This is a cut and dry question - and the reason why we try to lean away from having people ask "when will watches be issued"
It's cut and dry in the watch definition. https://www.weather.gov/lwx/WarningsDefined - that is an EXCELLENT resource page for newer members.
Winter Storm Watch
A Winter Storm Watch is issued when there is the potential for significant and hazardous winter weather within 48 hours. It does not mean that significant and hazardous winter weather will occur...it only means it is possible.
Significant and hazardous winter weather is defined as a combination of:
1) 5 inches or more of snow/sleet within a 12-hour period or 7 inches or more of snow/sleet within a 24-hour period
AND/OR
2) Enough ice accumulation to cause damage to trees or powerlines.
AND/OR
3) a life threatening or damaging combination of snow and/or ice accumulation with wind.
The snow/sleet criteria for a Winter Storm Watch for the five westernmost counties (Allegany, Mineral, Grant, Pendleton, and Highland) is higher (6 inches or more within a 12-hour period; 8 inches or more within a 24-hour period)