8:00pm: Downpours West Metro

June 4, 2012

Quite a cluster of showers (no lightning so far) moving through the western side of the Portland/Vancouver Metro area…these will continue moving east/northeast.  It’s going to be very wet across the metro area the next couple of hours.  Expect localized flooding.  Notice the shower that developed quickly (reddish colors) right over north Beaverton in the past hour and shifted off to the east:


Cluster of Showers & Storms Moving In

June 4, 2012

5:20pm

Earlier we had a line of thunderstorms in the south Willamette Valley; now it has turned more into a cluster of heavier showers and a few embedded lightning strikes.  Two strikes in the past 15 minutes near Marquam/Molalla areas.

These showers will continue to head north-northeastward, so anyone could still see a flash of lightning or rumble of thunder. Best chance is closer to the Cascades.

Severe thunderstorm watch for much stronger storms continues for extreme Eastern Oregon until midnight.  Watch out in La Grande and Baker City!  Yikes, I see a tornado watch was just issued for areas east of the Continental Divide in Montana too.

Chief Meteorologist Mark Nelsen


A Rainy & Chilly Week Ahead

June 4, 2012

I’m really glad I got all the outdoor chores done for the next 10 days or so yesterday, because it appears we have very few dry days between now and early next week.

The highlights:

1. Most likely the only dry day this week will be Wednesday.  The Junior Parade on Wednesday afternoon may be safe.
2.  Tuesday will be unusually cool with valley highs only around 60 and snow briefly touching the passes in the morning.
3.  The Grand Floral Parade (Saturday) will occur on a day likely to see rain and/or cold showers/thunder/hail etc…

This morning a strong cold front is moving into California just ahead of a sharp upper-level trough.  We are on the southerly and moist flow to the north of that; thus the steady moderate rain (mainly east of I-5 right now)  and through the rest of Oregon. 

Tomorrow we will be in the colder air mass behind with the usual showers, sunbreaks, and possible hail.  Lifted Index and CAPE are unimpressive, so I’m not too excited about thunder.

Thursday-Sunday:  A deep upper level trough drops in for a visit along the West Coast.  Check out the Friday afternoon 500mb map from the ECWMF.  That appears to be just about the deepest low anywhere near North America…sitting nicely right on top of us:

This one appears to be quite juicy if models are correct, note the ECMWF rainfall totals:

The 00z WRF-GFS extended version had decent rainfall all three days; funny that it paints the heaviest rain around 10am Saturday (parade time).  That’s right after 9/12 (4amSat) on the chart.

Of course no model or human can tell you 5 days ahead of time which hour will be wettest, but the trend is there on several models for a wet end to the week.

The other bit of bad news, unless you like cool and moist June weather, is that the pattern appears to stick around over the next two weeks.  Note the 500mb ensemble anomaly maps for two weeks from tonight.  Both the GFS and ECMWF ensemble mean remains below average along the West Coast. 

This doesn’t mean every day will be cool and wet, we might even get brief ridging and warmer weather for a few days next week, but in general the cooler and wetter than average weather will continue.  La Nina’s last gasp; or maybe just the last bit of cool before a searing hot summer?  Who knows…

Chief Meteorologist Mark Nelsen