Search / 57 results found

from
to
  • Updated

Friday, July 30th, 3:50 P.M. 

Happy Friday!

Clouds and a smoky haze kept today a bit cooler than expected, but it was still very warm with highs making it into the mid 90s around the metro area. We are seeing some showers on the radar, but most of the rain is very light and evaporating before it hits the ground. A chance of thunderstorms or light showers will linger tonight, especially over the Cascades.

Saturday brings more high clouds and a smoky haze above with highs in the low 90s. Expect that smoke to stick around on Sunday, but it should have little to no impact on our air quality.

After a couple more 90 degree days on Monday and Tuesday, things cool off midweek. Thursday and Friday bring our first decent chance of showers in over a month and a half!

  • Posted

Today was another fantastic early spring day. Other than patchy morning clouds, we saw sunny skies and warmer temps across much of the region. In fact the 61 degree high today in Portland was the warmest so far this season.

Tomorrow and Saturday should be similar, with Saturday likely the warmest day due to a warming airmass. Then a cold front moves inland Sunday midday, bringing a much cooler and wet day. So clearly SATURDAY IS THE "OUTDOOR" DAY THIS WEEKEND.

If we get up to around 64-65, that sure wouldn't be a record, those are around 70 or so this time of year. How warm do we get in March? Most years we get into the upper 60s or lower 70s at least once by the end of the month.

March has been drier than average...

Temperatures have been near normal across the state, a little cool west and warm east.

The temps we have been seeing are about as normal as it gets for the first 1/3 of the month. The green on the chart below is typical temperature range (highs & lows). Red is record high for each day and blue shows record lows.

What a strange "La Niña winter" this has been. Except for 2-3 weeks in mid-late February, the entire cold season has been quite mild. We're clearly out of winter weather now...EXCEPT for the cold showers behind Sunday's system. Snow levels could dip down to around 1,000' late Sunday night and Monday morning...maybe. 850mb temps dip down to around -7 to -8, although models don't show much precipitation. WRF-GFS snowfall forecast has a few inches in the Cascades, but none for the lowlands:

Next week we'll see a mix of dry and wet; not really a long & drawn out cool/wet pattern. Looks like decent March weather to me!

We just recorded a fun FOX12WEATHER podcast this afternoon. By "we" I mean me plus the other 3 meteorologists here: Anne Campolongo, Jeff Forgeron, & Brian MacMillan. It's full of informative and interesting weather tidbits, plus we answered some of your questions. And my coworkers say I'm being a bit "too controlling" with the forecast. Hmmm...

You can find it in Apple Podcasts or listen straight off the web at this link: https://www.kptv.com/podcasts/weather/

Enjoy the weekend; I'll be back at work Sunday afternoon...

Chief Meteorologist Mark Nelsen

There's a dearth of Black players on the LPGA Tour. This woman wants that to change

  • Posted

At the age of 36 Althea Gibson made history after becoming the first African American golfer to earn status on the LPGA Tour. She was also kno…

  • Posted

Noon Wednesday

I've heard the grocery stores are getting crazy now? Folks...this is a 2 day event at most for the vast majority of us west of the Cascades. You aren't going to be locked in your homes for a week... Although it's a different story in the Gorge. Read on...

KEY POINTS

Temperatures should remain above freezing tomorrow until after sunset west of the Cascades. Roads will most likely be just fine until sometime after dark. But since we don't know EXACTLY when it'll freeze in your neighborhood, MAKE PLANS ASSUMING ROADS COULD BE FROZEN AFTER 5PM. Either turning icy from freezing rain or snowy (especially north/east metro)

All of the metro area freezes tomorrow night. We should wake up to pockets of glaze (south metro) on roads Friday morning or snowy roads (all other parts of town). Enough for sledding central/north metro.

Expect a Trace (south metro) to 3" snow out of the "first wave" ending Friday morning

Roads remain partially frozen during the daytime Friday as temperatures remain at/below freezing.

An additional 3-8" snow could fall later Friday through Saturday morning with a "second wave" of precipitation. Heaviest will be north and east metro. From Newberg to Wilsonville to Molalla to Sandy there may be no snow, just pockets of freezing rain

This may be it for snow in the metro area, giving us a storm total of a Trace to 12" in the metro! Very little snow south, but Scappoose, Longview, Clark County, & East Portland get a lot.

The 3rd wave (Sunday) should be mainly freezing rain Saturday evening through Sunday morning and only near Columbia River in central/east Portland. This is the usual freezing rain area during typical wintertime events. You aren't getting out of this until Monday morning if you live around Camas, Troutdale, & Gresham.

Expect some thawing Saturday afternoon south/west metro, much better roads. Then substantially more thawing on roads everywhere except near Columbia River and Gorge Sunday.

For the majority of the metro area, most of the "action" (falling snow & freezing rain) will be done by Saturday afternoon.

TECHNICAL DETAILS

I know I've always been a bit biased with regard to the ECMWF model, but it has been leading the way for days with this event. It's been best tracking systems farther north than other models Thursday through Sunday and that continues this morning. It has been much more reasonable not only with upper-level temps but low-level cold air too. Remember just 2-3 days ago when it was alone NOT forecasting a major wave of cold arctic air?

Luckily the WRF-GFS, typically a stellar performer, and morning 12z run of Euro, are now in pretty good agreement. An arctic boundary (stationary front) will be sitting across extreme NW Oregon from tomorrow evening through at least midday Saturday as several waves of moisture move overhead. Precipitation type (rain, snow, ice pellets, freezing rain) in any one location will be dependent on how thick that cold layer is over your part of the region. Generally the farther north you go, you're deeper into the cold air = more snow. Farther south, very thin layer below freezing means you get freezing rain. Of course if that thin cold layer is only down to 33-35 degrees, you get normal liquid rain. Unfortunately 2.5 million people live in the metro area directly under that thin dome of cold air pouring out of the Gorge these next three days.

BTW, The only difference between freezing rain and regular rain is that the temperature is below freezing in the first case and that liquid freezes on contact.

The first surface low moves toward the central Oregon coastline tomorrow morning, pulling cold air out of the Gorge. It's going to take until after dark for most of us in the metro area to drop to freezing, so I'd be surprised if roads freeze up before the evening commute is finished. Here's the progression of things based on the WRF-GFS model. Euro is similar...

By 7am Friday morning the low has dissipated, cozying up to the central Oregon coastline. East wind is raging through the Gorge and cold air is everywhere north of Salem and Tillamook

Precipitation is turning showery Friday am & midday. Snow total through this time from WRF seems reasonable. Although precip seems a little light up in Clark County

By late Friday the "second wave" is approaching, a bit farther north

And by Saturday morning we've seen a ton of precipitation, but with the low farther north a warming southerly wind has arrived on the coastline and (overhead) in the central Willamette Valley

That's why I don't expect snow out of the 2nd wave south of metro area. This system knocks down the cold surface high quite a bit as well. By Saturday 4pm it looks like this...cold air is just barely hanging on in the metro area.

By this point, the ECMWF snow forecast looks good...this is total snow all the way through 7pm Saturday. A lot of snow on the ground from north Portland into Clark, Columbia, Cowlitz counties. And the Gorge has been buried by 12-24" at this point. Maybe more

WRF-GFS has slightly different placement, but the same general idea... very little snow on the coast out of this event (some up north), and from Salem south.

We may get a significant ice storm southwest and south metro down into the western part of the Willamette Valley. We will see, but these numbers are likely far too heavy.

Now check out 1pm Sunday...here comes the "third wave" with a low farther north. One last pull of cold air through the Gorge Sunday morning/midday. It's unlikely anywhere west of the West Hills or south of Lake Oswego to Clackamas would get freezing rain out of this. It's really becoming a "gorge-centric" event by this time. Lots of freezing rain later Sunday in and near western Gorge.

Why will this event end so quickly? Because it's not a case where a surface low is swinging by offshore. This time it just plows right across southern Canada since the upper-level pattern is becoming very progressive. A relatively strong and "warm" west wind is blowing in the Gorge Monday. #RIP_FEB2021_SNOWSTORM

So that's the plan for now. 3 more important notes:

  • We will have specific forecasts for the Coastline, Valley, Longview/Kelso, The Gorge & Cascades all through our evening shows. We are on FOX12 for an hour at 4pm, 5pm, 6pm, 10pm, & a half hour at 11pm. Also two hours on FOX12PLUS 8pm & 9pm. Find me and the weather team there!
  • We will be recording a FOX12WEATHER podcast with all four meteorologists early this afternoon and it should drop into your Apple Podcasts this evening
  • Make sure you are following me on Facebook at @MARKNELSENWEATHER and Twitter @MARKNELSENKPTV

Chief Meteorologist Mark Nelsen

  • Posted

11am Christmas Eve (Thursday)

Merry Christmas! It's almost here, although a much changed version from any other year...very quiet for obvious pandemic reasons. It's a dark time across the USA. That said, it HAS been nice to see bright sunshine the past two days.

I've been off the last 6 days, but will be back at work tomorrow evening through the middle of next week. We had quite a well-forecast soaking, warm temps, and gusty southerly wind. Now it's quiet except for dense fog in the Willamette Valley and strong easterly wind blowing in the Gorge.

A wet weather system moves inland Christmas Day. With cold air stuck in the Gorge, that means some of you will have a White Christmas! In this case I'll define that as seeing at least a dusting on the ground.

HIGHLIGHTS

  1. Nothing interesting happens through tomorrow morning, except lingering areas of dense fog south of Portland metro and easterly wind gusts 50-70 mph at the west end of the Gorge. Crown Point has gusted to 75mph this morning.
  2. Rain moves inland by late morning tomorrow; it'll be a gray, wet, & cool Christmas west of the Cascades
  3. As that moisture rides over cold air in place, snow begins falling early afternoon from Bonneville Dam eastward to The Dalles and down into north-central Oregon (Dufur, Maupin). Expect 1-5" Christmas afternoon through early Saturday morning in those areas. A White Christmas for Hood River, Stevenson, White Salmon, Lyle, & The Dalles. Least would be at freeway level and at The Dalles, most up around 1,000' and above. Expect there may be some snow on I-84 late tomorrow afternoon possibly through Saturday morning.
  4. Depending on how cold the airmass is, there could be the usual spots of freezing rain/sleet west of Bonneville Dam to hills above Corbett on Oregon side, and hills above Washougal on Washington side of the Gorge. Likely only up above 500-1,000'. East wind will increase further; gusting 60-80 mph midday/afternoon Christmas before suddenly turning light around midnight tomorrow night.
  5. A sudden surge of southerly wind should push up the coastline and Willamette Valley in the late afternoon & evening hours Christmas Day. Most models are relatively weak with the wind, but WRF-GFS suggest gusts to 40 in the valley and Portland metro area are possible around sunset and beyond Christmas evening. We will see...ECMWF isn't on board

A quick look at the "supporting documents". Sea level pressure forecast for 10am Christmas day shows a developing low offshore...

Then at 4pm the low has strengthened a bit. Pressure gradient through the Gorge is up to 8 millibars = cold & windy there.

Then at 10pm you see the surge of south wind and tight pressure gradient in the valley. It's important to note that this model is strong than others. Much weaker low would mean just light southerly breezes.

This WRF-GFS model brings 70kt wind down to around 2,000'. Again, the strongest I've seen of all this morning's runs

As for snow, ECMWF has been looking like this for the past 4-5 days! Several inches in Hood River and an inch or so at The Dalles.

That's because it's holding in a cold pool at 925mb tomorrow afternoon and evening. It also thinks Hood River and The Dalles only top out in the upper 30s today. If it gets well into the 40s (today), then it'll be obvious modeling has been a bit too cold.

The brand new IBM GRAF model (along with soon to be extinct RPM) thinks there will be no pool of cold air east of the Cascades and no snow anywhere near the Gorge. I think the GRAF missed the last snow event out there too.

It's interesting that the 2.5km (very high resolution) HDRPS model (Canadian) brings plenty of snow to the central/eastern Gorge. Strange little no-snow zone around Lost Lake to Parkdale, apparently punching in a little warmer air aloft.

But just for fun, you can see what it's doing. Slightly warmer air overhead = sleet. Accumulation graphic here "fills in" those no-snow holes.

The main message when looking at differing models/maps? You should never take any one image and say "that's going to happen". Far smarter to stick with ensembles, not just of one model but combine several of them together to get a general picture. In this case, "there will be some white tomorrow afternoon/evening and a little silver in spots east of Portland in the Gorge".

That's it for today. Enjoy your Christmas!

Chief Meteorologist Mark Nelsen