Competing Amplified Upper Air Pattern Coming To Fruition

Back in the Summer Outlook I displayed and discussed the two main weather patterns that seemed to me the most likely to "compete" during the summer months. Actually; I felt mother nature tipped her hand at the most likely weather pattern for the summer back in the spring and discussed that in the Outlook.

Overall; the strong ridge is expected to continue to be a dominant player and will oscillate from the center part of the country to the east; bringing the periods of heat. Normal to below trends will be brought about by the dubious North Atlantic Oscillation /NAO/ cycling lower into neutral to possible negative phases (more below) which would aid in emphasizing the upper low and troughing over central and eastern Canada.

This pattern has been well represented during the past several weeks with the cool and hot periods seen this June. Latest model trends continue to advertise this amplified competition... let's take a look at it on this hot day.

Present 500 MB: Tue 2PM 6/19

Present 850 MB: Tue 2PM 6/19
 

 Projected 500 MB Mon 10 AM 6/25


Note the complete flip-flop of the upper air jet pattern across North America! Not only the flip-flop change but the amplification is quite extraordinary one week from July!

Projected 850 MB Mon 10 AM 6/25

Likewise the cool surge of 850 MB temperatures (note the core of +3C over much of central and northern Michigan).

Another model for comparison to this anomalous pattern is the ECMWF and believe me it's no tamer. Just look the projected amplification of the 500 MB pattern, a strong ridge extends well into the Arctic circle while at the same time; the cold upper 500 MB vortex is displaced well south for late June over the eastern Great lakes. This is very reminiscent of some patterns seen earlier this spring!

 Projected 500 MB TUE 8 AM 6/26

What is even more fascinating is that the GFS strongly suggested this pattern way back on the 12th of June. Fascinating IF the actual upper air pattern resembles this anomalous projection that was about two weeks out!

Of course this is PROJECTED by both models and isn't actually observed data but with both models projecting such a strong amplified pattern...it bears watching.

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian