Midnight Special: Saturday Storm Looking Stronger!

October 12, 2016

11:50pm Wednesday…

If you are looking for info about Storm #1 coming Thursday evening, read the previous post down below.  This post refers to Storm #2 for Saturday…

Quick update…finally got a chance to look at all evening models.  A few thoughts:

  • The evening ECMWF run is now the 3rd in a row to bring a severe windstorm to the I-5 corridor Saturday afternoon/evening
  • The NAM model has now joined it, and the GEM (Canadian) is moving the low much closer to us as well.
  • Only the GFS is stubbornly hanging on to a position farther offshore.

That means 3 out of 4 major models are producing either a significant or (in the case of the ECMWF & NAM models) severe windstorm for the populated areas between the Coast and Cascade ranges.  That includes the Portland Metro Area.  By “severe” I mean the strongest storm we’ve seen since the December 1995 event for many of us.

Here is a comparison of those 4 models at either 5pm or 10pm Saturday evening.  Notice how the low is much closer to us except for the GFS

As a result the threat for a significant windstorm for all areas west of the Cascades is higher now than it was 24 hours ago.

IF it does appear in the next 48 hours that a big storm is coming, you will have Friday to prep for it…just lots of showers and regular breezy conditions.  I’ll keep you updated!

Chief Meteorologist Mark Nelsen


Thursday Storm Update

October 12, 2016

9pm Wednesday…

Playing catch up a bit this evening since I had half a day off for my son’s 16th birthday.  But in full storm mode now!

For those of you that just want the basics:

HIGHLIGHTS FOR STORM #1

  • Rain is beginning now, and we have a good 1.50″ coming up in the next 24 hours…get ready for localized flooding (not creeks or rivers) where drains clog up with leaves.
  • But we do not expect river flooding at this time, at least in the next two days.
  • HIGH WIND WARNING COAST/COAST RANGE: South wind gusts reach 65-80 mph along the coastline 4pm-10pm tomorrow.  Unusually strong for October.
  • South wind gusts 40-50 mph in the metro area 4pm-10pm tomorrow.  Not especially strong, but that’s a lot for October.  Leaves on trees mean more trees break/fall.
  • Expect power outages scattered about in the evening.  We saw these speeds two years ago in the metro area in late October and had something like 50,000 outages!
  • The wind remains breezy through much of Friday too…gusts 30-35 mph inland

By the way, WE DO NOT SEE A REPEAT OF THE COLUMBUS DAY STORM for Saturday at this point.  I saw a Facebook posting with that info and had an email about it today I figure I should squash that rumor right away!

markwarnings_wind_coast_valleys

 

markwarnings_wind_coast_valleys2

 

Let’s not forget the rain:

rpm_rain_nworegon

 

Often our RPM model overdoes the rain, but I think 2-3″ is a safe bet from now through late Saturday.  That is not enough for widespread river flooding, especially since we’re just now getting into the wet season.  I’m sure we will get a river flood warning somewhere (likely along the coast), but for now I think WIND is the big story the next 3 days.

WIND:

This first storm is a surface low pressure system tracking offshore during the 2nd half of Thursday.  By late tomorrow evening it likely ends up as a 980mb low pressure center near the NW tip of Washington as seen in this evening’s GFS model:

gfs_10pmthurspm

A 980 millibar low moving relatively far offshore and ending up well north of us is not a HUGE wind producer inland typically.  Hopefully we don’t get a surprise.  Nevertheless for October this is quite a start to the stormy season.

Friday will be the in-between day, by that I mean we’ll be between the Thursday night storm and Saturday’s monster storm.  More on that either later (when I get time) or for sure tomorrow morning.  I’ve got a 10pm show to get ready for.

Chief Meteorologist Mark Nelsen

 


First Storm of the Season Thursday

October 11, 2016

6pm Tuesday…

The NWS has issued a High Wind Watch for the Coast and Coast Range this evening.  That’s for the first system coming onshore Thursday.

markwarnings_high-wind

There is some disagreement on the details with this first system, and the following three I’m tracking for Friday, Saturday, & Tuesday.  That’s partly due to the fast-moving storms and a powerful Pacific Jet Stream.  It also doesn’t help that a large amount of energy is getting injected into the westerly flow by a Super Typhoon east of Japan.  Models have trouble handling those.

The plan for Thursday is a surface low tracking north along the coast, but some models are more intense than others.  The preferred ECMWF model has a surface low farther offshore. Based on that I could see gusts 55-70 mph gusts on the coast Thursday evening and 35-45 mph in the western valleys Thursday night and Friday A.M.  Those inland winds aren’t crazy strong for winter, but those speeds can down some trees this time of year due to the leaves still on many of them.  We have seen that the past couple of Octobers.  That’s storm #1.  There will be a LOT of rain with this system too since it’ll have subtropical moisture with it; hopefully we can avoid flooding since it’s the first huge soaking of the season.  We’ll see.  Check out our RPM rain totals:

rpm_12km_precip_nwor

What about Saturday?

Just east of Japan, now “Super-Typhoon” Songda is as intense as Hurricane Matthew was last week…150 mph winds!  It is forecast to fall apart and turn “extra-tropical”.  It’ll travel thousands of miles across the Pacific the next 3 days and end up on our doorstep Saturday as it develops into a massive mid-latitude low pressure system.

marktropical_typhoonpacific

Just so we’re all on the same page… A TYPHOON (SONGDA) WILL NOT BE HITTING THE PACIFIC NORTHWEST ON SATURDAY

At this point the ECMWF, GEM, & GFS models all have about a 956-960 mb low pressure center (same depth as Columbus Day Storm) tracking southwest to northeast somewhere near the Pacific Northwest coastline on Saturday.  The GEM and GFS have the low farther offshore making landfall up around the northern tip of Vancouver Island.  This track brings damaging wind to the coast but generally not inland…it’s too far away.  For the hardcore weather geeks, here are some interesting products off the WeatherBELL site.  They have an excellent array of maps and I highly suggest you get a subscription if you go through as many maps/models as I do!

The GEFS ensembles from the 18run today showing the low pressure center Saturday afternoon on the control run,

 

gefs_operational_satpm

all 21 low pressure center location & depth,


gefs_alllows

and the lowest pressure of any ensemble member (the deepest low),

gefs_slp_min_nepac_19

Yes, that is a 945-950 mb low much closer to the coast.  Interesting to see how many possibilities are out there.

The ECMWF has the low pressure center much closer to us and the storm comes from a more southerly latitude; that’s potentially a far more damaging hit that could bring high winds inland.  We’ll see how things shake out the next three days.

The Columbus Day Storm was much closer to the coast than anything forecast for Saturday.  It moved quickly and was still strengthening as it moved north.  Those three factors are what make that storm the standard we measure all other storms by.  By the way, here are the peak speeds from that storm…

markcolumbusdaystormpeakgusts

Can you imagine the damage 90+ mph wind gusts could cause nowadays?

Chief Meteorologist Mark Nelsen

 

 


Typhoon Songda’s Leftovers: Stormy PacNW Ahead!

October 10, 2016

11am Monday…

In the fall it is not unusual for tropical cyclones (referred to as typhoons) in the western Pacific to get caught up in the jet stream as they die.  Then the leftovers end up somewhere along the west coast of the USA.  They don’t survive the move over cold water, but their remains can help new storms develop much farther east.  They more or less transfer heat & moisture from the tropics into the mid-latitudes…where we live.  That’s going to happen later this week and it’s part of the reason Thursday through early next week is looking like the stormiest mid-October period we’ve seen in almost a decade.  I recall a strong storm in mid-October 2007, but none since that time.  October typically has quite benign weather until the last week when rainy weather kicks in. This year that rainy season has started early!

The Next 3 Days

They look great!  We have leftover areas of fog & low clouds today, but sunshine will gradually break out.  Tuesday looks incredible with bright sunshine and cloudless skies under a dry easterly wind.  This should be a great photo-op day with the blue, sun, & changing fall leaves.

Thursday through Early Next Week

A mid-winter strength Pacific jet stream sets up over the entire north Pacific ocean.  Check out one model forecast of wind speeds up at jet-cruising altitude:

jetstream_sat

jetstream_wide

That would be quite a tailwind flying from Japan to Portland if one followed the jet!

Note that as the strong jet arrives on the West Coast, it makes a slight curve to the left.   It’s a long story, but there is lots of lifting high up in the atmosphere in that spot (called the “left-exit region”) in the jet.  Powerful surface low pressure systems can spin-up in that spot and Thursday through Sunday it is quite close to our coastline.  This is the pattern than CAN produce big windstorms for us.

The gold standard of models, the ECMWF on last night’s run showed 3 deep lows that come relatively close to the West Coast.  Thursday night, Saturday morning/midday, & Monday.  All three will produce a round of wind and rain for our region.  This isn’t really an atmospheric river setup, but a series of separate storms that are all warm and very wet.  Regardless, it’s going to be mid-winter type wet.  Take a look at the ECMWF rain forecast for Salem:

ecmwf_ensemble_rain_sle

The bottom shows accumulation of rain from the operational model in blue…somewhere between 5-6″ by Monday afternoon!  The group of 51 ensembles averaged together are just under 5″.  The colored lines above each represent one of the 51 ensemble members.  Excellent agreement with very wet weather…a soaker!  Note it tapers off dramatically after Monday/Tuesday next week.  I mentioned in the 12 Day Trend last night at 10pm that the weather turns more reasonable after about 6 days of this crazy stuff.

The morning GFS shows the soaking as well, but for now not as extreme.

gfs_7day_precip

Looks like around 3″ in most of the valley.  You can ignore the bullseye over Portland, the model is pushing the south Cascades rain in Washington out over the lowlands.  That doesn’t happen.  Even with this “lighter” 3″ of rain, that’s more than we typically get in an entire October!

As for wind, lots more uncertainty on where the strongest wind is headed  as Typhoon Songda as it dies east of Japan and follows the jet stream.  If you are thinking this is similar to the Columbus Day Storm…it is somewhat, although the track was farther south in 1962.

gefs_wp23_2016101006

Songda’s remains turn into a deep low pressure center that ends up somewhere between Vancouver Island and Haida Gwaii according to both the GFS and GEM models this morning.  The overnight ECMWF was farther south with a 968mb low into central Vancouver Island.

ecmwf_satmidday

That’s a big windstorm for the coastline but too far north and west for a windstorm in the valleys.  It’s interesting to note that 6 out of 51 ensemble members have some sort of devastatingly deep low pressure center much closer to us for a big windstorm inland.  Yes, I counted…but that also means 45 out of 51 did not.  There was even one member that had a 945mb low center hitting Vancouver Island.

So we’ll keep a close on it all week as we get closer to see exactly where the deep low pressure systems are going to spin-up.  Otherwise enjoy these 3 dry days because we have a huge soaking ahead!

Chief Meteorologist Mark Nelsen


Sunny Sunday to Heavy Rain??? How Did THAT happen?

October 8, 2016

5pm Saturday…

No one has asked me yet, but lots of you must wondering…

How in the heck does the forecast of mostly sunny and low-mid 70s on Sunday go to rain, possibly heavy at times, and a high around 60???

TOTALLY REASONABLE QUESTION!

Here’s what happened:

  1. The “plan” for this weekend has been for a few leftover showers this morning to lift north and then an “atmospheric river” of moisture sets up the rest of the weekend over northern Washington and British Columbia.  We’ve known for days that a big wet weekend event was setting up just to our north in the northern half of Washington.
  2. In the past 24 hours it has become increasingly obvious that Sunday is going to be wet, and as of last night’s models…very wet, because…
  3. The whole band of rain is shifting about 200 miles farther south than expected.  That’s due to a stronger northerly jet stream pushing the whole event south.  It’s all getting pushed south right over us and ruining our Sunday.
  4. What’s 200 miles among friends…right?

RAIN HIGHLIGHTS FOR REGULAR FOLKS WITHOUT THE TECHNICAL INFO:

  1. It will likely rain all day Sunday in NW Oregon and SW Washington.  A steady rain much of the day.
  2. Wind is not an issue.  It will be LIGHT after 8am or so from the north
  3. Heavy rain is possible at times from midday through the evening from the metro area south into the Willamette Valley.  Total rain should be in the 1.00-2.00″ range.  Wettest since January!
  4. There COULD be areas of localized flooding if the rain is heavy enough for several hours.  At this point the event looks less intense than the one last October that flooded MAX.
  5. Some models are giving us .20″ to .30″ for a few hours somewhere between Portland and Albany during that time.  With leaves blocking drainage, that could contribute to flooding issues IF the rain is heavy enough…it may not be.
  6. The front moves south and we’ll be all dry Monday.  With dry east wind Tuesday looks spectacular with blue skies and leaves changing color under the bright October sun.

 

For the geeks…

Check out the precipitable water forecast for midday tomorrow:

gfs_pwat_west3_5

Looks juicy with 1.5″ or higher!  Lots of subtropical moisture to work with as a cold front drags south across our area Sunday.  The problem with forecasting tomorrow is that each model is a bit different on where the heaviest rain falls and final totals too.  Of course we all know the heaviest rain will be in the Coast Range and Cascades, but I mean north and south.  Does the Salem to Wilsonville area get a heavy rain band early afternoon as the WRF-GFS shows?  That’s .60″ in 3 hours.  I’ve noticed we start having urban flooding issues with several hours of .30″ so even this is at the lower end.

wrf_2pmsun_3hrprecip

The WRF-GFS has these totals for the entire event…which are pretty reasonable.  That’s maybe an inch to two inches for many of us in the valley, but less for others:

wrf_rain_tuesam

But the RPM (definitely not always a stellar performer) has it right over PDX with several hours of .30″ intensity in the evening hours:

rpm_rainhighlighted

After almost an inch during the day, it then dumps another 1″ in the next 4 hours!  I bet that is overdone.  But the GFS is extremely wet too, showing 2-3″ over the metro area.gfs_precip_mondayam

The ECMWF is more reasonable than the GFS…

ecmwf_precip_monam

Giving us 1 to 2″ in the metro area but lighter totals (more like 1/2″) down around Salem.

I feel confident saying somebody SOMEWHERE in the lowlands is going to really get dumped on tomorrow, but we don’t know exactly where.  Stay Tuned.

By the way, have you hardcore weather folks noticed this is a pattern that would give us a surprise modified arctic blast in winter followed by freezing rain or snow?  Check out the 48 hour old forecast of 500mb for Sunday PM:

ecmwf_500mbthuram

I’ve added the yellow line to show the main flow.  A cool upper-level trough was forecast to stay just to our north (thus the rain forecast up in northern Washington).  Now check out the forecast for tomorrow afternoon but made this morning:

ecmwf_current500mb

Much better!  In January we’d be real excited about a push of arctic air coming in, or at least just scraping by to the north.  In this October case, that means much drier air for clearing Monday afternoon and then a breezy “coolish” east wind Tuesday for a spectacular sunny fall day.  Then moisture returns with brief offshore flow later Wednesday and Thursday.

As for late next week, it looks rainy and windy…our first real stormy pattern of the season and it’s arriving early.  More on that tomorrow when I’m back to work.

Chief Meteorologist Mark Nelsen

 

 

 


Hurricane Matthew: Big Trouble For Florida

October 6, 2016

I generally don’t post about weather in other locations around the USA since it doesn’t affect us, plus I’m not an expert for other areas.  But Matthew is going to be a historic storm for Florida.

After many days of models gradually coming together on a path for the storm, this morning both the GFS and ECMWF are in perfect agreement.  The storm will be right over Cape Canaveral (yes, the Kennedy Space Center) at sunrise Friday AM.  Check out that monster on both models:

gfs

 

ecmwf

Several things to point out:

For one, the strongest wind stays over the water.  But also note the “weaker wind” still means gusts over 100 mph from just north of Miami all the way up the coastline.  That means what same wild wind we feel at Vista House in wintertime will be widespread across the entire eastern half of Florida and hit millions of people!  Even Orlando, a good hour inland by freeway, will see gusts in the 70+ mph range.  There is going to be widespread destruction from this storm.

For the latest from the National Hurricane Center you can go here through the entire event:  http://www.nhc.noaa.gov/graphics_at4.shtml?5-daynl#contents

And this is the latest forecast track:

matthew

The NHC is the official source of information, all other information you find online begins with those folks.

 

 

 


October Is Looking Wet!

October 4, 2016

4 out of the past 6 Octobers have been wetter than normal here in Portland as mentioned in a previous post:

markoctoberrain

As of 6pm Tuesday we haven’t seen all that much rain today.

plot_rain_metro_autoplot

The sunbreaks around 5pm sure did make for this beautiful rainbow from Joanna Burn up in Vancouver!

photo_joanna_burn

The rain action should pick up dramatically overnight through midday Wednesday as a low pressure system tracks directly over NW Oregon.  Here is the 8am view from WRF-GFS model:

slp-27-0000

The surface low appears to move right through an Astoria to Portland line in the first half of the day.  The showers taper off beyond that time and Thursday looks mainly dry.

Other than a warm front brushing us Friday and the early part of Saturday, the jet stream should lift north for a few days putting us on the very warm side of the jet stream.  We will be just south of an “atmospheric river” of subtropical moisture aimed at Vancouver Island and NW Washington.  As a result our forecast highs of 70 & 73 for Saturday/Sunday could be quite low.  We may end up closer to 80 if the clouds clear out both days.

Beyond that there is good agreement that we’ll see our first “stormy” period the latter half of next week.  Check out the deep upper-level trough and strong westerly jet on the ECMWF for next Thursday…looks more like November doesn’t it?

500vty_f228_bg_na

The GFS and GEM models keep the ridging over us a little longer next week, we’ll see how that pans out.  It’s definitely a warm pattern, much milder than the past week.  The 18z GFS is very warm with a bunch of 70s Saturday through Wednesday.

kpdx_2016100418_tx_240

If so that’ll be nice after the icy cold September!  Okay, a degree or so below normal, but I want to keep everyone happy…

Chief Meteorologist Mark Nelsen