Another Cool Summer?

Let’s talk long-term weather, then discuss some possible fun action tomorrow evening/night.

First, it’s a pregnant woman’s dream, or so I’ve been told by a co-worker.  Long range models show average or cooler than average temps will continue most likely through the rest of the month.  A 90 degree temperature in Portland appears unlikely during the next 2 weeks.  If so, it’s going to be the first time in PDX history that we haven’t hit 90 through the end of July for 2 consecutive years:

The reason?  We had 10 days of warm ridging nearby; that began on the 4th of July.  Now it appears upper-level troughing is going to linger closer to us (or overhead) for the next 10+ days.  At this point I don’t see an excessively cloudy and chilly pattern, but definitely one that will keep the heat away.  When those upper-level troughs linger nearby, most of the time that maintains a thicker than average cool marine layer; basically the cold Pacific Ocean dominates our weather a bit more than in a “regular” summer.  Get used to lots of 70-82 degree high temps; many would say those temperatures are just perfect.  But this also likely means more gray than we are used to during this normally sunniest time of year.  Models are in very good agreement on the general pattern.  Check out the 850mb temperature ensemble charts from the 18z GFS:

and the 12z ECMWF:

Both models, and their ensemble members, have a chilly upper low just to our north Sunday and Monday, the recover to slightly above average much of next week, then below again after a week from now.

Now lets talk short-term.  Some severe thunderstorm action today, but only over Union County, around La Grande.  Reports of golfball size hail and even a funnel cloud spotted too. 

Real quiet west of the Cascades with just one or two weak storms over the Cascades.  West of the mountains we had a very deep marine layer that kept us socked in low clouds all day long.

Tonight and tomorrow the upper low offshore moves slightly farther offshore, allowing warmer air aloft to move in along with weak easterly flow above about 3,000′.  This should break up the marine layer and bring us a much warmer day (80-85 degrees).

The the fun might begin, all models show the upper low suddenly moving north tomorrow evening through Friday morning.  The strong diffluence in the upper atmosphere on the northeast side of the low (over us) tends to promote rising motions in the atmosphere below it.   Not unlike a wood stove or fireplace starting much quicker when a breeze or wind is blowing over the top of the chimney, pulling air up through it.  The WRF-GFS is showing a large are of storms and showers developing starting tomorrow evening and into the night.  This COULD be a nice little overnight thunderstorm outbreak.  Now our RPM has the action and upper low moving slightly farther east.  It produces nice storms in a line from about Madras to Mt. Rainier.  I trust the WRF-GFS a bit more.  Either way SOMEONE in the Pacific Northwest is going to get a nice light show tomorrow night!

Chief Meteorologist Mark Nelsen

 

 

157 Responses to Another Cool Summer?

  1. W7ENK says:

    Don’t look now, but here comes the marine push again… >_<

  2. runrain says:

    Buildups now occuring in N. Vancouver. Amazing how fast, too.

  3. SPC Mesoscale Discussion
    http://www.spc.noaa.gov/products/md/md1506.html
    MESOSCALE DISCUSSION 1506
    NWS STORM PREDICTION CENTER NORMAN OK
    0611 PM CDT THU JUL 19 2012

    AREAS AFFECTED…OR…WA
    CONCERNING…SEVERE POTENTIAL…WATCH POSSIBLE
    VALID 192311Z – 200045Z

    PROBABILITY OF WATCH ISSUANCE…40 PERCENT

    SUMMARY…THE CHANCE FOR AT LEAST ISOLATED STRONG TO SEVERE STORMS WAS LIKELY INCREASING ACROSS PORTIONS OF NRN/WRN ORE AND SRN WA THROUGH THE EVENING HOURS. WHILE A WATCH MAY BE NEEDED…CURRENT UNCERTAINTY REGARDING OVERALL SEVERE STORM COVERAGE SUGGESTS THAT ISSUANCE IS NOT IMMINENT. CONDITIONS WILL CONTINUE TO BE MONITORED.

    DISCUSSION…MODEST BOUNDARY LAYER DESTABILIZATION HAS OCCURRED WITHIN A REGION WHERE STRONG DAYTIME HEATING HAS ACTED ON RELATIVELY GREATER LOW LEVEL MOISTURE FROM THE WILLAMETTE VALLEY NORTH AND EAST
    ACROSS THE COLUMBIA RIVER GORGE AND OVER THE COLUMBIA BASIN. WITH SOME AREAS NOW ACHIEVING CONVECTIVE TEMPERATURES AROUND 90F…ISOLATED ROBUST TSTMS HAVE DEVELOPED…ESPECIALLY ACROSS NERN ORE. ENTIRE AREA WILL REMAIN UNDER THE INFLUENCE OF A PRONOUNCED MID/UPPER LOW OFF THE COAST THAT WILL LIKELY BEGIN TO ADVANCE ENEWD LATER TONIGHT. MODEST DEEP-LAYER SLY FLOW IN THE ERN FLANK OF THE UPPER LOW WAS RESULTING IN EFFECTIVE SHEAR MAGNITUDES SUPPORTIVE OF UPDRAFT PERSISTENCE AND ROTATION. IN ADDITION TO HAIL…ANY STRONGER CONVECTION SPREADING ACROSS THE RELATIVELY DEEPLY MIXED BOUNDARY LAYER COULD PRODUCE STRONG TO DAMAGING WINDS.

    DESPITE GENERALLY FAVORABLE CONDITIONS FOR SEVERE WEATHER…STORM COVERAGE REMAINS SOMEWHAT IN DOUBT. IF GREATER DEVELOPMENT ENSUES IN THE NEXT 1-2 HOURS…A WATCH MAY BE NEEDED ACROSS SOME OF THE REGION.

    This is awfully close to the Willamette Valley. Hmmm…

  4. *BoringOregon* says:

    Grrr… So close I can see it.!!!!

  5. paulbeugene says:

    So far most everything terrain dependent. Need to see midlayer instability signs (accas). After 7 pm may be worth paying attention to radar.

  6. Thanks for the comments. I appreciate it and I know my Dad is looking down upon us and he appreciates it too. He was proud of my analysis and my music. I love doing analysis especially when we get storms!(Which usually we don’t, so I am often extensively doing so for my folks in Dallas/Fort Worth in my Severe Weather Facebook Group), and I can do it until my fingers literally fall off lol, but it’s just so much sweeter if the actual event we’re tracking pans out. Otherwise it’s almost painful to sit here doing this almost constantly lol.

    Okay so over the next 2-4 hours…..

    *What we WANT to see:
    MUCAPE remaining stout over the Willamette Valley and Cascades 500-1000J/kg+
    Shear advancing north
    Cells starting to survive a little further west in time.
    Storms to pop up down in Linn/Lane Counties west of the Cascade Crest.
    The ULL to track northward and not inland to our south

    *What we DON’T want to see:
    Storms hovering along the Cascades remaining terrain dependent.
    Activity fading to the south
    Instability axis shifting northeast
    Wind shift in Corvallis or Eugene
    ULL tracking northeast into the southern Willamette Valley.

    I’ll be back probably before 7 PM. Enjoy tracking the storms!

  7. Really nasty looking cell up near Timothy Lake. I wonder if it will track like the one the other day and follow along Bull Run?

  8. Brad says:

    Wow that’s a monster looking cell in SE Clackamas Co. 55 dbz.

  9. Wendy-Silverlake says:

    We just had a rumble!!!

  10. Muxpux (Castle Rock 175') says:

    Sprinkles and thunder!! Woohoo!!

  11. Brad says:

    Cascade Locks seeing a nice grouping of storms now.

  12. Ah what the heck? Just informed I am heading out to Dinner around 5PM-ish. Really? With potentially severe thunderstorms to track, and…. Really? I’ll be out at the Heidi’s in Gresham if you want an Autograph.

  13. Timmy_Supercell (Hillsboro, OR) says:

    Updated shot from over 15 minutes ago; looks flatter to my SE view.

    Shucks :)P

  14. What a surprise. HUGE t-storms with massive VIL core west of La Grande and it is severe warned.

  15. Brad says:

    Is that ground clutter or a new cell firing up just SE of Camas?

  16. Wendy-Silverlake says:

    There’s one just to the south of me that is building and heading this way. I guess we’ll see what it does. It’s been pretty sunny up here most of the day, but just clouded up within the last couple of minutes.

  17. pappoose in scappoose says:

    Trip to Portland out of the way…check
    Refreshments reinforced…check
    Power nap complete…check

    Ready for an all-nighter! Game on!

  18. Aloha Rainshadow says:

    Watch the storms popping in Western Deschutes for later tonight, with this trajectory, that’s really where we want to see them pop then hold together. They are starting to explode in deschutes right now!

    • Brad says:

      They can survive the Cascades?

    • Yep, but with CIN at 250-400J/kg over the Willamette Valley it looks very unlikely for any surface based storms to get too far west. Now, with this trajectory as you said this would be ideal for tonight and given MUCAPE shown to remain on SREF along with Shear I would not rule out an elevated severe thunderstorm west of the Cascades.

  19. We just have to wait for the better dynamics/shear to arrive from the south as the ULL moves north. The CAP will weaken probably for another 2-3 hours, but west of Cascades I doubt it will erode enough to allow these surface based monsters to make it into the valley. I assume we’ll have to sit, wait, and be teased until 9 PM or so. I think best chances are 10 PM – 8 AM.

  20. Timmy_Supercell (Hillsboro, OR) says:

    Nice cumulonimbus development in my SE view!

  21. alohabb says:

    Wow..that cell looks huge! I can see just how massive it is well on the westside…hope it continues to this side !!!

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