For people leaving at the grand depart I would guess that you are on about the Kaibab Plateau and Snowbowl. There will likely be patches of snow in the creeks valleys just north of the Mogollon Rim but it will be largely rideable and the Happy Jack area should be OK too.

Best of luck to all!

I can weigh in a bit on the snow levels because I just finished the 750 route (sort of, lots of snow detours in the north).

The Kaibab Plateau still has a TON of snow (5' minimum in most places and many places over 10' deep). The NPS is plowing at a rate of about 1/2 mile/day right now. When we went through on April 5 they had gotten to about 3 miles of the park boundary. The guys (Donald and John) plowing gave us the line about "you know it is illegal to ride this road when it is closed" but we helped Don fix his plow as we were going past so they were really cool to us after that.

The DOT had plowed to about a mile north of the Country Store as of the 6th when we went through. They were not actively plowing at the time so I don't know how fast they are moving. Total we did about 12 miles of HAB over the unplowed section.

They are still getting snow on the plateau so the snow is still pretty soft. If you are lucky it may be rideable if there is a hard freeze overnight but we banked on that and woke up to 3" of fresh slushy snow and it would only have been rideable on a fat bike at very low pressures.

On other notes...

The section from a bit before Pine up to the Mogollon Rim was mostly dry and snow free but there were a ton of dried in elk and cow tracks that made what likely are nice riding sections really rough. 

North of the Mogollon Rim there was a fair amount of snow but it was very firm and rideable late into the day when we went through. That said, some of the creek basins in that section still had a ton of snow and there were some sketchy crossings (one of the thru hikers we talked to got so spooked by falling through the snow into a creek that she bailed on her hike).

We jumped on the road before Happy Jack because the trail was turning into a river so I can't comment too much on anything between there and Flag. After talking to some hikers about the section north of Flag we stuck to road north of Flag to the canyon. Word from the hikers is that things are surprisingly good up to the snowbowl and also good from a few miles after the snowbow. From there to the Grand Canyon is good.

Hope that helps others!

Thank you for all your work on the route! Myself and another guy are touring northbound on the 750 route starting next week Thursday with a scheduled finish of April 7. Keeping fingers crossed on lots of snow melting between now and when we hit northern AZ!

Let me preface this by saying, a lot can change between now and April...

Myself and another guy are planning on touring the AZT route from Mexico to Utah starting the last week of March and into the first week of April. Because of that I have been watching the snow levels pretty closely. NOAA's interactive snow information page is the tool I have been using: https://www.nohrsc.noaa.gov/interactive/html/map.html?ql=station&zoom=&loc=35.748+N%2C+114.423+W&var=ssm_depth&dy=2019&dm=2&dd=18&dh=20&snap=1&o9=1&o12=1&o13=1&lbl=m&mode=pan&extents=us&min_x=-114.49166666667&min_y=33.758333333329&max_x=-108.71666666667&max_y=37.008333333329&coord_x=-111.60416666667&coord_y=35.383333333329&zbox_n=&zbox_s=&zbox_e=&zbox_w=&metric=0&bgvar=dem&shdvar=shading&width=800&height=450&nw=800&nh=450&h_o=0&font=0&js=1&uc=0

You can pretty easily compare the last 15 years worth of info on snow quantities on different dates. North of the Grand Canyon on the Kaibab Plateau, the snowpack looks to be deeper right now than any year they have on record (data goes back to 2003). Luckily the snow pack isn't as bad (exceptional?) in the Flagstaff area this year compared to other high snow years.

Based on 2010 (the only year that comes close to as much snow north of the rim as this year on 2/18) there will likely still be substantial snowpack from the North Rim to at least Jacob Lake at the beginning of April. Obviously a lot can change between now and April but does anyone have words of wisdom? Is it basically impassable if the snow is deep (unless you have a fat bike and hit it at below freezing temps or have snowshoes/skis)? I have heard rumors the DOT start trying to plow out the Grand Canyon Hwy in April so would the road possibly be an option if the trail is impassable? Does the trail see any usage in the winter so that it gets packed in at all? How about the Grand Canyon Hwy, does it get snowmobile traffic so that the snow get packed in?

FWIW, I live in Northern Michigan and fat bike all winter so I am used to snow riding and have the gear to do it comfortably. I am just trying to plan ahead and figure out possible strategies we may be able to employ if the snowpack is still deep when we need to cross the Kaibab Plateau. I wasn't planning on riding my fat bike on the AZT and am hoping to come up with some other solutions/options if needed.