All week long I having been keeping an eye on the ECWMF and the major ridge it’s continuously shown build over the Western United States from mid to late next week. The only change I see is that it’s strengthening further with each run. While heights really go to town from the Southwest to eventually Montana up into Canada with a sprawling 596dc high centred over southern Nevada, a MAJOR trough develops over the Great Lakes down into the Ohio Valley next weekend into the following week as a result. This will make for an increasingly cool end to June and possibly record cool start of July from the Lower Midwest to Atlantic coast. This trough has the potential to be one of the deepest early July troughs in many years with abnormally low dew points allowing for record cool nights and even days which may struggle widely to reach 70 in cities such as Rockford, Indianapolis, Cincinnati and perhaps Pittsburgh.

It looks highly likely that this could be a pretty dramatic turnaround for both West and East over the next 10 days as a surge of heat and humidity pushes into the Northeast now and will keep 88-92 degree temperatures going well into the upcoming week. There is also unusual late June rains setting it’s sights on central California.

It’s currently a few degrees below normal over the Southwest with below 100 in Vegas while it’s hovering around 100 in Phoenix. As for the Northeast, temperatures are pushing 5-10F above normal over the next 3 to 5 days while it pushes or likely exceeds 90 all the way to New York City. We could see the I-95 cities go from 90-94F to 70s between mid next week and late weekend, even cooler along the coast if we see some sort of backdoor front. Meanwhile a significant warm-up is on the way for the Desert region with temperatures likely to spike by as much as 10-18F within the next 5 days. Major seesaw in the height field coming.

While Thursday we are likely to see 100+ all the way to southern British Columbia and Saskatchewan. Believe it or not, the kind of ridge we’re likely to see in the West, we could see 110F heat reach eastern Montana while cities, typically hotter, such as Las Vegas and Phoenix, may push 115 and 118 respectively.

Firstly I want to show you the run from earlier Saturday rather than the later run because I want to show you just how warm the 850mb temperatures were for the period between next Saturday and the following Tuesday. Yes they’ve ‘cooled’ a touch in the newer run but even still, the last time I saw this intensity of ridge over southern Nevada was back in July 2005 when Las Vegas experienced 10 days in a row of 110+, 3 straight days of 115+ and a day which tied their all-time record of 117.

Next Saturday! (29 Jun)

The following Tuesday (2nd Jul)

Here’s the new run, now while it’s 850s aren’t just as warm, this would still be MAJOR record breaking heat but what I want you to notice is the trough in the East. Notice it is deeper!

Next Sunday!

Following Tuesday!

This is the type of setup in the Northeast where we should watch out for backdoor fronts which can produce, cloudy, damp chilly days with east winds blowing off the Atlantic, holding temperatures in the 50s along Long Island and the Cape while it holds in the 60s in New York and Boston.

Here’s the ECMWF projected heights/thicknesses for the same period.

Next Saturday!

Following Tuesday!

Wow, just look at those heights. 596 all the way to central Montana. Probably got a 600dc core over the Great Basin.. just as impressive is that downwind trough! A lot of rain can be expected in the Southeast and what a different year it is from Montgomery to Charlotte compared to last year..

Here’s projected rain over the next 168 hrs.

Plenty of it across the Northern Tier into Northeast and down across the Southeast.

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