Thunderstorms: Could Be a Wild Afternoon

9:45am Wednesday…

I’ve got an important haircut to get to (critical for this job), but I wanted to let you know we could see some exciting stuff this afternoon first.  A cold front moves across our area this afternoon and along with warm southerly flow plus arriving cool air above, we could see thunderstorms pop up.  Models have been showing this for almost two days but this morning I see SPC (Storm Prediction Center) has put us in a MARGINAL threat area for severe thunderstorms west of the Cascades.

Capture

Highlights:

  • Expect warm temperatures midday/early afternoon as the south wind arrives…around 60 degrees.  Both our RPM model and WRF-GFS put us up to around 65 early afternoon!
  • A line of heavy showers/thundershowers develop and/or move from SW to NE across the Willamette Valley and SW Washington in the mid/late afternoon (3-6pm).
  • Thunder and/or hail is possible as this line of showers moves over.
  • A strong southerly wind burst may accompany the showers as well.  S/SW wind gusts 30-40 mph possible.  Likely just in spots where the showers are heavy.
  • It’ll finally feel like winter (the stormy part) for a few hours!

 

We have a nice low lifted index showing up on models at 4pm, lots of CAPE too.  HRRR has the CAPE up over 1000 j/kg in the Willamette Valley mid/late afternoon!

hrrr_cape_portland_9.png

Our RPM, which isn’t always a stellar performer, has that convective look to the cold front at 4pm:

rpm_precip

 

Here’s the SPC discussion:

...SUMMARY...
   ISOLATED THUNDERSTORMS ARE EXPECTED FROM SOUTHWEST WASHINGTON
   SOUTHWARD INTO CENTRAL CALIFORNIA...A FEW OF WHICH COULD PRODUCE
   LOCALLY DAMAGING WIND.

   ...SYNOPSIS...
   AMPLIFIED BUT PROGRESSIVE PATTERN WILL PERSIST ACROSS NOAM THROUGH
   THE PERIOD. DEEP LOW NOW CENTERED NEAR 42N/135W EXPECTED TO DEVOLVE
   INTO A STRONG...SLIGHTLY NEGATIVELY TILTED TROUGH THAT SHOULD EXTEND
   FROM CNTRL CA TO JUST OFF THE ORE CST BY 12Z THU AS DOWNSTREAM RIDGE
   ADVANCES E INTO THE PLNS.

   AT LWR LVLS...COLD FRONT/OCCLUSION WITH PAC SYSTEM SHOULD REACH THE
   ORE/NRN CA CST AROUND 21Z AND CONTINUE EWD ACROSS THE CSTL RANGES A
   BIT LATER WHILE WEAKENING. A SECONDARY FRONT/TROUGH LIKELY WILL
   APPROACH THE CST TOWARD 12Z THU.

   ...N PAC CST THROUGH PERIOD...
   MOISTURE AND DEEP SLY FLOW WILL SUBSTANTIALLY STRENGTHEN ALONG THE
   ORE/NRN CA CST LATER TODAY AS FRONTAL ZONE NEARS REGION. LOW TO
   MID-LVL LAPSE RATES LIKELY WILL REMAIN MODEST /JUDGING BY CHARACTER
   OF FRONTAL CLOUD BAND NOW OVER THE PACIFIC/. NEVERTHELESS...WITH PW
   INCREASING TO AROUND 0.75 INCH...POCKETS OF SFC HEATING...AND DEEP
   UPLIFT STRENGTHENING WITH THE ARRIVAL OF THE FRONT...ISOLD THUNDER
   MAY DEVELOP ALONG AND AHEAD OF BOUNDARY. STRONG LOW TO MID-LVL WIND
   FIELD MAY FOSTER DEVELOPMENT OF OCCASIONAL SMALL BOWING SEGMENTS AND
   SHORT-LIVED LOW-LVL ROTATION IN SHOWERS/STORMS...ESPECIALLY ALONG
   THE NRN CA/ORE CST...AND IN THE WILLAMETTE VLY. WEAK
   BUOYANCY...HOWEVER...SHOULD LIMIT INTENSITY/DURATION OF ANY
   ASSOCIATED SVR THREAT.

   WDLY SCTD TSTMS SHOULD FOLLOW FRONTAL BAND OVER A LARGER REGION FROM
   SW WA SWD INTO CNTRL CA THIS EVE AND TNGT...AS MID-LVL TEMPS COOL TO
   AOB MINUS 25C AND ONSHORE MARITIME FLOW STRENGTHENS IN WAKE OF
   FRONT. SMALL HAIL MAY ACCOMPANY STRONGER/LONGER-LIVED UPDRAFTS.


Of course now that I've brought this to your attention, we'll probably only see a few heavy showers and nothing happens.  Or...we'll see! 

Chief Meteorologist Mark Nelsen

43 Responses to Thunderstorms: Could Be a Wild Afternoon

  1. Boydo3 N. Albany says:

    Big drop in temps in the mtns tonight. Santiam pass went from 50 degrees and sunny to a snowy pass and below freezing tonight.
    http://tripcheck.com/RoadCams/cams/Santiam%20Pass_pid2728.JPG?rand=1455775347035

  2. Some pretty balmy temperatures down there in Oregon. Here I was mostly around the 50F mark with showers, pretty boring stuff. (including little wind). Not looking forward to a replay of summer 1983: That one featured my wettest July on record and second wettest June. i think we’ll do better than that for sure.

  3. Tyler Mode in Battle Ground says:

    Today’s 66.4 is my warmest temperature at my Battle Ground station in the last 5 years. It beats out 65.5 set exactly a year ago today.

    0.54″ of rain so far. Today was the first “summer rain” smell of the year.

  4. High Desert Mat says:

    Its so windy over here. Its been windy for about the last 4 hours and it sucks. Wind is by far my least favorite weather event. Its bad for fishing, being outside, and basically everything in general except to clear out stagnant air. Its annoying. Sorry, rant over.

  5. JackFrost says:

    I forgot to add that in the summer of 83 the wetness was from several sharp systems that brought thundery patterns.

    83 was a pretty thundery year according to statistics and newspaper archives and the winter DJF of 82-83 was similar to this with a period of dry colder weather followed by fluctuating snow levels.

    Only difference is California got slammed hard with flooding in Central Cali with storm after storm.

    • High Desert Mat says:

      Is that really the only difference? If you look closer, the weather wasn’t all that similar, in fact it was quite a bit different. Just going off the numbers though.

  6. cgavic says:

    Mark, my opinion (& snow boarders who work part time at the Mtn.) winter is over. Too much fluctuating in snow levels. The last 2 days any snow would was limited to volcanic peaks(?)

    • JackFrost says:

      I’ve been pouring over 82-83 and there are so many similarities between both coasts that it isn’t funny.

      I predict a wet summer but instead of it being colder I think a more muggle…..I mean muggy summer is in store even worse then last year but lower overall temps.

  7. Hal in Aims says:

    flash…..boom…….rumble……..

  8. MasterNate says:

    Apparently we are in the heart of that crazy radar echo but what an under performer, such as our winter. Hardly a breath of wind so far. Plenty of the wet stuff.

  9. Jason Hougak says:

    Radar showing nice batch of weather just about ready to hit east side.

  10. Hal in Aims says:

    looks like it’s going to get real wet real soon……..

  11. runrain says:

    Is that barometer for real? 29.19?

  12. paulbeugene says:

    Not looking all that impressive at the moment with solid cloud deck moving in with some embedded convective elements . I would tornado watch can be cancelled, would issue swirling wind advisory instead

  13. paulbeugene says:

    I may be the first to get the convection . Will be reporting by 4pm

  14. WEATHERDAN says:

    A good TRW would be a nice change of pace. And the mild weather is a real bonus. But Mark warm stormy weather puts me more in mind of Spring than Winter. Peace.

  15. W7ENK says:

    Mark, the bottom/end of your text got cut off…

    Of course now that I’ve brought this to your attention, we’ll probably only see a fe

    Chief Meteorologist Mark Nelsen

    Though I get the gist, probably about the same as my usual sentiments…

  16. schrauf99 says:

    Isn’t “marginal” even less than “slight” risk? Wild indeed! =P I’m surprised there has not yet been a BREAKING NEWS alert from the Oregonian.

  17. What does the wind look like for tomorrow in and around woodland Washington?

  18. What does the wind look like for tomorrow around woodland Washington area?

  19. Some people get all the excitement!

  20. runrain says:

    We must be relentlessly alert!

  21. Longview 400 ft says:

    I look forward to a possible exciting afternoon.
    Thanks Mark

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