Hints Of Springtime In Vermont That Feel Wintry Happening, And Coming Up

River gauge readings from yesterday on the Mad River
in Moretown, Vermont. Click on the image to make
it bigger and easier to read. You can see an
abrupt rise in the river as water backed up behind
an ice jam. Then the river level dropped back down
suddenly when the ice jam broke up.

 No big storms are on Vermont's immediate horizon, but some subtle and potentially frustrating little weather events coming up are sort of signs of spring.  

Even though those signs of spring are paradoxically wintry.

ICE JAMS

The first of course is ice jams, something we had to keep an eye on during Thursday. 

Thawing weather and rain basically created piles of ice. 

There was a lot of ice movement on the rivers, and some of that ice got jumbled up into piles and clogs near obstructions. There were only perhaps a couple real ice jams in Vermont that I'm aware of. They caused at worst minor flooding and minor damage.

The jams didn't form in the "wrong" places - i.e. just downstream from a riverside town or city.  So in this case we didn't have to deal with a lot of buildings getting flooded, 

The most notable jam was - as mentioned yesterday - on the Mad River near Moretown. You can see on the chart in this post how the jam abruptly made the river rise to flood stage. Then the jam apparently broke and the water level almost instantly returned to normal levels.

With colder air in place, if there are any ice jams, they're probably pretty stable for now. They could always abruptly move, but the chances of new problems with these over the next few days is pretty low.

CONVECTIVE SNOW?

Convective clouds and updrafts gather themselves into
rain and snow showers last March 17 in St. Albans,
Vermont.  This time of year, the sun begins to get
strong enough to help power scattered hit and 
miss snow showers even on cold, blustery days.

In the warmer seasons, strong sunshine can cause updrafts.  Under the right conditions those updrafts can help form showers and thunderstorms. That's why we do have those hit and miss storms all summer around here. Those scattered showers and storms are known as convection. 

Now, today by any measure will be a chilly and blustery one, nothing summery about it.  Temperatures will barely get to freezing if that. It's so gusty that a wind advisory is up for most of Vermont outside the Champlain Valley. In the advisory area, gusts to 50 mph could cause some isolated power outages.

Helping with the gusts is the strengthening March sun. It's getting powerful enough to heat the ground to an extent, creating updrafts and instability that can bring higher gusts to the surface. The fields and forest floors are still snow-covered, so the effect isn't nearly as pronounced as it would be with bare ground, but the sun can have an effect. 

The air is a bit unstable to begin with, so a few snow showers are inevitable anyway. That sunshine peaking through the clouds today might help power up some scattered hit and miss snow showers, much like those summer thunder showers.  Since this is convective, a few might be very briefly heavy with stronger, gustier winds. 

Most of us won't see something like this today, but a few places probably will. So yes, a harbinger of spring will probably generate a few minutes-long little mini-blizzards here and there. Luckily, there will be no big snow accumulations out of any of this. 

You're probably going to see more of this type of situation on blustery days during the rest of March and probably a good chunk of April.

BATTLEGROUND

A frustrating aspect of spring - especially in March and April in Vermont - is those pesky stalled fronts in which it seems everybody in the central and eastern U.S. is enjoying spring weather except northern New England. 

The battle line this time of year between the forces of spring and the waning strength of winter is right along the Canadian border.  For the most part, that battle line is further north than, say, January. 

The result this time of year is that as most places warm up, often  a shallow, dense layer of chilly air oozes down from Quebec, making parts of Vermont shiver while places not that far south enjoy balmy, sunny spring breezes.

This set up seems to most often affect the northern Champlain Valley. They cold air hugs the surface and often extends upward only a few thousand feet. 

There's no mountains to block this shallow cold air between Quebec and northwest Vermont, so the chilly air floods in.  You end up with days in which say, Bennington, might be sunny and 60 degrees and St. Albans is stuck in the mid-30s. 

This set up looks like it might happen toward Wednesday. Initially, some warm air would bathe pretty much all of Vermont. Forecasts call for highs in the low 50s Tuesday, which would make it the warmest day so far this year. 

Then that pesky shallow cold air from Quebec seems to want to make an appearance. Currently, forecast highs in the northern Champlain Valley are around the low 40s Wednesday, but I think it might even be colder than that. This situation would probably linger into at least Thursday. 

These things are a little hard to predict and tease out days in advance, so things might still work out differently midweek. We shall see. 

Even so, that low level cold air is another paradoxal sign of spring.  Northern Vermont is in the war to reach spring. Chances are we'll lose the battle Wednesday, but we'll win the overall war eventually.