9:00pm Update: 16,000+ Strikes in Oregon Today

April 23, 2012

Well, we had no problem getting thunderstorms across the region today:  the last count was over 16,000 cloud to ground strikes here in the state of Oregon.  That’s exceptional for April, let alone July.  But just about all action has been over and east of the Cascades.

West of the Cascades we have a strong marine push in progress with gusty southwest wind entering the central and southern Willamette Valley. At 8pm it was in the upper 50s at Eugene with a southwest wind, but lower 70s here in the Portland Metro area. I’ve been hoping (and models have hinted) that we might see convection based on that push moving into the northern Valley. But as of 9pm there is no sign of anything building on radar. Our 00z RPM stubbornly hangs onto something developing over us around 10pm. I’ll believe it when I see it!

Check out the current radar/lightning image over northeast Oregon.  I wish I was right around Hermiston right now…

Those are all cloud to ground strikes within the past 15 minutes!

Chief Meteorologist Mark Nelsen

5:45 PM Update; Lots of Storms Over Cascades

April 23, 2012

Quite an afternoon with strong and some severe thunderstorms moving up the Cascades the last 2 hours.  Several severe thunderstorm warnings about an hour ago with large hail possibly falling over unpopulated areas east of Roseburg and south of Oakridge (not in our viewing area).  The farthest north storms are around Mt. Jefferson now:

Tops appear to be around 41,000′, quite impressive for the Pacific Northwest!  No warnings right now.  These appear to be headed NNE into north Central Oregon.  Mesoscale models, including our RPM, have shown this movement.

Of more interest to the Northern Willamette Valley, our RPM continues (on it’s 18z & 21z run) to show an east-west line of showers and thunderstorms developing directly over the Portland metro area between 8-10pm.  Maybe keying in on the marine push and that convergence of NW & SW wind at that time.  Here’s the image:

Models of course have big issues with small-scale details like this, but it sure doesn’t want to let go of the idea.  Other than that, our RPM shows no other area of thunderstorms west of the Cascades north of Salem tonight…we’ll see.

Chief Meteorologist Mark Nelsen

Nice Sunrise Pic & Quick Storm Update

April 23, 2012

3:00pm Monday

At work and cleaning up Inbox.  Have to share a great picture from Troy Rethaford, taken from Rocky Butte at sunrise:

Radar is still totally dead in northern half of Oregon…but thunderstorms have suddenly popped up across the southern half of the state.  Must be a great view from Diamond and Crater Lakes right now!

I’ll keep an eye on it the rest of the afternoon of course.

Scattered Thunderstorms Possible Through Tuesday A.M.

April 23, 2012

10:00 am:

For those of you just wanting the basics:

1. Today will be the last warm day.  Most, or all, of the day will be dry and mostly sunny.

2. Scattered thunderstorms COULD develop anywhere in our viewing area (least likely at Coast) after mid-afternoon.  The chance will continue through the overnight hours.

3. They may only be scattered, which means some of you may not see anything.

4. Thunderstorms are almost always spotty and randomly placed, which means we can’t say “Gresham gets one tonight but Camas does not”.  You’ve heard forecasting snow is tough?  We just plain can’t forecast exactly where thunderstorms will pop up.

5.  We are not in a Severe Thunderstorm Watch box.

My Thoughts:

Today will be our last warm day; it’s back to the usual April programming tomorrow, but it’s been a nice ride.  I really enjoyed waking up to warm temps outside this morning instead of the heater kicking on.

As mentioned in last night’s post, thunder is possible just about anywhere this afternoon through the overnight hours.  In fact a thunderstorm woke many of you up in the Battle Ground area around 1:30am…if you look closely you can see the strikes on the metro lightning map here:

We are in moist southerly upper-level flow right now and that continues through Wednesday morning.  This pattern often DOES produce some sort of thunderstorm activity west of the Cascades, although much of the time you need some sort of real “trigger” to allow thunder to develop (not including last night!).  A very warm day helps of course, but as of this morning there doesn’t appear to be a good vort max or upper-level disturbance coming north to set off a widespread event.  That, along with looking at model depictions of activity, makes me think it’ll be randomly scattered this afternoon/evening.

We will have a marine push (cooler ocean air) coming inland this evening, and there has been a time or two where the convergence of northwest winds coming through the Columbia River gap and southwest wind into the Willamette Valley has been able to develop a large area of metro-wide thunderstorms.  I clearly remember the first day of May ratings one year when it went on all evening.  Maybe in the last days of April  2003 or 2004?  The WRF-GFS shows a bit of that low-level convergence after 8pm tonight.

Any storms that develop will be moving south to north or SW to NE.

Once we get the marine layer in here after daybreak Tuesday it’s over.  The atmosphere will be more stable and we’ll be only 60-65 for a high temp tomorrow.   Wednesday could be interesting with a cold front coming in and southerly flow above still in progress…something to keep an eye on.  And Thursday/Friday sure look chilly with snow levels possibly briefly down around 2,000′ in the mornings.

I’ll update this afternoon when action starts to pop.

Chief Meteorologist Mark Nelsen