Thursday, May 21, 2020

Big Changes Ahead for the Holiday Weekend, Including Warmer Temps & Thunderstorm Chances

It took a while, but cloud cover during the day yesterday eventually gave way to some much needed sunshine. This allowed our high temperatures to climb into the upper 60s, which is still below average for this time of year as were typically in the low 70s. In fact, yesterday marked the 14th below average day of this chilly month of May. Fortunately, signs for big changes continue as we inch closer to Memorial Day weekend, including our first 80° day of the year.
Overnight, cloud cover once again was pretty quick to spread across the region. This is all because of two systems, the high pressure system that is over New England and the closed off low  that is sitting over the Tennessee River Valley. The location and the spin of these two system have placed the Stateline in the perfect spot for additional moisture to stream in, leading to this morning's cloud cover. Throughout the day today, cloud cover is going to remain tight as this upper-level low slowly retrogrades northward. A combination of the cloud cover, and our easterly surface winds are going to limit our heating potential this afternoon as highs climb into the upper 60s-low 70s. Hi-res models were consistent on developing a few sploshes of patchy drizzle by this evening. However, odds of that happening are on the low side, leading to many dry hours for our Thursday.

We'll see the return of southeasterly flow by Friday morning, which will help continue to influx moisture into the Stateline. This will allow this cloudy week to continue as mostly cloudy skies to persist into Friday morning. Fortunately, it looks like we will have a dry start to the day tomorrow, with models picking up on a slight chance for a spotty shower or two during the afternoon. As far as highs for Friday, the southeasterly flow will manage to help temps climb back towards seasonable in the low 70s. 

Now, let's talk about those 80°+ days. So far, in 2020, we have yet to record an 80 degree day at the Rockford International Airport. In fact, our highest temperature observed this year was 78° back on April 7th. It's been a long time coming, in fact since October 1st, 2019. But, I am happy to say that we look to see our first 80° degree day of 2020 over Memorial Day weekend. However, it does come with a few rounds of showers and thunderstorms.


As we head into the holiday weekend, an area of high pressure will settle across the Southeast, allowing for a train of deep moisture to track northward towards the Stateline from the Gulf of Mexico. Saturday morning is going to start off with with a few showers and thunderstorms. As of this morning, it looks like severe weather isn't expected with these storms, but locally heavy rainfall and flash flooding will be possible.


Towards the end of the weekend, a warm front will switch our surface winds to the south and southwest, bringing not only the first 80° day of the year to the Stateline (about time). However, this extra plume of humidity and warmth will lead to thunderstorm chances for the afternoon. Once again, the threat for severe weather seems to be on the lower side. But we'll have to watch out for any flash flooding, especially along the local rivers. We've been fortunately to have a nice dry stretch of weather with no heavy rainfall potential over the past few days. But any high amounts of rainfall will once again bring an uptick in river levels heading into Memorial Day and into next week.













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