Battleground: Cool Spring To North, Summer Heat To South, Loud Weather In Between

One forecast map for Friday. For most of the week a weather
front will divide steamy summer air to the south with
seasonably cool, dry air to the north, with lots of storms
and rain near the stalled front. 

A classic battle is shaping up over the eastern United States and southeastern Canada between the forces of spring cool temperatures to the north and summer heat and humidity to the south, with a loud, thundery, rainy and potentially dangerous zone between the two.

As you might have noticed, we here in Vermont at least for now are on the cool side of this seasonal battle. Frost was reported in many areas this morning.

That's not unusual for this time of year, but it is cooler than normal. Though the 21 degrees reported at Saranac Lake, New York was pretty nippy.

You'd think it would be even cooler to the north, closer to the source of the lingering winter chill, but that's not the case. The May sun is strong. It's a Canadian high pressure system to the north today, which means the further north you go, the clearer the skies become. The more sun, the more it can heat the atmosphere this time of year

Which is unlike the weak sun of winter. If this were three months ago, it would be brutally cold to the north, less so to the south. Now it's different.

In southern Quebec, including Montreal, and areas of New England closest to the Canadian border, it will be relatively mild this afternoon in the sunshine. The forecast high today in Montreal is 63 degrees. It'll get to the low 60s near the Canadian border in Vermont today, but might not get out of the 40s this afternoon in far southern Vermont.

That's because further south, there will be clouds and showers in this cool air. The clouds will block the sun, so no heating from that to speak of.  Showers will be pretty light down that way, though.

The real action will take place along and just south of the battle line between the cool forces to the north and the summer weather to the south. Near record heat will stifle areas from, say, Maryland south, and the humidity will be high. Think mid-summer temperatures in the low 90s.

The weather front separating the hot from the cool will sink south a bit today, providing lift and instability to the air. That means scattered severe thunderstorms are a good bet in places like Ohio, Pennsylvania and New Jersey.

Severe storms (in yellow and orange areas) are likely today near
the dividing line between near record heat to the south and cooler
conditions to the north

That nearly stalled front will linger, aligned west to east from the central Plains states to the Middle Atlantic through pretty much all of the upcoming week.

Repeated rounds of rain and thunderstorms could raise flood threats near this front, especially in the Middle Atlantic states as the week wears on.

South of the front, summer will stay firmly in place. North of the front, which includes us here in Vermont, we'll stay generally sunny and nice most of the week.

Mother's Day - tomorrow - will be perfect. That warm May sun is continuing to heat up the atmosphere, so it'll get up to around 70 degrees under sunny skies. It could warm up as high as 80 degrees by Tuesday.

But we're under that coolish, springtime regime, remember. There will be re-inforcing pushes of somewhat cooler air occasionally through the week, which will keep our temperatures into the 60s to around 70 most of the time until at least Friday. Humidity will be low and there will be quite a bit of sunshine.

Only weak moisture-starved cold fronts will come through, so chances of rain are small, and we won't get much. That's actually beginning to turn into a problem. After a sodden, wet April, it's turning kind of dry out there. On windier days, there will be a fire risk. Plus the gardens could use a drink.

We like sunshine and pleasant weather, but it would be nice to get a decent rainfall on one day here and there. Long range forecasts at this point anyway don't indicate any real soakers, but some rain could arrive at the end of the upcoming week.

From now through the rest of the summer, the optimal amount of rain around here is about an inch per week. Seems like we rarely get that, though. It's either much more or much less.