This is an extended heat wave.
I'm pretty sure most sites nicked 90 ( the old 89.9 er) Monday (chk that), and maybe low 90s Tuesday ..then of course yesterday. Looking at machine interpolations, it's 91 to 97 through Sunday... so the beat goes on.
I'm thinking the mid and particular late mid range the global guidance' are tending to moosh the heights too far S into what's evolved into an impressive garland around our side of the hemisphere for subtropical ridging. So vast it is getting more difficult to see the acmes embedded within, whereby the lower latitude R-wave 'roots' are situated. The 06z operational GFS is really onto this idea, with a whopping 600 dm tickling ridge max embedded in and very large 594 closed envelopment of WAR heights, partially eclipsing the MA, forcing the 588 dm contour into central NE... around D10. Notice what it does two days later... It attempts a Rosby roll-out through the west and completely demolishes that look with another of these (likely..) exaggerated +PNAP aspects that have proven to be in the 20%tile too much all season anyway.
I'm just not completely sold that these westerlies are going to be so obtrusive S of the 40 N during the last week of July into the first week of August. Another hint, both the EPS and GEFs mean ..right out to 300+ hours, almost never show the 582 dm non-hydrostatic height contour as successfully plumbing S of ORD-BOS latitude, despite having vestigial +PNA signature to the overall structure - which is an interesting tandem. It's not typical to see very cool air succeed S of the 45 N at those height persistence'