Yesterday was another day in which Portland again averaged well under the 30 year average for its high temperature. The high of only 70 degrees was nine degrees below the more typical reading in the upper 70s to near 80. There is heat across the country, but not excessive amounts of it. The very northern edge of the heat will brush southern Maine today and especially tomorrow, but cooler, drier and more refreshing air is coming for the middle and later part of this week.

I’ve written considerably about the comparatively cool summer we are having and likely will continue to have the next several weeks. The reasons for this are due to cooler than average ocean waters in the north Atlantic, warmer than average waters off the northern west coast and the strength of the oncoming El Nino.
Although we have two days of heat on the way, it’s not going to last. The humidity, which is on the high side today, will continue similar levels through much of Monday, before trending lower Tuesday and especially on Wednesday. Thereafter, the rest of the week looks cooler and drier.

This summer’s ever elusive 90 degree reading may occur tomorrow, but it’s more likely Portland will reach the upper 80s and the 90 drought continues.

Active Afternoon
There is risk for thunderstorms this afternoon, especially north and west of the coastline. These storms will then traverse towards the coast and be with us throughout much of the evening.

Some of the storms could become strong to even severe, but this isn’t, as usual, written in stone. As I have written multiple times, summertime thunderstorms are not always a sure bet and are often added to the forecast because the atmosphere is primed to produce them.

The primary threat from any strong to severe storms will be wind and heavy rain. With so much moisture in the air these storms will have rainfall rates of 3 inches per hour or more and this can briefly, but quickly create street flooding.

The storms will slowly start forming further south during the evening. This means from Portland and points east and south will also get into the action. If you have evening plans that call for you to be outside, I would have a place to go in case the storms roll through your area.

Eye To The Radar
The radar image below shows how the storms are expected to form this afternoon and evening. Don’t focus on the exact placement of the storms, rather watch the trend of them moving west to east and also south as time progresses. The red and orange colors represent the more intense storms.

Cooling Trend
Although tomorrow turns drier it remains very warm to hot. As I wrote earlier, this won’t last. The image below is from the GFS model for the next 10 days. Again, don’t focus on the exact numbers, rather look at the trend. Notice how temperatures are forecast to go down later this week before we see a moderating trend for the final full weekend of July.

The summer of 2015 is definitely shaping up to be one where any heat we do see is rather transient in nature and quickly followed by cooler and drier Canadian air after a few days. If you aren’t a fan of the heat, this is turning into a great summer.

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