The other thing is that many forecasts have a large range. So it might be that the left third of the forecast area has like a 99.9% chance of zero precipitation, the right third has a 99.9% chance of some precipitation, and there is some uncertainly about where the border will be, (and near the border might have less precipitation than the edge).
The result is that I will be told ~50% chance of precipitation, but the places I care about might well be in the essentially 0% or essentially 100% parts.
The single forecast for a decent size city problem impacts other parts like forecasted highs/low. Even without a front, in some cities that have incorporated much of their suburbs, it is not uncommon for the eastmost part and westmost part to differ by 5-6 degrees, and that is ignoring the inherent temperature differences found in the downtown areas.
The result is that I will be told ~50% chance of precipitation, but the places I care about might well be in the essentially 0% or essentially 100% parts.
The single forecast for a decent size city problem impacts other parts like forecasted highs/low. Even without a front, in some cities that have incorporated much of their suburbs, it is not uncommon for the eastmost part and westmost part to differ by 5-6 degrees, and that is ignoring the inherent temperature differences found in the downtown areas.