Thursday, January 17, 2019…4 P.M.

Subtle changes

If you’re a snow-lover you’re not going to like the small changes to Saturday’s forecast.  Both the GFS and NAM have drifted in the same direction, so I’ve got pretty good confidence the solution they are pointing toward looks realistic.

We’ve been tracking a storm system blasting northern California and a large chunk of Arctic air moving south from Canada.  Original thought was these two systems would merge over the Ohio Valley/midwest on Saturday.  The result of the merged system would bring us plenty of rain (2″-3″) Saturday.  Then, as the cold air rushed in Saturday night, we’d see an inch or two of snow.  I’ve heard talk of heavier snow, a “flash freeze,”  and single-digit temperatures (even sub-zero).

That’s all nonsense if the current model trends are correct.  The new idea is that the west coast trough and the cold air system will not get “in phase” until the primary surface storm system passes east of the Louisville area.  That means the storm system will not get to its rapid development stage until it gets to Ohio or beyond.

Consequences of the recent changes

1).  Rain remains likely most of the day Saturday.  But it won’t be as much.  Totals will probably range in the 1″ to 1.5″ range.

2).  Rain should end by Saturday evening and we’ll probably see some snow flurries and/or snow showers overnight.  Accumulation, if any, should be less than 1″.

3).  The initial surge of colder air will be slower to arrive.  Temperatures will not fall rapidly enough to allow a flash freeze.  Icy spots, however, will form on roadways during Saturday evening.

4).  Sunday will be very cold…probably near 20-22 all day.  Because the primary storm system will intensify north/east of Louisville, the cold air transport southward will be weaker.  Thus, it appears the local temperatures won’t drop into the single digits in the Louisville area either Monday or Tuesday morning.  Rural areas especially in southern IN could see lows below 10 degrees.)

Note:

The cold upper trough expected over the eastern parts of North America due to the Sudden Stratospheric Warning of late December is now in place.  This system should provide us with frequent snow opportunities and plenty of cold air for the next 2-4 weeks.  Forecasting should be lots of fun.

If you’d like a little more detail on what a Sudden Stratospheric Warming is, see my post from a couple of weeks ago.

Stuff:

We are constantly bombarded by the things that the climate change “hawks” want us to hear, so you probably missed the news that the U.S. is one of the world leaders in carbon emissions REDUCTION.  Yes, compared to the 2005 baseline, total U.S. emissions have dropped 11%, even though we had a small increase last year.  As a whole, Europe has dropped a little (1-3%) as well.  But, the rest of the world continues their rapid increases.  Roughly 80-90% of the nations which signed the Paris Climate Accord continue to increase their emissions.  China and India are by far the biggest offenders.

Let’s not blame China too much.  After all, they have a signed agreement with the U.S.  to keep increasing emissions as much as they want until 2030.  The Climate Gang praised that agreement as just about the greatest thing since (the proverbial) sliced bread.  I’ve always felt that the agreement gave China all the bread and the slicer.  Maybe we’ll get some crumbs out of the deal.