US July Outlook

Written by Mark Vogan on June 24, 2015 in United States of America with 0 Comments

Here’s how May and June have turned out so far temperature wise.

May

Credit: Michael Ventrice / WSI Energy

June to date

Credit: Michael Ventrice / WSI Energy

Notice how the heat has spread in the West, the cold over the Rockies extending into the Plains has all but been erased in June and as for the Northeast where May was warm, it’s the Southeast which gets the heat in June while it cools over the Great Lakes and New England.

As we go forward leaving June behind and head into July and the heart of summer, the El Nino continues to mature within the equatorial Pacific and the atmosphere is now showing response to the significant warming from below.

anomnight_6_22_2015

With stronger El Nino episodes comes greater amplification of the MJO. We’re seeing a rather strong wave 1 of the MJO (Madden Julian Oscillation cross into the western Pacific just now.

Credit: Michael Ventrice / WSI Energy

This should support increased western basin tropical activity, within 10 days or so the increase should make an appearance off Mexico and then mid July onwards, a period within the Gulf and Caribbean will have to be closely watched.

cfs

The MJO is heading into phases 5 and 6 over the next week as you can see from the below graphic. What does this mean for the United States?

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Historically, phases 5 into 6 suggests a cooler pattern during the summer months with warmth confined to the West as you can see below.

combined_image

While the heat has been on from Florida up to Philly in the last 2 weeks, it’s the northward migration of the SOUTHWEST ridge that will bring the much welcomed relief to the Southeast next week and for the open of July.

This means that while it cools significantly in the Southeast and throughout the East starting in the Great Lakes and Ohio Valley as the above indicates this weekend, it’s all about the Pacific Northwest when it comes to heat headlines. Dangerous heat is expected to build, particularly east of the Cascades with models printing out 110-115F for some spots in eastern Washington. Expect low 100s for Portland, 90s for Seattle.

See below how the CFSv2 weeklies go right to the above MJO temperature composites above.

500mb height anomaly.