2-3 Days of Weather Action: Thunderstorms Possible

Just about anyone in the FOX12 viewing area  could see a thunderstorm during the next 72 hours, but not everyone will; a challenging forecast ahead.  By the way, in case you ever wondered where our signal goes, it’s generally in the blue area.  Some people receive us via satellite outside the blue counties; but these are the counties we “service”.  Specifically, in forecasting weather and severe weather warnings we pay attention to these.

For those just wanting the basics:

1.  Warmer temps today and tomorrow, highs closer to 80 with a mix of sun/clouds.  We won’t see the gruesome clouds/drizzle we had Sunday morning!

2. We can’t (no one can) forecast exactly who or what spot will get thunderstorms or at what time.

3. We do know the best chance appears to be from later today through Tuesday evening. 

4.  Storms that DO develop will move from east to west; the opposite of our normal weather pattern.  They will come from the east (Cascades).

5. Don’t do anything outside that requires 24 hours of dry weather (staining, spraying etc…)…too risky.


More Details:

This morning an upper-level low, basically a circulation in the upper atmosphere, is moving south along the Oregon Coast.  It’s near Newport at 11am.   Click for a better view below, map shows the airflow at about 30,000′ or 300mb: Circulation around an area of low pressure is counter-clockwise, which means most of us are on the north and northeast side of the low by later today.  By 11pm tonight it’ll be right on the Oregon/California border.  But look ahead to Thursday afternoon:

Still in the same spot!  That means for the next 3 days we’ll have easterly or southeasterly flow in the upper atmosphere overhead.  This is usually a good setup for getting thunderstorm action west of the Cascades.  Indeed we’ve already seen storms on the north side of the low this morning up in SW Washington:

This is never a guarantee of widespread thunderstorms; I’ve seen this pattern end up with almost nothing over some spots.  But the screaming message is the potential is there for anyone to see a thunderstorm and just about anytime of the day or night the next 72 hours.  Take a look at the Lifted Index forecast for tomorrow afternoon from the NAM, it’s a measure if instability in the atmosphere.  When it gets to zero or below, that’s good: 

Very impressive -4 to -6 over the Cascades of Washington and very close to the Portland Metro area!   Easterly flow could bring storms out over the lowlands west of the Cascades.  Tuesday does appear to have the best dynamics/forcing for stronger storms too; it might be our best bet.  Afternoons/evenings do tend to have more “action” due to the stronger rising motions from daytime heating, but in a pattern like this the action can occur anytime of the day/night as small curls or eddies move around the big upper low setting off storms.

Once this all moves out of here on Friday, models show the hot upper-level ridge over the desert SW pushing closer to us again.  That’ll give us another run at 90 degrees over the weekend or early next week.  The 12z GFS ensemble chart shows above average 850mb temps Saturday and beyond.  The ensemble average generally agrees with the operational model:

The ECMWF is similar:

Chief Meteorologist Mark Nelsen

69 Responses to 2-3 Days of Weather Action: Thunderstorms Possible

  1. Mr Data says:

    Hey Rob. Since you’re on does that mean you and Mark worked out whatever squabble that got you banned hopefully?

  2. rianmuleback says:

    Seeing lots of towers and we drive through the Gorge into Pendleton. Decided to skip going to Maupin and if you check out the Pendleton radar you’ll see it appears we may a wise choice 🙂

  3. pappoose in scappoose says:


  4. Timmy_Supercell (Hillsboro, OR) says:

    I get a vibe from the air outside. Especially during a sunbreak I get a sense that the Titans are going to be Clashing in the skies sometime later…

  5. Aloha Rainshadow says:

    Storms starting to fire in southern deschutes county.

  6. *BoringOregon* says:

    Come on sun, and come on storm warnings !!!

  7. rianmuleback says:

    Headed to Maupin then Pendleton with Tyler. If we see something develop in a better area then we’ll go after it.

  8. W7ENK says:

    I thought I just heard thunder over downtown?

  9. New t-storm potentially developing east of Molalla. Cloud tops building a bit and yellow echoes(Similar to earlier t-storms)

  10. Early start to a stormy day.

    There has already been 8 or so lightning strikes(most CCs) from 2 individual cells. One was near Oregon City and the other just west of Wilsonville. Now looking at radar you’d see the returns and perhaps discount my posting as DBz were only 47-50, but storm tops have bumped up to 32-33k already. Is this the beginning of an epic day? Could be. Forecast instability parameters are incredible for us. CAPE now 2500-3000 forecast, LI -6, but shear may lack for a true severe weather potential. That being said I would not be shocked to see Severe warnings west of the Cascades today.

    • MUCAPE already 1000J/kg over PDX metro. SB/MLCAPES slowly increasing, but a large CAP(CIN) is in place which will slowly erode today. The atmosphere is super charging right now. A large area of clouds is moving W-NW off the Cascades into the PDX area, but VIS shows good clearing behind it. I think we will warm enough to weaken the CAP for surface based storms later this afternoon.

    • W7ENK says:

      Exciting! I particularly like the “beginning of an epic day” part… I like epic days, so I hope you’re correct!! :mrgreen:

      Thank you for your analysis.

    • Or not… Wow mid-level clouds quickly developing to the south-southeast. Not sure about a ton of sun this afternoon.

    • No problem, and I hope I’m right too. I’d be shocked if we all didn’t at least hear Thunder over the next 24-48 hours.

  11. JJ97222 says:

    Put some lawn food on the yard today hoping for a good shower to wash it in, then its on for great weekend weather looks fantastic at this point! This July is so much nicer than last years, extended weather looks warm to hot perfect!

  12. weathercrazy82 says:

    Sweet! I won First Prize in the Weatherwise Photo Contest! It will be featured in the September/October issue!

  13. weathercrazy82 says:

    Castellanus clouds this morning. 70% of the time I’ve seen these, storms have followed within 24 hours.

  14. paulbeugene says:

    Today should be a good convection day…sunny this morning..feels muggy down here in Eugene….the more sun the better as we head toward afternoon…looks like a 500mb vort max spins through late this evening…could be interesting then.

    • Had a nice wake up rumbler this morning about 5 AM. Lots of lightning and some good thunder.

    • Mark Nelsen says:

      I agree, everything looks good. But both our RPM and WRF-GFS keep just about all (most) of the action in the Cascades this afternoon evening. Interesting that the movement is supposedly not strongly east-west but more stationary. Like the marine push this evening runs into the easterly flow above. Should be fun to track at work.

    • weathercrazy82 says:

      Ya I noticed that…it just stays east then drifts around…That’s okay as long as I’m over there.

  15. runrain says:

    Mark says 80° for Sunday. NWS says 89° for Sunday. Let’s see who wins!

  16. bgb41 says:

    7/17/2012 Oregon (All) Temperature Summary

    High:94 at Rye Valley(I-84(2230 ft)
    Low: 67 at BULLY CREEK RESE(2500 ft)

    High:55 at Timberline Lodge(7001 ft)
    Low: 28 at Pine Ridge (4220 ft )

    Largest Diurnal Change: 54 degrees
    FOSTER FLAT (90/36 ) (5000 ft )

    Heaviest Rainfall:
    1.23″ at MINAM LODGE-PORT(3575ft)

  17. Mr Data says:

    Even though the airports say clear the last time I looked an hour ago it’s 00% overcast here in Silverton either marine layer or storms from the mountains coming in.

    I cannot exactly tell as it all looks alike!

  18. karlbonner1982 says:

    Looks like more muggy and unstable air; a classic humid-continental summer pattern!

  19. runrain says:

    Looks like a pretty good cell popped up SE of Cascade Locks and headed their way.

  20. Hal in Aims says:


  21. runrain says:

    Sort of looks like a Milwaukie-ish dome is over us, keeping the moisture and storms away. Can anyone verify? WENK7?

    • runrain says:

      Sorry. W7ENK.

    • W7ENK says:

      Hahaha! 😆

      WENK7 works too, I guess…

      Only showers I see on radar are well to the South of Portland this morning, like West of Albany, and moving West. A few lightning strikes associated with them.

      HOWEVER! There is a WALL of lightning moving toward us out of Central Oregon, range 150 miles and closing!!


  22. J in N Hazel Dell, WA says:

    And the roofers are just finishing our new roof. Great timing!!

  23. This is a GREAT setup! Let’s get this train outta the station! A week ago I was getting hammered in the mountains, which wasn’t so much fun cuz we were camping. But T-storms at home are just plain fun. Better check the fridge for to make such sure I’ve got a few cold view brews 🙂

  24. pappoose in scappoose says:

    NWS is in!

    National Weather Service Portland or
    212 PM PDT Monday Jul 16 2012

    Expect the upper low to move off the northern California coast
    Tuesday…allowing flow aloft to turn even more southerly and middle level moisture to increase. Tuesday highs are still on track to being warmer than today…which will help storm development during the peak warming hours. Model lifted index values drop to -6 late Tuesday morning through Tuesday evening…by far the most impressive values seen so far this Summer. Stretched the overall thunderstorm threat to encompass the entire Willamette Valley and Coast Range as well as the Cascades during this time.

    All are now Aboard the Stray Albino Donkey Train! Hahaah!


  25. runrain says:

    Pretty good cell just east of Madras headin’ this way. Big question is will it hold together. GOLU activation T -2 hours!

  26. gidrons says:

    Looks like the fun is starting on the east side of the Cascades

  27. *BoringOregon* says:

    Hey, mark what about this humidity well it ever go away or get worse when it heats up next week? can’t wait for the 90s. !!!

  28. runrain says:

    I hope that those bloggers who do get storms will report their observations.

  29. pappoose in scappoose says:

    I really like this screaming message! 72 hours of watching the GOLU model! Just about as good as it gets!

  30. weathercrazy82 says:

    I’m off until Thursday, so I’ll have time to chase…would be great to get some good overnight storms.

  31. bgb41 says:

    I like being north of the upper low like this. The weakened onshore flow is warmer and increases the threat of TS.

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