Forecast Discussion

Technical Discussion (9/8/10)

Synopsis...

A cold front will push its way across PA tonight and tomorrow morning bringing the chance of showers with the FROPA and cooler temperatures behind it. High pressure will build in from the North for the later half of the week keeping many of the zones dry with a few passing clouds. We will remain dry with fall-like temperatures until Saturday when we warm up ahead of the next system. The next chance of rain is late Saturday into Sunday as another cold front passes, but the threat for rain will diminish by evening.

Near Term (Wed)...

After a mild Tuesday, Wednesday will bring cooler, more autumn-like weather to the state. A cold front will pass through the state into the early morning hours, but it does not have a lot of moisture to work with as dew points ahead of the front are generally in the low to mid 60s. A spotty shower may affect the eastern regions towards sunrise, but many folks should stay dry. Behind the front, gusty westerly winds will aid in strong cold air advection meaning temperatures will struggle to reach the 70s especially in the north and east. 

Short Term (Thur-Fri)...

As the low pressure system pulls off towards the northeast, it is expected to slow down over Maine which will be close enough to keep some clouds in our northern zones, but farther south, sunshine should prevail. Current obs on the backside of the front in Ohio show clear skies which is why we went with mainly clear skies for Wednesday since the front would pass early, especially in the western zones. High pressure from the north will continue to keep us mainly clear, but NW winds will keep our temperatures slightly below average.

Long Term (Sat-Sun)...

Ahead of the next cold front, we should warm up more on Saturday as some southerly flow returns. Expect temperatures to rise a few degrees above average with sunshine continuing. The 700mb humidity panel keeps most of PA under 50% until a few hundred miles ahead of the next system. The front is expected to pass through western PA late Saturday and later in the eastern zones. Showers are likely and a rumble of thunder may be heard. Some of the moisture involved will be the remnants of Hermine as she gets picked up in the flow. By Sunday afternoon, most of the moisture will be focused in the eastern half of the state as high pressure starts to work back into the west beginning the clearing process.

- Adam Del Rosso