I'd like to understand what's going on here. Please take note of the TAT reading towards the upper right corner of each picture, the clock & DME read-out at bottom left and (if you can see it) the EGT gauge towards the bottom right corner.Over a relatively short distance (12 miles), TAT has gone from +5 degrees to -6, back up to +7 and then down to -2.You will note there is a button which momentarily shows SAT rather than TAT - not a toggle but a momentary display. I can assure you that the underlying SAT is moving also - it is categorically NOT the difference between the two figures which is changing.This may seem like a minor variation, but the aircraft is the PMDG Jetstream which is infamous for having accurately modelled engines, for which EGT management is critical if you don't like engine fires. Cruise power is 10 degrees below maxiumum EGT and here we appear to have air temperature varying rapidly by 13 degrees.You can see in the last picture that EGT gauge has gone into its over-temperature warning mode.Please convince me these very rapid variations are realistic.If so the realism has been introduced since ASX as I don't have the same problem with that as opposed to ASE which is driving the above.

Hi,I don't know what ASE was reporting, but you were changing altitude and you are between reporting layers from ASE so ASE does use the data from both reporting layers.

I was not changing altitude but cruising at FL190, as closely as changing temperature & therefore adjustments to the throttles to maintain EGT will allow.The altimeter shows movement only between 18,970 and 19,010 feet.

You are right. I was looking at the wrong numbers.