How Hot?

KPTV's 7 Day Forecast as of 7pm

KPTV's 7 Day Forecast as of 7pm

Of course that’s the big question in the 7 Day forecast isn’t it?

So while I drank my morning coffee today, I looked at some old weather maps.  There is no finer combination at 9am is there?

The maps and data I looked at were from several of our past heat waves.   Now I know several of you regulars do this sort of thing quite a bit and maybe you have numbers written down, so please correct me if you have better data.  The high temps are from PDX, the 850mb A.M. temp from SLE.

1. 107July 30th, 1965   590dm 500mb height, +23 deg. @ 850mb. (Nice surface high to the east, but not too chilly in Montana.  Closed upper level high just to our north, maybe that helped)

2. 102Aug. 9th, 1967   585dm 500mb height, +21 deg. @ 850mb (big push of cool air+high pressure moving into Montana with this one helped offshore flow)

3. 107Aug. 8th/10th, 1981   594dm 500mb height, +23 to +26 deg @ 850mb(Cooler air moving down to the east into Montana helped with offshore flow again)

4. 103July 20th, 1994   594dm 500mb height, +24.3 deg @ 850mb. (Sharp thermal trough)

So what did I notice most? 

No big surprises but some common themes:  One is that 850mb temps sure don’t have to be insanely hot, but the surface flow definitely needs to be good offshore with a sharp thermal trough to push us up around 105.  Seems like it’s all about the surface flow.  Once again, not brain surgery there.  I will admit that I expected 850mb temps of +28 to +30, but apparently that has not happened in Portland’s observational history.  I also noticed 500mb heights are not insanely high either.  I think the shape and placement of the upper level ridge is far more important.  Looks like a closed high is most “efficient” at producing heat when it’s slightly to the north of us (probably helps give more easterly flow in the mid-levels.  That was pretty obvious in the two 107 degree incidents.

Now you may notice (as of this evening) that our forecast 500mb heights and 850mb temps fall into line with all these record setting heat waves, but to get above 101 we’ll need a sharp thermal trough.  The 12z ECMWF as well as the 12z GFS showed this for at least Monday and Tuesday.  That’s why I decided to bump the 7 Day forecast up a bit.  I may end of regretting that, but in the last two big heat waves we’ve dinked around with the high temps in the days leading up to the heat.  Remember the time someone in town went with 107 or 106 and I had a 105?  I think that was 2006.  That was turning more into a “who’s got the biggest number” sort of game I think…maybe too competitive.  Those were the good old days…

Still, the big picture is an extended heat wave from Sunday through sometime later next week.  The latest ECMWF is somewhat historic if it proves correct; the 12z/18z GFS more of a “normal” 100-102 degree heat wave.  We’ll see!

Chief Meteorologist – Mark Nelsen

UPDATE:

Hey all, look at the new tab (at the top of page) I just added with some cool cloud pictures from this evening. Here is the direct link too.

https://fox12weather.wordpress.com/noctilucent-cloud-pictures/

-Rob Martin

161 Responses to How Hot?

  1. Matthew says:

    July’s 1990-2009
    Year 100’s /90’s /80’s /above 90/heat waves
    2009 0 7 8 6 2
    2008 0 5 15 5 1
    2007 1 2 16 3 1
    2006 2 4 12 6 1 (Last cat3 or major heat wave)
    2005 0 7 11 7 1
    2004 2 2 18 4 2
    2003 1 7 x 8 1 (cat3 or major heat wave)
    2002 0 4 x 4 2
    2001 0 1 x 1 0
    2000 0 2 x 2 0
    1999 0 1 x 1 0
    1998 1 5 x 6 1
    1997 0 1 x 1 0
    1996 1 11 x 12 2 (the last cat4 heat wave to hit Portland)
    1995 0 4 x 4 1
    1994 3 4 x 7 1 (Strong cat4-9 points)
    1993 0 0 x 0 0 Coolest July in the last 20 years
    1992 2 3 x 5 2
    1991 1 3 x 4 2
    1990 0 9 x 9 2
    1989 0 0 x 0 0 Another very cool July
    1988 1 5 x 6 2 Both Cat2’s
    1987 0 4 x 4 1 one cat2
    1986 0 0 x 0 0 hottest day was 88.
    1985 1 10 17 11 x Hottest July in Pdx history(All but 3 days above 80) 3? 7.5 and 5.5 heat wave(cat3 and cat2)

    Year 100’s/90’s/Above 90/ heat wave
    1956 1 3 4 1
    1957 0 0 0 0
    1958 1 7 8 2
    1959 0 7 7 1 (cat3)
    1960 0 5 5 1
    1961 2 1 3 1
    1962 0 5 5 1
    1963 0 0 0 0 Highest was 83f.
    1964 0 0 0 0 Highest was 89f
    1965 2 6 8 1 2(with one all time record)
    1966 0 0 0 0 Highest was 89f
    1967 0 3 3 1
    1968 0 5 5 1-2?
    1969 0 1 1 0
    1970 1 2 3 1
    1971 0 8 8 1 8points=cat4 (5 days straight of 90+!)
    1972 0 8 8 1
    1973 0 10 10 2 (2 cat3 heat waves) Holder of 6 straight 90 degree days
    1974 0 5 5 1 5 straight 90 degree days in a roll!
    1975 0 4 4 1
    1976 0 1 1 0
    1977 0 2 2 0 The start of the heat wave for early August
    1978 0 5 5 1 cat4
    1979 2 4 6 1
    1980 1 1 2 0 Came close but not quite
    1981 0 4 4 1
    1982 0 2 2 0
    1983 0 1 1 0
    1984 1 3 4 0

    ///////////////////////

    Portland heat wave scale
    Cat1 3 points
    Cat2 4 points
    Cat3 6 points
    Cat4 8 points
    Cat5 10 points

    85-89f .5 points
    90-94f 1.0 points
    95-99f 1.5 points
    100-104f 2.0 points
    105-109f 2.5 points
    110f 3.0 points

  2. Rob "Wrath" S.E. Portland says:

    I’m keeping an eye on a few things tonight.

    1)850mb temps and whether or not they are increasing, or staying put.

    2)Surface gradients and what kind of onshore push between AST-PDX also how much westerly flow remains between PDX-DLS.

    3)Local observations particularly the Foothills.

    4)WV Loop to monitor the low and see if we can get some energy down the back side of the ULL towards us, or does it meander SE leaving us out of any convective possibility.

  3. Andrew Johnson (Silverton) says:

    I’m currently at 68 right now. It did feel warmer out this evening. The 00z only has Salem getting above 100 for one day next week.

  4. Definitely feels warmer out tonight…Maybe the heat wave is starting to materialize…

    72.4F…Light northerly wind

    • pedro771-tigard says:

      Ya, it just feels like the heat is going to start tomorrow. It may be warmer than some think for this weekend.

  5. Snow-Zone/Monmouth-Elv200' says:

    Probably very little or no marine push of clouds come in, especially down here, it was already very weak this morning and was pretty much gone by 8:30 or so.

  6. Rob "Wrath" S.E. Portland says:

    I’m really surprised how well the atmosphere has recovered this quickly…

    • runrain says:

      Sitting on the deck, here, in Happy Valley am noticing a warm northerly wind picking up. Also, the hummingbirds were very active and agressive with one another this evening. Wonder if its a nature sign of impending heat. Notice blackberries are ripening much earlier this year, and my cukes and tomatoes now rippening.

  7. Snow-Zone/Monmouth-Elv200' says:

    Much warmer tonight then last night, I think 93-96F tomorrow for me could be done easily. Well I didn’t see any noctilucent clouds this evening… for some reason I feel you need a ULL real close perhaps to be a source of moisture to get up there that high in the atmosphere? I really don’t know just a guess.

  8. Tetra says:

    Think it won’t get below the 60F mark here in Silverton/Mt Angel foothill areas?

    I am sitting at 74F and it feels warmer then this time last night.

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