A Warm & Dry June Turns Into A Cooler July Start

July 7, 2019

8pm Sunday…

Back at work this evening!  After checking out the weather maps/models I can see I’ll be dealing with “why is it so cool?” whining this week.  More on that in a bit.

Apparently I missed a tornado?  Yep, that EF-0 in NE Portland on the 1st

Mid-summer and mid-winter are the tornado “off-season” in Western OR and SW WA.  The 1950-2019 records from SPC show this is the first July tornado on record in our area.  WAY back in the past a few were recorded in July (early 1900s), but that’s before detailed records were kept beginning in 1950.

The first official summer month (June) ended warmer and drier than average.  After an early June heat wave the weather has been pretty normal for early summer.  We haven’t seen a cool June in 8 years!

July has been a different story the past 11 years.  Only 4 have been unusually warm, the rest either cool or just a little warmer than average.

July Month In Review

So what’s ahead?

  1. There is NO sign of hot weather the next 7-14 days.  At least the first half of July will not feature any heat waves and 85+ is very unlikely through the 15th.
  2. Expect more cloud cover than normal to continue through the next week.  I don’t see many days that start sunny.
  3. Later Tuesday through early Thursday will be wet at times and even unusually humid as a subtropical airmass moves overhead.  Overnight lows will warm to above average with the cloud cover and humidity.
  4. Still, temperatures will remain near or only slightly below normal
  5. After some blazing hot summer weather the past few years, we ARE overdue for this kind of weather.

To summarize

  • Portland isn’t sunny Southern California, hot Atlanta, or sunny/dry/hot Denver (in summer).  We live in a temperate marine-influenced climate; notice the greenery all around us?  This is perfectly normal unless it continues for the next 6 weeks.  It doesn’t necessarily mean the entire summer will be cloudy and “cool”.  No need to panic for now if your livelihood depends on renting standup paddleboards.

 

Maps and models are in good agreement that an upper-level trough pushes up against the Pacific Northwest coastline later Tuesday.  This one has plenty of subtropical moisture.  Sea surface temps offshore are well above average too.  The anomaly map shows a warm “blob” in the Eastern Pacific

SST_Anomaly

WRF-GFS shows the IVT (Integrated Vapor Transport) quite juicy, but most of it is directed north of Oregon Tuesday evening through Wednesday.

ivt.60.0000 Because of that, this doesn’t appear to be a big soaking, well under 1/2″ in western valleys of Oregon and SW Washington.  More likely .10-.25″.  Enough to wet the dust and once again delay fire season.  There are no large fires burning in Oregon or Washington. Excellent news.

Looking farther ahead the ECMWF ensembles show the cool upper-level trough this Wednesday centered offshore

m500za_f072_bg_NA

Then this coming weekend.  Trough is there, but a bit weaker.  Temps warm to around average.

m500za_f156_bg_NA

Then 10 days ahead (Wednesday the 17th) a very unusual July pattern on both the GFS and ECMWF ensembles.  A large upper level negative anomaly covering the Gulf of Alaska.  Very interesting, but 10 days out.

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Chief Meteorologist Mark Nelsen