Tuesday, December 18, 2012

Christmas Day.. Rain, Storms, Or Snow?


1PM Tuesday Update...  As I have said, there's only 1 person who knows what will happen next week.  To hang your hat on 1 run of a particular computer model is sophomoric.   Here's what we do know, there will be a system coming through right around Christmas, but how it impacts our weather is not known.  We'll have to wait until we get into the 3-5 day window to get a better handle.  As I have said, this is not an ideal set up for snow in Arkansas at this point.  The models are pointing to more of a heavy rain/storm scanario with some snow on the back end possible.  We'll see.  Read the Monday morning and Tuesday AM posts below for more on that.

I want to show you how crazy and inconsistent the models are at this point (7 days out). Below you will see back to back runs of the Euro at the same time, Christmas morning.

The Tuesday morning run of the Euro shows the surface low over central Illinois with the cold front running south along the Mississippi River.  Rain and storms are pushing east of the state with barely any moisture wrapping up on the back side except for Iowa and Minnesota.  It's just cold and windy here Christmas day.
The same model just last night shows very heavy rain across Arkansas Christmas morning with snows in NE OK to KS northeastward.  The surface low is located in SW Arkansas.  That's a HUGE difference from run to run.  What's a few hundred miles anyway right? LOL.  My point, no one knows.  Let's just wait and see.

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 When you have such a huge interest in a long range forecast it's important to continue to remind everyone how much can change with the computer models this far in advance.  What kind of weather we will have next Tuesday and Wednesday is ONLY known by 1 person and it's not me.  As a matter of fact we're celebrating his birth next Tuesday!  Anyway, the computer models are guessing and guessing again and again.  Some 2 times a day and others 4 times a day.  Each solution is slightly or greatly different than the previous one. 

In the world of weather forecasting, we have to wait to get within 3-5 days to have a good sense of what will unfold.  When I looked at the data this morning (7-8 days away) it screamed HEAVY RAIN!  If you look at my previous blog post, I have maintained this is NOT an ideal set up for significant snow in Arkansas.  The ONLY way to get flakes flying is on the back side with the upper level low.  These can produce accumulating snows, but they usually don't produce much.  You also have to take into account that IF there's heavy rain, there will be a warm and wet ground and that's even harder to get snow to accumulate onto.

The timing and speed of the storm system is still in question as well.  The data suggests Christmas Day will be a soaker and thunderstorms will be possible as well.  IF there's any change over to snow, it won't be until very, very late Christmas Day into Wednesday the 26th.  Again, IF that occurs, it would take place from west to east across the state as the colder air comes in with left over moisture. 

Here are the maps below.

This is the 6Z GFS valid at noon on December 26th.  First of all, I don't like off hour runs in the long range.  However, I wanted to show you the difference back to back model runs can show.  This indicates a surface low in southwestern Missouri.  This is a major heavy rain producer if it were to verify.  Rain could change to a few flakes, but not until late next Wednesday.
This is the 0Z GFS late on the 26th.  Look at the surface low, it's in Mississippi!!!! HUGE difference which would have a tremendous impact on what kind of weather we would experience.  So what do you believe OR what do you WANT to believe?  This solution would change the rain to some wintry weather before ending late next Wednesday.  The heavy rain and severe weather threat is east of the low and in Florida to Alabama into Georgia.
And here's my friend, the European model from last night valid late Christmas Day at 6PM.  The surface low is over northern Arkansas (black closed line with 996 on it).  The very heavy rain and storms are mostly east of Arkansas.  Look at the blue dashed 540 line!  It's over western Arkansas so you're getting a transition to some wintry weather late in the day from west to east on the back side.
In summary, another day and another round of model solutions.  Timing and impact are all different.  Let's keep watching it and wait until we get to within that 3-5 day  window to have some clarity on the situation.

2 comments:

JasonBHampton said...

Im betting on a even futher N solution with Severe wx threat acoss Arkansas. Jmo. BTW have you seen my December Outlook? ;-)

SnowbirdBob said...

Hello Everyone, I am betting on the Southern Track of the Low next week, I see a Low Tracking from Houston,TX to Baton Rouge,LA to Jackson,MS to Nashville,TN..There will be to much Blocking across Central & Southern Canada to allow a Storm to Cut from AR Due North..Will I be right..O dont know..As Todd stated only one person knows that..Jesus Christ Our Lord..But, Hey, I am trying to get us some Snow :)...With that Track you could expect Accumulating Snow for Much of Ark & N La..How much..Well. I say as much as 8 Inches in some spots..Will the Models change. YES!~!..Will the Models change for the better for all of us..I Hope & Yes, I said a little prayer..I normally dont pray about weather events..But, I did on this one..:)
Very Cold & Blustery Temps will follow this Storm system also..Producing low Wind Chill Values...I think we are heading towards a very much Colder & Active Pattern that will lead right up until Mid Jan..The NAO & AO is taking a nose dive once again & The PNA heading towards Neutral-Positive..These are good signs to me...All this being said..Its my opinion only..Thanks for the Blog Todd..I have always said you have the Best Blog in the South & Maybe the Nation.

SnowbirdBob
AKA Bob Read