Rainy April? Doesn’t Feel Like It!

Looks like today is day #24 of measurable rain this month in Portland.  While making a graphic for that I thought “it doesn’t seem like it’s rained that many days!”. 

So I did some checking between shows tonight.  Our total rainfall is slightly above average, and will end that way tomorrow.  I see Salem and Seattle are more noticeably above average.  The record wettest Aprils are in the 4-5.25″ range here in Portland though…how did THOSE months not have more days of rainfall?  How is this nearly average rainfall month going to either tie or break a record for days of rain?  Well, we’ve had lots of light rainfall days…no long-lived (3-5 day) ridges of high pressure, and a wet period to start and end the month.  Apparently everything worked out right to get lots of light rainfall days.

Now notice I said “days”…that’s not really correct…and it goes with my thoughts about the month not “seeming” so wet.  Sure enough, we had a mainly dry two week period in the middle of the month where the only significant rainfall fell in the overnight hours twice.  On the 12th and 14th, more than a tenth of an inch fell both times, but during the dark hours of the day.  That means we went 17 days in the middle of the month with no significant daytime rainfall (9th through the 25th)!  That might explain why I’ve heard very few complaints about a “rainy April” and why to this long-time Pacific Northwest resident it seems like a very typical April.

I do notice we’ve only hit 73 so far this year…seems a bit strange that we haven’t hit 77 or 82 or something along those lines at least once.  That would go with the lack of decent upper-level ridging over the region.

The weekend looks slightly wet to start Saturday and then much better later Saturday and Sunday.  The ECMWF is still very cool and showery Monday while the GFS seems to be out in it’s own little world…unsure how strong ridging will be over us the beginning of next week.  We are now within the 84 hour forecast of the NAM (Monday) and it totally agrees with the big cold trough of the ECMWF.  Can’t wait for that GFS upgrade in June!

By the way, I don’t think the GFS is going to be extended in hours.  The T382 to T574 numbers refer to the resolution of the model, not the time period.  Someone correct me if I’m wrong.  I remember when it was exciting and new as the GFS was upgraded to T126!  Getting older…

Chief Meteorologist Mark Nelsen

353 Responses to Rainy April? Doesn’t Feel Like It!

  1. yevpolo1990 says:

    Temp check:41
    Dew point check: 36
    that is pretty damn cold for 8pm

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

    That batch of showers over the Vancouver area actually pushed a weak outflow boundary/gust front type feature out of it trailing behind it.

    Base Reflectivity

    Base Velocities

    See it?

    • Justin (Brush Prairie) says:

      Probably had around 40mph gusts with that.

      Also some hail late this afternoon, but no thunder.

    • Rob "Wrath" S.E. Portland says:

      Very cool. Imagine if we had a decent t-storm erractic wind gusts perhaps 50-55mph? …. Tomorrow could be real fun.

    • Rob "Wrath" S.E. Portland says:

      erratic*

  3. Tyler in Hazel Dell says:

    April finished with the highest average peak wind for any April in my 15 years. The average was SW at 20.6 mph.

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

    I thought I’d share this bit of info with you guys. I think it really helps better explain why the onshore westerly winds were/are so strong east of the Cascades in Washington and throughout the Columbia Basin.

    This is the OTH-GEG Cross-Cascade gradient.
    http://wxweb.meteostar.com/meteogram/link_pdiff.shtml?choice=KOTH+KGEG
    OTH = North Bend
    GEG = Spokane
    This measures the pressure difference between both locations. A -negative reading indicates offshore flow. A +positive reading indicates onshore flow.

    The peak was an impressive +24.8mb around Noon today! I have never seen this high of a reading for this gradient(Has anyone else?) To give you an idea when we have our really big damaging east wind events/downslope storms during the Winter the gradient is then typically 20-22mb. Imagine a -24.8mph gradient during the heart of Winter.

  5. Battle Ground Brian says:

    Just got a call at 6:30 from my parents in Oak Grove/Milwaukie area. The power is out in that neighborhood due to a tree on power lines.

  6. cliff says:

    it is 45 degs and windy at my place….I think tommorrow morning I’m going to drive up to a spot just out of sandy, musiccamp road – 1,600 ft. and check the conditions.

    sorry I don’t have any fancy meteorological terminology to converse with..

    wait…..the sun has just come out….

    talk soon bloggers.

  7. cliff says:

    well now,

    the noaa weather site is telling us that fall-like weather is moving in…I thought….fall? we haven’t hit summer yet.

    I was wondering after they said there were winter weather advisories for the oregon cascades, and foothills.

    from the list of towns and locations they mentioned, along with a conversation I had with one of the noaa staff recently, I guess higher foothills means 1,200 ft up to 2,500, and cascades is anything above 2,500ft.

    lower foothills is 1,199 ft, down to 600 ft.
    500 ft and lower is considered the valley floor.

    so, I imagine welches should get a dusting of snow tonight.

    from my historical data, (and memory) the first week of May is the latest that elevations below 1,500 ft. have ever had snow…

    • Rob "Wrath" S.E. Portland says:

      Seems possible Welches does I agree. This seems really chilly for early May.

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

    Radar image for Vancouver area

    Despite weak instability lapse rates are steepening giving the chances of showers/hail/and some lightning.

  9. Timmy_Supercell (Hillsboro) says:

    Just had a roaring wind gust that sounded like 40+ mph.

    • Timmy_Supercell (Hillsboro) says:

      All of sudden it got a lot windier than it was before… Sure its not that the wind gusts are coming late this afternoon?

  10. Mr Data says:

    56.1F and wind is cranking up with a few spotty power outages in the area. http://www.portlandgeneral.com/safety_outages/outages/outage_updates/outage_map.aspx

    PDX TO EGU shows 2.75 with a rising trend

    http://wxweb.meteostar.com/meteogram/link_pdiff.shtml?choice=KPDX+KEUG

    Maybe we will have a late wind event?

  11. Mr Data says:

    Thank you Timmy for reminding me to not go to your buisness since I can’t make a complaint as a customer.

    Timmy Quote: Tyler in Hazel Dell Says:

    May 3, 2010 at 2:12 pm
    I think anyone who calls someone else out on their job should be willing to do that job and put their neck out on the line…quote end:

    So I guess you walk into the blog Restruant and you find a bug in your soup as a result of a mistake:
    and Mark’s cook denies that there is a bug without even looking and you say that the customer is wrong just because Mark’s cook has higher authority?

    You think that give the cook the right to yell at you for not liking his soup because you found a bug or a piece of hair in it?

    You obviously have your priorites screwed and thank you for reminding me to not go to your resturant.

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

    Radar image of “storm” at its peak.


    Peak dbz 57.0 ….. Fell apart within 10 minutes. Maybe pea sized hail and gusty winds, but nothing to warrant a Significant Weather Advisory…. Just my thoughts.

    • Tyler in Hazel Dell says:

      Sister driving bus reported extremely heavy hail/rain with that storm and the strongest winds of the day, she estimates over 40 mph…

    • Rob "Wrath" S.E. Portland says:

      A few lightning strikes occurred.

    • Rob "Wrath" S.E. Portland says:

      Hmmm I suppose so then. well let’s get some more convection firing!

    • Mr Data says:

      Nice! That red looks like the eye of Sauron. :O

  13. Tyler in Hazel Dell says:

    These pretty much explain themselves

  14. Tyler in Hazel Dell says:

    GREATER VANCOUVER AREA WA-SOUTH WASHINGTON CASCADE FOOTHILLS
    WA-WESTERN COLUMBIA RIVER GORGE WA-
    425 PM PDT MON MAY 3 2010

    …SIGNIFICANT WEATHER ADVISORY FOR EXTREME SOUTHWESTERN SKAMANIA AND
    SOUTHERN CLARK COUNTIES UNTIL 500 PM PDT…

    AT 423 PM PDT…NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
    STRONG STORM NEAR HOCKINSON…OR NEAR BATTLE GROUND…MOVING EAST AT
    30 MPH.

    HAIL UP TO ONE HALF INCH IN DIAMETER AND WIND GUSTS UP TO 40 MPH ARE
    POSSIBLE WITH THIS STORM. ADDITIONALLY…THIS STORM HAS THE POTENTIAL
    TO PRODUCE DANGEROUS LIGHTNING.

    * LOCATIONS IMPACTED INCLUDE…
    CAMP BONNEVILLE…HOCKINSON AND SALMON FALLS…
    ELKHORN MOUNTAIN…
    LARCH MOUNTAIN…

    • Rob "Wrath" S.E. Portland says:

      ? I saw a few spots of red, but nothing to warrant that… Am I blind? Correct me if I am wrong I have no issues with that.

  15. Tyler says:

    This from my cousins in Yakima…
    “We can’t even be outside. U litterly can not stand up…no joke…really bad. Sucks…”. Sent via a text referring to the wind

    • Runrain says:

      I was in Yakima on Saturday. The wind was howling then too. Hard to open your car door to get out. On the way home Saturday evening to Portland, tremendous winds from Biggs west to The Dalles and much less wind west of that. The Columbia was unquestionably “nuking” in that 20 mile stretch between Biggs and The Dalles.

    • Rob "Wrath" S.E. Portland says:

      Sounds enjoyable to me, Tyler 😆

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

    I am seeing some decent vertical motion to the CU out there. I just checked upper air analysis and to see if there is any instability or anything else favorable…

    850mb: -2c to -3c
    500mb: -23c to -29c (Quite a range temps fall off dramatically from north to south)
    http://w1.spc.woc.noaa.gov/exper/mesoanalysis/s11/500mb/500mb_sf.gif?1272926103728

    MUCAPE: 100J/kg
    CAP: 25-50CINH (Weak)

    LOW-LEVEL LAPSE RATES: 8C/km

    MID-LEVEL LAPSE RATES will cool as the colder air mass aloft works in. Also LI buoyancy will become favorable tomorrow. As for the rest of the afternoon/early evening showers, some hail. I doubt any t-storms today.

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

    Convective Outlook …..

    MODELS BRING THE UPPER LOW ACROSS THE NORTHERN CWA LATE TUESDAY AND THEN SHOWING IT LINGER EAST OF THE CASCADES ON WEDNESDAY. SO A THREAT OF THUNDERSTORMS ACROSS THE NORTH TUESDAY/TUESDAY EVENING AND A BETTER CHANCE OF SHOWERS FOR WEDNESDAY THAN EARLIER THOUGHT.

  18. Tyler in Hazel Dell says:

    Look how well the Puget Sound Convergence Zone shows up…

    http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?vis1km_west_full+6

  19. yevpolo1990 says:

    21mph top gust between 2am and 11am…
    NWS=fail

  20. Tyler in Hazel Dell says:

    Wow, just had a wind gust to 35 mph out here in Hazel Dell. I’m not sure what my station hit in Minnehaha. Strongest winds of the day…and the sun is out, after a few hail showers earlier.

  21. Annie in Vancouver says:

    What are the chances that we will get some thunder and lightning today?
    We have been having lots of sun breaks today between rain showers. We have also seen a bit of hail today.

  22. Ryan (Walnut Grove) says:

    Nice little hail storm rolling through right now. Wind has been pretty stiff all day as well.

  23. Mr Data says:

    In a “nutshell” what dynamics went wrong with this?

    Let’s do a recap so we can do a better job next time. 🙂

    • Cherie in Vernonia says:

      Dunno, but it is sure windy & raining like heck here….wondering if I out to inflate the life boats 🙂

  24. muxpux says:

    oak harbor, wa: 35G56

    man i kinda miss living there. ALWAYS windy.

    http://www.wrh.noaa.gov/mesowest/getobext.php?wfo=sew&sid=KNUW&num=72

    • Andrew (Ellensburg, WA) says:

      Ya, the winds are really starting to ramp up here. Already a couple trees that have been knocked down.

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