|The Cutoff Low that will be with us for a few days.|
A low pressure system is an area of rotating rising air. Hurricanes, tornadoes, dust devils, waterspouts and those red "L"s you see on the weather map are all low pressure systems. All lows rotate counter-clockwise in the northern hemisphere (clockwise south of the equator). To be completely accurate a few small scale lows like tornadoes, dust devils and water spouts rotate clockwise in the northern hemisphere (counter-clockwise southern hemisphere) because of special circumstances.
In tornadoes the air rises violently and in an EF5 the upward velocity may be has fast as 160 mph or more. In the cut off low that will affect us for a few days the air rises much more gradually a realistic figure is half a mile per hour. Because the cut off low covers thousands of square miles much more energy is involved than a powerful tornado.
Even though the upward motion is relatively slow it is sufficient to create clouds and rain, but with only restricted amounts of moisture and the gradual lift showers are scattered and no heavy rain falls.
The showers are most likely during the warme4s part of the day when the upward motion is enhanced by the rising air warmed by the surface t hat was heated by the sun.