PORTLAND, Ore. (KOIN) – Usually when you’re taking a monthly rain total, you’re looking for a number. All that we have right now is a “T”. That is a trace of rain for the Portland airport this month, which is, of course, below average.
We have grown awfully familiar with little to no rain in Portland the last five months. We have near two weeks of July remaining and it sure looks like we aren’t going to get any rain in Portland. The deficit isn’t going to climb to towering levels, because the month of July is relatively dry, but it doesn’t look good as we find ourselves nestled deep into a drought.
Not only have we just had a trace of rain for July, but that is all that we’ve had since summer officially started on June 20. That means we have seen no rain all summer. It’s not unheard of, because July and August are on record, the two driest months that we have during the year. With that lack of rain, compounded with wildfire conditions, you are watching wildfires flare up on and off this summer. The deal we have going with mother nature right now isn’t all that great when you factor in all the concerns.
Right now we are at 33 days without measurable rain in Portland. We start entering the top five when we reach around 55 days. When August comes around, we are likely going to be at 45 days. That means we will either be nearing a chance of rain, or we will be leaning towards the odds of setting another top-five record. Extended weather models have a chance for rain in August, but not much in the forecast up to that point. There is some moisture moving our way, but it is only going to impact those east of the Cascades.
As we start the week we have a building ridge to the east, which is cycling monsoonal moisture around the core of high pressure like spokes of a wagon wheel. We have a batch that is moving through today, which will offer just enough moisture to support the development of rather “dry” thunderstorms for eastern Oregon. A scenario where lightning may strike, but there won’t be widespread rain to help dampen the dry conditions out there. This concern will only hang around for the next day or two, before conditions return to just a dry and breezy forecast for midweek. The graphic below will show that large area of high pressure that is essentially preventing that trough of low pressure from coming in and providing us cooler air.
Both systems have dreams, which means we will be in a back and forth battle with both that low pressure and high pressure this week. Until that high pressure flattens out, we won’t have much of a change in the forecast, but there are some subtle tweaks to discuss. Tuesday and Wednesday morning will offer more of a marine push which is associated with that trough to the northwest. That will keep temperatures cooler west of the Cascades in the Willamette Valley. I mentioned that the isolated t-storms are going to be producing very little rain for the ground to absorb. Check out the seven day quantitative precipitation forecast, providing an idea of how much rain will be produced across the United States this week. Plenty of moisture around the four corners region and for the southeast, but you know how the story goes around here.
When is rain in the forecast? I mentioned above that extended weather models are hoping for some rain come August. There are a few runs that even keep the rain out for most of the month of August (graphic below). That wouldn’t be ideal, but again, August is typically a dry month. There are a handful of model runs that are projecting at least some rain come August. We should start there because that is better than nothing. This means there will be a shift to the weather pattern, which may help us out around the valley, but it’s up in the air if it will be much of a help for central or eastern Oregon.
Something to think about, if we do end up with a few systems that bring in rain, that likely means our temperatures are going to stay closer to average or below. That has not been the case most of the summer. How does a cool and wet August sound? It’s unlikely, but it would sure help us out. August can only get so cool and wet in the first place, so it would just feel like a nice month.