Northwest heats up, monsoon picks up steam late next week
By
Brian Thompson, AccuWeather meteorologist
Published Jul 16, 2020 5:42 PM EDT
It's starting to feel more like summer across the Northwest these days after most areas started off the month 2 to 3 degrees below average.
Seattle started the month with three days in the 60s, and Portland didn't hit 80 degrees until July 10.
Looking at the temperature chart for Seattle, you can see that most of the blue bars do not reach the top of the brown area, indicating that the high temperature for that day was below average.
As I talked about on Monday, the cool party was going to come to an end later in the week, and that has largely been the case with temperatures steadily on the rise. Notice how those blue bars are now starting to get solidly above the top of the normal temperature range, indicating some warmer afternoons.
A ridge building over the Northwest early next week will send temperatures another leg higher in most areas.
In many places, it will be close to the hottest stretch of weather so far this year.
Seattle will likely reach the mid- to upper 80s Monday and Tuesday, with Portland getting into the 90s.
Outside of a couple of spotty showers early in the period in western Washington, much of the West Coast looks pretty dry over the next week or so.
There are signs, though, that a few disturbances will slide through the Northwest later next week into next weekend. That could introduce the opportunity for spotty showers and thunderstorms to develop. The lightning from those storms could spark some wildfires given how dry it has been.
Farther south, the heat has been the big story, especially across the deserts. Temperatures have come down a bit, but it's still a hot pattern overall even as the core of heat has shifted into the southern Plains.
The monsoon has come to life somewhat this week with spotty showers and thunderstorms mostly across the high ground of eastern Arizona and New Mexico.
While there will be somewhat of an uptick in activity into the weekend, it will remain mostly confined to the higher terrain.
During the second half of next week, though, things get a little more interesting. Both the GFS and European models show a weak upper-level low trying to develop near Baja California.
While not strong, that combined with the ridge building to the east of the Four Corners could really help to get a persistent flow out of the southeast later next week, which would help to pull moisture northwestward into the deserts.
In Monday's blog, I used precipitable water to show a modest surge of moisture this coming weekend, but look at how significant the surge next week is across Arizona. Precipitable water values near 2 inches would certainly be an indication that heavy downpours are a possibility.
This is not just on the GFS, either. Both the European and the European ensembles show a significant surge in moisture.
In addition, the ridge building eastward will open the door for more instability later next week to help thunderstorms develop. These storms can then tap the abundant moisture to produce some downpours and flooding. The rain is certainly much-needed, especially given the fire season.
If this setup comes to fruition, it would lead to fairly widespread thunderstorms that would have the potential to produce heavy rain. Plus, unlike this week, the storms would have a much better chance of getting into the deserts and impacting more population.
The influx of moisture will help raise humidity levels at the surface, which will bring temperatures down a bit in the Southwest. That being said, the increase in humidity across the deserts will still make the heat stifling during the afternoon.
We'll watch this pattern unfold over the next several days, and I'll have an update on where we stand with this potential monsoon surge in a new post early next week.
Report a Typo
Weather Blogs / Western US weather
Northwest heats up, monsoon picks up steam late next week
By Brian Thompson, AccuWeather meteorologist
Published Jul 16, 2020 5:42 PM EDT
It's starting to feel more like summer across the Northwest these days after most areas started off the month 2 to 3 degrees below average.
Seattle started the month with three days in the 60s, and Portland didn't hit 80 degrees until July 10.
Looking at the temperature chart for Seattle, you can see that most of the blue bars do not reach the top of the brown area, indicating that the high temperature for that day was below average.
As I talked about on Monday, the cool party was going to come to an end later in the week, and that has largely been the case with temperatures steadily on the rise. Notice how those blue bars are now starting to get solidly above the top of the normal temperature range, indicating some warmer afternoons.
A ridge building over the Northwest early next week will send temperatures another leg higher in most areas.
In many places, it will be close to the hottest stretch of weather so far this year.
Seattle will likely reach the mid- to upper 80s Monday and Tuesday, with Portland getting into the 90s.
Outside of a couple of spotty showers early in the period in western Washington, much of the West Coast looks pretty dry over the next week or so.
There are signs, though, that a few disturbances will slide through the Northwest later next week into next weekend. That could introduce the opportunity for spotty showers and thunderstorms to develop. The lightning from those storms could spark some wildfires given how dry it has been.
Farther south, the heat has been the big story, especially across the deserts. Temperatures have come down a bit, but it's still a hot pattern overall even as the core of heat has shifted into the southern Plains.
The monsoon has come to life somewhat this week with spotty showers and thunderstorms mostly across the high ground of eastern Arizona and New Mexico.
While there will be somewhat of an uptick in activity into the weekend, it will remain mostly confined to the higher terrain.
During the second half of next week, though, things get a little more interesting. Both the GFS and European models show a weak upper-level low trying to develop near Baja California.
While not strong, that combined with the ridge building to the east of the Four Corners could really help to get a persistent flow out of the southeast later next week, which would help to pull moisture northwestward into the deserts.
In Monday's blog, I used precipitable water to show a modest surge of moisture this coming weekend, but look at how significant the surge next week is across Arizona. Precipitable water values near 2 inches would certainly be an indication that heavy downpours are a possibility.
This is not just on the GFS, either. Both the European and the European ensembles show a significant surge in moisture.
In addition, the ridge building eastward will open the door for more instability later next week to help thunderstorms develop. These storms can then tap the abundant moisture to produce some downpours and flooding. The rain is certainly much-needed, especially given the fire season.
If this setup comes to fruition, it would lead to fairly widespread thunderstorms that would have the potential to produce heavy rain. Plus, unlike this week, the storms would have a much better chance of getting into the deserts and impacting more population.
The influx of moisture will help raise humidity levels at the surface, which will bring temperatures down a bit in the Southwest. That being said, the increase in humidity across the deserts will still make the heat stifling during the afternoon.
We'll watch this pattern unfold over the next several days, and I'll have an update on where we stand with this potential monsoon surge in a new post early next week.
Report a Typo