Saturday, July 11, 2015

Why Such a Hot Summer?

Saturday, July 11, 2015
5:04 pm

Check them out!

Hello everybody! I've been living in the woods for the past 3+ weeks up near Granite Falls, Washington, and there ain't no WIFI in the woods, so that's why the blogs have temporarily ceased. But right now, I am just relaxing at home, as I have a day off before I head back up to Hidden Valley Camp tomorrow. There are three camp "sessions"... the first one ended Friday afternoon, and the second one starts Sunday afternoon and ends in early August. For 1st session, I was a group counselor for a bunch of rowdy but lovable 10-year-olds, and 2nd session I will be taking care of 13-14 year-olds. I learned a ton during 1st session and had a great time, and I hope to have an even better time 2nd session. 

Anyway, let's talk about weather. It has been extremely dry and hot. Campfires are a big part of HVC, but we haven't been able to have them in many areas because of how hot and dry it is. I'm not getting my tan on this summer, but I am definitely getting my "dust" on, and when I go to take a shower at night, you can see a clear color change on either side of my sock, with lighter color below and darker above. The darker hues are not due to sun exposure. It is unbelievably dusty up there right now.

Why has this been happening? Well, there are two main reasons. The primary reason is that we have had a massive ridge of high pressure over our area. As my TV meteorologist friend Matthew Leach says, “high means dry”, and it also equals warm, as high pressure is associated with sinking air, and as a given parcel of this air sinks, it compresses and increases in temperature (note: because the temperature of this sinking air parcel increases but its volume decreases, the total amount of heat in the sinking air parcel remains unchanged). This process is known as adiabatic warming.

To illustrate how prominent this ridge has been, let's take a look at the 500 mb level heights from July 2nd. Sea-Tac had a high of 93 on this day (they had a high of 92 the previous day and had highs above 90 the next three days, tying the record for the most consecutive 90+ days (I believe it was set back in the early 80s)).  There is a huge ridge over the entire Intermountain West and Pacific Northwest.  

Valid 05:00 pm PDT, Thu 02 Jul 2015. Retrieved from UW mm5rt modeling site.

The secondary effect that contributes to our warmth is a large mass of unusually warm water off our coast. When we have onshore flow, the Pacific moderates our climate substantially, but if the air coming off the Pacific is passing over warmer-than-normal water, it will not cool off as much before it gets here, and we will see warmer conditions than one would expect without this warm water. As you can see, this warm water in the NE Pacific is quite expansive. This big mass of warm water appeared during last summer as well, and last summer was super warm, so when you consider that this summer is off to an even warmer start, it is not surprising to see the warm water reappear. Nick Bond, who is the state climatologist and a UW professor (I took a class from him and he is truly a first-class teacher and human being) casually named this big area of warm water "The Blob" last summer, and the name stuck. The Blob is back, and it is making us even warmer. The Blob tends to form under calm conditions where there are persistent ridges of high pressure that prevent warm surface water from mixing with cooler water from the depths below, and boy oh boy have we had our share of persistent ridges over the past couple weeks.

Retrieved from IRI Global SST Maproom

Was this predicted? You betcha! Look what NOAA's CFS model predicted earlier this spring. I couldn't find past CFSv2 simulations so I found this from Cliff Mass' blog post "Drought Misinformation," which I highly suggest you read. Contrary to popular belief, the Pacific Northwest didn't experience a precipitation drought this past winter. However, we are off to a hot and dry start to summer, so things could get worse for us if we don't cool off or get some rainfall.

Finally, the Pacific Northwest has been the hottest place (compared to normal) in the U.S. over the past month. Eastern Washington has been 6-7 degrees above normal. I remember reading the paper one morning late June and seeing the temperature forecast for the day. Walla Walla: 108. Riyadh, Baghdad, and Cairo: 105.

CPC Temperature Analysis

Thankfully, things have cooled off, and we will see some light shower tonight and tomorrow. It won't be long before the sun gives any remaining showers on Monday the boot, giving us mostly sunny skies and highs in the upper 70s for Tuesday-Thursday. There's a chance of more (gasp!) showers on Friday and Saturday, so the mega-heat looks to be gone for now. Thank goodness.

Thanks for reading! I'll update as often as possible.

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