Presidents Day weekend travel mostly OK

Presidents Day weekend travel mostly OK

In my last post, I showed a 10 mb map that led me to speculate about whether it was a signal for a change to persistent cold:

The vortex was displaced from the North Pole and was quite elongated. I wondered if this was a sign that the vortex would soon weaken. However, that idea was wrong. Tuesday morning's map showed the vortex was back near the North Pole and much less elongated:

This suggests the Midwest and Northeast are not likely to have a blocking pattern that favors snow and cold for the major East Coast cities. This is nothing new so far in 2020. While there have been cold shots, temperatures have run well above long-term averages, as shown by this map:

The current upper-air pattern at 500 mb shows the main vortex centered well north in Canada. A series of storms from the Pacific will move through the Southwest, draw in Gulf moisture and spread precipitation across the Ohio Valley and Northeast. With no blocking in place, low pressure areas often migrate toward the main vortex to the north.

Ahead of the next storm, it will be just moderately cold. But as the center of low pressure passes north of a line from Lake Erie to Massachusetts, rain will be the main product (except in northern New England). Temperatures will go toward or past 50 in Philadelphia Thursday. The storm will exit the New England coast by Friday. Air following the storm will be much colder than what moved in behind the storm that affected the Northeast early this week. It may be below freezing in Philly Friday afternoon.

Today's GFS model suggested that a storm moving into the Ohio Valley and Northeast next Tuesday could be similar to the system that affected the same area at the start of this week.