Sunday, October 14, 2012

Forecast for Monday, October 15, 2012

It will not be as cold as the last few nights. Some clouds are expected to develop as the evening and night progresses. The combination of increasing cloud cover and a southerly flow should keep temperatures from dropping below the fifties for most areas with temperatures holding around 60 degrees in the city and along the coastal waters.

Sunshine will peak through a lot of clouds on Monday in advance of an afternoon and evening cold frontal passage. Enough heating should occur with the peaks of sunshine to provide for a warm October day. Highs will max out in the mid and upper sixties in the higher terrain to upper seventies in the Delmarva. Further south, where the warmer temperatures are expected, better instability will result. The triggering mechanism for thunderstorms and showers will be a strong cold front that should approach during the late afternoon and evening hours. The modeling is showing a line of thunderstorms and heavy showers developing and becoming most organized in the area of greater instability which is expected to be in the southern half of the Philadelphia area. The Storm Prediction Center has now placed Southern NJ and Delaware under a slight risk for severe thunderstorms on Monday where the chances are highest for the development of severe weather. The main threat will be a few damaging wind gusts. Areas north of Philadelphia could still get a gusty t-storm despite not being included in the slight risk designation. Meanwhile, southwest winds will turn gusty ahead of the frontal passage.

Breezy if not windy conditions should develop for Tuesday and Wednesday. This is in response to a tightening pressure gradient in the wake of the departing frontal system and a fresh area of high pressure. Gusts to 35 or 40 MPH are possible, especially on Tuesday. However, it should be sunny during this period.

Later this week, temperatures will rise again into the seventies. However, a cold front with waves of low pressure will move eastward and it should mean a period of unsettled conditions timed around Friday, possibly lingering into Saturday. There is still not the greatest consistency or agreement with our computer models. Therefore, this is a low confidence forecast for Friday into Sunday at this time. Saturday may end up drier or wetter in future forecasts.