March 1992. Just a classic bust forecast. Forecast was clear at 9 PM on Thursday, then went from occasional flurries at 6 PM on Friday to 10-15 in the PWM area by 4 AM Sat.
Essentially the primary difference between an inverted trof and a NORLUN is the near stationary aspect of a NORLUN. Kind of like a square/rectangle argument. All NORULNs are inverted trofs, but not all inverted trofs are NORLUNs (there are some temp difference and moisture requirements, but most of those are typically met with inverted trofs anyway).