Reports of the early arrival of winter may have been premature after all. A significant coastal storm system, developing this weekend, will move from the Carolina coast to a position east of the Gulf of Maine. As it does so, it will organize off the East Coast and bring periods of showers and gusty winds to our area beaches. But the storm system won’t become truly organized and mature until it is well to the Northeast of our area. As a result of this, the cold air being drawn in behind the system won’t move in until the storm is well past us — and the precipitation that does fall (as rain) isn’t expected to be heavy.
Still, the disturbance is extremely impressive and quite anomalous for this time of year. The initial disturbance swings out from the Tennessee Valley on Friday, and a surface low will develop as a result. The second disturbance is much more impressive, however, surging southward from Canada through the Great Lakes. This shortwave will race through the Tennessee Valley and to a position near the Southern Mid Atlantic Coast late on Friday — bringing 500mb anomalies to nearly -6 standard deviation. It will be, without a doubt, the most anomalous feature on the globe at the time. But the system will shift northeast, a good length behind the initial disturbance, while the surface low pressure remains unorganized.
It won’t be until the two storm systems phase and interact that the surface low will mature and bombogenesis will occur. Fortunately for us, this happens — at least as indicated by all models — east of New England and into a position east of the Gulf of Maine. Widespread heavy precipitation and impacts won’t reach our area.
Still, gusty winds and some showers are anticipated. Forecast models indicate the potential for a weak “inverted trough” to form on Friday evening into Saturday as the storm system passes by out to sea. An inverted trough is essentially an area of enhanced lift extending from a surface low. They can aid in the development of precipitation (heavy at times) despite the fact that the surface low/center of the storm may be hundreds of miles away. They are, obviously, extremely unpredictable as well. Forecast models have immense difficulty predicting their position and the breadth of any precipitation associated with them. So while we have noted their appearance on some models, confidence in the occurrence is extremely low.
The cold airmass behind the storm system remains extremely impressive on all forecast models. Temperatures on Sunday will feel downright wintry, with a west-northwest breeze. And Sunday night, things will really cool off — into the 20’s and 30’s throughout the area — as clear skies return with the coldest airmass of the season sitting overhead.