MA’s morning push behaved as expected, so why did the Cape last so long? If we check out the pics below, the answer seems to be clear. Take a look at the surface map… See how the isobars between the high and the cold front reach way up into Canada? It’s cold up there;) Cold / cool air has an easy time descending from altitude to hug the surface as its denser than warm air. Cool / cold air tends to bring down the faster wind speeds at altitude to the surface.
Next is the surprise… See the mini low pressure center to our S out in the Atlantic? It helped “pull” the cool flow through our area. Winds travel from high pressure to low pressure and they do bunch up around boundaries, so you can think of this low as “opening the door” to let the air mass flow more efficiently. In all likelihood, the cold front probably runs through the mini low, and this mini low is riding along the boundary as the cold front continues to depart farther out into the Atlantic.
Hope the conservative heads up this morning was enough for most not to miss this one. Keep this day in the back of your mind as we move into fall… hopefully we’ll see more of these occurrences with out it being such a surprise.
Posted by WeatherFlow Meteorologist Dave Breckenridge