Monday Afternoon Technical Discussion

Synopsis:

Weather for the first half of the week will be dominated by a monstrous low pressure system developing over the western plains. We are currently on the eastern half of this low and the southerly flow associated with this have tapped into the Gulf moisture and has strewn precipitation along the Appalachians and allowed temperatures to climb way above average. The cold front will move through Pennsylvania Tuesday night and into Wednesday from west to east and will cause scattered rain and thunderstorms. Behind this system we will see sunny skies and cooler temperatures for Halloween weekend.

Short Term:

Rain tonight will be heaviest for the western half of the state however; a stray thunderstorm is possible in the eastern half of the state as this energy lifts through the region. Tuesday will be very warm, but otherwise boring from a weather point of view. The cold front with the monster low will swing through overnight Tuesday. PM, LH, NW, NC, SE, CR regions will see the most rain and the interior mountainous regions will see more in the way of light rain showers.  Also, Lifted Index values are high for South eastern PA so we could possibly see a chance for severe weather there. This front will lift out of the region on Wednesday for the majority of the state. However, 18z WRF has the front stalling out over Philadelphia and essentially training rain showers all day. I think this is unlikely and that the showers will move out by the afternoon but it is something to look for. Also, winds will be blustery when this front rolls through.

Long Term:

Behind this system we will begin to cold air advect however; due to the high winds from the great lakes we will not see immediate clearing. In fact, the clouds will stick around until Thursday night before finally clearing on Friday. But, once the clouds do clear for a night, I expect temperatures to become quite chilly for the Halloween weekend. Interesting thing to point out is that this giant system sort of gets hung up in Canada and as we move through the weekend the models try to make a weak clipper system move through. If this happens, temperatures may be chilly enough for Pennsylvania to get it's first snowflakes of the season.

RJ Patrizio