How Hot?

The big story this week of course will be the heat wave at the end of the week.

First, a pretty good onshore push is in progress this evening.  Portland to The Dalles pressure gradient is up from 3.2 mb. yesterday evening to 5.7 now.  Looks like wind on the river from Hood RIver to The Dalles are probably gusting over 50 mph, since DLS airport gusted to 48 mph at 5pm.  It has a lighter west wind than the big windsurfing spots downriver (Rowena/Doug's Beach/Swell City).  It is a northwesterly push (as opposed to the strong pushes that come up from the SW), which usually doesn't give us a ton of marine clouds.
Thinner marine clouds Wednesday allow temps to rise back into the lower 80's...that should be the last day below 90 for many days.
12z/18z GFS, 12z ECMWF & Extended MM5 from UW all show a very strong 595 dm 500mb ridge developing directly over or just north of Oregon Friday-Sunday.   Then it weakens, but summer warmth continues Monday and beyond.  So the question is how hot?  You've all discussed your theories (and will for the next 4 days I suppose), so here are my thoughts.
I checked the 1981 & 1965 heat wave maps (Surface, 500mb heights, 850mb temps) and found that the pattern is very similar to the forecast pattern. 
- 500mb heights are the same. 
- To get above 101 or so we need some easterly flow through the Gorge, maybe briefly making it to PDX (as in June).  Both of those old heat waves had it and that's in the works for Friday-Saturday.  Sunday is the calm wind day before we turn onshore for Monday. 
- 850mb forecast temps are the same as in the other two heat waves.  ECMWF has a crazy 28 deg. C on Saturday afternoon! 
     So technically there is no reason we can't get to 105 or higher.  I went for 105 both weekend days on tonight's forecast, which I've never forecast.  I'll revise upward the next few days if the maps remain the same.
Ever since I started my career here in 1991, I've wondered when/if we would see a repeat the 1981 heat wave, so maybe this is the year?

Comments

[Justin]

Note: I'm tired, so by NTW I meant NWS, sorry about the typo.

[Justin]

BTW, NTW has me looking bullish right now, with:

Friday: 96
Saturday: 99

Chances are, as always is the case during heatwaves, the temp will go up a degree or two, but the fact that they were not confident enough to place 100 in the forecast on Saturday tells me that conservative is the way to go right now, and gives me a little more confidence in my own forecast.

[Justin]

Well guys, I don't want to proclaim myself victor yet, but it looks like my conservatism paid off. Mark himself admitted several times on the forecats tonight that the models have indeed been trending cooler, and he had the high for Saturday lowered to 104 and said that even that might be too high for now. I'm still thinking 98/99 maybe on Friday as the heat sets itself up, Saturday being the hottest day with 101/102, and Sunday maybe being a couple of degrees cooler than Friday even. The winds look favorable for more moist, SSW air to mix in on Saturday, as we are well out of the strongest offshore push, so I'm thinking realistically maybe at PDX:

Friday: 98
Aaturday: 102
Sunday: 96

Friday has the potential to get hotter and over 100, but for now I'm skeptical.

Dave made a great point about the potential stratus/cumulus inhibiting the heat, and again the 594dm line will be SE of here again by Sunday, so the winds will have a good shot at mixing.

Again, not proclaiming myself vixctor yet as it all remains to be seen, but you see why I'm typically skeptical of long range extreme heat prognostications? I think this will be like July 1998 or July 2004, perhaps a 3 day over 95, maybe two days over 100, but not the all time record heat the models were shooting for earlier. I've seen and heard the same hype honestly for years during every major heat setup, this looks to be another time when it won't varify.

[Derek Hodges]

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[Derek Hodges]

Ok..well I know we shouldn't put up other boards but check out my 107 in forecast before I come to my senses....haha
Just click on my name for anybody who doesn't know.

[Dmitri K]

I think what Paul actually means is that its what's known as a "frost hollow." Usually the lowest area of a valley that sees cold air pool into it on a clear, calm night. Its especially amplified if there's vegetation, since there is no heat radiating from concrete and pavement in the immediate vicinity. Under any other circumstances there wouldn't be any temperature differences.

[Derek Hodges]

I bet it gets a fair amount of snow there in the winter if its that much colder.

[Paul]

45.7 degrees at 6:30 am this morning in Happy Valley. It was weird being able to see your breath, knowing whats coming. And its interesting: the heart of the park in the valley is usually 3-5 degrees cooler than the rest of town. You can literally feel a wall of cooler air as you move into the center of the park.

[Derek Hodges]

yeah, the most amazing thing about that was the length of days it was so high, and it only adds that it tied the all-time record twice.

[Dmitri K]

Well, Longview hit 108 in 1981...but that was a one of a kind heat wave as we all know.

[Ian]

so hows it look for longview, i know last 100 degree days, longview only hit about 98. seems we stay cooler in the summer but in the winter, never get as cold. frustrating.

i rfealize were in a bit of an odd microclimate. it seems were only a degree or two warmer than seattle, yet 5-10 degrees cooler than portland, though we are very close to pdx. oh well. i just hope it gets super hot for some good wakeboarding.

[Derek Hodges]

I don't think that will be a problem but only time will tell.

[Dmitri K]

Yeah, those high and mid-level clouds can be a real bummer. I'll never forget July 26, 1998 when we had a low of 72 and were supposed to hit 103 and maybe higher. But high and mid level clouds from the southeast almost completely hazed over the sun by 3:00 PM, and the airport only reached 99.

Where it was still sunny just to the west, Hillsboro hit 105 I believe.

[Derek Hodges]

I suppose that could happen, I hope not! Also the winds do look easterly so thats a good sign, probably NE too but I can't remember.

[Dave Lamb]

I would agree the moisture won't amount to much of anything because of the very dry air mass, but what it could do is stream high and mid-level clouds to obscure the sun and heating just enough to cap the high temps at around 98 or 99 degrees. I really would hate to see this happen, but I've seen it happen on a few occasions before. The other thing to really note for extreme heat is for the area to get the NE downslope winds for compressional heating, which usually means we end up getting a hot east wind from the gorge for those of us who are prone to east winds.

[Dmitri K]

The Weather channel did post a "partly cloudy" for Saturday instead of just sunny, so maybe that's a hint of something from the south. Their high low forecast is 103/72.

[Derek Hodges]

That must have been pretty hard on People, crazy stuff

[Derek Hodges]

I don't think we will have as many days in the 100's as 1981 but I can guarantee you, we won't have any moisture to deal with. Even if some makes it up here the combination of an extremely strong ridge, very hot temperatures aloft, and an easterly flow for part of the heat wave will not allow any moisture that gets up here to do anything.

[Dave Lamb]

One other long hot stretch worth noting was during the summer of 1977, which I also remember very well. If we lower the bar just a tad to include temperatures reaching or exceeding 85 degrees, PDX had an 18-day stretch of very warm to hot weather. Starting in late July into August, the streak went like this: 89,92,91,94,92,85,89,88,89,99,100,102,104/92/85/93/102/105. This type of pattern seems more likely to me, than a few day stretch of 105+ as the models earlier this week suggested.

[Dave Lamb]

The hottest stretch I ever experienced in PDX was August 1981. The official high temps at PDX went like this: 99,103,107,105,107,97. Interesting to note is that we had gusty east winds here during that heat wave, and it is also interesting to note that the low temps were in the mid to upper 60s. I remember that it would still be about 88-90 degrees at 11 PM on the days that hit 105 and 107. I have doubts that we can experience a heatwave later this week that will rival the one in 1981, but we'll see. I can see us having a very long stretch in the 90s with a couple 100+ days in the middle of this stretch. Just my guess. I also think that the monsoonal thunderstorm moisture might interfere with hitting 100 if this moisture makes its way far enough north.

[Derek Hodges]

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[Derek Hodges]

Nice to hear that Droppin, and it should keep going up. They amazing thing is that we still have 3 days in between and most of the time they bump it up that last degree or two the day or two before. Tonight I will do 107 on my sight haha. Lets see, in response to Dmitri, I guess we have about a 80% of getting something good then. Even if some things may point otherwise I can't wait to see what happens.

[Dmitri K]

As far as the extreme heat being followed by good winters, its usually accurate if you look back at winters that followed extreme (104+) summer heat waves.

104 in July 1926...5-10" of snow and 12 degrees in January 1927.
105 in July 1935...6 consecutive days below freezing in February 1936.
105 in July 1942...3 degrees with all-time record 14.4" of snow in Jan. 1943.
104 in July 1944...mild winter 1944-45, no arctic outbreaks.
104 in July 1961...9 degrees in January 1962.
107 in July 1965...normal winter 1965-66, 19 in December 1965.
104 in Aug. 1972...8 degrees and 10 consecutive days below freezing in Dec. 1972
105 in Aug. 1977...normal winter, but cold Nov. 1977 with 7" snowfall.
104 in July 1979...major snowfall in Jan. 1980, 13 degrees.
107 in Aug. 1981...14 degrees in January 1982.
105 in Sep. 1988...9 degrees in February 1989.

Out of the 11 possible winters that followed 104 degree heat,

9 had arctic oubreaks and snow,
1 was a normal winter without any arctic air but some cold (1965-66).
1 was a mild winter with nothing close to arctic cold (1944-45).

Interestingly, the winter that most fits our current climatic state is from 1944-45, when climatic conditions were similarly mild. And its the only winter out of the 11 that managed to be mild despite extreme heat the previous summer.

Take what you want from that.

[Dmitri K]

New 7 day from Mark shows 105 on Saturday but only 102 on Sunday.

[Droppin]

I know Derek I am waiting for an update also. Salesky just went with 106 on Saturday, very shocked to see that. As I said yesterday he's always very conservative during heat waves.

[Derek Hodges]

So Mark, can you update us with a "maximum high" for Saturday, likely our warmest day. I see +27 on both 12z models so to me 107-108 as I have been saying all day seems very reasonable, but I would like your take on it.

[Andrew]

nice, i hope that happens then. I'll be up at central washington university in ellensburg, wa, so i should get a very decent amount of snow and ice. While i am up there i'll report the weather there as well.

[Derek Hodges]

sorry, about messing up both of your names lol

[Derek Hodges]

Andrew - When you were gone me, Jusin, and Dimitri all did quite a bit of reasearch and we concluded that years where we reached 105 or higher there was a greater chance of above normal snowfall that winter.

[Andrew]

haha ya

[Derek Hodges]

While you were gone me and Dmitri were talking about how us and you last month were joking about 110 and now we will just be a few degrees away lol

[Derek Hodges]

I see what your saying, it took forever to get them to talk 100's before. I know I could go for another 2004 type winter. It was the best one in my lifetime memory for me.

[Andrew]

One thing i really like about weather is the unknown and the waiting. I find it really cool how close we may be coming to hitting the highest temperature recored in portlands known history.

[Andrew]

Even some of the more conservative forcasters are saying 100-103 for at least two days around this weekend.

*NOTE* Those forcasters last heat wave were saying high 90's to maybe 100, so this could really mean something.

As far as winter weather goes, i don't know enough information on the idea's around a heat summer= a cold winter, but i would like to see that. We have not really had much of a good winter since 2004, and even that was not great for many places except the west hills.

[Derek Hodges]

I think there is a very reasonable bet we will get 107-108, but if not your outlook looks correct Andrew.

[Andrew]

Just got back from a 3 day trip up to ellensburg, wa. It's really starting to come together now. I think the portland metro area could easily hit 103-106 at least two days in a row with a few days of upper 90's as well.

[salemphil]

WOW!!!!! What the heck!! I go off line for a week while I move and come back to talk like this!!! Sounds like it should be interesting. Guess I better get everything I want out of the garage while I can. I sure don't plan on being outside in weather like this. I don't care for the heat that much!! LOL.
On the other hand, perhaps we will get lucky and have some thunderstorms when we transition back to normal oregon weather.

[Sean]

Well, you guys can have all the heat you want.. I haven't been able to do much here, since it's been so hot and humid. Looking forward to some comfortable weather for both day & night.

[Derek Hodges]

ECMWF supports a +27 Saturday as well and a +26 on Sunday. Maybe even higher than those numbers in the late afternoons since they are for noon. Looks crazy, tonight I am going to forecast 107 or so. =>

[Derek Hodges]

Whats somewhat alarming as well is once we get to Thursday the GFS doesn't put us below a +16 the entire length of the forecast period, and a 107-108 still looking likely for Saturday. Also some really long range models do have some t-storms =>

[Derek Hodges]

yeah, just a joke for the fact we have had a strong heat wave in may, june, now july, so why not august? lol Right on schedule the GFS 12z gives us a +27 with easterly flow aloft, relitively calm at the surface.

[Sean]

Usually any chances of getting above 100, end by the middle of August. Not to say it isn't possible, but not very likely.

[Derek Hodges]

thats good then..what do people on here predict for the august heatwave...lol

[Hanson]

we do have a better chance in august-september cause that when the the cooler air starts making its way back in here but also we still have a strong sun during that time. I thinks cool how our chances also increase during winter.

[Derek Hodges]

I hope you see something. Do we typically have a better chance of thunderstorms in August?

[Sean]

Usually if you have heat of 100+, it's usually pretty difficult to get any sort of convection type activity. Due to the fact that even in the upper layers of the amtosphere are warmed significantly. That's the problem I'm facing today, the atmosphere here is quite unstable (temps in the 90s / dewpoints in the 70s) but the upper atmosphere is pretty warm also. Looking like Thursday will be the better day, with a stronger cold front sliding through the region here.

[Derek Hodges]

yeah, good chance it will be the hottest ever, if not, definately top 5.

[Sean]

Wow it definitely looks like it's going to be a scorcher this weekend there.

[Derek Hodges]

hmm...well I guess I will see how the models look in the morning

[Derek Hodges]

are you sure about that 109 and 110? lol could happen I suppose