Winter Pushes It’s Way Back Into St. Patrick’s Weekend

March 15, 2012

Ugh, I’m really tired of this…wintry weather just won’t go away this year.

There were hints of lower elevation snow (below 1,500′) on earlier models today, but this evening’s 00z runs threw a few more hints of winter into the mix.

1.  The previously expected deep low moves more or less right over us later tomorrow night and models seem to have it as more of a “blob” then nice tight low pressure center.  Translation: No strong south wind on the way, maybe gusty, but nothing wild.

2. As the low moves north tomorrow night and early Saturday morning, the wraparound moisture on the northwest side of the low is steady and heavy; could drag the snow all the way down to sea level.  Our RPM is showing that from maybe Tillamook up to Hoquiam.  Check out the 3 day snow total, I got smarter after the coastal snow the other day and turned off the ocean stenciling.  That previously blocked any snow “accumulation” over the ocean.  Now you can see it trying to stick snow down around Cannon Beach and the Long Beach Peninsula.   Something to keep an eye on.

3.  Instead of a dry Sunday morning, both our RPM and WRF-GFS show showers re-appearing right around sunrise and continuing through the day as the cold upper trough axis moves overhead.  This is with 850mb temps around -7 or -8.  That’s not good enough for low elevation snow in the afternoon, but at the very least there could be flurries around for the Shamrock Run Sunday morning…brrr!  Here is the 24 hour snow accumulation graphic from the WRF-GFS from 4am Sunday to 4am Monday.   Not a whole lot of snow, but hints of a dusting on the hills.

So yes, another cool weekend with a least a dusting in the hills, maybe a little more.  And anyone might see snowflakes in the air on Sunday, mainly in the morning.

Chief Meteorologist Mark Nelsen


WordPress Comment Problems

March 15, 2012

Some of you have been unable to leave comments for the past 24 hours.  This is the best I can find on WordPress support forums:

We’ve recently updated our commenting system.

Now, if someone tries to comment with an email address that’s attached to a account, they’ll need to sign into before they can comment.

If commenters have forgotten their password they can request a reset:

Not sure how to read that…does it mean all of you have to have a WordPress account to comment?  Hopefully not.  If you are not able to comment, could you leave me a note at  Let me know what happens when you can’t comment.

Chief Meteorologist Mark Nelsen

Weather Slows Down This Weekend, But Chilly Temps

March 15, 2012

Lots of rain today…a good soaking again with 1/2″ to 1″ across the Northern Willamette Valley:

The rain is changing to showers as a cold front moves south and east of us, but obviously the cooler air has been slow to move in.    In fact today’s high of 55 or 56 is the warmest in 6 days. 

With today’s rain, we’ve just about reached our normal monthly March rainfall of 3.68″.  We’ll probably top that either later today or tomorrow.  Yikes…we’re only halfway through the month.  Last year we had 6.43″.

We get a break through most of tomorrow which will let streams and creeks subside again, but then one more slug of rain and possibly some wind heads in tomorrow evening & night. 

Models have been teasing us the past 36 hours, showing a possible deep low pressure area tracking either offshore, through western Oregon, or to our east later Friday or early Saturday.  Most seem to have settled on a solution of a weaker low coming right up through western Oregon in the middle of the night tomorrow night.  Maybe a depth around 992-996 millibars.   Not major windstorm territory, but a quick movement and the right placement could easily give us a burst of strong wind here in the Willamette Valley.  The 12z 4km WRF-GFS shows the low around 993 mb, but the wind fields are not strong at all; here’s the cross section over Aurora, in just about the windiest spot.  Only 40kt southerly speeds right at 11pm.   Today’s wind was stronger, up above at least.

Our 18z RPM is the strongest I’ve seen, showing a burst of 50-55 mph southerly gusts right around 11pm-1am Friday night.  Note the yellow area (50+ gusts) on the map.  You can see the calm wind right at the low center just norhteast of Astoria on this map at 1am:

By the way, easterly flow tomorrow evening COULD bring snow back to the eastern Columbia River Gorge, but that’s after a day with highs around 50 degrees.  Could be tough to do.

Beyond that cooler air takes over for the weekend…

850mb temps drop to around -7 all day Sunday and into Monday morning.  Models are showing little or no moisture for showers at the critical “snow time” Sunday morning or Sunday night/Monday morning.  BUT, our RPM and the GFS imply convective afternoon showers Sunday coming off the Coast Range.  Those could be hail/snow mix with temps in the 40s (brrr!).  Either Sunday morning or Monday morning could be real chilly.  Sunday’s record at PDX is 28.  Monday is 25.

On to Spring…

The Spring Equinox is 10:14pm Monday evening.  It’s back to milder and rainy later Monday through the middle of next week with a WSW jet over us.  Slightly milder, but at best we might see temps approach normal.  Our chilly and wet March will continue.

Here are the 2 week GFS & ECMWF ensemble 850mb charts…generally near or below normal for the rest of the month: