Sunday, January 04, 2015

The Cold Will Be Bold


The coming cold is an "arctic invasion" in every sense of the phrase.  We're experiencing round number 1 with another arriving late Tuesday into Wednesday and that batch will be stronger.  I think it's entirely possible to spend most of Wednesday, Thursday, and Friday below freezing for at least the northern half of the state including the metro.

The winds will be strong as the arctic chill first sets into Arkansas.  I think it's very possible for "wind chill advisories" to be issued for the Wednesday/Thursday time frame across northern Arkansas.  This will be pipe busting weather and you will need to remember PETS AND PEOPLE TOO!

I want to make it clear, this will not be the coldest air mass we have ever seen in this state, but it will be a shock for a few reasons.  First, we have been relatively mild since the beginning of December with a trend towards colder air since Christmas.  Second, the time spent below freezing will be significant.  Third, it will come with strong winds taking wind chill readings below zero north and single digits central and south.

What good is cold without snow?  I know many of you are saying that.  There's a lot of chatter around social media about the chance for snow/ice next weekend.  It's there on the models and I even discussed that a couple days ago on the blog.   Once again, I will use my standard disclaimer.  This is several days away and forecasting specifics is useless.  It does appear IF any moisture arrives, the upper levels may be too warm to support snow for many of us, but the cold air at the surface may linger awhile.  It's really too early to say for sure though.  I think it's best to say the biggest weather story this week will be the cold and we'll have to watch next weekend.  The timing is not certain either.

The following maps are from weatherbell.com


This is the GFS surface map valid at noon Wednesday.  That's a 1057 mb high over South Dakota.  That's very, very strong signifying very cold dense arctic air.  The dark blue line is the freezing line and that's located just south of the LR metro area. Temperatures should fall all day Wednesday.  The flow around that high is clockwise so we have a strong northerly component to the wind.  The black lines (isobars) are lines of equal barometric pressure.   The gradient is strong which means winds will be up there.  I think it's very likely gusts we will exceed 20-25 mph and maybe above 30 mph at times.
Look at these lows Thursday morning.  Single digits north with teens elsewhere.  These are not records, but this will get your attention!!!!
The wind chill factor will really get your attention.  I think we'll have a chance for below zero wind chill readings north with the "feels like" temperature in the single digits central and south.  A wind chill advisory may be needed for northern Arkansas.
A cold area of high pressure will be located north of the state and that's our cold air pump at the surface.  At the same time, moisture COULD start overrunning that dome of cold air at the surface.  This indicates much of the state is at or below freezing with either sleet or freezing rain expected.  DON'T GET WORRIED AT THIS POINT!!!!!  This is a week away and forecasting specifics are useless.  Just know we need to watch this time period carefully.  Maybe the cold air will be deep enough and it will be snow.  There's even a chance this doesn't materialize at all.  But hey, it's my blog and I get to show you these things! LOL
This is the temperature profile next Sunday morning from the GFS.  The bottom is the surface and the top is wayyyyyyy up into the atmosphere.  See that diagonal 0 line?  I have it labeled "freezing line".  That's in degrees Celsius.  You can clearly see the push of low level cold air, then as you go up in elevation, there's a warm nose as southwesterly winds a few thousand feet up develop.  This is why I do not think snowflakes will be likely.   You must have that profile to the left of that 0 line all the way up.

IN SUMMARY, WE'RE VERY CONFIDENT THE COLD AIR IS COMING, BUT AT THIS TIME, THE CHANCE FOR WINTRY WEATHER NEXT WEEKEND IS NOT A SURE THING.  I KNOW MANY OF YOU ARE STARVING FOR SOME SORT OF WINTRY WEATHER.  I DON'T WANT ICE.  I MUCH RATHER HAVE SNOWFALL.  REMEMBER, WINTER IS JUST GETTING UNDERWAY AND I'M SURE WE'LL HAVE MORE FUN AND GAMES OVER THE NEXT 2-3 MONTHS.

I'LL HAVE MORE MONDAY.

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NOAA Winter Guidance