It Rained! Much Needed Soaking, but Summer Temps Are On The Way

10pm Tuesday…

How exciting, some nice downpours FINALLY arrived the past two days. It’s been a typical spring shower pattern; downpours in one neighborhood followed by sunbreaks and warm/dry conditions. That means we’ve seen widely varying rain totals. Today’s numbers…since midnight. A huge soaking east metro, but much lighter many other areas.

Ah, but some of you are thinking you’ve seen a lot more than these numbers show…right? Some neighborhoods have picked up more than an inch in the past two days! I see downpours passed over the Parkrose/Gateway area both days.

Meanwhile PDX, and many other locations, have seen less than 1/2″. This one ain’t pretty, but lots more numbers from the past 48 hours. ONLY LOCATIONS WITH .30″ OR MORE ARE SHOWN. Click for a better view of course.

Does this help our drought situation? Yes and no

YES: Sure, this is enough to water our lawns/gardens for a week. But this just puts off the continued drying as we head toward summer. NO: If we see a normal or drier than average June, this rainfall will just be a blip in a record-setting dry spring. And it appears Portland WILL likely end up with the driest spring on record by the time we get to next Monday night…the end of the month and meteorological spring. That’s because we don’t have any more significant rain ahead.

Tomorrow will be a spectacular spring day. A mix of morning clouds leading to widespread sunshine and warmer temperatures. Low 60s today are followed by low-mid 70s tomorrow. Fresh air after the rain too!

Another cool upper-level trough swings by just north of us Thursday. You can see it on the ECMWF ensemble forecast of 500 millibar heights Thursday. The cool colors represent lower than average heights

I’d be surprised if we get more than .30″ out of this system too. Steady rain tomorrow night quickly changes to scattered showers during the day Thursday. Ah, but then strong high pressure builds along the West Coast just in time for the holiday weekend. Check out the change for Saturday

Higher than normal heights and it becomes more obvious by Monday. That’s Memorial Day AND the last day of May. Looks like July or August.

Another way of looking at this is the 850mb ensemble chart. It shows temperature at about pass elevation (in celsius) over Portland for the next two weeks. Each single black line represents ONE of the 51 ensemble members. The green line is the 30 year average. The red line is average of ALL ensemble members (group average). Blue line is the operational high-resolution run. VERY good agreement with the dip on Thursday; the upper level trough. And then excellent agreement through at least Monday, the 31st. Agreement starts to fall apart after about the 3rd, but notice the ensemble average stays above normal through the next two weeks.

These plots are great tools. Situations like this can give us great confidence that a certain weather pattern IS on the way, not just a possibility.

HOW WARM WILL WE GET? At this time I don’t see the “perfect” east wind setup with a thermal trough west of the Cascades; because the upper-level ridge isn’t as sharp as it could be. But we’re still 6 days out from the warmest days (next Monday/Tuesday). You see those 850mb temps up around +15 or so. That’s not heatwave material for late May or early June, but very warm. Mid 80s seems like a good bet for now. That’s Sunday through Tuesday next week. Another reason to not get wild with high temp forecasts (90 or higher) is that all spring long we’ve seen the ridge offshore forecast to flop in over us, but then as we get closer to the event a trough swings down from the north and pushes the ridge slightly farther west. That would keep us a bit cooler too. We’ll see.

ANY SIGNIFICANT RAIN IN SIGHT? NOPE. Check out the ECMWF ensemble 24 hour rainfall forecast. Again, each horizontal line is one of the 51 members. It’s 6 hour blocks over the next two weeks. Time goes left to right. Not a single member (rare) shows any measurable rain from late Friday through Tuesday. One more reason we are quite confident forecasting a dry and warm weekend. You see some members forecasting rain of some sort returning later NEXT week. But many are totally dry.

To summarize

  1. You should continue watering all your lawns, plants, gardens. The late spring drying has stopped for a few days, but a lot of this moisture will evaporate or get used up by dry plants over the weekend next week.
  2. Prepare for summer weather this Memorial Day Weekend. If I recall correctly we had a warm & summer-like holiday weekend back in 2017 too…the warmest in two decades.

Chief Meteorologist Mark Nelsen

13 Responses to It Rained! Much Needed Soaking, but Summer Temps Are On The Way

  1. Mr T says:

    No posts since the 27th? Something tells me the Tik Tok delete police are sniffing around and are howling!

  2. W7ENK says:

    I don’t really recall, were 40mph wind gusts part of this afternoon’s forecast?

  3. Joshua Lake Oswego says:

    Prediction for PDX rain tomorrow? I will go with .08’’.

    Tim, remember when you kept posting about the ‘’wet week ahead’’, ‘’soaker’, ‘’at least an inch’’? Well, we will likely end up around .40’’ Total. Don’t underestimate the models’ dependability of overestimating our precipitation.

  4. Roland Derksen says:

    Tomorrow is supposed to be a soaker here- if so, it won’t be surprising: There’s a greater than 33% chance for me to see the heaviest day of rain for May within the last 7 days of the month.

    • Roland Derksen says:

      Well, it’s still only the morning, but it appears as if the great majority of our precipitation ended before 8am- and began long after midnight. My total so far for the day: 0.29 inches.

      • Roland Derksen says:

        I had more showers later in the afternoon, but the day’s total of 0.57 inches, sure fell short of the range of predicted amounts. Next week on Monday and Tuesday, i’ll probably see my first 80’s of the year.

  5. Michael Gelien says:

    Thank you Mark. I always look forward to your weather blogs.

  6. Nate’s Mom says:

    One day of rain was enough I guess, time to get back to the good weather. My handsome son Nate thinks I’m nuts, but I’m still not convinced that summer will be very hot and dry this year, but time will tell. Looks like Thursday will be a good day to bake some cookies for Nate, since it won’t be very warm like the weekend will. This weekend should be very nice with a pleasant car trip with Nate to Tacoma to visit his father. I would imagine the temperature will be a tad cooler to the north. Thank you for another good update Mark.

  7. Paul D says:

    Back to July weather – boo! I want spring!

    Oh well….

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