Possible Marble-Size Hail Near Hockinson

May 25, 2012

Radar is estimating marble-size hail may be falling just east of Battle Ground and moving into Hockinson at this hour. Dbz values are up to 65! 

The cell will continue to slowly move south the next 1/2 hour…toward northern Camas & east Vancouver

Lightning Strikes So Far…

May 25, 2012

Lightning strike map so far this afternoon. None IN the metro area, but lots in the past hour north and east of Vancouver & Camas. A few in the Coast Range too. This only detects cloud-ground or ground-cloud strikes.

Chief Meteorologist Mark Nelsen

Thunderstorms Developing

May 25, 2012

Looks like our RPM was right on, thunderstorms have developed north of Battle Ground and heading down towards Camas. Any of us could see one in the next 3 hours. Nice looking clouds to the north of the metro area too!

Chief Meteorologist Mark Nelsen

A Warmer Friday Ahead

May 24, 2012

A busy weather afternoon with heavy showers that developed just as expected.  One produced a nice funnel cloud southeast of Albany and was filmed by Coleen Dahlman of Milwaukie.  We have that on our Facebook page here:  http://www.facebook.com/#!/photo.php?v=10151161079322785

A warming and drying air mass comes in on northeast upper-level winds later tonight and Friday.  The result will be much warmer temps and more sunshine.  Our RPM model continues to insist showers develop on the Cascades in the northeasterly flow tomorrow and then drift down over the western valleys tomorrow afternoon.  The 00z WRF-GFS was  bit different with just some random showers popping up.  The screaming message would be that any of us in the western valleys MIGHT see a late day shower or thunderstorm.

Saturday should be similar, then a dying front moves onshore to give us lots of clouds and a few light showers.

Models have been vacillating between strong ridging for the 2nd half of next week or a flat ridge with moisture moving through.  The last few runs of the GFS have backed off on the big ridge idea, more like the ECMWF.  Our forecast runs down the middle, not nearly as warm as a ridge pattern would produce.  But warmer than the wet and cooler ECMWF.

Here are the two ensemble charts…first the 12z ECMWF, definitely hinting that June will begin cool:


Then the new 00z GFS, the +15 850mb temps next week appear to be “in the middle of the pack” as they say:

Chief Meteorologist Mark Nelsen

Memorial Day: Not the Start of Summer Here!

May 23, 2012

It’s common knowledge that Memorial Day Weekend to Labor Day Weekend is generally the summer vacation and/or travel season.  Schools start getting out after Memorial Day (somehow my kids are done a week from Friday) and the weather improves quite a bit.  BUT, west of the Cascades in the Pacific Northwest that’s not quite the case.  Take the average high for May 28th…70 degrees here in Portland.  That IS within 12 degrees of the hottest average high of the year (82 in late July and early August), but that’s the same as October 1st!  We sure don’t consider early October to be a great time to visit the mountains and/or go camping west of the Cascades due to the cooler days and chilly nights.  But lots of people will be out in the great outdoors this weekend.  Check out the past 5 years here in Portland:

Only one (2009) of those Memorial Day weekends saw nice weather with sunshine and warm temps.  In 2008 we had record rain Saturday night with a great round of thunderstorms…remember that?

This weekend doesn’t look so great.  The best weather still appears to be Friday, although now our RPM is showing a shower trying to pop up in the northerly flow over us.  Still, a good 10-12 degrees warmer than tomorrow’s cold shower day (hail and thunder likely by the way).  Saturday should be dry and partly cloudy; temps about average.  Then Sunday and Monday will be cool with lots of clouds and maybe a few showers.

Chief Meteorologist Mark Nelsen

Windy Afternoon and Some Weekend Showers

May 22, 2012

Today was the windiest day in about 3 weeks in the Northern Willamette Valley:

Combine that with clouds, rain a good chunk of the day, and cool temps and it sure felt more like early April rather than late May.

We get rid of the wind tomorrow, but keep the rest.  Although I suppose the showers will be a bit lighter.

A cold upper level trough drops through the Pacific Northwest on Thursday; this is likely to give us a round of heavier cold showers with some hail or thunder.  Lifted Index (measure of stability in an air mass) is right around zero all day Thursday…usually a very good sign, along with a chilly air mass, that we’ll see some active afternoon convection.

As that upper low drops off to the south Thursday night and Friday, we get a very dry northeasterly flow through the lowest 10,000′ of the atmosphere.  This is very similar to a cold and dry northeast flow in wintertime as arctic air moves down behind an upper-level trough.  But since we’re in the warm season, pressure gradients remain light through the Gorge and over the Cascades.  So no gusty east wind.  Just a breezy afternoon north or northeast wind here in the Portland Metro area.  The result will be a 10-14 degree jump in high temperatures and a mostly sunny day. 

Still some leftovers of that northerly flow Saturday for a second nice day, but then it’s back to onshore flow and more cloud cover for the 2nd part of the holiday weekend coming up.  This is where I made a change to the 7 Day forecast this evening.  The trend in models is to push a cool upper-level trough farther south into the Pacific Northwest by Monday.  In fact 850mb temps around 0 to +2 are quite cold for May 28th…I sure wouldn’t camp in the Cascades Sunday and Monday unless I had some solid sleeping bags, gloves, and a hat to wear overnight.  One more reason I don’t mind working Memorial Day Weekend most years.  This year I’ll be here Sunday and Monday. 

Each model and model run has been a bit different, but the trend is still there for a downhill slide weatherwise Sunday and Monday.  I’m not real confident we’ll actually see measurable rain here in Portland, but it’s far safer to go a little pessimistic on a big holiday weekend and be surprised by decent weather than have things turn out the other way around.  Here’s a graphic I used on-air tonight, the warmer temps refer to Friday and/or Saturday, the coolest temps on Monday:

Chief Meteorologist Mark Nelsen

Gusty Wind This Afternoon & Evening

May 22, 2012

That’s a nice looking little curl of low pressure approaching the Washington coastline this afternoon, bringing high winds to the Oregon Coast.  The loop (with movement) is at this link:  http://sat.wrh.noaa.gov/satellite/alternative.php?wfo=pqr&area=west&type=vis&size=1

The gusty wind will spread inland through the afternoon.  Expect gusts 50-65 mph on the beaches into the early afternoon before it backs off after 4pm. 


Inland, south wind will gust in the 30-40 mph range during the mid-late afternoon.  Plenty windy for May, although not quite as strong as what we saw earlier in the month when we had 10,000 PGE outages one afternoon.

Chief Meteorologist Mark Nelsen