Stay On Target…

Subject Line is courtesy of our 5-year old and his affinity for Star Wars, movies I’m getting to watch over and over… applies to this fcst too (Although, I have to wonder if they were able to build the original Death Star with a gravity beam to pull ships in, why didn’t they… never mind.  Sorry. )

Short Version:  A late winter storm is on the menu for Monday morning as cold air pouring into the area behind a strong cold front will cause rain to change to freezing rain, sleet, and snow.  Models still have notably different pcp types and accumulations, but if I had to pick a number 72 hours out, I’m thinking 3 to 6″ of snow on top of a layer of sleet and perhaps some freezing rain.

The It’s Friday and Reading This Will Make It Look Like I’m Working Version:  I hate these Cold-air vs Pcp races, and it’s what we’ve got going.  Warm front will lift north on Saturday – with little if any pcp – and then push back south as a cold front on Sunday.  Meanwhile, the little swirly-whirly readily apparent in today’s satellite loop off the coast of California…

http://www.ssec.wisc.edu/data/us_comp/us_comp_big.html

… will zip east, and use the cold front as a roadway to the Atlantic Coast.  As I’ve said probably too much already, the final placement of the front will make or break this forecast.  If the front ends up to the north in MD, we get rain; over central and srn VA, we get heavy ice and snow; and if it ends up over NC, we get light snow.  The consensus as of Friday is for option 2.

So, a warm Sunday will come to a crashing end late Sunday afternoon and evening.  Rain will arrive from the west during the evening, and then the race is on.  As cold air gets firmly established at the surface, but warm air remains entrenched aloft (~ 5,000 ft up), we’ll see freezing rain and sleet develop.  By early morning Monday, sleet and snow will likely become the dominant pcp type as cold air gradually wins out, with the change over occurring from north to south.  Pcp will be heaviest in the morning hours Monday, and be over by Monday afternoon.  I’m still bothered by the fact that we’ll be waiting for cold air to get here… these can be really tricky, and this is far from a done deal.  Prelim snow accumulation will – if this fcst holds – be on the order of 3 to 6″.  I also think sleet will be the other dominant pcp type, with hopefully not too much freezing rain.  Here are a few model forecasts…

NAM:  If you’ve been hankering for freezing rain and sleet, than this is your model.  It has very little snow, and actually has very little pcp south of DC.  It does suggest a heavy dose of sleet… with snow confined to far nrn and western MD and srn PA.  It kinda sucks, actually.

NAM Pcp Type for Monday morning... mostly sleet (in red).

NAM Pcp Type for Monday morning… mostly sleet (in red).

 

The GFS:  GFS has held steadfast that this would be a cold event.  The GFS has a coating of freezing rain and sleet, followed by 6 to 8″ of snow.  For everyone.

Snow (blue) is farther south in the GFS as of Monday morning, 7 am, EST.

Snow (blue) is farther south in the GFS as of Monday morning, 7 am, EST.

 

The Canadian:  The Canadian is colder but lighter… with a bit of light rain, followed by sleet and snow.  It’s pretty evenly split on how much of each we get, with ~ 0.25″ of sleet and another 0.25″ falling as snow, which would get us ~ 1-3″ of snow on top of a solid base of sleet.

Canadian Model pcp type is mostly snow, but lighter.

Canadian Model pcp type is sleet, changing to snow shortly after 7 am, EST on Monday..

 

The Navy NAVGEM:  This model went from being rock-solid sleet and snow to wavering like a drunken sailor; it offered up a warmer, rainier solution overnight, but has now come back in line with mostly sleet and snow Monday morning with the latest morning model run.

And now… down off the mountain, the moment you’ve been waiting for…

The European Model:  The European has come in surprisingly colder, with a period of moderate to heavy snow in the late morning on Monday.  The European has rain arriving earlier on Sunday, so we don’t get quite as warm as the NAM.  The model then changes rain to sleet and freezing rain shortly after Midnight, and then snow during the pre-dawn hours…. with a solid 4 to 7″ of snow across the entire region during the morning Monday.  It actually has the heaviest snow (locally more than 8″) falling south and east of D.C…

How you’ll know which way this is trending:  If it’s 60° and sunny on Sunday… that’s not a good sign… and the warmer, uglier NAM would be on track to verify.  If clouds and showers arrive during the afternoon, then the colder, snowier European and GFS are on track.

I’ll bother y’all some more about later.

Oh, and next Friday… more fun!


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