Monday, May 29, 2017

Heavy Rainfall Returns by the End of the Week

Seems we just can't catch a break this month with the rainfall.  There have only been a handful of days in a row that we've had dry skies.  Every other day, even if it was just a little, recorded rainfall.  A few showers are popping up on radar Monday evening as low pressure spins over the northern Great Lakes.  And until that low leaves, the rain chance continues.

We'll see the threat for widely scattered showers develop again Tuesday afternoon and evening.  Coverage may be a little more than what occurred Monday afternoon. 

But the rainy month has not only affected northern Illinois, it's had a major impact on other states across the country.  Earlier this month significant flooding occurred over the state of Missouri wiping out farmland, towns and major roadways.  Just this past weekend flooding occurred in Branson, MO killing at least two with one person still missing.  So, why have we seen such an increase in heavy rain events?  One possible cause is climate change.  According to Climate Central, for every 1°F of temperature increase, the atmosphere can effectively hold 4 percent more water vapor.  Meaning as the atmosphere continues to warm, it's capacity to hold more water vapor and produce heavy rainfall is increasing.  Climate Central also notes that Missouri is one of the states with strongest trends in heavy precipitation events.

Locally, let's take the rain from this past weekend as an example.  A line of non-severe thunderstorms rolled through early Sunday morning with the heaviest rainfall concentrated from central and northern Ogle County up to the state line.  Rain reports of at least one inch, or more, were recorded. 

Looking back to the month of April, Illinois recorded its second wettest April on record - according to State Climatologist Jim Angel.  Not only that, but three of the top five wettest Aprils since the late 1800's have occurred since 2011.  Jim Angel also notes that the period January - April was the warmest on record for the state with an average temperature of 44.5 degrees, 5.4 degrees above normal.  As we continue to experience a warming climate, the threat for heavy rain events will also continue.

A stationary front will rest over Iowa and Illinois Thursday through Saturday.  Gulf moisture will be pulled north with high pressure over the southeast.  With little movement in the front, heavy rainfall is possible between Thursday evening and Friday evening.  Some of those showers may even continue into Saturday if the front isn't pushed far enough south.

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