Last Warm Day for a While

Wednesday, August 21, 2013
4:17 a.m.

You ever have a night where no matter how hard you may try, you just can’t fall asleep? Well, tonight is one of those nights. I worked 5-6 hours straight before this on a citation guide for the employees at WeatherOn (but I’ll incorporate it into this blog as well), and then I tried to fall asleep, but I was still wide awake. The worst thing you could possibly do when you are trying to fall asleep is lying in bed awake hoping that you’ll drift off into dreamland. That’s like sitting at Barrow, Alaska in June waiting for the sun to set. It’s an exercise in futility. At least the sun doesn’t set later because you are staring at it. When you lie in your bed wide awake, you are only making yourself more vigilant.

The two main things that make me fall asleep are writing these blogs and reading the Bible. I’m not Christian. I’m not religious, I’m not atheist, I’m agnostic, because science can neither prove nor disprove the existence of a higher power. They are completely separate paradigms. The Bible is great because it’s without a doubt the most influential book ever written and is also one of the most boring, at least for me. Combine those two together, and you’ve got a book that you want to read that makes you doze off. Pretty good combo for getting some sleep.

I haven’t done a local forecast post for a long time because there is nothing of interest to talk about. However, the name if this blog is “Charlie’s Weather Forecasts,” not “Charlie’s Weather Aftercasts.” Let’s take a look at what the models are showing.

______________________________________________________________________
August 21, 2013
11:17 p.m.
I just felt like I needed to rewrite the date here. As promised, I fell asleep soon after I began the blog. Anyway, Thursday is going to be pretty darn hot. Let’s take a look at the evolution of temperature throughout the day.
Valid 05:00 am PDT, Thu 22 Aug 2013 – 12hr Fcst: 2m Temperature (F), 10m Wind (full barb = 10 knots). UW WRF-GFS 4km Resolution: Initialized 00z Thu 22 Aug 2013. Retrieved from the (University of Washington) Pacific Northwest Environmental Forecasts and Observations website.
Above is what our temperature is forecast to be at 5 a.m. Our low temperatures are nearly always between 50 and 60, and they will be again Thursday morning. Sea-Tac’s average low for this time of year is 56 degrees, and the record low is 46, only 10 degrees below average. Our record high is “only” 88, which is actually quite low compared to many other days. It’s easier to get really hot days than really cold nights because at night we cool by radiative heating and onshore flow and onshore flow is essentially always the same temperature. If we don’t have a marine push (for example, we have a system coming in from our west), then although the daytime high temperatures are colder, we can’t cool off as much at night because clouds prevent infrared radiation from escaping to space. I’m sure it has happened recently, but I can’t remember seeing a low temperature more than five degrees below average. Meanwhile, some places in Western Washington saw highs 30 degrees above average on July 29, 2009, which was the hottest day on record at Sea-Tac and for much of Western Washington.
It seems obvious that the temperature would be cooler at 5 A.M. than 1 A.M. Even though 1 A.M. is right at the middle of the night (and this changes to 12 A.M. when we end daylight savings time), the temperature keeps cooling off when we don’t have the sun to warm us up. One thing that I didn’t know going into college and learned in my atmospheric sciences 101 class with Cliff Mass is that the lowest temperature of the day actually occurs just after the sun rises! Here are the temperatures at 8 a.m. and they are cooler than the temperatures at 5 a.m. even though the sun rises at 6:14 a.m.! I would predict that the coldest time of the day would be around 6:30 or so, but don’t quote me on that.
Valid 08:00 am PDT, Thu 22 Aug 2013 – 15hr Fcst: 2m Temperature (F), 10m Wind (full barb = 10 knots). UW WRF-GFS 4km Resolution: Initialized 00z Thu 22 Aug 2013. Retrieved from the (University of Washington) Pacific Northwest Environmental Forecasts and Observations website.
Another thing to point out: the coldest temperatures in the state are right off Cape Flattery. Take a look at the map of sea-surface-temperatures below. The coldest SSTs are also off Cape Flattery. There are many times when Cape Flattery has a higher low while the lowest lows are found further east where the SSTs are sometimes lower due to increased upwelling. SSTs and surface temperatures are closely linked.
1:46 pm PDT, Mon 21 Aug 2013. Sea-Surface-Temperature. NOAA POES Satellite. Region: Washington Regional. Resolution: 1km. Retrieved (with permission) from the Terrafin SST-View website.
 Things start to warm up quickly as we head throughout the day. Here’s 11 a.m.
Valid 11:00 am PDT, Thu 22 Aug 2013 – 18hr Fcst: 2m Temperature (F), 10m Wind (full barb = 10 knots). UW WRF-GFS 4km Resolution: Initialized 00z Thu 22 Aug 2013. Retrieved from the (University of Washington) Pacific Northwest Environmental Forecasts and Observations website.

… here’s 2 p.m. …

Valid 02:00 pm PDT, Thu 22 Aug 2013 – 21hr Fcst: 2m Temperature (F), 10m Wind (full barb = 10 knots). UW WRF-GFS 4km Resolution: Initialized 00z Thu 22 Aug 2013. Retrieved from the (University of Washington) Pacific Northwest Environmental Forecasts and Observations website.

… and 5 p.m. …

Valid 05:00 pm PDT, Thu 22 Aug 2013 – 24hr Fcst: 2m Temperature (F), 10m Wind (full barb = 10 knots). UW WRF-GFS 4km Resolution: Initialized 00z Thu 22 Aug 2013. Retrieved from the (University of Washington) Pacific Northwest Environmental Forecasts and Observations website.

… and finally 8 p.m.

Valid 08:00 pm PDT, Thu 22 Aug 2013 – 27hr Fcst: 2m Temperature (F), 10m Wind (full barb = 10 knots). UW WRF-GFS 4km Resolution: Initialized 00z Thu 22 Aug 2013. Retrieved from the (University of Washington) Pacific Northwest Environmental Forecasts and Observations website.
As the below plot shows (look at the black line for the third sub-plot), temperatures generally increase faster during the daylight hours than they decrease during the nighttime hours, but the difference isn’t huge. They tend to increase and decrease logarithmically.
72-hour Rooftop Summary Plots. Begins 12:20 am PDT 19 Aug 2013. Station: UW Atmospheric Sciences Building Roof. Retrieved from the (University of Washington) Weather Information – framed version website.
Thursday will be hot. I’m forecasting a high of at least 80 for Sea-Tac with higher temperatures further inland near the foothills and lower temperatures by the Sound. The coast will experience onshore flow in the afternoon, so temperatures on the immediate coast will not get out of the 60s. The timing of the arrival of the onshore flow is difficult to forecast, so places further inland could stay in the 60s or break out into the mid 70s before the maritime air takes over. Most of Eastern Washington will be under a Fire Weather Watch and most of Eastern Oregon and points south will be under a Red Flag Warning, as some moisture from a low pressure system off the Southern California coast will direct moisture and instability into those regions. At this point, it does not look like thunderstorms will make it over the Cascade crest.
Friday will be MUCH cooler, as a strong marine push will likely drive down temperatures 15 degrees from Thursday’s maximums. Read my previous post on how marine pushes work here.
Marine pushes will dominate much of next week as a zonal flow resides over our area. Hold off on buying some air conditioning today… you certainly won’t need it by next week.
Time to do some more editing to my citation and formatting guide for WeatherOn. WeatherOn is getting bigger and bigger every day. If you want to get involved, contact me at editor@weatheron.net. In the meantime, like us on Facebook and enjoy the last warm day you’ll see in a while.
Have a good one,
Charlie
Ended 1:26 a.m.
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