A strong fall storm system is currently providing Iowa with plenty of wind and severe weather over the southern plains. Our sea level pressure has dropped below 1000 mb for the first time since May. The featured chart looks at some climatological aspects to the mean sea level pressure (MSLP) reading for Des Moines. The top chart presents the range of observations for each day of the year since 1960. The range in pressure is much smaller during the summer time due to the strong storm system tracks being further north and the air mass dominance of warm air. The bottom chart is an attempt at showing the relative frequency of pressure readings and the variability of the fall, winter, and spring months can clearly be seen. These larger differences in pressure help to drive stronger winds as will be the case for today!

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Tags:   mslp   pressure