July Chill & Showers Ahead

July 15, 2010

Just for fun, let’s take a look at the “spaghetti” charts for next week, specifically Tuesday morning.  The image below is the output from this morning’s ECMWF (the EURO as we like to say) Ensembles.  Those are just slightly different variations of the main model run that also run at the same time.  Basically atmospheric modeling people perturb the intial conditions in the model 20 different ways, then run it 20 times (an ensemble of runs).  I’m not sure if that’s exactly the number of ECMWF runs, but I see a lot of lines! For that reason you’ll want to click on the image to get a better view.

Focus on the red lines.   Each one is the 576dm line on one of the ensemble runs.  Here’s the reason we use ensembles;  to get an idea whether the operational model run is an “outlier” or if they all generally agree.  In this case…the cool trough dipping down over the Pacific Northwest next week…they all agree.  This is pretty good agreement for 5 days out.


Now check out the GFS ensembles from this morning (for Tuesday again)…

Note the same general pattern.   This is a much easier graphic to read.  The line we’re following this time is the 582dm line, that’s why it’s located a bit farther south.  You could imagine the 576dm line is a bit north, about where the other map showed.

The big picture on both models shows the same thing:  A chilly week (for the hottest time of the year here) is ahead as a cool trough descends on the Pacific Northwest.  I seriously doubt the entire week will be cloudy and cool,  but apparently I made the wrong choice on vacation dates. 

Each year here at KPTV we submit our yearly vacation requests in December;  I did mine during that cold spell last December.  The real hardcore FOX-12 viewers probably notice I tend to take most of my vacation time in July and August.  I like to have warm and sunny weather when I have days off since I am naturally an “outdoors” person.  I couldn’t imagine a week off in January, sitting around the house hiding from the rain.  That plus our active weather season here is November through February means it’s best to take time off during the deadest weather time…mid-summer.  So there I was in December, thinking that I should avoid the week after July 4th because it might “still be cool and wet”.  So I chose 3 different weeks starting next week and running through the 3rd week of August.  Well, the first one is going to be a bust. 

We’ve added showers to the forecast next Wednesday-Thursday due to a pretty good trough and very chilly air at that time.  The ECMWF holds off the best chance for showers until the end of next week (more like Saturday).  Either way, by putting showers in the 7 Day I want to make it clear that those of you getting a new roof or with hay on the ground (just some examples) should be ready for a chance of showers by midweek.

Chief Meteorologist Mark Nelsen