Yep, that is what happens 95% of the time. Sleet doesn't 'add' to OTG for a good while, it relentlessly beats whatever newly fallen snow to a pulp, reducing it by up to half depending on how fluffy (dry) or hard (wet) it was prior to the flip, and how hard/fast/heavy the sleet is falling. Once it reaches a compacted consistency, THEN sleet starts to add to the OTG totals.