Thunderstorm Chance This Evening

2:45pm Wednesday…

Radar

Looks like the first thunderstorms of the day have popped up right over the Bend area at 2:30pm.  Expect lots more on the radar screen over the next 8 hours or so.   Models are all showing increasingly unstable atmosphere over NW Oregon and SW Washington between now and 8pm.  We’ve got that unstable atmosphere, some moisture moving north with an upper-level wave of energy (shortwave), plus a strong low-level push of marine air surging into the valley between 5-8pm.

HIGHLIGHTS

  • Isolated thunderstorms build over the Cascades between now and 5pm, could see downpours and/or hail up there in spots
  • Thunderstorms will likely pop up in spots (not everyone will see one) in the lowlands from Eugene north into SW Washington after 5pm
  • Not everyone in the metro area will get a thunderstorm, but ANYONE could see one.  They will be randomly scattered around the area
  • Most likely metro area action will be in the 6-9pm timeframe.  Brief downpours and/or hail is possible
  • Expect wind gusts up to 30 mph between 6-9pm as cooler ocean air surges inland underneath the showers/storms.
  • After 9-10pm it’s over and then we’re dry until sunset Thursday.

I’ve seen better setups for thunder in our area, but this isn’t so bad…actually pretty decent for us.  Very similar setups have given us some nice thunder/lightning displays in the past.  Southeast flow aloft is always good, plus I’ve seen the marine push give a little added lift in the past as well.  That’s because it acts as a mini cold front plowing through the valley, pushing the warmer/unstable air up ahead of it.  Take a look at the WRF-GFS showing surface wind at 8pm.  Averaging SW 15-20 mph (that’s windy for a warm evening) running into the NW wind coming up the Columbia River.  I drew in the “convergence” area with the broad highlighter.  That convergence can sometimes work wonders too.

Capture

I’ve seen this in the past where storms bubble up right over that boundary.  Always fascinating to watch on radar of course.  The HRRR model is showing much of this nicely this afternoon.  Here’s the 7pm forecast from its latest run:

HRRR_7pm

It also thinks there will be many dry areas.  Here’s the total precipitation outlook through early tomorrow (all of it this evening) from the last two hourly runs of that model:

hrrr_t_precip_portland_16 (1)hrrr_t_precip_portland_16

Not exactly a widespread soaker tonight is it?  But for a few hours it could get real exciting just before/after sunset.

At this point there is no threat for severe weather in the lowlands.  By that I mean thunderstorm winds with gusts over 58mph or damaging hail.  Earlier SPC had put the Cascades in a MARGINAL threat for severe storms, but they have now removed that.

So how can you stay on top of the action this evening?

  1. We’ll be on-air 5-7pm on FOX12, 8-10pm on KPDX, and 10-11:30pm back on FOX12 (we like to be on TV)
  2. We’ll be posting any significant weather updates on Twitter and Facebook.  FOLLOW and LIKE us at FOX12WEATHER (all one word)
  3. On www.kptv.com/weather
  4. If I get time I’ll post here as well.

 

Chief Meteorologist Mark Nelsen

 

31 Responses to Thunderstorm Chance This Evening

  1. Boring Oregon says:

    Should we be watching the cascades right now?

  2. Dave in SW PDX (235') says:

    That line of showers kinda “domed out” over the metro area; disappointing but not unexpected. Saw a few flashes and heard some thunder, but not enough precip to even register a trace. Maybe the SW marine push will initiate more storms later this eve.

  3. Paul D says:

    What a great way to kick those 80’s in the butt and wave goodbye!

    That 7 day forecast is looking really good after Thursday!

    • EY (Oak Grove) says:

      I’d agree that it looks great if not for the fact that, whenever we do this stupid swing with temps over a few days, it seems to make me sick. Still recovering from a cold that I got last week on Monday… Don’t need another re-enforcing shot.

  4. Hal in Aims says:

    well…..that was fun……just plugged the electronics back in…..brief power outage…..heavy rain and lots of lightning…….not much in the way of wind though…………waiting for round two…….

  5. Steven James says:

    Gigantic storm up near government camp; at least four or five cells, right around thirty thousand feet, give or take a little, severe thunderstorm warning. So I guess the SPC was wrong, after all. They shouldn’t have changed their minds!

  6. Jason Hougak says:

    Awesome weather action
    Stay safe but enjoy

  7. jc says:

    Thunder in ne Portland/Gresham

  8. Hal in Aims says:

    way too close for comfort………

  9. EY (Oak Grove) says:

    Half dollar sized hail?!

  10. I’ll be keeping an eye on the southern horizon this evening. Right now it’s clear and 81 here, but the barometer has been falling and its only 29.75 inches. So either we will get the marine push overnight or some possible thundershowers (or plain showers).

    • rubusleucodermis says:

      72 here after a high today of 78, and nothing on my southern horizon yet. NWS has a 40% T-storm chance in tonight’s forecast. If it makes it up your way it will doubtless take another six hours or so. Maybe you’ll wake to morning thunder.

    • Okay, Rubus- you’re probably right. I’m rushing things along! 🙂

  11. cgavic says:

    From sandy…10 min. ago lightning and now rain. Thunder storm over us.

  12. Lurkyloo says:

    Heard some thunder just now.

  13. EY (Oak Grove) says:

    I’m hearing thunder out in Oak Grove. Quite a bit of rumbling, actually… Pretty surprised.

  14. Hal in Aims says:

    if that stuff to the south holds together……could get slammed here in a bit…….distant thunder……..

  15. Boring Oregon says:

    I can see lightning and hear some faint thunder.

  16. W7ENK says:

    SEVERE THUNDERSTORM WARNING
    (CLACKAMAS COUNTY)
    NATIONAL WEATHER SERVICE PORTLAND OR
    417 PM PDT WED APR 20 2016

    https://inws.ncep.noaa.gov/a/a.php?i=2206665

    • EY (Oak Grove) says:

      Was napping/sleeping when the Emergency Alert kicked in. Always freaks me out when it’s not the normal test and it wakes me up. But pretty exciting for that! Stay safe everyone!

    • Lurkyloo says:

      I thought NWS wasn’t yelling anymore … This must be serious!

  17. Garron 1/3 of a mile from Hillsboro Airport says:

    Things are really popping up over the Cascades right now! https://www.wunderground.com/radar/radblast.asp?ID=RTX

  18. My alter ego says:

    Sure feels more like June than April to me. Even our cool days of late are more like a normal day and not cooler than normal. We have a real good shot at being the warmest April on record. Peace.

  19. runrain says:

    Nice TRW heading towards Estacada. Let’s see if it holds together. Looks like the Happy Valley/Damascus/Boring area could get some action tonight (I know, wishful thinking).

  20. Shawn Weagle - Garden Home/SW Portland says:

    Well put, Mark. I agree with just about everything you say, fwiw. The wild card is how much of a trigger the seabreeze front will be. Models tend to either underestimate that (when they don’t grossly overestimate it), and that may be happening given our full sun and 80 degree temps. But sometimes the lift just isn’t enough to break whatever minor cap is in place.

  21. W7ENK says:

    Not a whole lot going on out there yet, I would have expected more…

    Humidity is nowhere near what was forecast for today. At least, it doesn’t feel like it.

    Got my fingers crossed, hoping for a surprise this evening!

  22. Steven James says:

    First, again. :]

    Nice report, by the way. I’m looking forward to seeing a storm tonight!

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