A strong non-tropical low pressure system spun up off the Southeast Coast of the U.S. on Thursday and there is some possibility that it could eventually develop subtropical or tropical characteristics.   At 4:00 p.m. EST on Thursday the low pressure system was centered near latitude 29.0°N and longitude 74.0°W which put it about 425 miles (685 km) west-southwest of Bermuda.  The low was moving toward the east-northeast at 18 m.p.h. (29 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 994 mb.

The low pressure system exhibits the structure of an occluded extratropical cyclone.  An occluded front coils away from the low until it splits into a warm front and a cold front.  Drier air is being pulled around the western and southern sides of the low and a dry slot has formed in the southeastern quadrant of the storm.  However, upper level divergence is pumping mass away from the center of the low and the surface pressure decreased quickly on Thursday afternoon.

The low is in an environment that is not favorable for the classical scenario of formation of a tropical cyclone.  It is moving over water where the Sea Surface Temperature (SST) is near 25°C and strong upper level winds are creating significant vertical wind shear.  However, research has shown that it is possible to get a transition to a subtropical or tropical cyclone over cooler SSTs, when a low pressure system moves into an area where the wind shear is less.

A trough over the southeastern U.S. is steering the low pressure system toward the east-northeast and that general motion is expected to continue during the next day or two.  An upper level ridge is forecast to move north of the low pressure system in a couple of days.  The upper level ridge is expected to steer the low pressure system toward the east-southeast early next week.

If the low pressure system takes the expected track, it could eventually move over slightly warmer SSTs and into an area where there is less vertical wind shear.  The more favorable environment could cause the structure of the low to change into a more subtropical or tropical form.  The National Hurricane Center is giving the low a 10% chance of transitioning into a subtropical cyclone during the next 48 hours and a 30% chance that it makes that transition during the next five days.