Saturday, August 18, 2012

Forecast for Sunday, August 19, 2012

Meteorological fall is now just a mere 13 days away now with astronomical fall approaching on September 22 or just 35 days away. So far, we have seen 36 days of 90 degrees or better this year with the majority of them during June, July, and August and 2 days that hit or exceeded 100 degrees. If we were not at or above 90 on any particular day, we have seen the thermometer flirting around 90 degrees with the rare exception involving days with extensive cloudiness. This is changing tonight and thus is the first real leap towards fall weather thanks to a cold front and dip in the jet stream that has occurred over the past 24 hours. While another hot period is possible at the very end of the month or in early September, at least we are starting to break away from consistently averaging hot and hence this is why I believe we are making that leap. Climatologically, it is bound to happen at some point soon with less and less sunlight each day.

With clouds exiting to the east, tonight should be clear in all areas. A light northerly wind eventually become calm with high pressure dominating that will allow for the suburbs to cool quite well and sufficiently by daybreak Sunday. The Poconos are expected to see the first night in months where temperatures are down into the mid and upper forties and areas north and west and in the Pine Barrens could drop into the fifties. The urbanized areas will likely drop down into the lower sixties. In the suburbs especially, light jackets may not be a bad idea to bring along if you will be out and about in the overnight hours.

Sunday should start off with plenty of sunshine and the mostly clear skies will continue into the early afternoon hours. Later in the afternoon into the evening hours, clouds will increase and skies should become mostly cloudy. Highs on Sunday should be in the upper seventies to lower eighties with comfortable dew points most of the day... with a rise in dew point temperatures as moisture increases late....but likely after the peak of daytime heating. A weak area of low pressure will approach from the southwest late and some scattered showers are possible beginning early on Monday. Monday should be generally overcast. The combination of cool air, scattered showers, and clouds should keep temperatures below average on Monday. Mid to upper seventies is about as high as we can go without much sunshine, but there is a path for temperatures to be even cooler than that should the showers be more widespread. At this moment, the latest model guidance is not indicating widespread steady rains with this system but rather occasional showers that are scattered in nature. On Tuesday, the low pressure area will lift northeast, but some remaining energy may continue the risk for isolated shower activity. The latest model guidance also points to the possibility of another weak wave riding from southwest to northeast later on Tuesday into Wednesday with additional scattered showers. For now, I will keep Tuesday and Wednesday mostly cloudy and include a few showers.
Thursday and Friday will turn sunnier with high pressure taking control again. With more sunshine, temperatures should max out into the lower and mid-eighties with cooler readings at the shore and in the mountains.

I have viewed and analyzed the long range portion of the GFS model from 12z. It shows a hurricane turning tropical storm affecting the East Coast of the United States around 324 hours from now or on September 1. This is one model run on just one of the many models we use. Over the past 24 hours alone, it has had this potential tropical system in various places throughout the Western Atlantic. While I would not focus on the specifics such as dates and wind/precipitation impact at this time, this model performs very well at signaling that something is brewing well ahead of actual development. The GFS did a very good job at hinting at something down the pike before Hurricane Irene emerged last year. It is interesting that this model has been giving signals about problems in the Western Atlantic for nearly two weeks now, on and off. Previous runs a week back had something lurking for August 22, but then it eventually lost that feature. It now has something lurking for September 1. We are approaching the peak of the Atlantic Ocean Hurricane Season. From a climatological stand point, we expect waves that emerge off of Africa to pose a risk to areas in the Western Atlantic in some form and we should always be prepared. We will continue to monitor this trend.  A lot can change in 13 days.