Vermont Weather Takes Uncertain Turn As Pesky Storm Lingers

People enjoyed a sunny day yesterday at the University
of Vermont campus in Burlington, Vermont.  It turns
out it might well have been the last sunny day
we'll see in Vermont for a week. 

 For at least a week now, computer forecasting models have been expecting a stalled  upper level low to set up in early May somewhere in or near the eastern United States.  

The problem has been where does it set up? Close to Vermont, we get a long spell of showery weather. Far enough away, it would be generally sunny and mild.  It's been a tossup.

Now, there's more consensus that this thing will be close enough to make us showery.  But how showery?

We're still not sure.

These sluggish, stalled systems are often very hard to nail down. Sure, you can pretty accurate predict where the upper low will be a day, or two even three days from now. But what that upper low does down here where we live is always a question mark.

At ground level, these upper lows produce stalled or nearly stalled weather fronts. They spin up weak storms that could go right over us, or miss.  The upper lows help bring in moisture from the Atlantic Ocean that comes in surges then wanes, changing the chances that it will rain. 

So, it you need help planning your Vermont outdoor weather plans for the next week or so, meteorologists will be of little help.  At least with the specifics. 

Broad brush, the forecast is set.  There's a chance of showers daily today through probably next Thursday. When on those days the showers hit, and where, and how heavy they might be is questionable.  Will there be breaks of sun? Quite possibly. When? Who knows?

Expect changes to forecasts daily. 

TRYING AT SPECIFICS

Meteorologists, including the National Weather Service in South Burlington, of course are taking a crack at the forecast.

The rain from this morning is leaving Vermont as of 9 a.m.   We'll still be near a weather front today, with a warm front to the north and a cold front to the west. 

That'll leave us in some warm, somewhat humid air.  So, with the fronts near by and the air being a bit unstable with that moisture, we could see some scattered showers and thunderstorms this afternoon and early evening. Those storms would be hit and miss, and not severe. Though a few might contain some briefly gusty winds. 

That upper low we've talked about looks like it will start out tomorrow in the Ohio or even Mississippi Valley - further west than first thought. 

That upper low will influence that cold front that's to our west today. It'll make the front stall near or just south of Vermont.  Little disturbances will track southwest to northeast along that front, which would push showers our way. 

Although it won't rain all day tomorrow, it will be our seventh rainy Saturday in a row. I guess we just can't escape that.  At this point it looks like most of the rain would be in the afternoon, and most persistent in southern and eastern Vermont. 

That front will be hanging around Sunday, so we're at risk for shower then, too. Best chances of showers I think would be southern Vermont. I don't think the entire day will be a washout. 

The rest of the forecast is of course very iffy.   The thought currently is that upper level low will come toward New England, increasing the chances of showers by Tuesday. The hope is it will get out of our hair by about a week from now, opening the door to some spring sunshine. 

At least temperatures during this episode will be close to normal by day, a little on the warm side at night due to clouds. That means daily highs after today in the 57 to 65 degree range and lows in the 40s to near 50. 

Bonus: No snow!!

A Summer Of Upper Level Lows Creates Strange Weather, We Are Experiencing The Latest Now

Upper level forecast map from NOAA for this
evening. One upper low spinning over northern
New England, and another northwest of Washington
State heading southward toward northern California.

 This is ending up being the summer of odd upper level cut-off low pressure systems that are all promoting strange, and sometimes dangerous weather here and elsewhere in the nation. 

An upper level cut off low is a storm in the upper levels of the atmosphere that's separated - or cut off- from the jet stream. 

Since the jet stream isn't there to push them along, these upper level lows - which are really pools of cool air aloft - tend to meander and move slowly. That, in turn, causes sometimes extended periods of unsettled, bad, or even dangerous weather. 

The latest of these upper lows is over us now.  I wouldn't say what we're experiencing this time is especially dangerous, though it does have its hazards.

Our current upper low is over-performing, as so many weather systems have lately. It's stronger and more persistent than many previous forecasts indicated. It's producing more rain than prior predictions hinted at too.  It's pretty damn chilly under this thing, too. 

Some places around Vermont will have near record low high temperatures today. Burlington missed that record by just two degrees Tuesday, as it only reached a high of 62 degrees. Burlington won't break that record today.  The lowest high temperature on this date was 58 degrees in 1982.  It was already 58 degrees as of 

I had said for the past several days that the rain with this system would fall far short of creating any flood risks. 

It turns out that it actually might cause issues, but the risk is pretty low. The upper low is pretty much right over us, which means any showers that get going today will move very slowly. 

This afternoon, the contrast between the meager (and I do mean meager) warmth near the surface and the very cold air aloft will give the showers a convective feel. Instead of the bland gray overcast with light rain we had this morning, things will evolve into tall billowing clouds which could produce local downpours. 

NOAA's Weather Prediction Center has actually put us under a marginal risk of excessive rains or local flash floods today. 

I still don't think this will end up being a major issue, though. There might be local, minor problems, but as you've surely noticed, we're lacking the deep tropical humidity that can lead to torrential downpours. So we're not going to have flood havoc today. 

Satellite view of a cut-off low centered over central
New England on the evening of July 29. This 
system would go on to cause a devastating flood
in the Northeast Kingdom of Vermont
several hours after this pic was taken. 

But since scattered afternoon downpours might have such a slow forward motion, we'll have local issues with ponding of water on roads, and minor washouts here and there, especially where recently repaired roads and driveways haven't been packed down and stabilized yet after prior flood damage. 

OTHER CUT OFF LOWS

Other upper level cut off lows have caused strangeness, and worse, scary danger here and elsewhere this summer. 

It was a meandering upper level low that tapped into deep tropical moisture that unleashed horrendous downpours on the Northeast Kingdom back on July 30.  We all know the calamity that caused. Don't worry, nothing like that will happen today in Vermont. This is a completely different situation. 

A more recent upper level low (related to the one we're dealing with now) contributed to dangerous flooding in and near Toronto last Saturday and deadly flooding in Connecticut on Sunday. 

Yet another cut off low is heading southward along the Pacific Northwest coast. It promises to briefly interrupt a very hot, dry summer in California and probably will lead to a very rare summer snowfall up high in the Sierra Nevada mountains. Snow levels could go as low as 7,600 feet above sea level.

Strong, dry winds ahead of this system are likely to stir up California, Nevada and Oregon forest fires today, making them especially dangerous. 

I'm not sure whether these upper lows are related to climate change or not.  Likely not. But the torrential rains associated with some of them probably are. As the atmosphere warms, it can hold more moisture. Meaning that when you get "perfect" setups, like July 30 over the Northeast Kingdom, it means the downpours end up being heavier than they would have been decades ago. Meaning bigger disasters. 

As for our that upper level cut off low meandering overhead in Vermont today, it will get a push to move slowly to the northeast and out of our hair by Thursday night. By Friday and the weekend, we should be back to our regularly scheduled, late summer warm but not hot weather.