The Chance of clear weather is inversely proportional to the cost of the equipment, the desire to use the piece of equipment, the length of time after purchasing said equipment, and also inversely proportional to the requirement to fulfill, matrimonial, filial or genealogical requirments.
X = 1/(absq + 5cd) * 1/Qsq
Where X = likely hood of clear weather
a= cost of equipment
b = constant (based on time of year and likelihood of la Nina, dust storms, burning off, etc)
c = desire to use the piece of equipment
d= time since purchase
Q = All clear from other duties
Truth