A Shorter Heat Wave; But 2nd Hot Spell Likely

The hot weather arrived today, a day earlier than I expected.  I forecast 88 but instead PDX hit 92!  This was the 5th day this June with a high temp 90+…we’re only one day away from a June record too.  We’ve never seen more than 6 days 90+ here in Portland.


If you want to cool off, head to the coastline.  No hot weather there.  At least partly cloudy and maybe even cloudy skies with a shower Sunday:


There is some good news though.  After a scorcher Saturday models are showing more mid-high cloud cover Sunday.  Plus at the surface a decent onshore push of cooler marine air cools things off too.  As a result, the heat wave has been shortened to just today through Saturday.  Temps Sunday-Tuesday will likely only be in the mid-upper 80s.

The big ridge of high pressure rebounds a bit the 2nd half of next week as we head towards the 4th of July Weekend.  I think we’ll see high temps back into the 90s Wednesday/Thursday, and possibly into Friday & the 4th.  That’s how we could end up with a 2nd heatwave.

Chief Meteorologist Mark Nelsen

19 Responses to A Shorter Heat Wave; But 2nd Hot Spell Likely

  1. Garron near Washington square says:

    It looks to me like the “cooling” in to the mid 80’s for Sun/Tue time frame, the models have back pedaled a little bit according to this morning’s AFD. It may stick around 90 during those days, IMO as the convective out look remains just a bit cloudy in the mornings. But super adiabatic conditions in the afternoon and 20+C conditions @ 850 MB remain in place. With temps starting around 70 D/F, it wouldn’t be hard to hit 90 any of those days as well with enough breaks in the clouds during the afternoon hours.

  2. Tyler Mode in Battle Ground says:

    Post your low temps today (6.26.15) below:

    58 here in Battle Ground

  3. paulbeugene says:

    Looks like a hot day today.

    Eugene 100F
    PDX 99F
    Salem 101F
    Roseburg 103F
    Medford 104F

    Looks like good lightning show for the Sisters-Redmond-Bend area around 11pm-1am tonight.

    Batch of convection may swing by Roseburg and head toward Florence this evening.

    Best guess Eugene will miss out on convection to east and west but will have plenty of mid-high level clouds, lows in upper 60s at best, if not around 70F.

    PDX probably won’t drop below 70F tonight

  4. Lee Wilson says:

    All I know , my plants are loving this weather.

  5. **** Convective Outlook ****
    1:14 AM
    Valid 6/26 – 6/28
    Surprisingly the SPC has turned a bit more bullish in terms of T-Storm potential now painting ‘General Risk’ opportunities beginning Friday. Friday we’ll be lacking moisture, so I can’t imagine storm coverage being too great and I’d target southern Oregon to southern/central Cascades highest threat with a lesser risk over northern Oregon Cascades/Foothills. Saturday and Sunday chances increase and overspread all of western Oregon. Interesting. I do tend to think the SREF is overdoing things, but who knows perhaps not. We’ll have to keep an eye on runs today and tonight.

    Latest 21z SREF
    Valid 6/26 – 6/28
    CAPE 1750-3000J/kg, 3000-4000J/kg southern Oregon. LIFTED INDEX -5 to -7, -9 to -11 southern Oregon. 0-6KM Shear 20-25kts, Effective Shear 25-30kts, PWAT 1.10″ to 1.25″, Dewpoints 64-68, Supercell Composite 3-6, Simulated Radar: Few storms southern Oregon/Cascades, 24hr T-Storm Probability 5% Willamette Valley/PDX, 10-20% Northern-Central Cascades, 30-40% southern Cascades(Chances increase overnight south of Mt. Jefferson) Severe Thunderstorm Probability 5% southern Cascades/southern Oregon(Increases overnight 10-20% into Saturday morning)

    [Saturday-Sunday morning]
    CAPE 3000-4000J/kg Willamette Valley/Cascades. LIFTED INDEX -8 to -11, -9 to -12 southern Oregon/Central Cascades/Foothills of Lane-Marion-Linn. 0-6KM Shear 30-35kts, Effective Shear 30kts, PWAT 1.50″, Dewpoints 68-72, Supercell Composite 3-5 PDX, 8-12 central/southern Cascades, Simulated Radar: Numerous storms Foothills/Cascades. Several more rounds overnight with perhaps additional areas of storms Willamette Valley/PDX/Coast Range. 24hr T-Storm Probability 25% Willamette Valley/PDX, 30-50% Northern-Central Cascades, 50-60% southern Cascades(Chances increase overnight 30-35% PDX/Willamette Valley, 40-60% Foothills/Cascades, Severe Thunderstorm Probability 3-5% PDX/Willamette Valley, 5-10% Northern Cascades, 10-20% Central Cascades, 20-30% Southern Cascades. Threat increases into Sunday morning) On Sunday 20-30% chance PDX/Willamette Valley, but not sure I buy that as Thermodynamic parameters shows the instability axis shifts east of Foothills targeting Cascades/central Oregon.

    00z WRF similar CAPE values perhaps 500-700J/kg less. Modeled IR shows big explosion of storms Friday evening over southern Oregon/southern Cascades, drifts north but should fall apart. Saturday more storms to the south and over Cascades. Chance storms Willamette Valley. Early Sunday morning Precip develops(T-Storms) over Willamette Valley moving northwest. Sunday afternoon-evening more convective precip over Willamette Valley/PDX….

  6. WEATHERDAN says:

    76 at 11:00 PM. Very warm night tonight. I can remember July’s in the 1960,s when it would drop to around 40. There were whole Summers when not even one night stayed above 60. Last year we had 33 such nights and 40 seems reasonable this year. Urban growth would account for some of the increase in warm nights, but not all. Call it what you want our climate in Oregon is considerably warmer than 50 years ago. Peace.

  7. schmit44 says:

    6/25/2015 Oregon (All) Temperature Summary

    High:101 at MEDFORD PORT #2(1900 ft) & John Day River B(305 ft) & RUFUS(185 ft)
    Low: 70 at BLALOK(277 ft) & Rye Valley(I-84(2230 ft) & MEARES Cape Mear(1421 ft)

    High:59 at Newport(30 ft)
    Low: 34 at CROW FLAT (5172 ft )

    Largest Diurnal Change: 52 degrees
    CW5507 Camp Sher (95/43 ) (3020 ft )
    Beatty (93/41) (4320 ft)
    EW6078 La Pine (92/40) (4259 ft)
    KLAMATH NWR (92/40) (4531 ft)
    KIRK (88/36) (4519 ft)
    CROW FLAT (86/34) (5172 ft)

  8. Paul D says:

    “only” in the mid-upper 80’s? I call that a heatwave too. It’s a heatwave until we’re within 5 of normal.

    • Mark Nelsen says:

      80s isn’t a heatwave in Portland…sorry!

    • Mark Nelsen says:

      Maybe in Juneau or Anchorage though

    • Paul D says:

      Wikipedia: A definition based on Frich et al.’s Heat Wave Duration Index is that a heat wave occurs when the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 °C (9 °F), the normal period being 1961–1990.[3]

      It’s a heatwave.

    • EY (Oak Grove) says:

      Not to be a goon or anything… But…


      A formal, peer-reviewed definition from the Glossary of Meteorology is:[4]

      A period of abnormally and uncomfortably hot and usually humid weather.

      To be a heat wave such a period should last at least one day, but CONVENTIONALLY it lasts from several days to several weeks. In 1900, A. T. Burrows more rigidly defined a “hot wave” as a spell of three or more days on each of which the maximum shade temperature reaches or exceeds 90 °F (32.2 °C). More realistically, the comfort criteria for any one region are dependent upon the normal conditions of that region.

      If you’re gonna call upon the Ancient Ones of Wikipedia, make sure that you don’t skip the part that states it’s “peer-reviewed” and, especially, the part that actually mentions what basically everyone else is quoting (The A. T. Burrows part, y’know where the shade temperature reaches or exceeds 90 °F (32.2 °C) for three or more days, as is the definition most meteorologists seem to point to in this area.)

  9. Paul D says:

    Why is 2014’s zero on a taller pedestal than the other zeroes?

  10. Jason Hougak says:

    Hey Mark
    How about some ⚡️⚡️⚡️storms!

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