A Rather Wild May Weather Month Continuing In Vermont, Elsewhere Too

On this cool, cloudy morning, the progression of spring
continues in my St. Albans, Vermont gardens. The
daffodils have faded away, and now the irises and 
peonies are budding, preparing for their show. 

After a stunningly gorgeous, perfect spring day on Wednesday in Vermont, we're back to the roller coaster ride of changeable weather.  It's a pattern that's affecting much of the nation. In some places much more dramatically than here in New England. 

We'll start with the local stuff first. Today will certainly not be as brilliant as Wednesday as a fast moving weather disturbance zips through.  

We're starting off cool today. There's even a little frost in the cold hollows of the Northeast Kingdom. With the clouds with this weather disturbance now in place, temperatures won't be able to rise much today. Especially as the rain moves in.  

Most of us will stay in the 50s, which is more than 10 degrees on the cool side. This relative chill is not that odd for this time of year. (The record lowest "high" temperature on this date in Burlington is 43 degrees in 1976).

Rainfall will only amount to a quarter inch today, give or take.  There might be some embedded heavier showers or even a rumble of thunder which would create locally higher amounts of rain. But we'll fall far, far short of any flooding concerns. It's just a little water for the gardens so that you won't have to drag the hoses to the raised beds today. 

The weather variety show continues on Friday as things turn dramatically different again. Winds will turn gusty from the south, especially in the Champlain Valley. By Friday afternoon, instead of 10 degrees cooler than normal, we'll be ten degrees above normal - near 80 degrees. 

Another couple of acts arrive for our variety show on Saturday. It will be a sultry summer day, with highs in 85 to 90 degree range. It will be humid. 

As the National Weather Service in South Burlington points out, some ingredients for strong storms will be in place by later Saturday afternoon, but there won't be much in the way to trigger much of anything.

When forecasting thunderstorms, one of many things meteorologists look at is CAPE, or Convective Available Potential Energy.  This is all a way to determine instability in the atmosphere and the strength of updrafts. The higher the CAPE value the higher the risk of thunderstorms, some strong to severe.

Here in Vermont, if you see CAPE values above 2,000 joules per kilogram (J/kg) we have ingredients for bopping boomers for sure.  CAPE values Saturday afternoon or evening are expected to be in the 2,500 to 3,000 J/kg range.

But CAPE is just one ingredient. You need multiple ingredients, not just flour, to make a cake. Likewise, numerous ingredients need to come together to create a tasty thunderstorm. 

It's unusual to see northern New England and Near
York highlighted in the Storm Prediction Center's
four day outlook, but there we are! 

On Saturday, just to make things confusing, a cap will be fighting the CAPE.  A cap is a warm layer in the atmosphere that stops those CAPE updrafts in their tracks, preventing thunderstorms from developing. 

Sometimes updrafts can break through a cap. There's a chance that could happen in a couple places in Vermont toward the end of the day Saturday. 

If that happens,  a couple strong thunderstorms could abruptly develop.  NOAA's Storm Prediction Center has the northern half of Vermont in a marginal risk zone (level 1 of 5 risk category) for severe storms Saturday for this reason. 

More interestingly the Storm Prediction Center Day 4 outlook for Sunday has us in a risk zone for severe storms. Usually, when the SPC is bullish on severe storms that far in advance, you really want to pay attention.

Still, everything has to come together just right for this to happen. Sunday could be an active day, or it could be a bust. It's just something to watch for now.  

The variety show continues after Sunday when the hot, humid air is replaced by the kind of weather we had yesterday. A springtime beauty curtain call, if you will. 

COLORADO VARIETY PACK

If you really want variety, go to Colorado. In some parts of that state, they were under a severe thunderstorm watch last evening, and find themselves this morning simultaneously under fire alerts and a winter storm watch. 

Hot, dry winds today will increase the risk of wildfires in Colorado and most of the rest of the Southwest today. 

A developing storm will pull cold air into the high country of the Rockies. Highs today around Denver will be in the upper 80s but only in the upper 40s and falling through the day Friday. Two to six inches of snow are likely in much of the Denver and Boulder metro areas. With leaves on the trees, this situation might cause a lot of damage as the weight of the snow on leaves snaps branches and power lines. 

The mountains could see a foot or more of snow.

Meanwhile, parts of Iowa and Wisconsin are bracing for tornadoes today, one or two of which might be quite strong. And North Dakota is flooding again. 

I guess Vermont's weather variety show isn't as scary as that in other parts of the nation.