A Week of Showers Ahead and First Look at Memorial Day Weekend

May 16, 2019

6:45pm Thursday…

Yesterday we saw vigorous showers move through the east metro area around this time, dumping up to 3/4″ of rain.  Today the heavy showers are east of the Cascades with lighter showers west of the mountains.  Models are shoving lots of moisture into far eastern Oregon tonight and Friday; NWS Pendleton has a flood watch out for that area

Mark Flooding California

The reason for all that rain is an upper level low moving into Northern California this evening.  I expect two more of these disturbances to take a similar track over the next week.  They show up nicely on the ECMWF model’s ensemble forecast.  First, Sunday morning you see that cold low in the same position as tonight’s low


Then a second low on Tuesday as the first low spread severe thunderstorms and tornadoes into the Great Plains…


Both of these are forecast to drop a little farther south than what models were showing earlier in the week.  That means most of the rain the next seven days heads into California and we see lighter showers across NW Oregon and SW Washington.

This setup of lows moving by just to the south is a forecast nightmare as well.  Little waves of showers spin north; each model run is slightly different on placement and timing.  It’s safe to say we’ll see light showers at times, but there could be large windows of dry weather some days in the next week.  Right now it appears the first 3/4 of Saturday will be dry and much of Sunday could be as well.

Check out the ECMWF rain forecast for California…FAR more than anything they typically see in late May

ECMWF Precipitation Accumulation

Now the big question…

How long will this cool/wet pattern continue?

There are strong hints that we’ll return to a drier/warmer pattern as we head toward/into the Memorial Day Weekend.  No, I’m not saying we have a sunny/hot/warm/dry holiday weekend on the way (for now).  And yes, it’s 9 days away, but we can see general weather patterns that far out.

For several days most long range model solutions are showing the cool upper-level troughing sinking farther south into the Desert Southwest and high pressure (ridging) developing once again just to our west.  Similar to what happened in late April and early May.  Notice the ensemble forecasts from the GEM, GFS, & ECMWF for Saturday the 25th all look the same

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This would say mainly (or all) dry weather with average to above-average temps.  We’ll see how that plays out.

You can see the drastic change from week #1 to week #2 in last night’s 45 day ECMWF run.  This is surface temperature anomaly.  First from this coming Sunday to the Sunday of Memorial Day Weekend.   Look at that cold anomaly over Nevada/Utah, 15 degrees below average next week…Brrr!


Then the following week; cold moves farther east/south.  The west coast of North America from Oregon to Alaska would be very warm


So there you go.

Cool and showery this next week but not too much rain.

Enjoy your weekend!  Chief Meteorologist Mark Nelsen