ROCKFORD (WREX) — A large-scale pattern is going to build the heat and humidity, but thunderstorm chances are going to be limited. As July gets underway, the hottest month of the year on average is off to a scorching start.
What the heck is an "omega block?":
When one looks at the synoptic, or wide scale, an omega block is a large blocking pattern.
For gardeners, think of it as a kink in a water hose. Blocking patterns are notorious for bringing in the heat to the Central U.S. and that is exactly what is going to unfold through the second half of the week.
Two troughs of low pressure keep the East and West Coasts cooler and unsettled. In fact, temperatures in parts of Nevada Tuesday morning dropped into the 30s. On the opposite end of the weather spectrum, high pressure leads to widespread heat advisories across the nation's midsection.
No heat advisories or warnings are in place locally, but that could change depending on how warm heat indices climb. As of early Wednesday, it looks like heat index values are going to remain below heat advisory criteria for the upcoming weekend.
This building dome of heat is going to effectively squash all precipitation chances, as high pressure promotes sinking air. The sinking air is actually part of what makes this pattern so hot. As air sinks, it compresses, thus the overall air mass warms! How neat is science?
What about rain chances?:
As high pressure continues to build beyond midweek, rain chances become increasingly sparse. A very widely scattered shower or storm is possible Wednesday afternoon. The best chance for this exists west of a line from Freeport, through Byron, to Paw Paw. Any storm that manages to develop is likely to do so during the late afternoon and early evening.