April remains cool, humid, at the limit of records

PORTLAND, Ore. (KOIN) — It’s no secret that we’re having one of the busiest Aprils in quite some time. We have broken snowfall records, there have been power outages due to storms and we are about to have one of the wettest and coldest Aprils on record.

We also increased snow accumulation across the state, contributing to the snow water equivalent for the season. Our last week of the month will seem more docile than the others, but it will still be busy.

Before we jump into the predictions, let’s take a look at what we’ve accomplished so far. We had 17 days of below average temperature, leaving our month at -3.3 degrees below average, which is on pace with one of the coldest Aprils on record (46, 5 degrees, 1955). The rest of the month should be cooler than average. Will it be enough to drop our average in the top 5? We will find out this weekend.

If we happen to break out of the top five, it will be because of the hot weekend we had in the upper 60s and lower 70s. If you go to the next graph, you will find the current rainfall total for the month. We’ve only had five dry days this month and we’re looking at a week that could bring showers pretty much every day.

We are currently in the eighth wettest April on record in Portland. We had one day with over an inch of rain and two days with over a half inch of rain. However, it was a group effort this month, with most days dropping rain for Portland. Are we going to put it higher on the list? If you swipe, you can see two weather patterns that project rain totals through Thursday evening. One would propel our rain total to number one, the other to the top five. With five full days to bring more rain, we can definitely make the list. I would feel confident with Portland finishing in the top four, surpassing the 1955 rain total. A reminder that 1955 was the coldest year on record.

Let’s look at the next day or two and discuss what will help with those two variables above. We have a cold air pool right above us on Monday. This type of pattern usually brings cooler showers for the Pacific Northwest (PNW). This configuration is also advantageous for the development of thunderstorms. That might be enough to form a convective cell that produces a shower or two.

These types of storms can really add to rain totals; however, they are very risky. If you scan the suite of charts below, you will see the cold air moving over us with the dynamic nature of the future release by Tuesday afternoon. It will be the scattered showers that could turn into a storm for the northern Willamette Valley and points to the north. You can find the potential mixed storm chart in the slideshow below.

If we take that cold air and carry it over the mountains, it lends a helping hand to more snow. This will also happen this week, as temperatures remain cold enough for mountain snow. Although the snow totals will be trending down, it is still beneficial for the region. Not only is the snow helpful, but the cold air keeps snow levels low. This will keep temperatures cold aloft, preventing the snow from melting.

The tandem of a cold and wet April was both lucrative and conservative!

Dale D. Schrum