Backdoor front brings clouds, cooler air

For the fifth time this Spring, a well defined backdoor cold front has swung southwestward from New England and brought marine air into our area. On the heels of three warm days in a row, with temperatures in the 80’s to near 90 on the last two days, the backdoor front gained steam initially in Maine and moved through New England on Tuesday. By Tuesday Night, the front progressed past New York City and Wednesday morning it was south of Philadelphia. The front featured a dramatic thermal gradient, with temperatures now in the 50’s and 60’s in areas where they were in the 80’s on Thursday. Northeast winds and cooler, more damp air were to blame as clouds infiltrated the area as well.

The culprit in the development of the backdoor cold front is a persistent trough from Eastern Canada into New England and the Northwest Atlantic Ocean. This feature has reappeared several times this Spring season, and continues to bring an abrupt end to any warmups which surge into the area from the Central US. The front will eventually weaken later this week, but troughing is expected to maintain its hold on the areas weather — keeping any major warmups back into the 80’s at bay for the time being.

The clouds, drizzle and damp air on Wednesday will carry over into Thursday and Friday although the latter two days will feature some more peaks of sun. Most notably, yet another upper level trough will sink southward from New England during this weekend. Although widespread showers are not expected, cooler than normal temperatures will prevail and north winds will develop very similarly to last weekend. Showers and thunderstorms will be possible during the afternoon hours with cool air aloft.

NAM model showing an upper level low (top left panel) meandering over the Northeast US this weekend, bringing unsettled weather.

NAM model showing an upper level low (top left panel) meandering over the Northeast US this weekend, bringing unsettled weather.

It is not until this upper level low shifts east/northeast that our area can begin talking about another temperature moderation. That doesn’t look likely to occur until the middle part of next week. And even then, while the warmups may briefly take hold of the pattern with amplifying ridges over the Central US, the amplified pattern to our north seems likely to continue bringing troughiness into New England and Eastern Canada. This means continued chances for cool shots, stormy weather and yes: more backdoor cold fronts.