Possible Thunderstorms Tonight

September 2, 2013

Monday, 9:45pm…

MarkThunder_MetroOutlook

Welcome back!  The weekend is over and once again we are in a setup with an upper level low spinning offshore.  It’s far enough away that we aren’t getting a marine push to give us cool and cloudy weather, but close enough to put us in a moist southerly flow overhead.  Models are strongly hinting that SOMEWHERE in Northwest Oregon or Southwest Washington we should see thunderstorms overnight.  There is a very weak disturbance off to our southwest, but no real obvious trigger on satellite imagery.  That said, this is very similar to what we saw last week when thunderstorms popped up in the overnight hours.  I totally missed out on those because no storms passed within 10 miles of my home and my window faces southeast.  Maybe tonight?  All 3 local mesoscale models: the UW WRF-GFS, MM5-NAM, and our RPM show something popping up by daybreak.   Our model shows the first storms developing soon after midnight, the MM5-NAM starts them over the Cascades by 1-2am, and the WRF-GFS gets things going between 2-4am.  Now remember that models don’t handle details with small weather features well, that includes thunderstorms of course.  That’s why I said SOMEWHERE over our area SOMEONE will see something later tonight.  Can’t give you much more detail than that, although I think whatever happens will likely be from Salem northward.

Looking farther ahead, this upper low moves inland on Thursday.  So once again Thursday appears to be the day this week where we see the wettest conditions.  If the timing is right I could see a severe weather episode east of the Cascades again.  Hopefully not right over Madras this time.  I was in Maupin this weekend and heard losses were in the millions from damage to crops and irrigation equipment with that severe thunderstorm last week.

Here’s the 12z ensemble chart from the ECMWF, showing the cooldown Thursday-Friday, then a big warmup next week:

tseries_850t_000-360_Portland

Similar look on the 12z GFS chart:

tseries_850t_000-384_Portland

Speaking of Maupin, I somehow stayed upright while rafting through Oak Springs Rapids on the Deschutes River.   Here’s a pic from Imperial River Company.  Hope they don’t mind that I borrowed it…free advertising.

MarkRaft

That’s me on the front left side.  My wife and daughter flipped out into the frothy maelstrom.  One made it to shore and the other back into the raft.  Good times on Labor Day Weekend!

Chief Meteorologist Mark Nelsen