Strong East Wind & Sunshine Ahead

November 25, 2012

The next two days will feature a mix of SUN & WIND for the Portland/Vancouver Metro area.   Our first real chilly and strong gorge east wind of the season is here and will continue through Wednesday.  Just the beginning of lots of cold winter wind!

Then it’s back to lots of gray and rainy weather systems moving in off the Pacific Ocean as we enter a new storm cycle.

An upper level ridge is moving overhead during these next two days.  At the same time surface high pressure is building to our east rapidly this evening.  Pressures are rising over the lower elevations of Eastern Oregon and Washington and falling west of the Cascades (slowly) this evening.  As a result an easterly pressure gradient is growing quickly, already approaching 6 millibars at 9pm from Troutdale to The Dalles.  This is well ahead of even the mesoscale model forecasts of a 6-8 mb gradient during the daytime tomorrow.  It’s a nice “cold pool” developing in the Columbia Basin, the first one of the winter season.  What does this mean?  Wind gusts have already reached about 45 mph at Corbett and they’ll easily touch 60 tomorrow and/or Tuesday out in the western Gorge.   Probably gusts around 35-40 mph in Troutdale and 25-35 mph anywhere east of I-205 near and south of the Columbia River.  This is strictly a gap wind event, not a downsloping wind, the amount of wind you get will be directly related to how close you are to the west end of the Gorge.  So most of Clark County will see mainly calm conditions (away from the Columbia).  Same with anywhere south of Tigard/Oregon City or west of Beaverton.  Wind does tend to whistle over the top of the West Hills and come down the west slope there.  Places like Bonney Slopes, Providence St. Vincent and Sylvan get real windy in this pattern.

As several deep low pressure areas approach the coastline late Tuesday and into Wednesday, the pressure falls west of the Cascades will keep the wind going.  We also get a much warmer airmass OVERHEAD tomorrow and Tuesday.  This means a sharp inversion.  East wind events in the Gorge are helped out by a sharp inversion.  In fact the strongest east wind episode of the past 10 years at the west end of the Gorge was with 850mb temps up around +15 in early January 2010, yet high temps were only in the upper 40s in the metro area.    This doesn’t look anywhere near as strong, but still, a lot of raging east wind in the Columbia River Gorge and east metro area the next 3 days.  And it won’t totally go away until next weekend.

Important Note:  The Vista House wind sensor has been offline for about 6 weeks; there was flooding or some sort of water issue in the basement where the sensor/computer are kept and they haven’t gotten it all cleaned up.  Sensor is fine, but office space is not.  It is also illegal to walk down to Vista House for one more month due to a road closure at Larch Mtn. Road.  The next strongest windspeed is at the Corbett Grade School here:  http://www.cascadeaccess.com/~mnelsen/screenID005.gif

For the areas NOT in the east wind zone, we’ll get patchy areas of dense fog overnight along with some freezing temps.  Even though the airmass will be too dry for fog just a few hundred feet up with the dry wind moving in, there should be enough moisture for that fog.

Chief Meteorologist Mark Nelsen 


Happy Thanksgiving

November 21, 2012

After a wild start ot the week, much calmer the next few days…good news since I won’t be back at work until Saturday.

Tomorrow is a dry day between Pacific systems, then a cold front sits almost directly over us for about 24 hours from Friday to Saturday morning.  Models are a bit wetter with this too; showing an inch or more rainfall over the western valleys…nice, just what we need.  This won’t be enough to bring flooding back though after 3 days of light or no rain between the new system and Monday’s.

Translation = Rainy all day Friday and a good chunk of Saturday too.

Bad news too for ski areas, the snow level will be at least up at 7,000′ or even higher on Friday and possibly into early Saturday…so ski Thursday or Saturday PM.

Happy Thanksgiving!

Chief Meteorologist Mark Nelsen


Travel Forecast: Not Bad For Thanksgiving

November 20, 2012

If you’re headed out on the road between Wednesday and Sunday, it doesn’t look too bad.  Just watch out in the Cascades, mainly Wednesday morning, evening, and again briefly Thursday morning.

In the short term, a burst of wind and rain coming up around midnight-3am in the metro area as another small system quickly scoots on through.  A surface low pressure area is offshore and headed to about Olympia by 2am.  We get the south wind after it passes by.  Peak gusts likely the next 3 hours around 50 mph on the Coast and 30-40 mph here in the Valleys.  Likely real up/down gusty wind too since we’ve got heavy showers coming through at the same time.

At 10:15pm lots of lightning just moving onshore between Florence and Lincoln City. 

Radar coverage is just about the worst of the entire USA coastline in this area (especially bad now since NOAA is headquartered in Newport), so the radar returns don’t look very impressive.

Chief Meteorologist Mark Nelsen


Peak Metro Gusts

November 19, 2012

I sure expected strongest wind to be on the west side of the metro area last night and today, but the disparity between the two sides of town was more than I expected.  This storm in the north Willamette Valley seemed to be a weaker version of the December 2007 big storm.  Heaviest rain and wind on the west and northwest parts of the metro area.  And less than expected wind on the east side with just occasional strong gusts surfacing out there.  In fact the Nehalem river at Vernonia had it’s highest crest since the 2007 storm this evening; luckily about 5.5′ lower this time around.

Here are the peak gusts, from official NWS sites and some MADIS sites too.  For the first time someone has a home weather station online up on Bald Peak, about halfway down it’s length from west to east, at 1300′.  It recorded a gust to 60 mph.  The NWS put that down as Newberg, but I’m pretty confident it didn’t gust to 60 IN Newberg!

Chief Meteorologist Mark Nelsen


Wind & Rain Storm Over At Coast; Still Pouring Inland

November 19, 2012

2:00pm update…

Windstorm and Rainstorm has ended (mostly) at the Oregon Coast
Most locations are seeing gusts 30-50 mph (breezy) instead of 70-100 mph just 3 hours ago since the cold front has moved onshore.  The back edge of the solid and heavy rain is moving through the Coast range, so it’s just light showers from here on out at the coast.

Strongest Wind is Likely Finished In Metro Area
Peak gusts seemed to be right around noon at Hillsboro (48mph) and here at the station in Beaverton (43 mph), since then it has back off a bit.  The entire central/eastside of the metro area didn’t even have strong wind, just gusts 25-40 mph briefly this morning.  It might get a bit stronger over there between now and 4pm.

Heavy Rain for 1-2 more hours in Metro Area
After that it’ll just be light showers the rest of the afternoon/evening.

FLOODING IN WESTERN OREGON

Right now, 2 rivers are at/above flood stage…Nehalem and Wilson rivers near Nehalem and Tillamook.  Also, the Nehalem river at Vernonia is above flood stage.

These are the only 2 rivers in western Oregon forecast to rise to/above flood stage right now.

You can see from the map below why we aren’t seeing huge flooding issues inland except on the westside in Washington & Columbia counties, the rain has been much lighter central/east valley:

Chief Meteorologist Mark Nelsen


Peak of Storm Hitting Now at Coast; Heading Inland Next 6 Hours

November 19, 2012

9:30am…

The height of the storm appears to be hitting in the 9am hour on the North Oregon Coast as the expected 2nd wave of wind is here.  

Peak gusts in the past hour, all the strongest so far:

Astoria Airport:  67
Rockaway: 70
Lincoln City: 85
Megler Hill (1,000′):  100
Naselle Ridge (2,000′): 106

The next 2 hours will be the height of the storm on the coast, then it’ll die down dramatically after 11am as the cold front sags south.  It’ll be totally over (windwise) by 4pm everywhere north of Florence.

Here are the other storm highlights so far:

  • Strong wind in the valleys has been almost totally confined to only the west of I-5 in the Woodburn-Clark County section.  Peak gusts 40-50 mph at McMinnville, Forest Grove, and other areas westside.  It’s a no-show (so far) westside, just 20-30 mph.
  • As the front approaches even those areas should see increasingly strong wind through late afternoon, then it’ll back off dramatically during the evening rush hour.  Gusts 35-50mph are possible anywhere until that time.
  • Rainfall has been concentrated mostly west of I-5 from Portland south too.  But as the front sags south the next 8 hours, so will the heavy rain
  • Heaviest rain in the metro area and Salem will be midday through afternoon, then back off quickly after the evening commute.
  • Ski areas have been saved by the slow movement of the front, hardly ANYTHING has fallen up there so far.  Rain will arrive in the afternoon, but then change to snow after 7pm.  Just 6 hours of heavy rain won’t ruin the snowpack too badly.  The snowpack won’t wash away!
  • The storm will be over this evening for most of us as the heavy rain shifts south and the wind calms down
  • More rain/wind Tuesday and Wednesday, but just the usual gusty wind and less than 1″ more rain.
  • Thanksgiving looks pretty decent, partly cloudy and probably dry

Chief Meteorologist Mark Nelsen


Sunday Morning: Stormy 36 Hours Ahead!

November 18, 2012

8:30am Sunday…

Everything still appears to be on track for a VERY wet 3 days ahead…and maybe more.  Here are the highlights for those not interested in too much detail

  • Rain picks up the rest of the day, and turns heavy at times through Monday afternoon in the core of our viewing area west of the Cascades (Longview-Salem and Long Beach to Newport)
  • Flooding appears most likely on the North Coast rivers, but as always, it totally depends on exactly where the heaviest rain sets up
  • Since rivers are starting pretty low, we’ll PROBABLY avoid a major, widespread flood, just barely…
  • Strong wind arrives at the coast this afternoon/evening and continues through the morning Monday before relaxing quite a bit
  • Peak gusts 80+ mph likely out there, a pretty good windstorm even by “storm season” standards
  • Peak gusts 40-50 mph here in the Valley late tonight through midday Monday, could be strongest on the west side of the Valley, we’ll see.  Strong enough for some power outages and a few trees down.  This isn’t a significant windstorm here in the Valley, but enough to get everyone’s attention!
  • Cascades pick up more snow through this evening, but then all rain for about 24 hours following should erase just about all of the 10-15″ that will have fallen by then.

RAINFALL

Take a look at the 72 hour rain forecast from now through Wednesday morning off our RPM model:

Right around 10″ in the wettest parts of the Coast and Cascade Ranges from SW Washington down through SW Oregon.  The other local mesoscale model, the WRF-GFS, is similar.   Here is it’s 24 hour forecast from 4pm this afternoon to 4pm tomorrow afternoon…A solid 2-4″ in the Valleys with 5″+ up in the Cascades!

The heavy rain will be covering a large geographic area, heaviest the next 24 hours in SW Washington, then heaviest the following 24 hours south of a Newport to Salem line as the “firehose” of moisture slips a bit farther south.   Once the whole front shifts farther south later Monday, we’ll see the rain taper off quite a bit, but still very wet through Wednesday.

WIND

Looks quite impressive for a big storm at the Coast.  Models sure don’t handle little low pressure areas tracking along the front very well, so it’s safer to just say that the entire wind field overhead is very strong from this evening through midday tomorrow when the front shifts farther south.  I’ve been surprised at how strong the wind is just above the surface late tonight and tomorrow morning on the models; 70kts at 850mb over the North Willamette Valley.  The orientation of the isobars is definitely not the best if you’re looking for a big windstorm, and that orientation seems to often lead to strongest southerly winds on the WEST side of the Valley closer to the Coast Range.  In the December 2007 event (much strong than this one!) the wind blew strongest over in the west metro.  Regardless, the Monday morning commute looks particularly nasty with rain blowing sideways.  Once the front shifts south of us in the late afternoon, the wind should calm suddenly.  The new 12z WRF-GFS is a bit faster pushing the strong wind south of us soon after 10am.

CASCADE SNOW

8-10″ fell up at Timberline and Meadows since yesterday afternoon, and about that much could fall again before it rises above freezing up there this evening.  From late this evening to Monday evening, 4-6″ of rain will fall in those spots!  Yuck, but hey, it’ll make for a real nice hard base won’t it?  Then it’s on to a bit more snow Tuesday and maybe Wednesday.  If so, maybe a Friday opening???  Maybe.  I see Timberline has the Pucci running today, and little Bruno too.  Gotta love their attitude!

By the way, during stormy weather, when we’re not on TV, we post updates here of course.  And we’re on Facebook (with more frequent updates) as “fox12weather”.  Same on Twitter.

Chief Meteorologist Mark Nelsen