July 07, 2010

The Perfect Heat Wave

Thursday AM Update: Temps this morning are running about 5-7F ahead of yesterday, so today will peak in the lower to mid 90s for most. Low clouds on the coast, where it is much cooler today...a sign of the changes coming

This week we are having the perfect heat wave--long enough to get the feeling of warmth, but short enough that our homes and apartment won't heat up completely before the cool-down occurs...and there will be a substantial one on Saturday.

Tonight I am cooling down my house with lots of fans. I find that by putting on all the bathroom fans (which draw heat out of the house), coupled with four box fans in windows blowing cool air in, I can quickly get the house down to a decent temperature. The key with heat waves is to cool the house down at night...and to get shades down on the sunny side during the day. If the interior spaces warm up, you are toast...so to speak. I just watched Jeff Renner and he also suggests eating spicy foods. The theory is that it makes you sweat (as if we needed help doing that in hot weather!). So buy some fans and some 5-star Thai food and you should be good.

As advertised, today we warmed up into the upper 80s to lower 90s in the region. Take a look at the regional temperatures at 5 PM...near the time of maximum warmth. Click on the image to expand it. With offshore flow, even the coast was warm and Portland and Willamette Valley was way warmer than Puget Sound country. Why is the Willamette so torrid? The reason is that they don't have the proximity to water through a low-level passage. It is often 5-10F warmer there than near Seattle.

The warmth will continue tomorrow (Thursday)....I expect the temps to be very similar to today.

Below are the pressure and temperature plots for this afternoon and Thursday afternoon.....warm temperatures for both. At 5 PM today the thermal trough extends from the Willamette Valley into western Washington and easterly flow descends the western slopes of the Cascades. A very warm pattern.

Thursday afternoon we are still warm and the thermal trough appears split between western and eastern Washington.

On Friday, the trough of low pressure over western Washington "jumps" into eastern Washington and greater onshore flow will occur.

Expect Friday to a be a few degrees cooler. This process continues over Friday night and Saturday should be WAY cooler, with low clouds in the morning and temperatures in the upper seventies.

One final thing...some people like to make fun of meteorologists...saying their forecasts are wrong 50% of the time. Lets face it, my profession nailed this one....days ahead!


  1. I agree Cliff, this heat wave was forecast quite well.

    But to have your insight added to the available forecasts is an excellent addition.

    Looking forward to that onshore push.

  2. Fight back, Cliff, you guys have been spot-on with the predictions for the past week.

    I'm enjoying the warm up and will appreciate the cool down this weekend just as much.

    My hometown (Raleigh, NC) hit 104 on Wednesday with "real-feel" temps at 110... that's some ACTUAL hot weather! We are finally just getting our annual "hot for here" weather... glad to have it a week or two a year, but on the whole, I prefer to leave Raleigh's swamp-heat behind. :-)

  3. I suggest folks to get an inside/outside thermometer. When the temperature outside is higher than inside, close your windows, draw your blinds, etc. It is amazing how much of a difference that makes and how much longer you can keep your house relatively cooler. When the temperature outside is finally lower, usually a couple of hours from sundown, I throw open everything, run the bathroom fans, open windows, etc...

  4. Update from Aberdeen: Onshore flow is in effect here...fog and very cool southerly wind. And it's still only in the low 60's. I'll be surprised if we hit 80. That's after a 97 degree scorcher yesterday!

  5. Thanks for the update M'sFan. I wonder if the onshore flow will move in faster, thereby reducing tomorrow's high temp?


  6. how long will it take for the onshore flow to make it inland on friday?

  7. Michael's strategy works -- at 5 pm, the house is 8-10 deg. cooler than outside. When it's hotter outside there's no point in having the windows open. Also ... I paid a few bucks extra when I put in low-E windows with sunscreens last spring, but wow! Stuff on the windowsill does not even get warm. Less heat re-radiating into the house.

  8. You were watching Jeff Renner! Cliff . . . say it ain't so! Nooooooo!

  9. I strongly suggest the "targeted" box-fan approach: Put a box fan exhausting air out of the apt/house in a location some distance from where one sleeps. Open 1-2 windows only (presumably near where one sleeps) and force the cool air to come in those windows. It works most hot spells (except the 107 scorcher last summer).

  10. Is this technically a "heat wave"

  11. I don't know about spicy foods, but the one thing I turn to in hot weather is gin and tonics. Hot weather ups the risk of malaria and one must be vigilant against such things.

  12. Ha - gin & tonic! I'll toast to that.

    Now why oh why is the NOAA site "predicting" temps 10 degrees different for the weekend than ProbCast? I expect a wee bit of difference but that is sizable.


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