Saturday, March 01, 2014

Winter Storm Update

This could turn out to be quite a mess.  Remember what I always say?  Arctic air usually arrives faster and stronger than the models predict.  I think they are playing catch up right now.  This is why each run of the models come back colder and colder.  In these situations, it's important not to flip your forecast with each run of data, but use history as a guide and so far that has served us well with this storm.  Of course, the storm isn't even here yet.

My thinking has not changed much at all.  There are a few things I want to point out The winds late Sunday into Monday morning will be very strong.  In places that receive significant freezing rain, this could add insult to injury with more power outages.  I have seen Entergy tweeting quite a bit today so they are getting prepared.  I'm really hoping the majority of the frozen precipitation will be in the form of sleet and that's definitely a possibility, but there will be freezing rain and it will cause problems.  Also, this is nothing to play around with.  If the forecast pans out, traveling late Sunday is not advised.  Imagine getting stuck with all that frozen precipitation falling and gusty winds.  

The other issue I want to point out is the potential for record breaking low temperatures Monday morning and again Tuesday morning.  Many times the models will be too warm with predicted low temperatures because it doesn't see snow/ice over.  The record low Monday morning is 11 degrees set in 1943 and the record Tuesday morning is 15 set in 2002.  Also,  we could have the coldest daytime high temperature Monday.  That record was also set in 2002 at 31 degrees.  I'm not saying these will be broken, but they could be challenged.

Some of the frozen precipitation will come with thunder and lightning.  This "convection" will likely enhance amounts.

One more thing before I get to the maps.  There is a slight risk for severe thunderstorms across far southern Arkansas.  The main threats will be hail and wind.

These maps are from  Remember, the precipitation is the amount over the previous 6 hours.  Green is rain, blue is snow, orange is sleet, and purple is freezing rain.  The red line is the freezing line and the blue line is the 35 degree line.

Here's my usual disclaimer... even though the models are in agreement, things can and still will change.  No snow/ice forecast is ever perfect.

By 6AM, we already have sleet and freezing rain across northern Arkansas with scattered showers further south.  It's still "mild" across central Arkansas.  You will know when the front passes (7-9AM).  the winds will abruptly change out of the NE and there will be a very noticeable drop in temperature immediaately.
Between 6 AM and Noon, the rain really begins to pick up and temperatures are falling.  Roads across the north are deteriorating with sleet and freezing rain falling.  As of noon, we should still be rain across central and southern Arkansas.   Remember, the danger is the cold air arriving faster and stronger.
Between noon and 6PM Sunday, the transition has occurred in central Arkansas.  I'm thinking we'll first have freezing rain, then it will go to sleet.  I expect a changeover sometime between 2-5 PM in the metro.  Southern Arkansas is still rain, but temperatures there are now falling.  The north is getting plenty of sleet and maybe some snow near the Missouri border.
Between 6PM and midnight, the transition has occurred across much of southern Arkansas and sleet is falling across the large majority of the state.  There's even snow in northwest Arkansas.  Do you see the darker oranges in central and eastern Arkansas into western TN?  This could be an area where sleet amounts are greater.
By Monday morning at 6AM, it's basically over and moving away.  This may end as some snow across much of northern Arkansas, but the majority of the precip will be freezing rain and sleet.
Temperatures Monday morning could be in the single digits north and teens elsewhere.  Look at Little Rock.  This 1 model shows temperatures around 11.  IF that verifies, the 1943 record low could be challenged.  AMAZING.

In summary, the confidence level for a significant winter storm is high.  Things can and do go wrong with the forecast and I'll be adjusting and letting you know of any changes along the way.  Right now, we're really hoping a lot of this falls as sleet.  This would cause travel problems, but lesson the power outage danger.  However, some will fall as freezing rain and we need to be prepared for that.

Thanks for coming to the Arkansas Weather Blog and I look forward to providing you with more information here, on twitter, facebook, and on the air Sunday.  Have a good one.

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