Showing posts with label uncertain. Show all posts
Showing posts with label uncertain. Show all posts

Tuesday, February 25, 2020

Enjoyed Vermont Taste Of Spring? Good! Back To Winter!

The National Weather Service snow map is back! Click on it to
make it bigger and easier to see. As you can see, the current
forecast has highter snow totals, more than six inches, in the
higher elevations, with less in the valleys, where a mix
with rain is more likely 
Well, that was a nice couple of spring days in Vermont, wasn't it?

Certainly more than warm enough to play in the snow.

If you don't like the snow, you got rid of some of it, especially in the valleys.  Plus, I believe sugarmakers got some early runs in for this year's maple syrup harvest.

This taste of spring is just about over now, and it's back to winter.  We're only in late February, so that's to be expected.  

Given the kind of winter we've had, you'd think we're overdue for another one of many mixed precipitation winter storms. You would be right, and such a storm is on its way.

This time, it doesn't look like there will be a big amount of sleet and freezing rain. But it will rain and it will snow.  Where what falls and when is the challenge.

Pretty much all the storms we've had this winter were a nightmare to forecast, given the temperatures in each one were near 32 degrees. Plus each storm brought complex temperatures to different layers of the atmosphere. If you were off slightly in temperatures, even a degree or so, the forecast would be a bust.

The upcoming storm, in anything, is going to be the most difficult of all to forecast. True, sleet and freezing rain are mostly, but completely out of the picture. But when the heaviest precipitation hits, will it be rain or snow?  Again, being off by a degree in temperature will throw the whole forecast off.

As the National Weather Service in South Burlington sees it, this will be an elevation dependent storm.  This type of scenario becomes more likely as we head into late February or March.  Overall temperatures have begun to warm up toward spring, so valleys tend to be more likely to support a cold rain.

But not always.

Anyway, it looks like there's going to be sharp differences between what goes on in the valleys and up the road 800 or so feet higher.

Here's how the NWS in South Burlington thinks things will play out.

The rest of today will be much cloudier and somewhat cooler than it's been for the past couple of days, but still on the mild side for this time of year. There will be a few spits of wet snowflakes and rain drops around, but it won't amount to anything, really.

There will probably be areas of light sleet and snow around tonight, causing a few slick spots as temperatures fall to near or below freezing.

On Wednesday, things will pick up a bit with somewhat steadier light snow, with a little rain in the valleys. It won't rain and snow all day, but it will be dank and wet and somewhat slushy.

Wednesday night and Thursday morning will bring the main show.  And the part of the forecast that is by far the trickiest

As heavier precipitation arrives, that will tend to cool the atmosphere, which favors snow. But slightly warmer air will trying to come in from the south and east, favoring rain, at least in the valleys.

National Weather Service meteorologist believe it will be cold enough for wet snow, even in the valleys. But it will be so slushy, and possibly mixed with rain, that the warmer low elevations will only get a couple inches of soggy snow.

Go up a few hundred feet in elevation and it would be a completely different scenario, forecasters believed as of this Tuesday morning. If you're up at an elevation of 800 or 1,000 feet, you could easily see four to eight inches of wet snow.  The mountain summits could see a foot or more.

Then there will be the local effects. On the immediate lee of the Green Mountains, on the eastern side, strong maybe even damaging downslope winds seem like they want to get cranking later Wednesday night and Thursday morning.

Those winds could cause local power line problems and bring down a few trees. The downslope winds also tend to dry the atmosphere right up against the west side of the mountains, so precipitation could, maybe, be much lighter there.

Since this will be wet, heavy snow, there's definitely the risk of power failures.  If you live in areas out of the valleys, be prepared for that. The heaviest snow will come down on the eastern and southeastern slopes of the mountains.

Things will taper off Thursday afternoon.  Then, Thursday night and into the weekend, it will turn much colder.  Persistent snow showers will continue, especially in the northern and central Green Mountains, where several more inches of snow could pile up betweeen Thursday afternoon and Saturday.

This bodes well for the ski areas.  There, the warm, but rather dry weather over the past couple of days didn't cause much damage to the snowpack.  Plus, by the time the weekend hits, it looks like there will be a decent addition to the snow on the slopes.

By the way, I said it will turn much colder, but it's late enough in the winter in which cold snaps often don't have the bite they did in January.

This means highs on Friday and Saturday will be within a few degrees of 20, and lows will be in the single numbers. Cold, yes, but not unbearable.

It'll start to warm up again somewhat toward Sunday and Monday.

Bottom line, get ready for another messy storm that will probably make your commutes to and from work annoying  on Thursday and maybe cut your power.  And, unless you live in a warmer valley, you face a backbreaking chore of clearing heavy, wet snow after the storm is over.

Also, definitely be ready for surprises.  The valleys that are now forecast to get an inch or two of slush could end up getting much more, if the temperature is a degree or two colder than now forecast.  Or, the rain could creep a little further up the hillsides if it's just a degree or two on the warm side.

I'm sure there will be a few refinements and changes to the forecast before we get to Wednesday evening. We'll monitor!


Sunday, December 7, 2014

Once Again, New England In For Big But Uncertain Storm

A storm is forecast in New England this week, but
its effects are very uncertain.  
I feel a little bit like Bill Murray in "Groundhog Day," but once again I'm watching a pretty big storm headed toward New England, but I still have no clue exactly what will happen with that.

If this sounds familiar, it should. A few days before Thanksgiving, forecasters were all scratching their heads over a storm headed into the Northeast, with uncertain predictions of heavy snow and rain.

The storm ultimately dumped six inches to more than a foot of heavy wet snow on the Northeast, especially New England, causing travel problems, and worse, wide spread power failures that lasted into Thanksgiving and beyond in parts of the Northeast.

Now, we're faced with another oncoming nor'easter, and this one is more tricky to forecast than the one that hit the day before Thanksgiving.

Most nor'easters chug up the coast, or just off the coast, heading at a steady pace from, say North Carolina to Cape Cod and on up into the Maritime provinces of Canada.

This one looks to form off the mid-Atlantic coast, maybe even fairly far off the coast, then head northward, or north northwestward toward New England, which is kind of an odd path.

Worse, once the storm gets to southeastern New England, it looks like it wants to meander around that area of the country instead of just marching off to Canada like most storms do.

This weird potential outcome for the storm makes forecasting its effects much harder. How much warm air will flow into New England from the east as the storm sits there? Will it be heavy rain?

There will be snow, but how far inland will the heaviest snow set up? Just in the mountains? Or in most areas of Vermont, New Hampshire and Maine?  Will it rain hard enough along the coast to cause flooding? What about storm surges and coastal flooding?

The details are still murky. But suffice it to say, Tuesday through at least Thursday are looking quite stormy in New England. I just don't know yet what kind of storm any particular spot will get.

When storms stall out and meander, like this one could, they gradually just sit there and weaken. So by around Friday,  the storm might still be around, but will be petering out. Eventually, it will just skulk out to sea, and things will improve by the end of the week.

Stay tuned for later forecasts. We'll have a somewhat better idea what to expect by tomorrow.