Weather Outlook for September 19, 2012
Posted: September 18, 2012
Temperatures will be seasonably cool on Wednesday with an active breeze until mid-afternoon. Light winds and residual moisture from the recent soggy front will lead to numerous patches of fog on Thursday morning with readings dropping into the 40’s (or lower) in all but the urban areas of the southeast and southwest (and along the lake shore). Some sunshine is likely on Thursday afternoon and part of Friday, but clouds will increase later Friday.
A strengthening cold front will slide across the Commonwealth during Saturday with the majority of the region receiving about a tenth to a quarter of an inch of rain, though parts of the east may see up to a half inch. The front will be followed by the chilliest air mass of the season as daytime readings are expected to stay in the 50’s in the hilly terrain on Sunday and only reach the 60’s in the valleys of the southeast. A slow warming trend is expected early next week as another front approaches at mid-week with scattered showers.
Odds still favor a spell of very warm weather during the first week or two of October. The late autumn and winter outlook hinges on the dominant signal in the Pacific. At this stage, there are conflicting indices with the slowly evolving El Nino (warmer than average waters near the equator) competing with a large pool of cooler than average water in the North Pacific (known as the PDO). Their effects on the cold season weather in eastern North America are nearly opposite. It is expected that the balance of the winter (Dec-Jan-Feb) will average above normal temperatures in the eastern half of the nation, though a 4-6 week period of cooler than average conditions are also quite likely between November and mid-January.
- Pennsylvania State Climatologist