May Begins Mild & (Mainly) Dry

May 5, 2015

9:30pm Tuesday…

It’s been awhile since I last blogged; but I’ve got a few random notes tonight:

1.  Mt. Bachelor is closing.  They are the last ski area to throw in the towel on the horrid ski season.  They typically stay open daily through Memorial Day since USUALLY there is plenty of snow left on the ground.  Not this year!  You can read all about it on their web page.  This coming Sunday will be the last day.  http://www.mtbachelor.com/site/winter/ski/update

Capture

2.  Detroit Lake has stopped filling.  I noticed the level hasn’t changed in a week; it appears the very low flows on the streams feeding into the lake aren’t keeping up with the discharge.  That’s due to little rain and hardly any snow to melt.  A neat graphic here shows the leveling off.

Capture

Rainfall has only been around 50% of normal for much of Oregon in the past 30 days.

anomimage

This is exactly what you DON’T want after the worst snowpack on record.  Forecasts of decent stream flow across parts of the state have been based on NORMAL precipitation in April and May, before the dry season really kicks in.  If May continues dry, we’re probably even going to see some issues on the westside of the state too.

3.  Split-Flow and/or Ridging seems to want to hang around.  Here is the forecast for next Monday from tonight’s GFS:

gfs_namer_132_500_vort_ht

A pattern of systems cutting off and dying as the approach the West Coast has been causing problems with models in the 5-10 day range.  The warm stretch we just had late last week and over the weekend was forecast very well way out in time.  Over the past couple of weeks models have repeatedly shown cool/wet conditions in the long-range only to have the splitty pattern reappear.  That seems to be happening again for this coming weekend and early next week.  Some of that is not unusual in the spring season, but it IS strange to see upper-level lows diving down towards California in May.

The 12z ECMWF Ensemble 500mb height anomaly for NEXT Wednesday shows the troughing to the south…

ecmwf_wed

But ridging returns to our north again mid-month, note Monday the 18th…

ecmwf_mon_18th

I have a feeling May is going to return us back into “Above Average Temperature” territory.

4.  Short term we have a chance for thunderstorms tomorrow afternoon/evening, although most action appears to be over the mountains.  There’s always a chance that we get something to drift out over the valleys though so maybe we’ll get lucky.  Today was sure underwhelming with many spots getting very little rain.   Then it’s back to 70s and maybe even touching 80 for Friday and Saturday.  It appears we have ANOTHER very nice weekend ahead.  Moms will be happy with that.

Chief Meteorologist Mark Nelsen