Wednesday, February 26, 2014

For Entertainment Purposes Only

For almost a week there has been a persistent rumor that another snowstorm is on the way.  I traced this back to radio spreading the rumor that Farmers’ Almanac had predicted the past two snowstorms and was predicting a third.  I was frequently asked if there was another snowstorm on the way, for which I answered no.  The response was almost always “Well, Farmers’ Almanac is predicting another snowstorm and it predicted the last two.” What?

So I investigated this claim.  First let me point out that there is a Farmers’ Almanac (dating back to 1818) and an Old Farmer’s Almanac (dating back to 1792).  It was Old Farmer’s Almanac that was predicting snow.  Second the forecasts are so vague as to be of little value.  Neither ever forecasted sleet or freezing rain and thus the ice that was so devastating.

Yet there were a few that were adamant that Old Farmer’s Almanac got it right.  If that is the case, then why ever watch the media.  Let’s explore the claim.

I do not have the forecast breakdown for January, but I did get it for February.  For the period of February 7-14, the forecast is for “periods rain and snow, then sunny, cold”.  It was during this period that the snowstorm occurred (11-13).  But, wait!  The forecast is for the entire region from south Georgia to southeast Virginia.  It also includes the Piedmont as well as coastal areas.

Does this forecast apply equally to all locations?  Are we to apply this with rain in the south and snow in the north?  If so, where is the rain/snow line?  Where is there any mention of ice?  Where does it even say snowstorm?  Merriam-Webster Dictionary defines snowstorm as a disturbance of the atmosphere marked by a heavy amount of precipitation in the form of small white ice crystals.  In their forecast how much snow will fall?

Saturday, February 22, 2014

Remembering #WinterMess 2

Little did we know that the winter storm at the end of January would be the prelude to a bigger storm two weeks later (February 11-13).  A complex storm system came through South Carolina in two waves.  The first occurred on Tuesday with snow over the northern Midlands and rain/sleet elsewhere.  This was followed by the main batch of precipitation on Wednesday ending Thursday morning.

Most of the snow occurred over the northern half of the Midlands.  It was mainly sleet with some snow in Columbia, but the precipitation became more snow farther north.  The northern most counties of the Midlands saw a considerable snowfall.

Total snowfall as of 7 a.m. Thursday, February 13, 2014.  This is based on observations from the National Weather Service Forecast Office in Columbia, SC.  Image Credit: WLTX-TV.

South of Columbia it will a sleet/freezing rain mix.  The farther south you went the more freezing rain occurred.  The southern Midlands saw the greatest accumulation of ice as shown on the map below.

Total ice accumulation as of 7 a.m. Thursday, February 13, 2014.  This is based on observations from the National Weather Service Forecast Office in Columbia, SC.  Image Credit: WLTX-TV.

The Midlands ended up on the dividing line between snow and ice.  The northern half saw a snowstorm while for the southern half saw an ice storm.  Travel became difficult if not impossible through some sections.  The worst of the storm occurred over the southern Midlands with the accumulation of ice.  An estimated 350,000 people lost power at the end of the storm.  Some were without power for over a week.  Schools remained closed for Wednesday through Friday with some of the northern counties closing schools on Tuesday.

Tuesday, February 18, 2014

The #BigMelt

There is finally some relief after a week of snow and ice followed by an earthquake.  It was quite cold this past week following the 12th coldest January on record for Columbia.  It was the 11th coldest for South Carolina as a whole in January.  The weather warmed after the first winter storm at the end of January.  Little did we know that it was a warm-up act for the next winter storm.

Most of the snow and ice melted as the sun returned on Friday and a warming trend began.  A cold shot of air on Saturday only slowed the melt, but the warming trend continued on Sunday.  This week will be noticeably warmer this week.  In fact, temperatures will be in the mid to upper 70s by Thursday.

The 7-day forecast for Columbia, SC, for February 18-24, 2014.  Click on the image for a larger view.  Image Credit: WLTX-TV.

Monday, February 10, 2014

#WinterMess the Sequel

And this time she means business!

The big picture described in yesterday’s blog post is still on track, but the details are a little different.  This is based on the latest computer model runs.  Basically, an upper-level system now in the southwestern part of the country will combine with a disturbance moving in from western Canada and will intensify over the Southeast.  This will induce a surface low to form first in the Gulf of Mexico and then off the Southeast coast.  High pressure over New England will push cold air into the Carolinas setting the stage for winter precipitation.  It will be a “big ol’ mess” when all comes together.

A Winter Weather Advisory has been issued for the northern midland counties of Saluda, Newberry, Fairfield, and Kershaw.  This will be for an accumulation of snow and sleet mainly Tuesday morning.  The following is an update from the previous post.

As mentioned yesterday the forecast is a difficult one based on the timing and various forms of winter precipitation that will occur.  The Midlands will see it all; rain, freezing rain, sleet, and snow.  It appears that the onset of precipitation will be late tonight as rain moves into the area.  The rain will likely change to snow during the early morning hours for the northern part of the Midlands (Saluda, Newberry, Fairfield, and Kershaw counties).  There could be enough accumulation to cause travel problems, so travel through the northern Midlands needs to be monitored.  The snow will change to rain and taper off during the afternoon.  This will be the first surge of moisture into the region.

A computer model view (RPM) of precipitation at 6 a.m. Tuesday.  This is from the 21z RPM model run.  The bluish areas are snow and could contain sleet.  The green areas are rain.  The pink is for a wintry mix.  Click on the image for a larger view.  Image Credit: WLTX-TV.

Sunday, February 9, 2014

Another #WinterMess?

Just two weeks ago a winter storm moved through the region producing a combination of rain, freezing rain, sleet, and snow.  Many thought this was it for the winter, but Mother Nature had other ideas.  Look here for a rundown of WinterMess #1.

Incredulously another winter storm is headed through the Southeast.  This time it will be a little different from the previous storm (i.e., no two storms are identical).  A complex weather pattern will develop over the Southeast with an upper-level disturbance moving east and helping to develop a low pressure system off the Carolina coast.  A surge of cold air will be pushing into the Carolinas ahead of this which will turn the rain into a wintry mix.

The models are a little better in converging on a solution.  There is still considerable uncertainty due to the tight area that the worst will fall.  A difference of just 20 miles can make a huge difference in the forecast even at this time range (less than 48 hours).

This blog post is designed to give you a heads up on our thinking and the time frame that things will occur.  There is only moderate confidence in the details, but the overall picture has good confidence.  The scenario and forecast that follows was derived from the 09z, 12z, 15z, and 18z runs of the WSI RPM model along with the 12z runs of the WRF, GFS, ECMWF, and GEM models on Sunday, February 9, 2014.  Each model is slightly different, but the details were mainly from the RPM model.  This represents my best guess at this point.