Some Maps

November 21, 2013

Last night’s monthly run of the ECMWF, broken down into weekly 500mb anomaly maps:





Interesting that the ridging way out to our west and northwest keeps wanting to pop up.  Maybe something interesting will happen in that week 3 period.

Here’s the ECMWF ensemble chart from the 12z run today…nothing to see except the ridging over us weakens a bit:


Chief Meteorologist Mark Nelsen


Sunny, Chilly, and Very Dry!

November 19, 2013

The big weather story this evening should read “NON-STOP SUNSHINE AHEAD FOR 5+ DAYS!”.


Skies are clearing this evening behind the morning cold front and temps are the coldest we’ve seen all day.


The well advertised dry air is coming in from Canada.  Models have been very emphatic shoving dewpoints down into the 30s, then 20s, then teens over the next 24 hours.  The airmass moving south out of Canada is the driest we’ve seen since sometime last winter.  It’s not exceptionally cold, just chilly.

But with such dry air, even daytime highs in the mid-upper 40s means low temps drop like a rock at night.  I expect widespread 20s tomorrow night as the wind calms down, and at some point between now and Sunday we should see some upper teens in the coldest outlying areas.  A similar pattern produced similar temps in November 2000.  Meteorological Pacific Northwest winter has arrived!


Other than that, ridging is the big story through the short-term and long-term.  The 00z GFS had some sort of ridging over us through the entire 16 day run, with only one weak system squeezing through the ridge around Thanksgiving.  However, that IS the GFS.  The ECMWF turns a bit wetter and cooler sometime over the Thanksgiving Weekend, at least the 12z did.

With warming temps above 2,000′ late this weekend and over the weekend (50s at ski resorts), easterly wind through the Columbia River Gorge will turn very strong after Thursday, probably the strongest we’ve seen since 1 year ago when peak gusts were around 70-75 in Corbett and 85+ at the Vista House sensor.  Yes, that means some 100 mph gusts on the steps possibly over the weekend.  Nice timing…I’ll be keeping an eye on that.

Chief Meteorologist Mark Nelsen


Windy Coast

November 18, 2013

Peak gusts were stronger than I expected on the central coast, but lighter than I expected here in the metro area.  Here in town most speeds were between 20 and 30 mph…not exactly a storm.


Just showers the rest of the night as we wait for the cold front to come in from the northwest.  Behind this cold front is the cooler and much drier air that will give us some sunshine and dry weather…for quite awhile as mentioned in the previous post.

Chief Meteorologist Mark Nelsen

A “Classic” November Day Monday: Then Coldest So Far This Season

November 17, 2013

Tomorrow looks like a soaker, especially the second part of the day as a vigorous Pacific frontal system arrives.  Rain should pick up in the 2nd half of the day at the same time a surface low pressure center tracks from off the Oregon Coast to around Seattle.  That gives us gusty southerly wind the 2nd half of the day and through the evening.  Gusts should reach around 55 mph on the Coast and 30-40 mph here in the valleys.  Not a big wind or rain storm, but just enough of each to make for a miserable evening commute whether you are in a car or not.  Note the relatively light precipitation totals (no flooding) for the next 48 hours:


The bad news for skiers is that we’re going to see 1-2″ of mainly rain at all the ski resorts (snow above 6,000′ only) tomorrow afternoon through early Tuesday.   Not good.

This is the only rainy weather system we see for at least the next week!  What’s going on?  A ridge of high pressure in the atmosphere is going to take hold across the Pacific Northwest.   This one will be a bit different from the last in three ways.

1. Unusually dry air from the north comes in quickly behind the cold front Tuesday morning.  So the rain will just stop, and then we’ll see dewpoints plummet to the lowest values we’ve seen since last winter.  That’s the measure of moisture in the air.  Models are saying 15-25 degree dewpoints.   As a result, we’ll see lots of sun starting Wednesday.

2.  With the much drier air, fog should disappear in all areas west of the Cascades from Salem north through at least Friday-Saturday.

3.  Coolest airmass so far this year settles east of the Cascades, and now it’s inversion season so it won’t go anywhere.  Cool air will be spilling out of the Gorge.  Highs in the mid-upper 40s west of the Cascades with a dry airmass says 20-25 degree lows later in the week in the colder spots (Hillsboro, Orchards, Vernonia etc…).

The low temps I put on the 7 Day forecast this evening are meant to be representative of the entire metro area, not PDX where the wind will be blowing the 2nd half of the week.  In windy areas it’ll barely get below freezing:

7 Day


What won’t be different with this ridging?  That gorge wind will start blowing some on Wednesday, then really ramp up towards the weekend.  We’ve seen that this fall already.  Although this time we’ll get very warm temps aloft along with the cooler air below; a good setup for a very strong gorge wind event Thursday through ????.

As I mentioned on Friday’s post, looks like ridging is going to want to stick around.  Both the ECMWF and GFS are keeping things quiet weatherwise to at least the last few days of November.

Chief Meteorologist Mark Nelsen

Weekend Update: Friday Evening

November 15, 2013

Nice snowstorm in progress up in the Cascades this Friday evening.  Looks like Timberline has seen about 6″ so far.  Here’s our forecast:


The snow tapers off dramatically after midday tomorrow.

Down here in the lowlands, a pretty quiet weekend for weather weenies; just partly cloudy with a few showers Saturday and mostly cloudy with more widespread showers Sunday.

Bad news for skiers though as some of this snow is going to melt.  I expect snow levels back up around 6,000′ from late Monday through early Wednesday, then dry weather.  As a result, I don’t think we’ll see ski areas opening up next weekend, the 23rd-24th.  Of course that’s the weekend before Thanksgiving, which this year is the latest it can be (the 28th).

Let’s talk long range maps…I’ll highlight the similarities.

Big picture appears to be warm system Monday-Wednesday AM, then ridging/drier later next week through the weekend.  Note the 500mb height anomalies from the GEM (12z), ECMWF (12z), and GFS (00z) all line up similarly for Sunday the 24th


…possibly another warm and wet system (bad for skiing) for next weekend.  These maps are 8-9 days out.

Then Thanksgiving week, wide variability again, but at day 15-16, all three models develop ridging nearby once again, although it’s quite weak on the ECMWF:


These solutions would imply November will remain mild and it’ll be tough to get ski areas open for Thanksgiving.  However, we’ve seen huge swings in that Thanksgiving Week outlook the past few days.  So this is definitely not a sure thing.

Here are the two latest ensemble charts from 00z GFS and 12z ECMWF:

tseries_850t_000-360_Portland tseries_850t_000-384_Portland

The ECMWF sure has it chilly mid-late next week after the cold front slides through Tuesday night or Wednesday AM.  In these charts you can also see the warmer atmosphere next weekend.

The brand new 00z ECMWF coming in right now is almost the same as the 12z.  Strong and chilly offshore flow next Thursday behind the cold front:


And stronger ridging next Saturday:


Chief Meteorologist Mark Nelsen

Episode 34: Winter Forecasts, Super Typhoon Haiyan, & Mars One Update

November 15, 2013

Fresh NW Weather Podcast just posted!

And here is what actually occurred on the Ed Forman show that we referenced in the podcast:

Northwest Weather Podcast

Portland Snowfall

Episode 34: Winter Forecasts, Super Typhoon Haiyan, & Mars One Update

This week, Brian, Mark and Joe break down this year’s Winter Weather Conference and give their thoughts on Northwest snow.  They’ll also take a look at Typhoon Haiyan, one of the most powerful storms ever to hit land.

Typhoon Haiyan

The guys will also answer your weather questions and enjoy a rousing game of Cities of the Week!  Can you guess the city before they do?

As always, thanks for listening!  Our appearance on the Ed Forman Show was an absolute blast.  Pics and video will be up soon.

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Fog Tonight, Then A Bunch of Mtn. Snow

November 13, 2013

Some real dense fog in spots around the metro area tonight, be careful driving!  At least temps are way above freezing so we don’t have to worry about freezing fog tonight.

Looking ahead, a Winter Storm Watch has been issued for the cold and wet system Friday:

MarkWarnings_Winter Wx Advisory

It’s for the Blue Mountains, which are oriented SW to NE.  With a system coming in from from the north/northwest, that’s great lifting as it runs into the mountains.  There will be plenty of snow in the Cascades too.  Right now I’m thinking 10-15″ in the Cascades from noon Friday to noon Saturday (or maybe ending a little later):


Models have backed off on the offshore flow for late weekend and early next week as real cold air to our northeast won’t be quite as close as models showed just 24 hours ago.  So no changes in the forecast; cool showers tomorrow afternoon, some steady and cold rain Friday (highs only 45-47!), then drying out Saturday and Sunday.

One change in models the last 24 hours is a quicker return of moist westerly flow next week.  The latest 00z ECMWF, which has totally gone nuts with a very wet week ahead, shows rain already returning to our area by Monday!  Forget about any crisp/cool weather…here are the 1-10 day rain forecast graphics from tonight’s Canadian and ECMWF:



Here’s the latest 00z GFS ensemble chart, after this weekend some pretty wide variability eh?


Chief Meteorologist Mark Nelsen