00z GFS Ensemble Chart

January 31, 2013

Looks like models are all keyed in on the cool trough the 2nd half of next week; snow levels probably down in the 1,500-2,000′ range.  Then some disagreement whether we enter a cooler and wetter period or upper level ridging takes over after that time.  This chart shows the 00z cold GFS might be an outlier. 


The actual operational run is the blue line; very cold with several bouts of snow in the hills (or lower) between the 12th and 16th.

By the way, I have no idea why sometimes the images post all gray like that…I know it’s annoying.

Chief Meteorologist Mark Nelsen

00z ECMWF Monthly Maps

January 31, 2013

A little late, again, but here are the 4 weekly maps from LAST NIGHT’S ECMWF run:





12z GFS Ensemble Chart

January 31, 2013


Interesting to note the GFS operational is colder than any of its ensemble runs later next week, but the warmest beyond 11-12 days.  Many ensemble members are hinting at ridging farther offshore for colder weather by Valentine’s Day.

The Rain Ends; More Sun Ahead

January 30, 2013

For some of you/us, it’s been raining almost constantly for over 80 hours, since midday Sunday. 


That’s just about anyone from Battle Ground down to Washougal to Troutdale and into the foothills of the Cascades.  That includes my home out in Corbett where I’m up to around 5.50″ of rain.  One would think it would produce flooding, but it’s just been a light-moderate rain the whole time…EVERY hour, EVERY day, for day after agonizing day!…sorry, distracted a bit there.

For comparison, I see Hillsboro and most of west metro area has only seen .25-.50″.  This is an extreme example of orographic lift, where moisture pushes up against the mountains (for 3 days!) and has to drop its load of rain on the windward slopes.  The west side of the metro area was in the lee of the Coast Range, thus quite a bit of a rain shadow there.

The flow of moisture shifts north on Thursday so the rain should finally cutoff in even the wet areas.  As mentioned yesterday evening it appears we get some mild weather Friday through early next week.

Long range models show cool troughing the middle of next week with snow levels somewhere below 2,000′ again.  Then ridging again afterwards as we head towards the middle of February.  I always like February because it seems to pass by quickly compared to January, I suppose 2-3 fewer days in the month helps; maybe it’s the anticipation of Spring right around the corner too.

Here is the 00z GFS ensemble chart:


You can see the cool dip later next week and then a little warmer temps beyond.  Note a few of the ensemble members probably have the 2nd ridge a bit farther offshore, thus putting us into cooler high pressure with a cold north-central USA trough a bit closer.  The 12z run showed that, or was it the 18z?  I forget.

As for the comments…sigh…there was some very brief drama earlier today in the comments.  Luckily it didn’t turn into a big blowup as it did a year or so ago.  Yes, it’s been that long.  It was unrelated to anything that occurred here.  I didn’t want to deal with that stupid behavior; it sounded like middle school kids arguing, so I just shut off the comments for the rest of the afternoon/evening.  I’m much busier with more shows and responsibilities nowadays and don’t have time for that crap anymore.  I don’t care what happened elsewhere and I don’t want it to spill over into this forum. 

So this is how it goes:

1.  Comments are back on
2.  NO mention of any issues from any other group or forum.
3.  If you bring it up or participate in an argument, you’re on moderation for at least the next two weeks.
4.  If you don’t like something someone says about you I strongly suggest you don’t get into an argument about it.

Chief Meteorologist Mark Nelsen

Evening Earthquake

January 30, 2013

We just had an earthquake at 5:03 pm near Amboy.  Not strong, but enough to be felt by most of us close by:


Comments Closed

January 30, 2013

I just got into work and don’t have time for blog drama, so comments are closed for now; at least I think they are.  I’ll deal with it later.


30 Hours of Rain; But Mostly Dry Weather Ahead

January 29, 2013

With just two days to go, January is going to end mild and mainly dry. 

Now as a whole the month was very chilly at the lower elevations due frequent inversions.  Portland will end up with its coldest January since 1993!  But much drier than average; probably just under 3.50″.   The mountains will end up about average, buoyed by the warm weather above the inversion for part of the month.

Take a look at the rainfall totals since midnight:


Portland saw rain every hour between 5am Monday and 11am today (Tuesday)…about 1.5″ during that time.   Notice the strongly orographic effect to the rainfall.  Lots more rain the past two days eastside metro compared to westside.

Most of the rain lifts to the north the next 2 days as a warm upper level ridge builds in from the Pacific.  Snow levels have already risen above 4,000′ this evening and rise closer to 6,000′ tomorrow as the ridge gets closer.  By Friday, it’s close enough that cloud cover and all rain will be pushed well to the north.  At that time 5000′ temperatures are pushing 50 degrees.  Those warm temps at the higher elevations will continue through early next week. 

Last time this happened we saw very chilly temps in the valleys and lots of fog/frost.  This time it’ll be different for two reasons:

1. We start much warmer with the current mild surface airmass overhead.  Last time we started with a snow level almost at sea level.

2. The sun angle is getting higher and it’s a LITTLE easier to break some of the inversion.   Not a total breakout.  In fact the same atmosphere overhead in late February would push our high temps into the low-mid 60s!  It’s a few weeks too early for that.

Thus, I think we’re going to see our first 50-57 degree mostly sunny days west of the Cascades we’ve seen since early December.  We saw highs in the mid 50s earlier in January, but that was with rain and gusty south wind.

What about the big picture as we head into the first half of February?  I sure don’t see any pattern that would produce low elevation snow, extremely cold temps, or wild and wet storms.  Yes, for the weather geeks this slow winter weather will continue.  Here is a look at the 00z GFS ensemble forecast chart for the next 16 days.  You want to see 850mb temps down to at least -6 or -7 to get snow down in the lowlands.  Notice you don’t see that in the next two weeks:


Chief Meteorologist Mark Nelsen