Sunday, August 05, 2012

Forecast for Monday, August 6, 2012

Gusty winds this afternoon have actually caused a few isolated power outages across the region. This is occurring as temperatures are rising a bit above what the guidance had projected. Several wind gusts in the 25 to 35 MPH range out of the south-southwest have been occurring. While this is mixing the air and lowering dew points for a few hours, the dew point temperatures are still in the upper sixties and lower seventies making today feel oppressive when combined with 90 degree or greater temperatures.
An active late afternoon and night is anticipated across the region as a strong cold front approaches the region. Numerous showers and thunderstorms are forming to our west and these will be heading eastward as the night progresses. In the meantime, with strong instability and ample moisture in place, some isolated thunderstorms ahead of the activity to our west are certainly possible. The highest probabilities for severe weather are to our west where daytime heating will be coinciding with frontal convergence. However, a few severe thunderstorms are expected even in our region before this front passes offshore later on Monday. It is interesting to note that some of our most significant severe weather this year has occurred during the nighttime hours. Besides damaging wind gusts and possibly some large hail, thunderstorms will be capable of producing the elements of frequent cloud to ground lightning and heavy rainfall. Some training of thunderstorms is possible and thus we will have to watch for the possibility of flash flooding. Much of the region is included under a slight risk of severe thunderstorm at this time from the Storm Prediction Center which includes the period up until 7 AM Monday.
On Monday, the cold front will be clearing the region from northwest to southeast. There is still some question as to how far this front moves south on Monday before stalling. Showers and thunderstorms are expected to be ongoing on in at least a scattered nature on Monday Morning with gradual clearing expected after the morning commute. Areas south and east of Philadelphia may not see the front completely clear the region and this raises the prospect that some of these thunderstorms may remain over these areas for much of the day. Meanwhile, sunshine and lower humidity will be briefly returning to areas north and west of Philadelphia.
Tuesday continues to look like the driest day of the next seven with mostly sunny skies and low humidity.
By Wednesday, the front reverses itself as warm front. This warm front should slowly move through during the rest of the week as waves of energy ride along it. This weather feature should increase the humidity by Wednesday back to sticky and uncomfortable levels. In addition, scattered showers and thunderstorms are possible. By later on Friday into Saturday, a cold front may approach the region and push a series of pre-frontal troughs our way as well. This may increase the shower and thunderstorm coverage a bit until the frontal passage. At this moment, temperatures will be close to 90 degrees (Wed thru Fri)...there is a chance if sun prevails over storms...that we can get another heat wave. As for Saturday, if the front timing slows down, then Saturday might also have a shot at 90 degrees.