Wednesday, June 05, 2019

Mid to late June 2019 Outlook

We start with the northern Pacific: 

The pressure patterns show a pretty consistent storm track off of Asia east into the northern Pacific undercutting the Bering Sea high as of June 4th.

Superimposing the US over the Bering Sea region--Bering Sea Rule--you can see how the actual storm track line up with the continental US down the road--8 days and 16 days out.  A fairly persistent eastern US trough with the central US high pressure ridge.

This pattern is pretty different from the late May pattern which featured the SE ridge east and the central US trough which drove the heavy rainfall across the corn belt.

Another interesting feature has been the "Greenland Block". We noticed this earlier in May. A high latitude block like this does what it's name says.  It block the pattern thus the heavy rain/high soil moisture content this spring.

This Greenland Block can't be ignored this month. Notice how the high over Greenland continues through mid month.  The trough redevelops over the eastern US. 

The daily SOI changes (Southern Oscillation Index--difference in pressure pattern between Darwin and Tahiti) offer some additional insight.

There have been some decent rises and falls over the last week. 

SOI rises similar historically correspond to short-lived high pressure over the eastern US at day 17, 20 and 23.  Notice on day 23, it also shows a southern low over Texas. 

DAY 17 after RISE
DAY 20 after RISE

DAY 23 after RISE
SOI drops historically show these pressure patterns:

Notice the eastern ridge is further off the coast and an Ohio Valley low with a central US ridge...

Day 20 analog show the ridges pretty strong with the Ohio Valley low breaking down a bit...

Day 23 shows the lingering southern US/Ohio Valley low with high pressure continuing to flank it.

While these rises and falls show some conflicting signals, the idea for a southern storm position between the 24th and the 27th seems pretty good. Long range projections show pretty good agreement on well above normal rainfall across the southern states over the next 14-17 days. I believe this trend will continue into the last week of the month.

In summary, this is how I envision the next 3 weeks overall:

*  Storm track takes a southern route heading into mid June/3rd week of the month. 
*  Small periods of heat but nothing sustainable through June 20th

* June 5-9:  Temperatures near normal/slightly above

* June 10-14:  Temperatures below normal

* June 6-14:  Rainfall near normal with longer breaks in between weather systems

* June 15-20:  Temperatures near normal.  Little chance of any extreme heat (90+) or long                                         stretches (3-5 days+) of 85-90 degree heat

* June 20-27:  Temperatures near/slightly above normal. 

How do we derive these long range outlooks?   Here is brief explainer with a few other links:

* Outlooks are different than day-to-day outlooks

* Summer Outlook Elements From 2015

* Why We Dismiss Science So Easily?

* Evolution and Devolution of Social Media Comments