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July's forecast: A bit of conflicting ideas between hot or cool...

Photo: Shubha Tirumale

SEATTLE -- With the fresh start of a new month comes the updated forecasts for how long-term forecasters think the month will shape up, weather-wise.

But July brings a bit of conflicting reports, with NOAA leaning the forecast around Seattle as having slightly better odds for being warmer than normal, while the meteorologists are trending in the cooler direction. Although it should be said neither is giving a strong opinion in either direction.

Let's start with NOAA, which is leaning slightly warmer than normal for July, and is also picking up a drier than normal signal:

For the temps, only the I-5 corridor in Washington is in the weakest warm shading, while the coast is showing closer to normal. They believe that the big heat ridge of high pressure that is currently anchored over the Desert Southwest and is stretching up through the Inter mountain West will remain anchored there for a while with most of the intense heat remaining well inland with Washington just on the edge -- probably has the Puget Sound /I-5 corridor just on the outer fringe of that heat.

The Weather Channel is actually painting Western Washington as near-to-slightly below normal for July temps:

"The biggest heat relative to average in July is likely to remain anchored in the Southwest where a prolonged heat wave set numerous record highs in the second half of June," the Weather Channel wrote. They didn't specifically mention their reasoning for the cool shading for Western Washington, but as we've seen over the past couple of weeks, with the heat ridge centered far enough inland, it allows for marine breezes and onshore flow to continue just along Western Washington, keeping our temperatures at or a little below normal (like what's happened Sunday and Monday). So I'm gathering that's their logic.

Combine the two and we get a forecast around normal for July. So far the first two weeks support that -- high temperatures going forward are expected to bounce between the mid 70s and low 80s for a while which would put us pretty close to normal heading into the second half of July and as long as that ridge stays a bit inland, we should remain in that ballpark.

However, if I had to bet between the two, I'd probably put a few more chips on the warmer side than the cooler side. As we saw Friday, Seattle seems to have enough power to reach the mid 80s in the current set up if the marine winds slacken so I suspect we'll have a few more surprise mid 80s pop up this month in addition to any regular heat spells that bubble up in the summer.

Rainfall may be a challenge

On the other hand, NOAA has changed course from predicting a July rainfall around normal and is now leaning dry across Washington. They think the desert Southwest ridge that, while not close enough to really bake us has been close enough to keep any rain away, will remain in place and keep our region dry.

So far, Seattle is already working on an impressive dry streak -- Monday makes 17 days since Seattle last had measurable rain and the forecast for the next two weeks remains dry.

If you're curious if that might be approaching a record, we have a long way to go. The all-time longest dry streak in Seattle is 51 days set in 1951. Seattle had a 48-day dry streak in 2012. We need to get to 37 just to get into the Top 10.

What's up with El Nino?

Latest data from NOAA shows ocean conditions are still in the neutral phase of the El Nino/La Nina oscillation, although they remain right on the cusp of going into a weak El Nino.

The latest update has forecasters thinking we're about equal odds of having El Nino or neutral conditions this fall, with neutral conditions taking a more significant lead as we get into winter. Note that La Nina's chances, while still pretty small, are now past 10 percent -- they had been in single digits at the previous update.


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