Wettest Spring On Record In Portland

May 14, 2017

3pm Sunday…

Well, I take that back, we can start whining about the amount of rain this spring.  Note the previous post.  But now the soaking Friday and Saturday has put us in record territory…

As of midday this Sunday, the 13.00″ precipitation (mainly rain) that has fallen since March 1st is the MOST WE’VE EVER SEEN IN A SPRING THROUGH MID-MAY!  That’s pretty bad.  The airport records go back to the late 1930s…so that’s just about 80 years.


Note the chart just goes through midnight last night.  We’ve had .05″ since that time, putting us up to 13″.  Most interesting is that the top 4 wettest have occurred in the past 7 years.  Note that if we get 1.51″ of rain in the next 2+ weeks (by May 31st) that will be the wettest spring on record at PDX.  We’ll see what happens.


Salem’s weather records go back further in time…124 years.  It appears you folks are at #5 wettest.  Yet there have only been 2 wetter (1963 & 2012) in the past 80 years.  Yeah, it’s time to start whining…I’m right there with you.

Luckily another taste of summer is coming later this week.  More on that later…

Are We All Whiners? A Look At Spring So Far

May 11, 2017

10pm Thursday

The last 5 days were sure nice…totally dry with warming temperatures each day.  By yesterday the soil around my home was all dry and it finally looked like late spring out there as I planted a few more veggies.  Then a strong cold front moved through the region today with much cooler air behind.  Scattered heavy showers, hail, & even a few thunderstorms have popped up this evening…that chilly spring of 2017 is back!  But is it REALLY that bad?  I’d say no.  Take a look at our spring so far.  It began March 1st and of course we’ve gone through May 10th:

This really surprised me.  In the past 20 years, we’ve seen two 5-year periods in which temperatures were colder than this one so far.  1999-2003 springs were all colder than this one and 2008-2012 were all cooler too.  So no, this year is pretty close to normal temperature-wise; just slightly on the cool side.  What we’re really noticing is the dramatic shift from 4 warm springs (especially last year) to this one.  Back to normal!

Now check out rainfall:

I think we have a right to whine a bit about the rain…it has been WET.  We haven’t seen it this wet since 2012.   In fact it’s one of the wettest springs on record here in Portland.  Only 2011 & 2012 were wetter.  It’s also interesting to note our springs have been gradually turning wetter since around 1980.  But again, we have been spoiled by the past two years of warmer and drier than normal weather.  Not it’s back to “reality”.

The Big Picture:  It’s not Global Warming, Chemtrails, or HAARP.  We don’t live in San Francisco, Sacramento, Denver, or Salt Lake City.  We just live in a wet maritime climate; this is what happens here every few years.

It is pretty clear that this cool & showery weather will continue for about 6 days then we get a break again.  The 12 Day Trend I use in the 2nd half of the 10 O’Clock newscast shows that with milder and drier May weather beyond next Tuesday.

So if the cool and showery weather annoys you just wait…it’ll turn a bit more pleasant again in less than a week.

Chief Meteorologist Mark Nelsen

3 More Sunny Days, Then Back to Wet & Cool

May 7, 2017

9pm Sunday…

It’s a new workweek for me but for most of you it was a fantastic end to the weekend.  Sunshine covered the entire Pacific Northwest this afternoon and we ended up right at normal here in Portland = 66 degrees.

If you’ve been outside the past couple of hours you know temps are cooling off quickly.  With high pressure overhead, a dry airmass, and clear skies, temperatures will plummet tonight.  Lows drop way down into the 40s with even a few upper 30s in the colder outlying parts of Portland.  Hopefully you didn’t plant your warm weather veggies yet…it’s a bit too early.  Not just because of another chilly night but we see quite a change in the pattern after Wednesday.

The good news is that we have 3 warmer days ahead.  We should be somewhere between 70 and 80 degrees each of the next 3 afternoons.  But then the cold showers return.  Take a look at the ECMWF ensembles showing 24 hour precipitation amounts the next 15 days:

You can see the very good agreement among the ensemble members showing pretty solid .10 to .30″ 24 hour rain totals for at least an 8 day period beginning Thursday.  This goes along with the 850mb ensemble chart

A nice warmup for 3 days, and then those pass-level temperatures (in the free atmosphere) plummet down to around freezing during that 8 day period.  Of course with the strong May sunbreaks we’ll get very little snow down to 4,000′, but the point is snow returns to the higher elevations late this week and the valleys will feel more like early April again.  Lots of showers, hail showers, and probably cold thundershowers here and there.  Also note there is a tick upward about 12 days out.  You see the decreasing rain totals on that previous chart as well.  The GEFS (GFS ensembles) have more ridging near the end of the 16 day period too.  You can see the upward trend in temps when average.    Of course the blue line is the operational run and it appears to be much warmer than the mean (average) of the ensembles.  Remember these charts show the temperature around 4,000′ or so.  The GEFS surface temps look like this, showing the same 8-10 day cool spell ahead:

So buckle up, enjoy the 3 warm days ahead, put off all your indoor tasks and enjoy the sunshine!

One more bit of good news…ALL Willamette Basin reservoirs are full and it’s just the first of May.  You can see it on the Army Corps of Engineers “teacup diagram” page.

There will be PLENTY of water for this summer, including irrigation (more of an issue typically east of Cascades) and water recreation.

Chief Meteorologist Mark Nelsen


Lots of Thunderstorms, But Big Storms Avoid Portland

May 4, 2017


Thunderstorms popped up all over the place this afternoon and evening, with numerous severe thunderstorm warnings issued by Portland/Seattle/Medford NWS offices.  In our area Vernonia saw 1″ hail, 1.3″ hail fell near Carson, and two tornado warnings were issued around Crater Lake.  No tornado was actually seen, just indicated as a possibility on radar.

The far westside of the metro area saw hundreds of lightning strikes around 6pm as a cluster of storms moved north there.  In the central Gorge a severe storm moved through and sure looked dramatic in a pic from Julie Vance:

That led to some flash flooding and mudslide in the Dodson area…as if the 2″ of damaging ice wasn’t enough in January…

Yet we seemed to have a “dome” over the metro area.  Check out the lightning strikes today (cloud to ground only):

Apparently Yamhill and Carlton were the places to be if you wanted to see a light show?  I suppose Government Camp would have worked as well.

There is a new batch of weaker thunderstorms moving up the Cascades right now and we’re seeing lots of flashing from the metro area…enjoy the light show!

Check out the hot temps in parts of Oregon today:

Things will gradually die down overnight and we’re back to typical cool showers tomorrow.  It should be a refreshing day compared to today.

Chief Meteorologist Mark Nelsen

A Crazy Afternoon & Evening Ahead

May 4, 2017

3:20pm Thursday

I hope you’re enjoying our summer day…on this May 4th.  We’ve reached our 83 degree forecast high here in Portland, making it the warmest day of the spring so far.

Thunderstorms have arrived earlier than expected and farther west too!  Several severe thunderstorm warnings have already been issued by the Portland NWS the past 2 hours, mainly for large hail around Elsie, Mt. Hebo, and north to the Columbia River.  Most of the big storms have been over the Coast Range and just inland from the Coast…SO FAR.   Here in the valleys we’ve seen sprinkles and a lightning strike or two but as of this hour its real quiet.

I think that will change as we head into the commute and early overnight hours.  The atmosphere is primed for thunderstorms to pop up just about anywhere during these next 8-10 hours.  Plenty of moisture, “heat”, and cooling coming in high above our heads leads to a very unstable atmosphere.  These storms are moving quickly from south to north, so even though you may get a torrential downpour in this subtropical airmass, it shouldn’t last too long.

Take a look at the GOES-16 visible loop and you can see plenty of clearing through the Willamette Valley right now which will keep temps up and help initiate more thunderstorm action.


Radar at 3:10pm also shows that window to our south

KPTV 2017 Default Earth

To summarize:

  • ANYONE in our viewing area could see a thunderstorm between now and midnight.
  • ANY thunderstorm could turn severe, which means it would contain strong wind gusts (over 58 mph) or large/damaging hail (1″ or quarter size).  When the NWS sees a storm which could contain either of these, it issues a Severe Thunderstorm Warning
  • Local flooding is possible if a thunderstorm passes over your neighborhood…expect Florida-style raindrops this evening!
  • AFTER midnight the cool air surging in from the Pacific Ocean down here near sea-level will stabilize things and thunder chances end west of the Cascades

Remember that we are on Facebook and Twitter as FOX12WEATHER.  Make sure you like/follow us there (seen to the right as well) since we tend to update those sites more frequently.  I’ll be on-air 5-7pm and again 8-10 pm on KPDX and 10-11:30pm on KPTV.

Chief Meteorologist Mark Nelsen

82 in Portland Today: Possible Thunder Tomorrow Evening

May 3, 2017

10pm Wednesday

What a day!  Temperatures reached into the lower 80s today with our first real taste of late spring/early summer weather.  PDX officially hit 82, the warmest day since late September

It appears that Medford was the warmest spot in Oregon (of the official METAR sites) with a high of 90 degrees

We did this with a relatively humid atmosphere, morning clouds in the valleys, and very little offshore flow.  You can see how we could be close to 90 in this pattern with dry offshore flow.  That happened on this date in 1992.  We hit 89 on that day and the following one.  I remember that hot weather spell; my first spring living in Portland and sitting on a very sweaty MAX train coming home from a downtown job.

The warm weather means we hit our first 70 AND first 80 degree day together, which hasn’t happened in the past in Portland.  Here are a few other weather facts for you:

Tomorrow we start sunny except in the southern Willamette Valley where some low clouds might come in off the Pacific Ocean.  Then things get interesting in the afternoon.  Models have consistently been showing convection breaking out over the Cascades & Coast Range, then popping up over the valleys too.  Each model is slightly different, but they ALL show very low lifted indexes, abundant CAPE, and precipitable water values well above 1″.  This means we have a POSSIBILITY of seeing a strong thunderstorm anywhere from the Coast Range to the Cascades, but not everyone will see one.  They are always tough to forecast.  The evening WRF-GFS and our RPM imply most of the action stays near/over the Cascades in the south-southwest flow aloft.  I’m not sold on that, but I also don’t see a setup like the June 4th, 2009 event which brought damaging wind to the metro area from a line of thunderstorms.  That event was the last time we saw a Severe Thunderstorm Watch west of the Cascades.


Yes, that’s 8 years back.  We don’t get damaging thunderstorms west of the mountains very often!  In early August 2014 severe storms developed over the North Cascades and north-central Oregon, but a watch only extended up to the Cascade crest as you can see on this image:


For now SPC has part of our area under a MARGINAL threat for severe thunderstorms tomorrow:

Beyond tomorrow evening/night, we’ve got a cold front coming through Friday morning followed by light showers the rest of the day and Saturday today.  Sunday through Tuesday looks pretty nice with typical May clouds and sun mixed.  Note the ECMWF ensemble precipitation product shows little/no rain from Saturday through early next Wednesday.  This is quite an improvement over last week!

We’ll be watching the radar and trends closely tomorrow and I’ll keep you updated.  Don’t forget to follow us on Twitter and Like us on Facebook.  I update info more frequently there.  You see those posts over to the right.

Chief Meteorologist Mark Nelsen

First Taste of Summer This Week!

May 1, 2017

9pm Monday

I’m back at work this evening and it appears I missed nothing weatherwise the past week.  Just rain and some mountain snow.

This first week of May sure looks interesting.  The #1 thing we’ll all notice?  Summer temps arrive Wednesday and Thursday.  Then a chance for thunderstorms later Thursday and Thursday night both east & west of the Cascades.  Last year we saw 9 days in the 80s in May, but we had a very warm spring.

80 Degree Days in May 2017

In the short-term, a warm front moves overhead tomorrow…that means gloomy skies and drippy conditions at times.  Temperatures will remain a bit below normal.  Then on Wednesday a warm upper-level ridge builds overhead with the warmest airmass so far this season.  850mb temperatures reach +15 or +16…midsummer values for our area.  The combo of thick cloud cover tomorrow and then the sudden break to sun Wednesday plus warming atmosphere means a dramatic jump in our temperatures here at sea level.  We’ll jump at least 20 degrees in one day.  We won’t see any records set since they are around 90 this time of year.

By the way, assuming we hit 80 on Wednesday as forecast, it’ll be the first time we’ve seen the first 70 AND first 80 degree day at once here in Portland.  We have been close…on April 14th 1984 we hit 79 degrees in Portland and that was our first 70 of the season.

We don’t get any sort of decent offshore flow Wednesday or Thursday, which means we likely won’t reach the upper 80s; that’s possible with such warm 850mb temps in May.

There are two other parts to our mini warm spell;  Humidity and Thunderstorms

Humidity:  Plenty of moisture gets left by the warm front (along with our wet ground) so all models are pointing to relatively high dewpoints Wednesday and Thursday.  That means a humid feel for our first warm spell and very warm nights.  Low temps will likely be within a few degrees of 60 both Tuesday and Wednesday nights.

Thunderstorms:  All models also develop strong instability in the warm and humid airmass later Thursday afternoon & night.  This plus the southerly flow is usually a good setup for thunderstorms.  We could see some good weather action!  I’ll be keeping a close eye on that.

Chief Meteorologist Mark Nelsen