A Very Early Dry Season Start?

May 2, 2016

11pm Monday…

It’s starting to get dry out there…you know that if you’re a gardener like me.  In the past 16 days Portland has seen less than 1″ of rain.  If you add in the much warmer than normal temps, soils are quickly drying out.  Feels more like June…

What’s ahead?  Unfortunately I see drier than normal or even mainly dry conditions over the next 10+ days.  That takes us to mid-May.  Why?  It’s that persistent upper-level ridging over the Western USA we’ve seen off & on this spring.  It is breaking down right now, we get some normal temps midweek along with some showers, then the ridge pops back up over us this weekend and early next week.

Take a look at the GFS rain forecast for Portland for the past 3.5 days. GFS_precip  Each horizontal line is one run of the model out to 10 days, the most recent forecast is at the bottom.  Incredibly dry isn’t it?  Looks more like July.  All models are staying with the “much drier than normal” theme through mid-month…PDX rain for the next 10 days:

MarkRain_ModelForecasts

Do you realize that 8 monthly record high temperatures have been tied or set in the past two years?  One of those occurred twice (both Oct 2014 & 2015):

AUG 2014
SEPT 2014
OCT 2014
MAR 2015
JUN 2015
OCT 2015
FEB 2016
APR 2016

So when you look at the all-time warmest months here in Portland, 7 of the 12 have occurred in the past two years!  That’s an amazing run of warm weather.  Wow.   A huge climate test will be this fall and winter if/when La Nina conditions take hold.  If we turn cooler than normal with abundant mountain snow that will be great.  If we get a so-so winter with just average winter temps then it’ll be a bit more clear that the warming seen around the globe is beginning to have more of an effect in the Pacific Northwest.  Deep thoughts for 11pm…enjoy the more reasonable temperatures tomorrow!

Chief Meteorologist Mark Nelsen


Record Warm April

May 1, 2016

11pm Sunday…

You just experienced the warmest April we’ve ever seen here in Western Oregon.  That’s assuming you are younger than 80-90 years old.  Here in Portland it was the warmest on record

MarkApril_RecordWarm

Those records go back to around 1940.  April 1926 and 1935 were warmer in many places though so in those spots it wasn’t the warmest on record.   Regardless, we are in a 26 month warm period that shows no sign of ending; we’ll see if a possible La Nina this fall/winter puts an end to that (or not).

We broke another record last month in Portland…most days in April above 70 degrees

MarkApril_70DegreeDays

A strong upper-level high is just to our northeast and tomorrow we’ll be in a southeast flow overhead.  That plus some moisture and some decent instability  mean we COULD get a thunderstorm in the late afternoon or evening in western Oregon.  Models are definitely not as bullish on thunder prospects as they were with the event last week so I’m not quite as wound up about it this go around.

So…we MIGHT see something interesting in the late afternoon and evening so I’ll be watching that radar pretty closely!

Chief Meteorologist Mark Nelsen


A Quick Snow Melt This Spring

April 26, 2016

11pm Tuesday…

April has been a record warm month here in the lowlands; as of tonight it’s the warmest April on record in Portland.  That, plus a warm end to March, means the snowpack is melting earlier/faster than normal again this spring.  Take a look at the numbers from the SNOTEL sites operated by the NRCS:

MarkSnowpack_Oregon_PlusFacts

MarkSnowpack_Oregon_PlusFacts2

The faster melt means reservoirs fill quickly of course, but it also means less water in the streams in the late spring and early summer.  A warm/dry May would definitely cause a few issues, but even just a few weeks of cool/wet would be extremely helpful.  We’ll see how things go.  Speaking of snowpack, I love this pic sent in by an anonymous photographer:

CascadeLakesByway

It’s the Cascade Lakes Scenic Byway just beyond Mt. Bachelor a few weeks before it opened LAST spring.

We have warm spell #3 of this spring coming up starting on Sunday.  You can see it on the GFS meteogram from this 00z run this evening:

KPDX_2016042700_tx_240

Also note the very dry weather for late April and early May.  I love this chart that shows the last 3.5 days of GFS runs and their respective precipitation forecasts:

KPDX_2016042700_qpf_240

The latest run is on the bottom, from left to right.  The run 6 hours ago is the 2nd line up, and you continue back in time through previous runs as you go up.  Notice how dry the model is showing us for the next 10 days.  Almost time to start watering this year already!

Chief Meteorologist Mark Nelsen

 

 


Cool & Showery Weekend

April 22, 2016

11pm Friday…

The weekend is here and now it’s time to pay for those warm and dry April weekends so far.  It won’t be a total washout, but the 2nd half of Saturday and Sunday both should be cool and showery.

MarkTemp_Last12Days

Again, it’s overdue after the bizarre warm temperatures early this week; and by the way, as of today April is the warmest on record here in Portland.

Snow levels in the Cascades fall Saturday night and I think we’ll see snow sticking down to just under 4,000′ Sunday and Monday mornings.  That’s pretty low for late April.

MarkMtHoodCascadeForecast

Stay warm and dry this weekend!

Chief Meteorologist Mark Nelsen


Downpours & Thunderstorms Tonight

April 21, 2016

9:30pm Thursday…

We’ve been expecting downpours tonight, but now a few thunderstorms have been showing up in the central/southern Willamette Valley as a wave of energy moves north over the region.  These showers/storms will continue their northward trek during the overnight hours.

As a result, we’ve put thunder back in the forecast:

MarkThunder_MetroOutlook

I’ll be tracking the storms through 10pm on PDX-TV and then on FOX12 from 10-11:30pm.

You can also check out the radar here:

http://bit.ly/Fox12Radar

Happy Storm Watching!


Thunderstorms Arrived, Now Mainly Gone

April 20, 2016

9:45pm Wednesday…

For awhile things were getting exciting in the weather center with 3 different severe thunderstorm warnings for storms over the Cascades.  That was in the 4:30-6pm timeframe.  We saw large hail and then Hans Wipper from Skibowl sent us the best video of the day showing unusually large hail bringing traffic to a halt on U.S. 26 in the construction area west of Govy.

It appears the main lifting has moved north as we head towards 10pm.  So we are probably done with the storms, for sure if we don’t see something in the next 2 hours.  Here’s a chart showing all the cloud to ground strikes:

lightning3

Everything was on the far east side of the metro area and then up into the Cascades.  Now I know almost everyone heard thunder and/or saw lightning strikes.  I know for a fact that our transmission tower was struck in the West Hills (engineer saw it), so it’s obvious lightning detection isn’t perfect.  Most likely there was plenty of cloud to cloud action too.  Hope you all enjoyed a little taste of the warm season.  We’ll have some short videos on our 10pm show as well.  Here’s a great pic from Happy Valley.  I love the play of the clouds obscuring Mt. Hood, the trees, the strike, and the scotch broom blooming.  Very nice.  Pic by Nathan Zaremskiy

photo_happyvalley

Chief Meteorologist Mark Nelsen


Thunderstorm Chance This Evening

April 20, 2016

2:45pm Wednesday…

Radar

Looks like the first thunderstorms of the day have popped up right over the Bend area at 2:30pm.  Expect lots more on the radar screen over the next 8 hours or so.   Models are all showing increasingly unstable atmosphere over NW Oregon and SW Washington between now and 8pm.  We’ve got that unstable atmosphere, some moisture moving north with an upper-level wave of energy (shortwave), plus a strong low-level push of marine air surging into the valley between 5-8pm.

HIGHLIGHTS

  • Isolated thunderstorms build over the Cascades between now and 5pm, could see downpours and/or hail up there in spots
  • Thunderstorms will likely pop up in spots (not everyone will see one) in the lowlands from Eugene north into SW Washington after 5pm
  • Not everyone in the metro area will get a thunderstorm, but ANYONE could see one.  They will be randomly scattered around the area
  • Most likely metro area action will be in the 6-9pm timeframe.  Brief downpours and/or hail is possible
  • Expect wind gusts up to 30 mph between 6-9pm as cooler ocean air surges inland underneath the showers/storms.
  • After 9-10pm it’s over and then we’re dry until sunset Thursday.

I’ve seen better setups for thunder in our area, but this isn’t so bad…actually pretty decent for us.  Very similar setups have given us some nice thunder/lightning displays in the past.  Southeast flow aloft is always good, plus I’ve seen the marine push give a little added lift in the past as well.  That’s because it acts as a mini cold front plowing through the valley, pushing the warmer/unstable air up ahead of it.  Take a look at the WRF-GFS showing surface wind at 8pm.  Averaging SW 15-20 mph (that’s windy for a warm evening) running into the NW wind coming up the Columbia River.  I drew in the “convergence” area with the broad highlighter.  That convergence can sometimes work wonders too.

Capture

I’ve seen this in the past where storms bubble up right over that boundary.  Always fascinating to watch on radar of course.  The HRRR model is showing much of this nicely this afternoon.  Here’s the 7pm forecast from its latest run:

HRRR_7pm

It also thinks there will be many dry areas.  Here’s the total precipitation outlook through early tomorrow (all of it this evening) from the last two hourly runs of that model:

hrrr_t_precip_portland_16 (1)hrrr_t_precip_portland_16

Not exactly a widespread soaker tonight is it?  But for a few hours it could get real exciting just before/after sunset.

At this point there is no threat for severe weather in the lowlands.  By that I mean thunderstorm winds with gusts over 58mph or damaging hail.  Earlier SPC had put the Cascades in a MARGINAL threat for severe storms, but they have now removed that.

So how can you stay on top of the action this evening?

  1. We’ll be on-air 5-7pm on FOX12, 8-10pm on KPDX, and 10-11:30pm back on FOX12 (we like to be on TV)
  2. We’ll be posting any significant weather updates on Twitter and Facebook.  FOLLOW and LIKE us at FOX12WEATHER (all one word)
  3. On www.kptv.com/weather
  4. If I get time I’ll post here as well.

 

Chief Meteorologist Mark Nelsen

 


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