A rapidly deepening storm center – one that many pieces of model guidance bottom out near or even a bit below 970 mb…28.64″ on the standard home barometer – will pass very near to Cape Cod tonight and bring us a round of heavy rain, maybe some thunderstorms and plenty of strong wind.
That alone makes the upcoming storm system impressive and worthy of some headlines and consequently we do have a Wind Advisory (tonight) and a High Wind Watch (Thursday) posted for the area by the National Weather Service.
With the rapidly deepening storm nearing and passing the region, several hours of strong, gusty east winds are anticipated tonight followed by a much lengthier period of strong southwesterly winds throughout most of the day on Thursday. This is a near certainty at this point. Gusts over 50 mph are highly likely and will cause some pockets of tree damage and some power disruptions.
However…there is a small window of time overnight tonight…likely between 12AM and 3AM…when we will have to be on the lookout for a short-lived period of powerful east and southeast winds that have the potential to cause quite an issue.
This is a rather complex evolution…
Before the system consolidates into one primary deep occluded low pressure center over Southern New England on Thursday morning, it will consist of multiple smaller-scale low pressure centers embedded within a larger strung out trough of (deep) low pressure passing from southwest to northeast through the Mid-Atlantic and into New England.
Numerous pieces of model guidance – too many to ignore – show one of these small but very strong meso-low pressure centers passing near or over Cape Cod as part of the overall maturing of the entire weather system (this meso-low feature has been shown for several days by guidance but placement and timing has been all over the place.) As this “mini-storm” nears the Cape it will undergo explosive deepening concurrent with the overall deepening of the entire weather system.
For example, on the 06z ECMWF (euro) the feature is represented as a non-descript 990 mb low east of the Delmarva at 8PM this evening. 6 hours later, the meso-low is shown at ~974 mb just south of Cape Cod and 3 hours later it’s at ~972 mb just north of the Cape. The 00z euro had a similar look and overall there are multiple pieces of high-resolution guidance and global guidance that have an evolution that is close to this.
The worry is that this meso-scale low will undoubtedly have a very intense but localized wind-response. Should this feature pass over or just west of Cape Cod, we’d potentially be dealing with a one to three hour period of extremely strong (70+ mph gusts) wind. Such an evolution would cause widespread problems…during the middle of the night no-less.
The hope is that guidance is doing one of the following things: A ) overdoing the deepening of this meso-scale feature B ) misplacing the feature too far west or C ) keying in on the wrong feature all together.