Thursday, June 24, 2021

Rainfall Roulette: Will Squeeze Play Between Two Heat Waves Bring Needed Precip?

A rainfall forecast for the nation for the next several days.
Reds and oranges depict heavy, likely flooding rains in
the Midwest. The heatwave-plagued Pacific
Northwest would be bone dry. Here in Vermont,
we're on the southeastern edge of all that rain.
 The United States has a pretty unusual weather pattern setting up, especially for this time of year, which makes some aspects of weather forecasting tricky for our neck of the woods around Vermont and nearby spots. 

The jet stream is more amplified than it normally is for summer. Big ridges will be near both coasts, with a deeper than average dip in between. This sets up some weather extremes. 

As we talked about yesterday, a record-shattering heat wave is set to begin in the Pacific Northwest and British Columbia. 

Here in Vermont, it's another delightfully cool morning. Most of us were in the 40s at dawn today. 

That notorious cold spot in the Adirondacks of New York, Saranac Lake, touched 32 degrees for the second morning in a row. There were also a few upper 30s in Vermont's Northeast Kingdom

Today will be nice, too, breezy and mild and not humid.  But here, too, we're going to get into the heat and humidity by Sunday.  This will all be caused by the Bermuda High poking northwestward to bath us in tropical air. This will be the East Coast ridge.

 It won't be nearly as bad here as in the Pacific Northwest, but we're still in for temperatures well into the 80s to maybe around 90 toward Sunday and Monday, and perhaps beyond. 

Between these two heat waves there will be a lot of rain over the next week or more stretching all they way from New Mexico up through the Midwest and on into Ontario and western Quebec. 

After the stories about the extreme heat in the Northwest, you'll probably hear of flooding problems in that long band. 

I'm pretty sure this overall broad brush forecast for the United States and southern Canada are pretty damn accurate. 

The problem is in the details for us in Vermont. The edge of that big rainy band will be just to our northwest. 

How much of that needed rain will creep into the Green Mountain State? Some forecasts have the northwestern extension of the Bermuda High dominating, keep us hot and humid with just widely scattered afternoon and evening thundershowers.  Which means very little rain. 

Other forecasts have weather fronts with that band of wet weather making runs at us from time to time nexrt week, giving us decent amounts of badly needed rain. The best chances of that happening are over northwestern Vermont, with the smallest chance to the southeast. 

NOAA's Weather Prediction Center is fairly bullish on rainfall over the next seven days, giving most of Vermont roughly an inch of rain over that time period. An inch of rain per week is pretty close to average this time of year. 

Don't bet on that, though. It could still go either way. For now, I'm really not trusting forecasts for rain more than two days out.  We do know the earliest chance of rain for Vermont is Saturday.  At this point, it does not look like any showers that do get going on Saturday will be particularly heavy. 

After that, we'll just have to wait and see as to whether the rain gods smile on us or not. 

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