Driest Spring in 14 Years, But Rain Ahead!

June 6, 2018

6:00pm Wednesday

Meteorological spring has ended in the Northern Hemisphere since we’ve moved into June, so let’s take a look back.  First the temps…very warm!

MarkSpring WrapUp

Of course the warmth comes from the past 7 weeks.  It’s as if a switch was flipped in mid-April and we suddenly jumped into June.  May was only .10 degree from the warmest on record.  Only 1992 was warmer in Portland.  It was the 4th warmest May on record in Oregon and 2nd warmest in Washington.  You can see how crazy warm the entire USA was last month:

divisionaltavgrank-201805-201805

For spring as a whole (March-May) it was a warm one in the West and near average in the Eastern USA

divisionaltavgrank-201803-201805

How about rain?  VERY dry this spring west of the Cascades, just about all of that due to record-dry 2nd half of spring:

MarkSpring WrapUp2

Note the driest May on record for the Washington Coastal climate zones.  Much below average all other areas west of the Cascades in the PACNW.

divisionalpcpnrank-201805-201805

Note the result of a low winter snowpack plus warm and dry spring = drought across a good 2/3 of Oregon

Drought Monitor Autoplot

What’s ahead?  We have a cold upper-level low + showers coming this weekend.  Pretty clear signal from the ECMWF this afternoon

ECMWF 12z Rain Graph 6 Hourly QPF

All other models are similar showing a cold front with brief steady rain Friday evening west of the Cascades followed by two days of “convective” showers Saturday and Sunday.  That means the most vigorous showers will show up each afternoon; hail or thunder is possible.  It’s hard to believe, but this will be our first widespread soaking since mid-April!  That said, models are also implying this will probably be a “one-shot” deal.  Check out the ECMWF ensemble member precipitation forecast for the next two weeks:

KPDX_2018060612_eps24_precip_360

The bottom chart is the ensemble average 24-hr rainfall.  Note the big spike this weekend, then just scattered light showers showing up on only some ensemble members beyond that point.  We could use a 2-3″ soaking the next week, but that seems unlikely at this point.  But anything will help with the fire situation; right now fuels in the north Oregon Cascades are as dry as what we’d typically see in mid-summer!

Chief Meteorologist Mark Nelsen