Snow For Some Sunday AM

December 26, 2015

11pm Saturday…

A cold front moves into Western Oregon and Washington tomorrow morning.  At the same time we have a cool airmass overhead, along with colder and dry air pouring out of the Columbia River Gorge.  The combination of these means we have a marginally good potential for snow to the lowest elevations again.  ANYONE IN THE LOWEST ELEVATIONS MAY SEE SNOW FALLING, BUT ONLY SOME AREAS WILL GET SNOW STICKING ON THE GROUND.

Similar to Christmas Eve morning, pinpointing the locations where we see snow to the valley floor is tough.  Unlike Christmas Eve, everyone will get steady precipitation west of the Cascades by 10am.  So instead it’s all about temperatures then for your Sunday morning snow/rain forecast.  Here’s the forecast graphic I used at 10pm:

MarkSnow_PDX_2Elevations

I say west metro for the lowest sticking snow because there are strong hints based on the easterly flow and models that cold air will be deepest as it banks up right along the east side of the Coast Range and Tualatin Mtns.  This is similar to the “Forest Grove Effect”, but kind of a weak version of what we’ve seen in the past.  The 00z WRF-GFS and our RPM have a similar look.  Tomorrow morning would be a good time to be in Vernonia, Buxton, Banks, or Forest Grove.  Possibly St. Helens & Scappoose too.  Also I think a dusting to 1″ is possible anywhere higher up in the West Hills.

Your next question is…”what if I live at 600′“?  Then you’ll likely see conditions between those two text panels.  No matter what someone tells you, we can’t forecast snow level with that much detail.  I’ve seen snow level forecasts for 250′, 750′ etc… in the past.  That drives me nuts.  Precipitation intensity and location will affect snow level far more than elevation in most cases.  For example at 1,000′ I had no snow Christmas Eve morning, yet people near sea level around Woodland/La Center had snow because heavier showers were falling in those locations.

For those of you travelling through the Coast Range tomorrow, I’d delay until the afternoon hours when the snow backs off.  Roads should be better at that time.

For the Cascades and Gorge, the issue is that a lot of the moisture won’t even make it that far.  As a result I said just 1-2” in the Gorge and it’ll probably be mainly wet on I-84 through the entire day.  A few more inches in the Cascades won’t make any different on the snow-packed roads either.

Chief Meteorologist Mark Nelsen


Flurries/Showers This Evening

December 26, 2015

7:45pm Saturday…

Merry Christmas!  Sorry a little late, but hey, it’s only the 2nd day of Christmas; I’ve got 10 more days in which I can say that.

I’m working this evening and I’ll put together a blog post about this upcoming week after 00z models are in.

But, I notice a band of precipitation which no models seem to have accounted for is crossing the Coast Range.  It’s REALLY light stuff, but taking a look at the 4pm Salem balloon sounding:

Sounding

It’s pretty obvious the atmosphere is cold enough for snowflakes to survive down into the lowlands.  Temperatures are a degree or two above freezing up around 2,000′, but it’s dry air and precip falling into that dry air will evaporate, cooling the atmosphere.  That’s what we call Evaporational Cooling or, as slang, Wetbulbing.  The highlighted column is what the temperature will be if the airmass “wetbulbs”.  Note below freezing all the way down almost to the surface.

So IF the precipitation survives the drier low levels and IF the band doesn’t fall apart entering the valley?  Then you may see snow or snow/rain mixed in the next couple of hours in the metro area.  It’s cold enough so that IF the precip holds together a dusting could accumulate at the top of the West Hills, Mt. Scott, Western Gorge etc…

A lot of IFs, but you get the idea.

Chief Meteorologist Mark Nelsen


Snow In The Hills

December 23, 2015

8am Wednesday…

Lots of heavy showers moving through this morning.  I woke up to about 1/4″ snow here at 1,000′ and it’s been going back and forth between sticking and then melting in lighter showers.  A friend up the road has 3″ at 1,800′.  We never saw this pattern last winter and rarely saw it the winter before; cold showers streaming inland.  It’s like the good ‘ol days have returned.  At least for now.  Check out the Troutdale radar estimate of snow level this morning…right around 1,500’.  I think it’s a temporary radar installed for a big Columbia River Gorge and Basin wind power research project.

Capture

The same cold/showery pattern continues through Thursday afternoon, then we pretty much dry out through at least the first part of Sunday.  Looks to me that snow levels will be SLIGHTLY lower for Thursday morning, so probably a more widespread dusting down to 1,000.  BUT I DON’T SEE IT LOW ENOUGH TO AFFECT TRAVEL IN THE METRO AREA.  IT’S MAINLY A “CONVERSATIONAL SNOW”.  That means it looks nice with green trees all frosted and you chat with friends about it, but you can still go about your daily lives.

Looks like a dramatic pattern change to splitty/much drier after Christmas Eve.  That may (or may not) be the usual slowdown in weather we see in El Nino years.

The main message for skiers is…get the good powder now because this COULD be the best snow of the season!

I’m still on vacation through Christmas Day, but you know that “relaxing” for me is looking at weather maps, eating, sleeping etc…

Chief Meteorologist Mark Nelsen


Storm Wrap Up

December 21, 2015

7pm Monday…

The storm was quite powerful for some, but underwhelmed for others.  Lots of gusts 45-55 mph on local airport official observations, so a bit higher than I forecast, but very few spots were above 55 mph in the lowlands.  Seems to me the “Lower Columbia” area from Vancouver to Longview was slammed hardest, along with Clark County. I’m really glad we didn’t say (at FOX12) 60-70 mph gusts; that would have been a huge windstorm that we haven’t seen in quite a long time.

PDX officially hit 55mph, which makes it a bit weaker than the March storm this year (58 mph).  That storm put 70,000 PGE customers in the dark. This time PGE outages were only a bit above normal for a typical winter windstorm.  Around 35,000 at the peak. Of course in YOUR neighborhood the storm maybe have been stronger than what we saw last March.  That’s how it goes with storms.

I notice the Longview/Kelso damage was from a WEST wind, not a southerly wind.  Something we might expect with a low moving quickly west to east.

Chief Meteorologist Mark Nelsen

Peak Gusts from the NWS…sorry about the coding gaps, I might clean that up when I get home:

PUBLIC INFORMATION STATEMENT

 
 NOUS46 KPQR 220006
 PNSPQR
 ORZ001>008-010>016-WAZ019>022-039-040-045-046-221204-
 
 PUBLIC INFORMATION STATEMENT
 NATIONAL WEATHER SERVICE PORTLAND OR
 404 PM PST MON DEC 21 2015
 
 
 ...WIND REPORTS PAST 12 HOURS ...
 
 LOCATION                       SPEED     TIME/DATE       ELEVATION            
 
 ...CASCADES IN LANE COUNTY...
 SUGARLOAF                    66 MPH    0706 AM 12/21   4328 FT       EMIGRANT                     44 MPH    1253 PM 12/21   3840 FT              
 
 ...CENTRAL COAST RANGE OF WESTERN OREGON...
 MARYS PEAK                   82 MPH    0900 AM 12/21   4137 FT              
 
 ...CENTRAL COLUMBIA RIVER GORGE...
 2 WNW COOK                   85 MPH    0225 PM 12/21   2990 FT              
 2 WSW UNDERWOOD              49 MPH    0323 PM 12/21   569 FT               
 1 S HOOD RIVER               48 MPH    0300 PM 12/21   570 FT               
 1 W UNDERWOOD                48 MPH    0238 PM 12/21   25 FT                
 
 ...CENTRAL OREGON COAST...
 1 N LINCOLN BEACH            67 MPH    0940 AM 12/21   49 FT                
 1 S OTTER ROCK               61 MPH    1105 AM 12/21   141 FT               
 YACHATS                      60 MPH    0613 AM 12/21   32 FT                
 1 SSE HECETA BEACH           59 MPH    0645 AM 12/21   25 FT                
 LINCOLN CITY                 57 MPH    0956 AM 12/21   187 FT               
 1 N NEWPORT                  55 MPH    1010 AM 12/21   165 FT               
 WALDPORT                     54 MPH    0914 AM 12/21   42 FT                
 NEWPORT MUNI AP              51 MPH    0655 AM 12/21   0 FT                 
 2 N LINCOLN CITY             50 MPH    1040 AM 12/21   88 FT                
 HECETA BEACH                 48 MPH    0752 AM 12/21   30 FT                
 2 NNE YACHATS                47 MPH    1051 AM 12/21   81 FT                
 2 N SEAL ROCK                46 MPH    1004 AM 12/21   65 FT                
 NEWPORT                      44 MPH    0656 AM 12/21   127 FT               
 YACHATS                      42 MPH    0719 AM 12/21   32 FT                
 DUNES                        41 MPH    0804 AM 12/21   120 FT               
 
 ...CENTRAL WILLAMETTE VALLEY...
 ROCKHOUSE 1                  67 MPH    1212 PM 12/21   1797 FT              
 3 WSW SCHOLLS                60 MPH    1143 AM 12/21   1348 FT              
 MC MINNVILLE MUNICIPAL AIRPO 54 MPH    1112 AM 12/21   0 FT                 
 SALEM AP (MCNARY FIELD)      52 MPH    0742 AM 12/21   205 FT               
 4 NNE COLTON                 48 MPH    1127 AM 12/21   1407 FT              
 AURORA STATE AIRPORT         45 MPH    0829 AM 12/21   0 FT                 
 SCOTTS MILLS                 41 MPH    1005 AM 12/21   518 FT               
 1 NE AMITY                   41 MPH    1139 AM 12/21   751 FT               
 
 ...COAST RANGE OF NORTHWEST OREGON...
 4 E HEBO                     73 MPH    1015 AM 12/21   3160 FT              
 TIDEWATER                    71 MPH    0114 PM 12/21   2035 FT              
 4 E HEBO                     69 MPH    1140 AM 12/21   3170 FT              
 
 ...GREATER PORTLAND METRO AREA...
 1 S RALEIGH HILLS            73 MPH    1255 PM 12/21   236 FT               
 1 NNW TROUTDALE              59 MPH    1205 PM 12/21   120 FT               
 1 ENE HAPPY VALLEY           56 MPH    0120 PM 12/21   610 FT               
 1 NW FOREST GROVE            55 MPH    1245 PM 12/21   200 FT               
 PORTLAND INTERNATIONAL AIRPO 55 MPH    0151 PM 12/21   21 FT                
 SCAPPOOSE INDUSTRIAL AIRPARK 54 MPH    1135 AM 12/21   0 FT                 
 PORTLAND-TROUTDALE AIRPORT   52 MPH    1211 PM 12/21   35 FT                
 HAPPY VALLEY                 50 MPH    1205 PM 12/21   1000 FT              
 2 W EAGLE CREEK              50 MPH    0107 PM 12/21   13 FT                
 WILLAMETTE RIVER NR OREGON C 50 MPH    1200 PM 12/21   49 FT                
 HILLSBORO AIRPORT ASOS & LAW 48 MPH    1245 PM 12/21   204 FT               
 1 SE TROUTDALE               46 MPH    1158 AM 12/21   203 FT               
 FOREST GROVE                 45 MPH    1255 PM 12/21   200 FT               
 2 SE THE OREGON ZOO          45 MPH    0131 PM 12/21   750 FT               
 TROUTDALE                    45 MPH    1215 PM 12/21   262 FT               
 2 SSE WILSONVILLE            44 MPH    1245 PM 12/21   141 FT               
 WILSHIRE PARK                44 MPH    0134 PM 12/21   255 FT               
 1 W BORING                   44 MPH    1209 PM 12/21   600 FT               
 SCAPPOOSE                    42 MPH    0153 PM 12/21   65 FT                
 OREGON CITY                  42 MPH    1200 PM 12/21   475 FT               
 
 ...GREATER VANCOUVER AREA...
 BATTLE GROUND                50 MPH    0133 PM 12/21   346 FT               
 2 SW RIDGEFIELD              47 MPH    1222 PM 12/21   25 FT                
 3 NW FELIDA                  45 MPH    1210 PM 12/21   114 FT               
 PEARSON FIELD AIRPORT        44 MPH    0103 PM 12/21   0 FT                 
 1 WNW BATTLE GROUND          43 MPH    0110 PM 12/21   278 FT               
 1 NE LACAMAS LAKE            41 MPH    1235 PM 12/21   387 FT               
 
 ...LOWER COLUMBIA...
 1 WSW SAINT HELENS           42 MPH    0145 PM 12/21   100 FT               
 
 ...LOWER COLUMBIA AND I - 5 CORRIDOR IN COWLITZ COUNTY...
 2 W LEXINGTON                46 MPH    0155 PM 12/21   921 FT               
 KELSO-LONGVIEW AIRPORT       46 MPH    0215 PM 12/21   0 FT                 
 
 ...NORTH OREGON COAST...
 2 E OCEANSIDE                87 MPH    1149 AM 12/21   1420 FT              
 2 WNW GARIBALDI              67 MPH    1200 PM 12/21   75 FT                
 MANZANITA                    61 MPH    1152 AM 12/21   42 FT                
 CANNON BEACH                 59 MPH    1218 PM 12/21   22 FT                
 TILLAMOOK AIRPORT            55 MPH    1215 PM 12/21   36 FT                
 ASTORIA AIRPORT              51 MPH    1239 PM 12/21   9 FT                 
 OCEANSIDE                    51 MPH    1242 PM 12/21   21 FT                
 BAY CITY                     50 MPH    1224 PM 12/21   104 FT               
 TILLAMOOK                    50 MPH    1240 PM 12/21   62 FT                
 PACIFIC CITY                 49 MPH    1038 AM 12/21   27 FT                
 ROCKAWAY BEACH               48 MPH    1229 PM 12/21   450 FT               
 CLATSOP SPIT                 47 MPH    1230 PM 12/21   29 FT                
 2 ENE ASTORIA                47 MPH    1242 PM 12/21   0 FT                 
 3 SW SANDLAKE                42 MPH    0917 AM 12/21   13 FT                
 TILLAMOOK                    41 MPH    0112 PM 12/21   11 FT                
 
 ...NORTHERN OREGON CASCADE FOOTHILLS...
 YELLOWSTONE MTN              51 MPH    1217 PM 12/21   3080 FT              
 MILL CITY                    49 MPH    0758 AM 12/21   1007 FT              
 EAGLE CREEK                  47 MPH    0213 PM 12/21   731 FT               
 2 SSE SHORTYS CORNER         42 MPH    0123 PM 12/21   1600 FT              
 
 ...NORTHERN OREGON CASCADES...
 MT HOOD MEADOWS              65 MPH    0300 PM 12/21   5370 FT              
 TIMBERLINE BASE              60 MPH    0300 PM 12/21   6000 FT              
 GOVERNMENT CAMP SKI BOWL     58 MPH    0300 PM 12/21   4000 FT              
 WANDERERS PEAK               57 MPH    0207 PM 12/21   4350 FT              
 2 NW WHITE RIVER SNOW PARK   44 MPH    0200 PM 12/21   5880 FT              
 2 SE MOUNT HOOD              41 MPH    1100 AM 12/21   6601 FT              
 
 ...OREGON...
 3 ENE WESTPORT               59 MPH    0114 PM 12/21   25 FT                
 NEWPORT                      56 MPH    1008 AM 12/21   120 FT               
 21 W YAQUINA HEAD            54 MPH    0450 AM 12/21   0 FT                 
 NEWPORT                      49 MPH    1000 AM 12/21   0 FT                 
 1 WSW SOUTH BEACH            47 MPH    0900 AM 12/21   29 FT                
 1 WNW ASTORIA                47 MPH    1247 PM 12/21   355 FT               
 
 ...SOUTH  WILLAMETTE VALLEY...
 EUGENE-MAHLON SWEET FIELD    43 MPH    1055 AM 12/21   353 FT               
 CORVALLIS                    41 MPH    1230 PM 12/21   229 FT               
 6 ESE CROW                   41 MPH    0613 AM 12/21   810 FT               
 2 S PHILOMATH                41 MPH    1107 AM 12/21   308 FT               
 CORVALLIS                    41 MPH    1145 AM 12/21   308 FT               
 
 ...SOUTH WASHINGTON CASCADES...
 6 NW NORTH BONNEVILLE        94 MPH    0300 PM 12/21   3450 FT              
 
 ...SOUTH WASHINGTON COAST...
 1 NW MEGLER                  64 MPH    1230 PM 12/21   1189 FT              
 3 NNE NASELLE                51 MPH    0645 AM 12/21   2008 FT              
 1 NW NAHCOTTA                44 MPH    1210 PM 12/21   42 FT                
 
 ...UPPER HOOD RIVER VALLEY...
 MIDDLE MTN                   48 MPH    0314 PM 12/21   2544 FT              
 2 NNW PARKDALE               41 MPH    0200 PM 12/21   1480 FT              
 
 ...WASHINGTON...
 21 W CAPE DISAPPOINTMENT     60 MPH    1150 AM 12/21   0 FT                 
 1 ENE CAPE DISAPPOINTMENT    59 MPH    1245 PM 12/21   120 FT               
 
 ...WESTERN COLUMBIA RIVER GORGE...
 STEVENSON                    62 MPH    0145 PM 12/21   25 FT                
 CAPE HORN                    57 MPH    1215 PM 12/21   1416 FT              
 1 SW ROOSTER ROCK STATE PARK 56 MPH    1146 AM 12/21   751 FT               
 1 NE BONNEVILLE DAM          52 MPH    0100 PM 12/21   79 FT                
 ROOSTER ROCK STATE PARK      51 MPH    0812 AM 12/21   50 FT                
 1 SW CASCADE LOCKS           44 MPH    0200 PM 12/21   110 FT               
 PRINDLE                      43 MPH    0200 PM 12/21   239 FT               
 LOCKS                        42 MPH    1108 AM 12/21   127 FT               
 1 E CORBETT                  41 MPH    1245 PM 12/21   839 FT               
 
 ...WILLAPA HILLS...
 ABERNATHY MTN                64 MPH    0301 PM 12/21   2000 FT              

 


Will There Be A Windstorm Monday?

December 20, 2015

8:15pm Sunday…

The short answer is…possibly.  If anything does happen, it’ll happen  between 11am-1pm.

Here’s what’s going on:

  • A deep area of low pressure will track almost straight west to east just to the north of us tomorrow.  From around Willapa Bay on the Washington coast late morning to around Pullman on the Idaho border by late afternoon.
  • Central pressure should be around 985 millibars, plus or minus 5 mb.
  • Theoretically there should be a strong rush of wind up the valley as the isobars align east/west at midday when the low passes by north of us.
  • It’s moving very quickly, so it’ll occur quickly and leave quickly.

You can see the WRF-GFS forecast for Noon:

slp.20.0000

One would think that this could produce 50-65 mph gusts in the northern Willamette Valley with this setup.  But there are some problems with that:

  1. We have very few situations in the past where the low pressure takes this west-east path, so not many past examples to learn from.
  2. Last time we saw a track like this we were totally “burned” overforecasting windspeeds…December 17, 2012  That low was even deeper, but farther north.
  3. There are other examples where the same track has given us wind gusts to 60 mph.  Early January 1990 is one good example.
  4. Almost all models are producing very weak wind fields in the very lowest part of the atmosphere (where we live).  Interesting don’t you think?  Are they all wrong, or are human forecasters going to lose on this one again like in 2012?  Our RPM would say gusts only 30-40 mph…just windy for a few hours like we’ve seen 15 times this month already!
  5. This is likely due to the low level southerly pressure gradient being southerly like in a typical windstorm, but all wind from just a few thousand feet on up is straight westerly at that time.  The two don’t line up like last winter’s 3 windstorms where the surface low travelled almost south to north.  We won’t see strong wind from above mixing down.

You can see the sounding from the WRF-GFS for 1pm…notice all westerly except right at the surface?

kpdx.21.0000.snd

Now I am still on vacation…and I hopefully don’t have have VACATION-BIAS* (see below) right now, but…

THIS IS WHAT I WOULD FORECAST

PORTLAND METRO & WILLAMETTE VALLEY:  Southerly wind 20-30 mph with gusts 40-50 mph between 11am-1pm.  Then dying off.  Similar to what we saw about 10 days ago.  Plenty of power outages, but not a huge wind storm.  I know this is way below the NWS forecast of 65 mph gusts, we’ll see how that works out.  For betting purposes…I bet no higher than a 46 mph gust at PDX.

COLUMBIA RIVER GORGE:  This is a spot that just about has a guarantee of seeing some high winds…not sure why there isn’t a high wind warning out from Multnomah Falls to Carson area.  SW wind 30-40 with gusts 60-70 mph suddenly arrive around Noon-1pm.  It’s a similar event to the damaging wind about a month ago.  Wind gusts 50-60 mph possible from Hood River all the way out to Arlington/Hermiston.  This could be a big windstorm all across North Central Oregon too.

Alright…we’ll see what happens now.

Chief Meteorologist Mark Nelsen

* VACATION-BIAS DEFINITION:  When forecaster hopes that nothing exciting happens when on vacation in a warm place so he/she doesn’t miss it.  Thus he/she forecasts less exciting weather than he/she would otherwise.


Christmas Vacation

December 17, 2015

11pm Thursday…

It’s just about Christmas time and I’m on vacation now through Christmas Day.  I’ll be out of town through Tuesday the 22nd too.


Thursday Morning Update

December 17, 2015

7:23 am…

Whew…that was a close one in the western Gorge; but I’m glad I backed off at the very last minute before my 10pm broadcast last night.

There appears to be some freezing rain at/above 1,000′ in Cape Horn/Corbett areas, but below that too warm.  Vista House has seen wind gusts to 70 mph with moderate rain and temperature bottoming out at 32 degrees.  Must not be freezing on anemometer because it’s still working.   Same thing at Corbett except it has bottomed out around 34-35 instead.  Higher up at Biddle Butte (1400′) the anemometer has frozen so you folks will get a lot of ice the next 12 hours.  Maybe a solid inch.  Whatever your temperature is at your location in the Gorge right now, it will not fall any lower today.  We’re done with the evaporational cooling.

Farther into the Gorge the sticking snow level DID drop to river level in the deeper cold air; it appears to be snowing heavily at Hood River too.  Note lots of snow on Cascade Locks and Hood River ODOT cams:

 

Enjoy the snow out there!

The Cascades are just getting DUMPED on right now as precipitation intensifies ahead of the warm front.  8-10″ new already at Timberline and Meadows.  That snow will change to mainly rain by mid-morning as snow levels rise.

By the way, as the last wave along our wet front passes by late this evening we can expect a surge of southerly wind.  Gusts 35-45 mph are likely in the Willamette Valley for at least a couple hours…probably centered around 10pm-midnight.

Chief Meteorologist Mark Nelsen