Monday, July 17, 2017

Heat and Humidity Bring an Active Storm Pattern

It's been a great start to the work week with clear skies, low humidity, and mild temperatures.  The reason for this is a high pressure system off to the east over Michigan.  This has been keeping the heat and humidity out of our area, and has kept the storms and clouds at bay off to the west.  This high pressure influence will continue through the overnight, where temperatures will cool down to the upper 50°s.

However, the nice weather doesn't last forever as that low pressure system off to the west will begin to influence our area.  Most of tomorrow will be nice, but the high will track southeast during the afternoon and the low will bring in a warm front around 7pm.  This will bring back the heat and humidity, and allow for thunderstorms to develop.  We are under a Marginal Risk for severe weather in Jo Daviess, Stephenson, Green, and Rock counties, with a slight risk in place for northeastern Iowa and southeastern Minnesota.  The storms will track towards our area, but they'll get weaker as they get closer to our area as we'll be farther from that low, so instability will be lower for us.  At the most, we'll see nickel-sized hail with our storms.  Storms are expected to die down around 1am, but rain will linger afterwards.

We have an active storm pattern set up for this week, with a pool of hot and humid air sitting in the plains and a strong upper-level ridging in the jet stream.  These two things combined will allow for strong low pressure systems to develop out in the plains, which will allow for a strong inflow of heat and humidity to move through our area.  Along with that, the strong inflow will be continuous and last for most of the week.  This strong heat and moisture inflow will allow thunderstorms to develop easily, and also increase the chance for strong to severe thunderstorms with that upper level ridge in place.  Stronger thunderstorms are expected after Tuesday evening, but weaker thunderstorms will be expected for the weekend as the jet stream will return to a more zonal flow, pushing the low out of our area.

With this heat inflow, temperatures will get into the upper 80°s to low 90°s, with dew point temperatures looking to be in the mid 70°s.  This will allow for heat index values to be around 100°, so take precaution if you plan on going outside from Wednesday to Saturday.

Temperatures will cool down a little to start next week, with a chance for rain on Monday.

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