Wednesday Afternoon Technical Discussion

Synopsis:

The stationary front that has been strewn across the heartland of America over the past few days will remain in place tonight. This frontal boundary will continue to pump energy up into Pennsylvania and keep conditions ripe for convective development. This will cause warm and humid conditions tonight with the possibility of thunderstorms especially in the western portions of the state as a low pressure system slides northward along the front and into Canada. This system will finally break down tomorrow and a cold front will propagate west to east through the day. Heavy rain will be associated with this cold front and thunderstorms will again be a possibility in the eastern half of the state. Behind this system a shortwave will swing through the state on Friday keeping the skies cloudy and even bringing a few rain showers to the state. High pressure will take control of the eastern seaboard by Saturday allowing for decreasing cloudiness and moderating temperatures to dominate the weekend. Our next system will approach the state on Sunday evening bringing another shot of wet weather for the beginning of the next work week.

Short Term (Tonight):

The atmosphere is ripe for convective initiation as the stationary front that has caused numerous severe weather reports this week remains mired in the Mississippi River Valley and Northward into the Great Lakes region. Although, the WRF and GFS don't show exceptionally strong storms developing this evening; the National Weather Service in State College has issued a Tornado Watch until 10pm. There is a substantial amount of CAPE this evening and correct amount of wind shear for vertical cumulonimbus cloud development. Both the High Resolution Rapid Refresh and the experimental 4km WRF models show a line of storms firing west of the Alleghenies, rapidly intensifying and then pushing eastward. The radar is beginning to pick up on this line however, the satellite imagery still doesn't look too impressive (Texture isn't impressive and cloud anvils have yet to glaciate.) But, I feel that this line will rapidly develop over the next few hours and produce some severe weather. (Although, probably not a tornado).

Mid-Term (Tomorrow):

The persistent weather pattern will finally break down tomorrow and the final cold front will move west to east through the state. Rain should begin by the morning in the west and will slowly propagate eastward. Current model guidance suggests that the system should be through the state by tomorrow night; however, the guidance hasn't been perfectly consistent so keep an eye out at later shifts. The timing is important because the later in the day the front passes through, the warmer it will get. And due to the instability of the atmosphere, warmer conditions will correlate to a higher probability of severe weather as opposed to the synoptic thundershowers which are currently being modeled.

Long Term:

On Friday a shortwave will swing through and cause cooler conditions and rain showers. High pressure will take over for the weekend before the next storm system approaches on Monday.

RJ Patrizio