a forecast, but I just want to show you the latest version of it to illustrate a point.  

On the left (graphic below), you will see the forecast snowfall late this weekend.  It has shifted the track of the surface low further north and thus the accumulating snow up there too.  Notice the temperatures on the right valid next Monday morning.  You can clearly see the white into southwest Missouri into northern Arkansas.  These are temperatures below zero!  Yesterday, the Euro had the snow further southeast along with below zero temperatures.  It indicated readings next week below zero across eastern Arkansas and northern Mississippi where there was a heavy snowpack.  Since that is no longer there on the current model run, the temperatures are not even close to zero.  It's much warmer.

So what are you saying Todd?  A lot actually.  Yes, when there is snow on the ground, under the right conditions, it will be colder than areas without snow.  But the European model lately takes this to the extreme in my opinion.  I brought up an example back in February of 2010 where it was extreme in northwest Arkansas and Oklahoma.  Readings dropped to all time record lows with deep snowpack, BUT that was due to the perfect conditions setting up... NO wind, clear skies, and deep snow.  It doesn't always happen like that in reality.  Clouds and wind can keep temperatures from really dropping off sometimes.  While it is true the snow will make it colder than places without snow, it's not always extreme.  Hope I'm making some sense?  In my opinion, the Euro sees the snow cover, but over estimates the cooling due to it.  This is something I have noticed over the past month or so with this model.  

Now, in regards to the snow.  Will it be north or south (the swath).  It's impossible to know the track of the low this far out so I would expect variations with each model run until we get closer.  Sorry, that's just the reality of forecasting.

This is the morning run of the Euro on Dec. 31st.  See what it's doing with the temperatures under the snowpack in north AR and southern MO?

The is the Euro from Monday morning.  The swatch of snow is much further south (left).  The temperatures on the right indicates below zero temperatures where that deep snowpack is located.  That's in the white and green areas.  So again, I'm not making a forecast here, just showing you what I have a problem with when it comes to the Euro.  Thanks and Happy New Year.
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Every morning I make coffee, sit down, and study the latest data.  During this morning's regular routine, I couldn't help but think, where do I start?  There's a ton to look at, analyze, and compare.  This is the time of year that brings out the weather geek in me. Well, that's all the time, but it's really amplified in the winter.

As I stated yesterday, the Euro is extreme!  It's still bringing in below zero temperatures into Arkansas next week.  At this point, I'm still not buying it.  It has advertised this a couple of times over the past month and it never verified.  The American GFS model is cold, but not like the Euro.  I'm not sure about this, but a friend of mine told me the Euro physics were tweaked a little and it's doing this over North America.  It's way too cold, especially in areas where it sees snow on the ground.  I have noticed that.  So as much as I love cold weather, I'm not going to "wishcast" and use the Euro until I'm more confident in its solution.  Could it end up being correct? Yes.  I'll take you back to February of 2010 when almost 2 feet of snow piled up in northwest Arkansas.  We had about 7 inches here in the metro.  The skies cleared up that night over Oklahoma and northwest Arkansas and the winds went calm.  It was the perfect set up for maximum radiational cooling.  The lowest temperature you could possibly have was realized because any warmth at the surface was able to escape.  That night, Oklahoma recorded its lowest state temperature EVER and portions of northwest Arkansas got close to 20 degrees BELOW zero.  I'M NOT SAYING THAT'S GOING TO HAPPEN HERE NEXT WEEK, but it seems like the Euro is seeing this on a constant basis where it sees snow/ice on the ground.  So my bottom line, I'm NOT COMPLETELY IGNORING IT.   I would not put much faith in it at this time until I see other models trending in that direction.  I'll of course keep you updated on that.

Now let's talk about the rounds of precipitation we might deal with on Thursday and again early next week.  A new arctic front will arrive Wednesday night into Thursday.  Rain can be expected with a change over to some wintry weather Thursday morning.  There's another chance on Sunday.  The Euro is stronger with a surface low along another arctic boundary Sunday and produces more snow compared to the GFS.  I'll explain all of it below with maps.  I should make it clear, I'm comparing the 00Z run of the Euro with the 06Z run of the GFS with maps below.

Before I get to that.  I hope you have a happy and safe New Years.  Thanks for sharing in my passion for the weather here on the blog.  We're ending December with the biggest month ever here.  It shattered the previous record.  THANK YOU, THANK YOU, THANK YOU!

The top is the GFS and bottom is the Euro valid Thursday morning.  The blue dashed lines is usually close to the rain/snow line.  That's very dependent on surface temperatures too.  The blobs indicate the precip. amounts over the PREVIOUS 6 hours.  While the GFS is stronger with surface low development in the northern Gulf (black circle with "1012"), both are in good agreement the rain may change to a wintry mix as cold air comes in on the back side.  This could bring accumulating snow (not anything huge) to northern Arkansas.

The GFS top and the Euro bottom.  Both are in good agreement Thursday morning with northern Arkansas seeing some light accumulations.  However, the GFS does show a LITTLE across central sections.


This is where we see some disagreement.  This is Sunday afternoon.  The top is the GFS and the bottom is the Euro.  Both show another arctic boundary coming in, but the Euro is more enthusiastic with a surface wave along the boundary.  See that black, closed line labeled 1012?  It's deeper with the upper trough and brings in more moisture within the cold sector.  If the Euro is right, it would bring accumulating snows to much of Arkansas.  The GFS on the other hand, not so much.
The GFS top and the Euro bottom.  This is valid Sunday afternoon.  BIG DIFFERENCE.  Remember, the Euro really gets that surface low cranking and dumps a statewide snow.  The GFS wants nothing to do with that.  So we have problems here in the long range which is very typical.  Many times, neither is correct and it's somewhere in between.  Like I said, there is SO much to look at with our weather and this post doesn't even hit on the very cold air associated with yet another arctic boundary following Sunday's.  WE MIGHT NEED TO BREAK OUT THAT SCHOOL:CON INDEX.... MIGHT.   STAY TUNED.

1 comment:

Angie Smith said...

Awesome Job Todd I kinda hope the Euro is right!!