All Clear on the Central Flyway Today, here is why not a single contrail is to be seen:

Fabulous cool clear blue day with dry upper air and not a spit of an aviaticus trail or hint of a drifting cirrus to be seen.  Where are the aircraft? They can be heard flying over but only with a sharp eye or binoculars can they be spotted today.  They are all laying out sub-visual aerotrails of water vapor, cloud condensing nuclei such as soot.  The cloud mass exited over night and during that time the boundary line passed over the Central Wisconsin Flyway, even if conditions were right for contrail formation not that many flights were scheduled then.

Here are some photos that demonstrate why the aviaticus clouds (contrails) are not forming today:

A wide swath of dry air is covering most of the state of Wisconsin so exhaust vapor is not condensing on the cloud condensing nuclei spewed by the aircraft. Maps of Water Vapor &  Infrared from NOAA Site.

Below is a map of cloud cover with a line drawn to show the approximate corridor of jet traffic

We have a forecast for light rain Friday night 4.24.2015 so the best chance of an aviaticus event would be Friday when a moister boundary line passes through the Flyway from the Northwest prior to overcast.

Update:  Only light non-persistent aviaticus continued through Friday until the overcast covered the view. But as the overcast broke a bit Saturday morning remnants of persistent trails could be seen but no new trails could be seen in the broken cloud cover the rest of the day. 4.25.2015

4/26/2015  0600 CT:  This morning a huge mass of clear day air swung in from the north but it appears a blurred boundary line is following with a bit more moisture so by the time air traffic begins in another hour the transports should sport only short whiffs, if any at all.  The rapid update cycle map does show possible contrail forming conditions in the eastern segment of this flyway but I won't know until the Sunday morning traffic begins if those conditions remain or pushed south and aviaticus actually form.

Note small blue circle within the large white circle near Green Bay on the east side of our east/west Flyway on the Rapid Update Cycle Map:

4/27/2015 1800 CT: The same weather pattern continues. Short to no contrails, none persistent from morning until noon.  Interesting water vapor pattern.  Again the dry area dominated the flyway as moister air pushed in from the east and surface winds were from the north, the dry air (browns and blacks) became faintly stratified with bands of moister air (white) as seen on this map (water vapor site): 

At this time loose bands of natural cirrus clouds were moving through.  By noon a few segments of persistent aviaticus clouds could be seen as aircraft would traverse these areas.  By later afternoon the stratification was gone. Then that air mass had pushed over the flyway as seen in the map with more moister air (white area) replacing it. Infrared Map Site

Some trails became longer but none would persist and a few depending on altitude left short segments as they passed through the cooler moister air:

This photo is looking east from the east/west Flyway. Note a persistent segment of aviaticus clouds.  The natural cirrus may be at or near the same altitude as the aviaticus segment.  These cirrus clouds did not show up on the infrared map but I'm associating these natural and aviaticus cirrus with the bands or lighter areas of moister air.

4/28/2015 0700 CT: It appears by the indicators we should have good aviaticus cloud production by this afternoon. An air mass is moving in from the west-northwest and it appears a distinct boundary line (sheet) will precede this.

http://theorioninitiative2.blogspot.com/2015/04/all-clear-on-central-flyway-today-here.html