Easterly Flow Arriving

Snapshot A change in movement on the radar imagery the last few hours shows the change on the way the next few days.  We had "surprise" showers late this afternoon and evening that developed over the I-5 corridor and streamed down to the south and east.  These were caused by the moist marine atmosphere bubbling up with weak convection.  But between 10-11pm, showers have begun to approach from the northeast.  I see it's now raining and The Dalles and Hood River.  This is the return flow around the back side of an upper level low centered over Utah.

That upper level low retrogrades (backs up) over Oregon the next 24 hours.  This is a great setup for good soaking rain east of the Cascades.  Much better than any "wet" Pacific system in the winter.  Eastern Oregon grain growers (wheat, barley etc…) that depend on soil moisture alone…no irrigation call a good May rainfall "May Gold".  A good soaking now as the wheat is in it's most active growth is the best they can ask for.  Most years there is no significant rain in May.  We'll see how much they pick up over the next few days.

The biggest forecast problem the next few day is timing the impluses moving around the upper-level low.  One moves into Western Oregon tomorrow, giving us a good soaking.  Then another "wave" of rain/showers comes in Saturday night.  Assuming models are correct in timing, we get a break during the day Saturday.  If timing is off by 8 hours, Saturday will be a rainy day.  Obviously the forecasting is quite difficult for this holiday weekend!  Mark Nelsen

33 Responses to Easterly Flow Arriving

  1. TheTriforce says:

    I am now suppose to take flexeral which makes me drowsy in order to help my jaw pain as the doctorss think I may cliench in my sleep.
    “I’ll be helping my older son celebrate his birthday this weekend. Otherwise just working on projects around the house.” Well happy birthday to him then. (sends him money by Time machine) 🙂
    I am at 52F and cloudy skies. Thanks mark for the explanation for the last week of June 1968 or 1969 that brought that 4.00″ of rain to me. Good night.
    (Falls asleep in Time Machine while driving home and crashes into Mark’s garden ruining his food)
    Mark says: “GET OUT OF MY GARDEN YOU FOOLISH INTRUDER!!” 4th Triforce piece: “NO ONE CALLS ME A FOOL YOU FOOL!” (Bambi walks up to the scene to chew on garden) *Mark comes out with shot-gun since he’s a country folk* “Out I say before I call the cops.” (gets out scared) “Noo! not the cops.”
    http://www.starstore.com/acatalog/Fierce-Deity-
    (Fierce Deity from MM who is TheTriforce’s buddy runs while holding weird sword thing in a threataning matter, In order to not get shot up by the gun.)

  2. The NWS sure nailed that, Larry… It’s very humid out. I wasn’t expecting such a drastic change to the “feel” of the atmosphere tonight. This is only going to aid in our chances of storms. We need sun breaks of course.
    So I’m checking the models tonight.
    I see the WRF-GFS still wants to develop CAPE sometime in the 2:00 PM – 8:00 PM range. It is also still projecting robust values of 400-800J/kg which is down from the 800-1,100 the 12z had shown.
    [Saturday – 8:00 PM]
    http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?mm5d2_mcape+//72/3
    Now read the AFD from PDX NWS
    CLOUDS SHOULD DISSIPATE BY LATE MORNING…ALLOWING SOME SUNSHINE TO MAKE IT TO THE SURFACE DESTABILIZING THE ATMOSPHERE BY MID AFTERNOON. SHOWERS WILL BEGIN TO TURN INTO SCATTERED THUNDERSTORMS FUELED BY A THETA-E RIDGE EXTENDING FROM WYOMING TO ASTORIA. ONSHORE FLOW AT THE SURFACE AND SOUTH EASTERLY FLOW AT MID LEVELS WILL LEAD TO A SHEARED NEAR SURFACE ENVIRONMENT WITH ANY CONVECTION THAT DOES DEVELOP MOVING FROM SE TO THE NW. MODELS SUGGESTS UNIFORM SOUTHEASTERLY FLOW AT MID LEVELS WHICH WOULD CAUSE ANY THUNDERSTORMS…IF SUPPORTED ENOUGH… TO SPLIT. CAPE VALUES OF 1000 J/KG AND LI OF -3C SUPPORT THE DEVELOPMENT OF THUNDERSTORMS SAT AFTERNOON. ONE CAVEAT FOR THUNDERSTORM DEVELOPMENT IS THE LOW WIND SPEEDS THROUGHOUT THE PROFILE WHICH COULD PROMOTE MORE PULSE TYPE CONVECTION. WILL LET MID SHIFT ANALYZE THIS FURTHER.
    WOLFE
    The plot is thickening……

  3. all of a sudden…it’s really jungle humid out….

  4. I’m not sure how many people up there heard about the fire down here… but the wind unexpectedly switched this morning and blew the smoke right into the valley. I’d take your rain over lung-crushing smoke any day!

  5. Backwards is right, it has even been raining/misting lightly out here this evening.
    Dead still, almost eerie, sky is indistinct and it’s starting to feel humid even though it’s only 53 degrees.

  6. Not related to our region, but at least one town has been a direct hit tonight in Kansas by a tornado. Protection, Kansas was one. I’ve been with my analyst geeks in chat sessions tracking things. It’s just one after another couplet and gate-to-gate with possible tornadoes.
    Given just about everyone so far within the large, massive circulation of the unseasonably and cold upper low has experience either unusual or severe weather I’d like to think we will be next to get active weather….
    C’mon sun breaks!

  7. Luvry says:

    That was me Mark…so we can count on continuous tstorm updates all evening tomorrow from Fox12? You should do some storm chasing forecasts tomorrow night!

  8. Mark Nelsen says:

    Someone asked about “plans for the weekend”? I work each of the next 3 days. That’s exciting isn’t it?

  9. …so, if i had been rendered unconscious, transported here (by one of Tri-Heats’ machines, i suspect)and told to figure out which way is which by the sky, i would be completely baffled…no bright spot in the sky, and clouds moving backwards….

  10. High of 56.2 today, 42 degrees less than last Friday (98.2). What a difference a week makes.
    Wheee… I’m up to .52” of rain for the month. Boring Larry has been hogging it all.
    I’ll be helping my older son celebrate his birthday this weekend. Otherwise just working on projects around the house.

  11. wow…no water coming down for more than a half hour!!!!!

  12. TheTriforce says:

    quote by Mat:
    “Luvry, are you drinking again??
    I don’t really know why, but the only weather I really get excited about here is a serious ice or snowstorm. 100 degree heat would be second followed by our “garden variety” t-storms.
    P.S. Luvry, I need a loan!! lol”
    Same here Mat. I am with you on those weather events!. I am back and am waiting for food while it’s 54F and kind of a drizzle out there.
    Hamburger: DON’T EAT ME NOOOOOO!!!.

  13. Ryan (Walnut Grove) says:

    Very excited for high T-Storm chances. I just hope they hold off long enough so my hiking group can get in the Multnomah Falls/Wahkeena Falls loop.

  14. Mat ne portland says:

    Which outlets Luvry? Woodburn or Troutdale. I don’t really know of any others.
    Maybe you should fake a stomachache so that MAYBE you can get out of it?? Just a thought.

  15. Good afternoon everyone.
    Very chilly today due to the persistent fetch of moisture/clouds covering the area as it moved from east to west. This kept our temps down into the 50-55F range. Do you realize temps are running 45-50F colder than during our past heat “spell”? Insane….
    Well this just keeps becoming more promising for storm chances.
    12z WRF-GFS
    [Saturday – 2:00 PM]

    CAPE begins to develop 200-300J/kg with a stripe of 400-850J/kg up and down the foothills of the Cascades.
    Oh but wait! It gets better….
    *Dramatic music plays loudly*

    [Saturday – 5:00 PM]

    CAPE 200-400J/kg overspreads the entire metro area with a solid tongue of 800-1,000J/kg along the foothills. Even the Coast Range at this time is projected to have CAPE 200-700J/kg developing.
    For the grand finale….

    [Saturday – 8:00 PM]

    A large area of CAPE (Convective Available Potential Energy. A measurement to tell how unstable the atmosphere might/is becoming.) values 800-1,100J/kg engulfs the entire metro area. All up and down western Washington and Oregon CAPE is present. From this point on CAPE slowly begins to diminish.

    [Saturday – 2:00 AM]

    Appears our storm chances really begin to dwindle after midnight to 2:00 AM.
    Well this looks very promising indeed. We only need sun breaks to get the instability beginning to work creating showers/t-storms that could develop fairly rapidly under a moderately unstable air mass. One thing I wanted to point out is the PDX/Vancouver metro areas do not often see CAPE values this high, so that’s fairly impressive.
    – Dr. Rob

  16. Mark, Triforce,
    I ride from SE Hillsboro near Noble Woods Park (W Basline & 231st) to the corner of Science Park and Cornell. I take Baseline to 158th on the way in (6-7am) so I pass near Fox Studios. I have started going home that way recently as well. Mark if you’re on Cornell or the first part of 158th you might see me going by (in the afternoon!). Before that, I would take Murray and cut through Nike to Baseline and then home.
    Mark, that’s a good climb up to Sylvan from the studios. Do you take Cornell to Barnes and then along 26 or are you able to take a back road to Butner out of Greenbrier Prkwy?
    When my wife and I lived in an apartment near here we used to ride up Thompson to Skyline (1000ft elevation gain) and then back down either Springville or German Town Roads. It was a blast coming down those roads. This was over a decade ago when there was not much but farmland outside of Oak Hills.
    Also, I want to make it clear to everyone that when I ride, I obey traffic laws and devices and do my best to be courteous to drivers. Portland area drivers (when paying attention) really are very polite.

  17. Luvry says:

    So what kinda plans does everyone have for the holiday weekend anyways?
    Me, not much…gonna be loungin to the fullest, except i have to go the outlets to look at dresses with my gf for a wedding we have to go to…and I’m a shopaphobic!!!! BLEAH!
    Maybe the outlets will get struck by lightning and they’ll lose power and not be able to support business tomorrow…JUST MAYBE????

  18. Luvry says:

    LMAO, Mat, what gives you the impression I’m drinking?
    I’m actually sitting here staring at my computer screen because all my clients have left for a 4 day weekend already…JERKS!!! Wish I had the same luxury!

  19. TheTriforce says:

    54F and I am going to the dentist bye bye.

  20. Mat ne portland says:

    Luvry, are you drinking again??
    I don’t really know why, but the only weather I really get excited about here is a serious ice or snowstorm. 100 degree heat would be second followed by our “garden variety” t-storms.
    P.S. Luvry, I need a loan!! lol

  21. Luvry says:

    Umpire, thanks for the update. Although I’m pretty sure we all know that the PAC NW tstorms rarely reach that level! The storms here are garden variety and again, rarely reach the severe level BUT most people that live here have not expierenced the midwest/east coast storms for comparison, thus anytime we do get any type of severe storms, it’s even that much more of an exciting event! I’ve been through a few myself, even through a tropical storm and you are correct that they are insane, but I do have to say, I get more excited for the storms here, just because they are so much fewer and far between 🙂

  22. umpire says:

    I just returned a few days ago from the Mississippi Coast – talk about thunderstorms! NW storms barely qualify! We had storms on Wednesday evening and Thursday morning – with the rain pouring down so hard you couldn’t hear the thunder at times. When the rain let up, the thunder was nearly simultaneous with the lightning. The storm Wednesday evening probably dropped close to two inches of rain; then another inch or so on Thursday over several hours. The T-storm on Thursday also went on for 2-3 hours – it would seem like it was over, then wham! more lightnning and thunder.

  23. Derek-West Gresham says:


    The forecast now has t-storms for 4 days in a row. 🙂
    I reserve the right to change this but here are my expectations the next 4-5 days.
    *Thunderstorms will be widespread and impact the metro area Saturday evening.
    *Sunday may feature some very early or very late convection but should be quieter than Saturday.
    *Monday and Tuesday should both have convection over the cascades and I would say about a 40-50% chance that something drifts off either day into the PDX area.

  24. Derek-West Gresham says:

    even 32snowwish?

  25. TheTriforce says:

    HTO Phill: From where do you ride your bike to work. Where is point A to point B?. I would like to look up on Google Earth.
    You bloggers can name me whatever name I have used that is easiest for you to remember.
    I am at 52.4 says the therometer. I am a bit chilly outside. Very unusual for THIS time of day in May. I am not sure what my low was as I was conked out this morning as I take Melatone at night to sleep due to my jaw pain. It’s lightly raining. WOW!!

  26. HIO Phil…you got the haiku thing right…5-7-5
    Wendy…us foothill folks are getting drenched!!!…and Mark, is it Raining virtually non-stop in Corbett like it has and IS STILL for us?
    …and just to add insult to injury, 46.6 ain’t my idea of a nice May day….
    Silver Lining:..perhaps i’ll get hit good with T-storm excitement the next few days!!!

  27. Mark Nelsen says:

    HIO Phil, where do bike commute to?
    I’ve been riding up to Sylvan (from the station) on that new patch along Hwy. 26 to get up into the hills during my lunch break. Have I passed you zooming downhill?

  28. Sir Triforce,
    I ride my bike to work a couple of days a week. When I ride home its east to west, so a strong west or northwest wind with gusts over 20mph makes for a lot more work.
    Looks like the rain has made it as far west as downtown.
    Larry, Wendy, I’ll happily trade you a couple of sunny days for some of your rain. We’re well below average over here. Maybe we’ll get our share over the weekend with this weather pattern.
    Starting to rain in Beaverton.

  29. Jessica says:

    Thanks for the update… 🙂 A lot of Tornados in the MidW touched down…

  30. I just read the AFD from the PDX NWS office…
    Interesting to say the least.
    ————————————————–
    RAIN SHOULD OVERSPREAD THE FORECAST AREA TODAY…SOME AREAS COULD SEE AS MUCH AS 0.50-1.00 INCH QPF OUT OF THIS SYSTEM BY TONIGHT…MAINLY NEAR THE CASCADES. AS OUR SURFACE TROUGH PUSHES WEST…ORGANIZED PRECIPITATION SHOULD TAPER OFF THIS EVENING ACROSS THE DISTRICT. SHORT-RANGE MODELS SHOW FAIRLY GOOD AGREEMENT IN LATE FRIDAY NIGHT AND EARLY SAT MORNING BEING DRY…THEN MODELS BEGIN TO DIVERGE. AFTER OUR FIRST BATCH OF RAIN MOVES OUT…A FAIRLY HUMID AIR MASS WILL BE LEFT IN ITS WAKE…ALLOWING MORE POTENTIAL FOR CONVECTION INLAND SAT/SUN. THE UPPER LOW APPEARS TO STAY TO OUR SOUTH THROUGH MONDAY…WITH OCCASIONAL WEAK LOBES OF VORTICITY MOVING EAST TO WEST ACROSS WA/OR. WITH A RELATIVELY HUMID…FAIRLY HIGH THETA-E ENVIRONMENT…THESE WEAK DISTURBANCES WOULD PROBABLY BE ENOUGH TO FIRE OFF CONVECTION OVER THE CASCADES OR EASTERN OREGON…WITH THUNDERSTORMS POSSIBLY DRIFTING INTO THE VALLEY SAT/SUN AFTERNOONS AND EVENINGS. CONFIDENCE IN ANY TIMING AT THIS POINT IS LOW…BUT 00Z/06Z GFS RUNS SEEM TO BE KEYING IN ON ONE SUCH DISTURBANCE LATE SATURDAY. BOOSTED POPS TO LIKELY FOR THE CASCADES DURING THIS PERIOD…OTHERWISE KEPT GENERAL CHANCE OF SHOWERS/THUNDERSTORMS THROUGH SUNDAY WITH A CHANCE OF SHOWERS LINGERING INTO MONDAY. ALSO ADDED MENTION OF THUNDER TO OREGON INLAND ZONES TUESDAY AS 00Z GFS BROUGHT SE FLOW AND MODESTLY UNSTABLE AIR INTO DISTRICT. THIS WILL CERTAINLY BE AN INTERESTING PATTERN TO WATCH UNFOLD OVER THE NEXT 3-4 DAYS.
    WEAGLE
    ————————————————–
    What a great discussion. Very nice job this go around NWS.
    Ok well this sounds quite promising to me. The thing that stands out most to me is the high THETA-E environment. Why do I say this? In tracking and studying summer t-storms here I often find that THETA-E is quite frequently favorable across eastern Oregon or the Cascades, but it is hard to get that same environment favorable west of the Cascades. So with that being favorable, with vort maxes projected to spin out rotating around the upper low, with CAPE building, with LI favorable things look really possible. It’s just going to depend on how far south the upper low meanders. If it stays around the Oregon/Idaho/Utah border vicinity then things look unchanged. If it drifts any further south and east then the vorticity lobes and subsequent energy would remain probably south of Salem-Eugene to Bend-Baker City. We would ideally want the upper low a bit further northwest, but if it remains where it’s forecast we could score some storms.
    – Rob

  31. Mark, thanks for the update.
    3rd!
    We will need good sun breaks to heat the lower layers to begin the destabilization process. Without if it won’t matter much how much CAPE develops or if LI becomes favorable. Of course we also have the ‘wild card’ thrown in which is needing a spoke of energy rotating around the upper low to move over us at the right time, with a reasonable amount of heating. It sure is hard to get favorable t-storm patterns in the PNW, isn’t it?

  32. KE7DKG says:

    Tornado in SoCal today…Riverside County. Reminded me of “The Day After Tomorrow”….j/k
    It’s a little chilly out tonight. 44 here.

  33. Derek-West Gresham says:

    hey first!…and hoping for storms still. 🙂

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