Monday, February 18, 2013

Parade Of Storms

10AM Monday Update... I was suspicious of this when I noticed it on the models Sunday, but it now appears there's a good chance a weak disturbance will produce some precipitation Wednesday, especially across western and northern Arkansas.   Some of this could edge into central sections of the state.  If you read the morning post, you know cold and dry air will move into the state in the wake of Monday's system.  As this weak piece of energy moves overhead, some light precipitation could break out.  Conditions do appear somewhat favorable for very light snow across far northern Arkansas with a wintry mix further south. At this time, it appears surface temperatures will all be mostly above freezing.   This is all ahead of the main storm scheduled to arrive Thursday.  By the way, what did that rodent in Pennsylvania say earlier in the month?

Check out the maps below.

This is hi res modeling showing you simulated radar late Wednesday.  Look at the precip over western, northern and some portions of central Arkansas.  The blue is snow, the orange is sleet, the pink is freezing rain, and the green is rain.  You can clearly see the mixture here.
This is the NAM seen with Bufkit.  Read this from right to left.  See the orange line on Wednesday.  That's a period of sleet in Little Rock, then it changes over to rain.  I expect temperatures to be above freezing so any impact on travel would be very minimal at this point.  I'll watch it.

Everyone loves a parade, right?  This weather parade could be loud at times and each performance will be short.  We're in a highly active pattern where systems coming through are fast moving.  This limits the amount of heavy rain which can fall.

The system coming through today (Monday) will bring a good round of rain and a few thunderstorms.  I would not be surprised to see a strong to severe thunderstorm, but at this point, I don't expect this to be widespread. The Storm Prediction Center has outlined the south for a slight risk of severe weather. Strong south winds will howl today at speeds of 15-25 mph and gusty.

Over the past several days I have said we need to keep an eye on the Thursday system.  If you scroll down, you will even see a run of the Euro last week which indicated a chance for wintry weather for far northern Arkansas.  Other model runs showed the potential for severe weather and I stated it could be a combination of both for Arkansas.  Well guess what?  It looks like the later.  The Euro was picking up on that potential last week showing its reliability once again.

There will be an area of cold high pressure located well northeast of the state in the wake of the system coming through Monday.   This will supply a large portion of the state with low level cold air.  This prevents any major severe weather from affecting us.  I still think we could have thunderstorms, but the rough stuff will likely stay across east Texas, Louisiana, Mississippi, and far southern Arkansas.  

The real forecasting headache will be far northern Arkansas where thermal profiles indicates the surface will contain not only cold air, but dry air as well.  There will be a significant push of warm air just a few hundred to a few thousand feet above the surface.  Whatever falls will be rain, but once it starts raining into the cold and dry layer, temperatures could cool even further due to a process called "evaporational cooling".  In other words, ice could form across far northern Arkansas late Wednesday into Thursday.  The duration of this will of course depend on how long those surface temperatures stay below freezing.  

For the remainder of the state, I think it's a cold rain and a few rumbles of thunder.  Again, we'll see how much instability can make it into far southern Arkansas.  There will be the potential for severe weather there.  So how about that?  Ice, rain, and severe weather in Arkansas at the same time!  It has happened before and it's at least a strong possibility Thursday.  This of course can change and I'll keep you posted.  Check out the maps below.

This is the overnight run of the Euro valid Thursday at noon.  Look at the dark blue line.  That's the freezing line near the surface.  This in laying across northern Arkansas indicating a chance for ice north of that line.  The remainder of the state is dealing with a cold rain and thunderstorms.
The HPC indicates a very good chance for at least .01'' of freezing rain across northern and central Arkansas late Wednesday into Thursday.  In my opinion, I think this is too far south, but we'll watch this.
The other component to the Thursday system will be severe weather.  The Storm Prediction Center has this area outlined in red.  Notice this is mostly across Louisiana and Mississippi.  We'll continue to watch far southern Arkansas.
Here is the Euro in one week and guess what?  There could be another significant storm system.  We would be in the warm sector with rain and storms according to this model run.  Soooo much to watch!

1 comment:

Anonymous said...

R.I.P. Winter