Metro Thunderstorm This Evening?

Warmest night of the year so far last night with a low of only 59.  Sure feels like a summer morning out there and I think I like it!

Lots of clouds out there this morning and we’ll only be partly cloudy today as the upper level low off the California coast spins the moisture up over us.  Assuming we get plenty of sunbreaks between the cloud cover, we should still be able to hit 80.  If it stays too solid, it might only be a 76 degree day instead.

I’m not too excited about the chance for thunderstorms later this afternoon and evening except for one spot

Our RPM model (the only one that shows it) has shown an interaction of a northwesterly marine push this evening and the available mid-upper-level moisture right over the Portland Metro area.  I couldn’t include the whole loop, but notice the 10pm forecast shows a cluster of showers/thunderstorms right overhead.  They form around 7-8pm on this model and hang nearby until about midnight.  There is a slow movement from NW to SE.  This is about the 6th run of our model showing the same thing; we get a new 27 hour run every 3 hours.  Now the WRF-GFS from the UW doesn’t show anything similar, so it might be some sort of convective feedback on the model.  Either that or it’s the only one implying there will be just enough lifting with the arrival of the marine air this evening to set off a few thunderstorms or showers.  Of course the fun part of weather watching/model riding will be to see what actually occurs.

Chief Meteorologist Mark Nelsen

72 Responses to Metro Thunderstorm This Evening?

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



    Forest Grove storm just blew up! Hope this persistent and isn’t pulse nature.

    • Rob "Wrath" S.E. Portland says:

      66.0 dbz… Scanning Base velocities to see if any outflow boundaries are evident where we could see further storm initiation…

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

    Lightning strike just occurred with the Forest Grove cell.

  3. Timmy_Supercell (Klamath Falls @ 4200') says:

    I’m so glad I wasn’t 100% sure of anything today, or I’d be paying lots of debt. This is so a bust for most of you folks.

    • Austin (Cornelius) says:

      Sorry to bust your bubble…but me and my sister just heard a rumble of thunder. HA!

    • Jesse-Orchards says:

      Don’t speak so soon Timmy!

    • Rob "Wrath" S.E. Portland says:

      It can’t be a bust when we only had a 5-10% chance. If we had a 40-50+% chance and nothing occurs THEN you can call it a bust. It’s only 4:53 PM. The best time for storm initiation this time of year is 5-7PM.

    • Timmy_Supercell (Klamath Falls @ 4200') says:

      Ha thats why I said ‘most’ folks!

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

    (For Portland/Vancouver Metro and Willamette Valley)
    4 PM Update

    *Upper Air Analysis
    925Mb: +18c
    850Mb: +13c
    700Mb: +1.5c
    500Mb: -16c to -17c

    SBCAPE: 500-800J/kg, 1000J/kg Salem vicinity, Foothills of Marion/Linn Counties
    SBCAP: 25-40J/kg CIN, NONE-25J/kg CIN Salem vicnity, Foothills of Marion/Linn Counties
    MLCAPE: 500J/kg
    EML: 25-50J/kg CIN, NONE-25J/kg CIN Foothills of Marion/Linn Counties
    MUCAPE: 1000-1200J/kg
    LIFTED INDEX: -3 to -4, -4 to -5 Salem vicnity, Foothills of Marion/Linn Counties
    PWAT VALUES: .91″
    BULK SHEAR: 10kts

    CAP continues to weaken and CAPE/LI have well exceeded forecast/sounding projections. No t-storms yet seen north of Mt. Jefferson. Due to increases instability I don’t think we can yet entirely rule out storms in the metro area(As Mark’s RPM model suggests) as a possible trigger may arrive as the marine push arrives later.

    • Rob "Wrath" S.E. Portland says:

      34,800′ tops near Detroit Lake now.

    • Josh (Gresham) says:

      Nocturnal T-Storms maybe? Please weather gods….

    • Rob "Wrath" S.E. Portland says:

      Interesting… Appears to possibly be some activity developing west of Banks in the Coast Range. I need a few more scans to verify, but per radar loops it does show cloud tops developing/growing which would lead one to believe this is a legitimate cell.

    • Josh (Gresham) says:

      That looks like it could be fun

    • Austin (Cornelius) says:

      Looks to be convection in coast range in forest grove area! 😀

    • Aloha Rainshadow says:

      Confirmed development west of forest grove pic was just sent to me.

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

    31,800′ tops on the storm near Detroit Lake.

  6. Timmy_Supercell (Klamath Falls @ 4200') says:

    Wow, Timberline Lodge cam stops updating when thunderstorms are there. What has the world come to?

  7. Timmy_Supercell (Klamath Falls @ 4200') says:

    I should have moved to Detroit Lake! 30,000 ft. tops do sound pretty high to me. 😆

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

    Lightning Detection maps are working again

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

    (For Portland/Vancouver Metro and Willamette Valley)
    3 PM Update

    *Upper Air Analysis
    925Mb: +17c to +18c
    850Mb: +13c to +14c
    700Mb: +1c
    500Mb: -16c
    **Slight cooling aloft in the 700-500mb column

    SBCAPE: 250-500J/kg, 500-1000J/kg Salem vicinity
    SBCAP: 50-75J/kg CIN, NONE-25J/kg CIN Salem vicnity, Foothills of Marion/Linn Counties
    MLCAPE: 250-500J/kg Salem vicinity
    EML: 50-100J/kg CIN, 50J/kg CIN Salem vicinity
    MUCAPE: 800-1000J/kg
    LIFTED INDEX: -1 to -2, -3 to -4 Salem vicnity, Foothills of Marion/Linn Counties
    MID-LEVEL LAPSE RATES: 6.5 to 7C/km
    LOW-LEVEL LAPSE RATES: 7 to 7.5C/km
    PWAT VALUES: .91″
    BULK SHEAR: 10kts

    Showers and t-storms are developing along the central Cascade crest with steering currents pulling them west-northwestward. The strongest cells are just northeast of Detroit Lake and eastern Linn County with tops 29-30k tall. Based on Mesoanalysis and convective trends I think there is a reasonable chance these either hold together as they drift towards the Willamette Valley or intensify a bit. Due to weak shear profile I do not expect any severe warnings. It is unclear if the CAP breaks north of Salem/Wilsonville or if there will be enough lift available for storms in the PDX metro area.

    • Rob "Wrath" S.E. Portland says:

      Storms are already starting to shift west-southwest it appears as they likely run into the infamous marine air…. This sucks.

  10. Aloha Rainshadow says:

    Cascade crest is blowing up and some development taking place in eastern clackamas county.

    • Josh (Gresham) says:

      What development do you see in Clackamas county? Everything looks to be south of Salem

    • Rob "Wrath" S.E. Portland says:

      I see it also… stuff is trying to develop near Mt. Hood.

  11. pedro771-ashland says:

    Just getting some light rain now. Temperature is all the way down to 66 degrees.

  12. Timmy_Supercell (Klamath Falls @ 4200') says:

    If the first storms around 12:30pm had rain cooled some of the atmosphere, that’s probably why things have slowed down. And I wouldn’t be surprised. It takes more than just instability and daytime heating to get thing to pan out like we had anticipated.

  13. Timmy_Supercell (Klamath Falls @ 4200') says:

    Storms have stopped for now. Maybe in another 45-60 minutes it will pick back up.

    • Timmy_Supercell (Klamath Falls @ 4200') says:

      Best chance for storms since last year and I’m still not overly impressed. Clouds didn’t look all that tall either.

    • Josh (Gresham) says:

      It’s not gonna do anything today, don’t you know the state we’re in?

    • Timmy_Supercell (Klamath Falls @ 4200') says:

      This state has nothing to do with it, hope you haven’t forgotten about 2009 😆

    • Timmy_Supercell (Klamath Falls @ 4200') says:

      Sometimes we can have almost midwest type convection. It just takes more dynamics than what we are seeing today.

    • Josh (Gresham) says:

      I’m juss playing around haha, and ya I remember that, but weren’t the parameters better then?

    • Josh (Gresham) says:

      *dynamics, not parameters

    • Timmy_Supercell (Klamath Falls @ 4200') says:

      Yeah I remember SB CAPE values were ranging from 1500-2000 J/kg, and Lifted Indexes around -4 at least. Plus adding temperatures approaching 90F in many locations, that created the “exploding cumulus” effect. 😆

    • Josh (Gresham) says:

      Looks like nothing today, the NWS sure thinks it’s all gonna be south of Portland

    • Timmy_Supercell (Klamath Falls @ 4200') says:

      Well everything is still to the west of Klamath Falls… And 65F right now from 70F. Also much windier than earlier. Looks like I was right about before, our first storms here have cooled the atmosphere. Now Medford/Roseburg have the best chance for storms. Well, its a bust for me pretty much. I need to wait a couple weeks before recording anything exciting.

      Lately my YouTube channel has just been used for video games. C’mon Mother Nature. Where’s your pride?

  14. Josh (Gresham) says:

    I have this bad feeling that the farthest north we’re gonna see anything is maybe north of Salem…

  15. Timmy_Supercell (Klamath Falls @ 4200') says:

    Storms are nearly stationary… Is this a good or bad sign? For those in the big cities who want storms???

  16. muxpux says:

    Longviews in a nice spot looking at the sat loop, we get the heat, in between the clouds… muggy as heck, but so was yesterday

    • Jesse-Orchards says:

      The air was actually very dry yesterday. Made the first real warm weather of the year more bearable.

      Dps were in the low-mid 40s in Longview the entire afternoon yesterday. In the Portland area we had DPs in the upper 30s to low 40s.

      Yesterday is a bit muggier, though. 75 here with a DP of 53. It’s noticeable and probably a good sign for storms.

      People in the South would laugh at us for calling this muggy, though. For a muggy day down there, take our temp, make it the dewpoint, and add 20 degrees for the actual temp.

    • Jesse-Orchards says:

      *today* is a bit muggier, though.

    • Punxsutawney aka HIOPHIL says:


      I’ve been in Kentucky where the road was steaming, after a thunder shower, and it was 88 degrees outside. That is humid!

  17. pedro771-ashland says:

    I have also heard some distant rumbles of thunder, but nothing really promising coming my way yet.

  18. Josh (Gresham) says:

    Not excatly scientific, but it FEELS like stormy weather today. It feels more like I’m back in Illinois on a muggy June day.

  19. Timmy_Supercell (Klamath Falls @ 4200') says:

    Okay I was able to watch some of the cumulonimbus development outside to the west and north of my location. Took some pictures and so far looking nice. When everything unfolds this evening I will upload an album to and of course share that with ya all.

    • Timmy_Supercell (Klamath Falls @ 4200') says:

      Btw, heard a few rumbles from a storm north of here. Definitely was not a jet or plane, thats for sure.

    • Timmy_Supercell (Klamath Falls @ 4200') says:

      70.3F here. Not very muggy here. Dew point 31F, humidity 23%.

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

    (For Portland/Vancouver Metro and Willamette Valley)
    2 PM Update

    *Upper Air Analysis
    925Mb: +17c
    850Mb: +13c
    700Mb: +2c
    500Mb: -15c to -16c

    SBCAPE: 100-250J/kg, 250-500J/kg Salem vicinity
    SBCAP: 100-150J/kg CIN, CAP eroding quickly south of Wilsonville
    MLCAPE: 100J/kg, 250-500J/kg Salem vicinity
    EML: 100J/kg CIN, 50-75J/kg CIN Salem vicinity
    MUCAPE: 500J/kg
    LIFTED INDEX: 0 to -1, -2 Salem vicnity
    MID-LEVEL LAPSE RATES: 6.5 to 7C/km
    LOW-LEVEL LAPSE RATES: 7 to 7.5C/km
    PWAT VALUES: .90″
    BULK SHEAR: 10kts

    WV Loop and Mesoanalysis indicate a strong shortwave over south-central Oregon around Chemult/US 97 pivoting northwestward. Also I notice the southeast flow aloft is lifting north to just south of Olympia. Why do I mention this? The most favorable flow aloft was supposed to be south of the Columbia River with the northern extent over extreme southern Washington being squashed down as the next trough begins to approach from the Gulf of Alaska. With the flow bulging just a bit further north that could allow for the chance of t-storms north of a line from Three Sisters-Bend-Oakridge-Eugene to perhaps even further north Mt. Jefferson-Salem. I do think there is an outside chance of storms near Mt. Hood, southern Clackamas County areas. We’ll have to monitor Mesoanalysis, WV/VIS, radar, and convective trends.

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

    Good afternoon all. It is 77.4 here and a bit muggy. Mesoanalysis update coming soon….

  22. W7ENK says:

    That graphic sure looks nice, Mark! 🙂

  23. Timmy_Supercell (Klamath Falls @ 4200') says:


  24. pedro771-ashland says:

    Action is already starting to heat up down here. First lightning strikes have started in the mountains.

  25. Timmy_Supercell (Klamath Falls @ 4200') says:

    There’s already a great deal of cumulus development out to my west. Mark, you should be excited about chances of thunderstorms!

    Well, I decided to postpone what I needed to do, time to track some thunderstorms already.

    • Derek Hodges says:

      You may as well do whatever you have to do now while nothing of consequence is occuring so you can have the afternoon to watch. I am going to do what I need to do now so come late afternoon I will be free to watch them form.

  26. Jesse-Orchards says:


  27. Derek Hodges says:

    Its going to happen…hopefully. 🙂 I have been watching this for several days and its been iffy the whole time but I feel pretty good about somebody getting at least a little something.

    • Josh (Gresham) says:

      Derek if we have them I’ll have to hand it to you, you’ve been talking about it for a week

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