Wx Moment : Triple Point and Upper Atmosphere-Surface Relationship

NOAA’s Ocean Prediction Center (OPC) 48-hour 500mb and surface forecasts have an interesting weather feature today.  Clipped and overlaid on each other in the video above, this weather system to the SSE of Newfoundland depicts a mature surface low pressure and the associated upper level low isoheight.  

The surface low pressure is mature, showing the distinct comma shape created by the occluded, cold and warm fronts.  The upper level low isoheight in vertical alignment over the surface low pressure area is another sign that this surface system is fully mature and will not deepen.

With a good amount of lifting and instability at the triple point created by the intersection of the occluded, cold and warm fronts, there is always the potential for a new surface low to form there.  Additionally, if there’s adequate moisture, we could see significant rain and thunderstorms in this area.

While not a new low, we see the surface low moving to the triple point with pressures rising from 966mb to 981mb.  This would be cold comfort for those in the SW quadrant of this system where hurricane force winds are developing, but is an excellent example of the relationship between upper atmosphere and surface systems.  With the upper atmosphere features moving faster than the surface, they will pass by and eventually stop supporting the surface systems, regardless of their own maturity.

Let’s be safe out there.


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