Downpours Have Arrived: Rough Evening Commute Ahead!

October 22, 2014

3pm…

There are going to be some spots of local flooding during the evening commute in the urban areas.   Just some spots, not everywhere, but allow extra time to get to your destination!  At this point there are no flood warnings or advisories, or any weather warnings for that matter.  But I wouldn’t be surprised if the NWS issues a small stream flood advisory soon.

Take a look at rain so far…

PLOT_Rain_NWOregon_Autoplot

At PDX .93″ has fallen just since 11am.  The rain has been particularly heavy on the west/southwest side of the metro area too. In my experience, when you get several hours of .30″ or more, that’s when local flooding issues start popping up across the inland valleys.  Portland saw .38″ in one hour from 1-2pm.

The HRRR model says we could see another 1/2″ or more by midnight, most of that before 7pm as the last real “wave” on the front over us moves by.  After that time we turn more showery and the threat for local ponding/flooding will pretty much end.

Thursday is a showers/sunbreaks sort of day, but still a pretty good soaker.

I’m working on the forecast right now and taking a very close look at the Saturday forecast.  Some models are producing a lot of wind in the afternoon…others not so much.

More later…

Chief Meteorologist Mark Nelsen


A Soaker For Wednesday

October 21, 2014

Let’s get this out of the way right now…

There isn’t a major wind or rain storm of any sort heading into the area the next 24 hours

That said, it sure is going to be a wet day Wednesday and windy at times too!

So why do you see BREAKING WEATHER ALERTS, STORM TEAM COVERAGE etc…on TV and splashed across Twitter and Facebook?  Or why does your weather radio suddenly go off on its own at 5am?  Well, it’s the first windy and wet system as we head into the rainy season and we news folks have a lot of pent-up weather energy.  We need a good storm!

Here are the wind details:

  • Gusty south wind picks up the next few hours at the coast…gusts to 60 mph are possible in the windier spots
  • Southerly winds pick up around daybreak in the valleys.  Southerly gusts 30-35 mph possible in the morning; about what we saw a week ago

MarkWarnings_Wind_Coast_Valleys1 MarkWarnings_Wind_Coast_Valleys

How much rain?  Our RPM model says almost an inch by sunset tomorrow.  Note the PRECIP ACCUM column.  web_RPM_Text_00z_PDX_4km

A big soaker, but nothing that would cause anything more than temporary ponding on streets or highways.  Of course in the fall any storm drain blocked by leaves can produce a quick local pond can’t it?

It looks like another inch could fall from that time through Thursday evening, so we could see two inches.  Our RPM tends to be a little heavy, but here’s what it shows:

RPM_12KM_Precip_NWOR

Yesterday it was pretty obvious that this is the beginning of our wet season…take a look at today’s ECMWF meteogram for the next 10 days:

KPDX_2014102112_dx_240

The rain sure isn’t very heavy further into the extended forecast, but there is no really good dry period.  Also notice we are done with 80s and 70s too.  Temperatures should be much closer to normal for the next ten days.  The average high in Portland 10 days from now is 58!

Stay dry tomorrow!

Chief Meteorologist Mark Nelsen


Sunday…A Spectacular Day!

October 19, 2014

Bright sunshine and temperatures well into the 70s on October 19th; no wonder I saw a lot of people outside today as I found the end of the Springwater Trail!  At 3pm the temperature is 74 at PDX, likely headed for a high of 75-77.  The record for the day is 78 so we probably won’t hit it.  Still, it was great to bicycle outside in the sunshine as if it was summer.  At least this will make winter come a bit faster mentally.

As for the Springwater Trail, that’s the paved bike/walk/hike path that goes 22 miles from Downtown Portland to Boring.  The last 2 miles or so were just paved withing the last couple of years and were especially smooth.  My son and I rode from Gresham out to Boring this afternoon.  Officially the trail ends there…for now, and the trail becomes the Cazadero Trail at that point. The next 3 miles of the old railroad bed are an improved gravel surface which was really easy on mountain bikes, actually a bit better than my driveway.  IMG_0593  It heads downhill along the north fork of Deep Creek.  You only pass 2 or 3 homes otherwise you are in the woods.  At the 3 mile mark the trail suddenly ends at a dropoff.  There used to be a railroad trestle at that location; all that’s left is the concrete abutment.IMG_0592  At this point you are only 1/4 mile or so from Hwy. 224 at Barton, just above Barton Park.   Obviously it’s not going to be cheap to get the trail down to the highway, but from what I read online, the plan is to finish the trail to Estacada or a little beyond to one of those dams.  For now you have to turn around and go back uphill to Boring, which was only about 300′ up in elevation.  It’s also interesting that when bicycling the 6 miles from Gresham to Boring, you really don’t notice that you’re going uphill, but you can sure feel it coming back…significantly faster.  Reminds me of my big bicycle ride last year from Elgin to Joseph.  In 35 miles you climb around 2,700′, yet it’s just barely noticeable…mostly you just feel like you’re getting a little lazy and pudgy.

I hope you all were able to get outside and enjoy the beautiful weather because the chance of us hitting 70 degrees again is pretty slim.  Take a look at the 12z ECMWF meteogram…lots of wet and much cooler as temperatures really fall off over the next 10 days.  KPDX_2014101912_dx_240

Chief Meteorologist Mark Nelsen


A Record Long Growing Season; At Least in One Spot

October 16, 2014

Have you noticed what is missing this October?  Frost!  Not here in the metro area, but elsewhere.  Only the higher parts of Central and Eastern Oregon have seen frost so far.  It hasn’t even been close west of the Cascades.  Considering we have lots more above average nights in our 7 Day Forecast, that means many areas that should have had a frost by now are seeing an unusually long growing season this year.

Tim Dearden from Trout Lake WA (north of Hood River) says there has still been no frost since April 28th at that ~2,000′ location.  He looked up the records and found that Trout Lake Ranger Station is already 15+ days ahead of its longest growing season ever!  He too noticed that nights have been much warmer than normal during the summer and early fall.  If you’ve ever been to Trout Lake, troutlake it should be obvious to you that there is no urban heat island in that location!

Tim took the numbers and plotted out the growing season length over the past 90 years.

Plot

Isn’t that interesting?  It appears the growing season IN THAT LOCATION is averaging 2-4 weeks longer than 100 years ago. I don’t have the time to research it, but I’m wondering if it’s mainly the fall dates that are changing the past 30 years at least and not the spring dates.  I was thinking it might be related to summer warmth that seems to be spreading into early fall more often.

I’d love to see how the numbers look for a few other rural locations, like maybe Corvallis, Aurora, or Hillsboro (still mainly rural at airport).  Someone get to work on some spreadsheets!


A Windy Day, And A Tornado That Never Was

October 15, 2014

The gusty southerly wind showed up as expected this morning, with peak gusts in the 25-35 mph range for most of us.  PDX hit 35 mph.  That of course prompted some scattered power outages, but those were pretty much gone by early afternoon.

Around 4pm we got an email from a viewer that thought a tornado may have gone through the part of Woodburn just west of the Outlet Stores.  So we sent a reporter down to check it out.  I assumed it probably wasn’t much, but you never know.  In the past I’ve found that unless several viewers call/email/tweet from a populated area like that, there’s a good chance that it wasn’t a tornado.  So I was surprised when I read two tweets (from other news organizations) that said there was a small tornado in Woodburn.  I said “What?”, fearing I had fallen woefully behind in the information business.  I checked the “pre-2010″ channels of National Weather Service information, which involves checking Public Weather Statements and Storm Reports…Nothing.  So then I went to the “pre-2000″ level…I called the NWS.  Of course they said “What?” too, noting they sent a team down to investigate but as of that time (5pm), there was no tornado.

Sure enough, damage pictures came in from our reporter Laura Rillos…

Woodburn Tornado 3 Woodburn Tornado 1

and showed what the NWS told us in a Tweet around 6pm…”Storm survey concludes down tree limbs on Butteville Rd (west of Woodburn Outlet Mall) was from 30-40mph straight line winds & NOT a tornado

It was just a heavy shower that sent out a strong straight-line wind.  A lot of drama for that, but it sure made two hours of TV pass quickly!

Chief Meteorologist Mark Nelsen


Spaghetti Plots…Storm Approaching Hawaii

October 14, 2014

Tropical Storm Ana is revving up and should become a hurricane within 24 hours.  This storm is forecast to end up somewhere over or quite close to the main Hawaiian Islands.  If a landfall actually happens, as far as I’m aware it will be unprecedented in historical times.  Here is a map showing all the storms that have passed within 75 miles of the main island chain…not as many as you would think:

hawaii

Of course there is always error, especially 4 days out.  The official CPHC forecast looks like this right now:

MarkTropical_HurricanePacific MarkTropical_HurricanePacific2

But you might find this more interesting…a loop showing all the different model forecasts for where the center of the storm will go.  Each line is one model.

Interesting stuff eh?  Shows you why the forecast track can be so uncertain and also why it’s so important to not focus on a specific track in the middle of the “forecast cone”.  And you can also see why we call these types of charts “Spaghetti Plots”!

So as of right now it might not be a big deal, or it might be a huge storm.  For it to be a big storm, the center has to hit one of those little dots of land!

Chief Meteorologist Mark Nelsen


How Windy Tomorrow? Not a Storm, But Windy

October 14, 2014

We stayed mainly dry in the metro area today since the main rain band with a cold front has been just to our south.  We figured it would be right over us instead.  Nice way to bust a forecast though!

You may have heard rumblings of strong wind coming tonight or Wednesday.  Here’s the latest:

  • A windstorm is not on the way
  • But gusty southerly wind will develop across the western valleys of Oregon/SW Washington and the coastline late tonight and then die down after mid-morning tomorrow
  • Peak gusts 30-35 mph are likely for most of us.  About 5-10 mph stronger than last night’s gusts.
  • 40-45 mph at the Coast
  • This is strong enough for a few limbs to fall since most leaves are still on the trees, of course there will be a few scattered outages.

The NWS issued a Wind Advisory earlier this afternoon for peak wind gusts around 40 mph in the central/north Willamette Valley tomorrow morning.  I think that’s a bit much and 40 mph gusts are a bit high.  I bet PDX ends up with a peak gust 30-35 mph at best.  That said, 30-35 mph gusts in mid October will easily bring down some branches…and lots of leaves!  That means some scattered power outages are possible again like this morning.

Where is the wind coming from?  A surface low or open wave will scoot quickly north along the coastline later tonight and tomorrow morning, giving us the rush of air behind it from the south.  Models are in some disagreement on how much wind we get (lowering my confidence that anything interesting will even happen!).  The NAM has no strong wind at all, the HRRR shows no gusts over 30 mph (or even less) in the Valley:

HRRR_WindGusts

The ECMWF gives a little more energy to the wave in the afternoon, which means no closed low and not much wind in the morning.  The WRF-GFS is alone showing wind gusts maybe 35-40 mph late tonight and early tomorrow:

wgsfc.27.0000

Our RPM model looks like this:

RPM_12KM_Wind_NWOR

That would imply gusts close to 40 mph, but our model almost always is too high…note the text output

web_RPM_18z_Text_PDX_4km

With most wind events you can assume this text output is 5-10 mph too high on gusts, so this tells me not much is going to happen tomorrow other than the effects I noted above.

Chief Meteorologist Mark Nelsen


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