29 Nov 2020

Pittsburgh’s November cloud forecasts often leave me scratching my head. What does “Partly Cloudy” mean?

Thanksgiving Day was partly cloudy. See that tiny patch of blue, above? That’s the sunny bit. No, it did not rain.

The official NWS forecast Sky Conditions ought to shed some light (copied below). Though the cloud cover percentages are fixed the names are flexible and disappointing. Mostly Cloudy has two definitions (see italics) and Cloudy is an anemic word for Pittsburgh’s really Overcast skies.

National Weather Service Sky Conditions

Sky Condition	Opaque Cloud Coverage
Cloudy / Overcast	88% - 100%
Mostly Cloudy / Considerable Cloudiness	70% - 87%
Partly Sunny / Mostly Cloudy	51% - 69%
Mostly Sunny / Partly Cloudy	26% - 50%
Sunny / Mostly Clear	6% - 25%
Sunny / Clear	0% - 5%

Something was brewing in the sky below. Would it be Mostly or Partly Cloudy … or Partly Sunny?

An hour later it was calmer and “Mostly” something.

What would the weatherman call this sky condition (below)? Mostly Cloudy? Cloudy? Overcast?

While pondering the answer, look for four crows among the clouds.

(photos by Kate St. John)