Category: Monthly Outlook

The first month of meteorological summer is here and right on cue, we’re expecting a significantly warmer pattern to emerge. Does that set the tone for the month as a whole? In the words of Lee Corso: “not so fast my friend.”

After a refreshing weekend the first week of June, overall, is expected to be dominated by a MUCH warmer and more humid pattern. This is courtesy of an upper level ridge building east over the region (in response to the MJO moving into Phase 1, along with a strongly positive EPO).

Deeper into the month, it’ll be tough to hold onto this warm, humid regime as the EPO trends negative and the MJO shows signs of rumbling into Phase 2. In the month of June, Phase 2 delivers cooler than normal temperatures into our portion of the country, along with a good chunk of the East.

Sure enough, the latest European computer model is seeing this cooler trend developing by Week 2:

Given the longer range data, there’s reason to believe the cooler than normal temperatures will also be transient (similar to the warmth to open the month). Overall, drier than normal conditions are expected through the first month of meteorological summer. We’ll have to keep close tabs on where the drier pattern sets up as this can “feedback” on itself the deeper into summer we go.

Given the MJO and EPO forecasts, there’s reason to buy into a “transient” pattern that June should dish out. After a drier than normal 1st half of the month, precipitation should average out close to normal by month’s end. The one exception to this will have to do where remnant tropical moisture tracks inland in the Week 2 time period. From this distance, there are 2 camps pertaining to the potential track of soon-to-be Cristobal: TX/ LA coastline or FL panhandle. The next 7-10 days will be interesting. We’d recommend getting used to an ever-changing temperature pattern in the upcoming 3-4 weeks that should balance out close to average for our neck of the woods by month’s end.

Our official June Outlook looks like this:

While a good chunk of the 1st half of the month likely features below normal temperatures, is there potential for a “sudden summer” flip in the pattern for the 2nd half of the month? Let’s discuss!

First and foremost, averages in May for Indianapolis feature lows rising from the upper 40s to the upper 50s by month’s end, highs increasing from the upper 60s to the upper 70s, and 5.05″ of rain. Of note, on average, May is the wettest month out of the year in Indianapolis.

Teleconnections are aligned in a manner to drive rather widespread and persistent cooler than normal anomalies across the eastern portion of the country through the better part of the 1st half of May. Note the positive PNA and negative EPO and associated upper air pattern.

A persistent eastern trough will deliver an extended period of below normal temperatures through the first couple weeks of the month.

As chilly Canadian high pressure builds south behind departing cold fronts, we’ll have to remain on guard for the threat of late season frost/ freeze conditions lingering into the middle of the month.

To no surprise, the cool Canadian air will be much drier than a “typical” May pattern that can occasionally tap into the Gulf of Mexico. Accordingly, the pattern should run drier than normal through the 1st half of the month.

While we’re confident on the cool, dry (relative to average) theme carrying the day through the 1st half, there will likely be a snap back in the pattern that will promote at least the threat of a “sudden summer” regime during the latter part of the month. Timing this adjustment will be a bit challenging, but we believe that’s on the table at some point late week 3 or week 4. Accordingly, we’re building our May Outlook to feature this warmer (to hotter) potential late month or else it would be even cooler across the East- overall.

We’ll, obviously, also have to keep close tabs on the MJO throughout the middle and latter part of the month for influences on the pattern.

Without further ado, here’s our May 2020 Outlook…