Did anyone see what they were applying?
I mean, could it have been a 0-0-7 with pre?
Are you sure they were applying N at all?
Now I'm not making excuses for them because applying on lawns with snow on them is just wrong...No way you could control weeds in patchy areas with snow...just wrong.
Predicted rainfall is just that...a prediction. That's out of your control and about all you can do is keep a close eye on local radar and forecasts on almost a day to day basis and use your best judgment based on what you see in the forecast for the next 24-48hrs. 5-10 day forecasts are generally not real reliable.
And, I'm not going to lie, we apply plenty when it is in the 35-45 degree range. (Absolutely no snow on the ground...anywhere) We use a hose and gun to apply. Are there cool season weeds out there to kill at that time? I don't know about your area, but in my area there is. Fert in the mix is generally higher in K and lower amounts, if any at all... N.
I started spraying around the first of February here. It very possibly could have snowed mid February covering apps I had done for 2 weeks prior and as long as they had that post emerg on them for 24 hrs before snowfall, I would have confidence in the kill. If your pre emerg doesn't last longer than a few inches of snow on top of it for a few days then you're using the wrong Pre...or you're applying it wrong.(We apply almost the max rate of Prodiamine for approximately 5-6 months control. Our growing season is longer than yours) Again, weather is out of your control.
This is just how I see it. We do have quite a few accounts and there is no way we could get them done in 2 or 3 weeks though.
"The Poor Fish" circa 1930's: The Poor Fish wouldn't have been caught if he'd known enough to keep his fool mouth shut.
"Opportunity is missed by most because it is dressed in overalls and looks like work"- Thomas Edison, businessman/inventor