Friday, January 02, 2015

BIG Cold Shots And Watching The End Of Next Week


6:30 PM Saturday Update....  You may remember several blog posts ago (last weekend), I showed you the arctic oscillation index.   It advertised a sharp rise from the negative into the positive.  When it makes a rapid rise, we usually get big rain events and big storms.  Look what has happened in the last 24 hours.  Some portions of Arkansas had more than 3 inches of rain and Mississippi and Alabama had tornadoes today.  That recognition worked out well with the forecast.

Now what about down the road?  The models continue to indicate very strong surges of arctic air into the central portions of the country.  There will be a parade of fronts.  One arrives tonight (Saturday) and that will cool temperatures down Sunday and Monday significantly.  As a matter of fact, lows could reach the upper teens and lower 20s as early as Monday morning.  We'll have a brief warm up Tuesday ahead of a stronger batch of cold air.  It's possible not to get out of the 20s Thursday with lows in the single digits and teens.  After that, the forecast becomes a little "muddled" as some moisture may try to overrun the cold air at the surface.  It's too early for specifics.

I'll update Sunday, but not sure when.  I'm taking the weekend off work.  We celebrated my 3 year old birthday so it's family time this weekend.

_____________________________________________________________________________



All winter weather lovers are getting anxious for some snow.  I keep hearing people say it was supposed be a harsh winter and they want to know when we'll get a good snow.  It's important to understand winter has just started.  Our two main months for snow and cold are January and February. We all know March can come into play at times too.  The last two years have brought big early season snow/ice events so us snow lovers have gotten a little spoiled.

Now about the forecast for a harsh winter.   I don't know where this was predicted.  Was it the Farmer's Almanac or some of these Facebook posts with wild predictions which get shared all over the Internet?  The forecast I showed in the fall was from weatherbell.com because they have a very good track record.  They called for the worst of winter to be just north of us with temperatures here below average and snowfall up to 133% of average.  This is based upon 30 years of climatology statistics.  Based on that,  total snow should be around 4-5 inches in central Arkansas for the months of December through February.  That's not a lot compared to the past few years!  Remember, we can get 4-5 inches in less than 6 hours around here easily.  So will it be harsh?  There's still so much winter in front of us, it's still possible, so we'll see. I liked the weatherbell predictions in the long range.

Now let's talk about what I specialize in... a forecast for 7 to 10 days.  The forecast I put out there last weekend for mainly a cold rain has worked out well.  I even thought there was a chance for thunderstorm activity over southeast Arkansas and that's possible tonight into Saturday morning.  Once the rain clears out Saturday afternoon, clouds will stick around.  I expect some clearing Sunday as a new arctic air mass moves through the region.  A weak disturbance will also come through Sunday morning with a few snow flurries possible over northwest Arkansas.  Sunday and Monday will be chilly with a brief and small warm up Tuesday.  There's the potential for an even stronger arctic front by the middle of next week with highs in the 30s Wednesday and Thursday.

Just yesterday, Meteorologist Ryan Vaughan at KAIT, tweeted about a possible overrunning event late next week.  It's showing up well on the GFS model.  Normally I bash this model, but for us, it has done well this winter.  PLEASE, do not get your hopes up.  This blog is all about looking at what's down the road and my thoughts.  It's not always a forecast, but a look at forecasting behind the scenes.

The following maps are from weatherbell.com

This is the surface map valid Sunday morning at 6AM.  The black lines are isobars (lines of equal surface barometric pressure).  You see where low pressure is located over the Great Lakes with a 994mb low and a 1048 mb high coming out of Canada.  The flow out of the high is clockwise with the flow into the low counterclockwise.  There's a weak disturbance bringing flurries over southern Missouri.  I have seen other data which indicates there could be flurries over NW Arkansas too.  See how tightly packed those black lines are?  That's a strong pressure gradient between high and low pressure.  This is a stiff north wind bringing a new batch of cold air into the state.
After a cold Sunday and Monday, temperatures will warm a little Tuesday.  There's a new arctic high coming out of Canada, but it won't arrive until later Tuesday.  This is valid Tuesday at noon.  This model implies a small warm up between air masses so it's possible to see upper 40s and lower 50s Tuesday.  These fronts are coming in from the NW so they are dry with only a few clouds.
By Wednesday, a potentially stronger area of arctic high pressure is located over South Dakota.  This is valid at 6PM Wednesday.  The solid red line is the 32 degree isotherm and that's located over far southern L.A. (Lower Arkansas). LOL.  Sorry, I had to go there.  Anyway, this is a very cold air mass with very low wind chill values.
Another area of high pressure moves in late Friday into Saturday morning (January 9th and 10th).  This is what Ryan Vaughan was looking at.  There's some energy coming out of the west throwing moisture on top of the cold air with light ice and snow breaking out over OK, TX, and even LA.  PLEASE DO NOT TAKE THIS LITERALLY... PLEASE!  These specifics will change at least 30 times between now and then assuming this actually materializes.  But it is something to watch with all these cold air masses coming down.  Hopefully, we can get some moisture in here too.  I'll keep you updated.

No comments: