High temperature forecasts get tricky this time of year. There are several reasons for that.
- Dry air heats and cools very efficiently. With dry air, it is common for the temperature to swing 25°-32° from morning to late afternoon. Introduce more moisture in the lower levels of the atmosphere - measured by the dew point temperature - and air doesn't warm as easily.
- Increased low level moisture aids development of cloud cover.
- The Indianapolis airport thermometer has historically struggled to click from 89° to 90° the first time of each year. This has been the case for decades. Something meteorologists have to factor in when forecasting the high temperature in Indianapolis.
All of the above items are in play for Monday's and Tuesday's forecast. Because of that, I have lowered the forecast high in Indianapolis for both days. We may very well hit 90° Monday, but I'm hedging my bet on 89°.
You should notice a jump in humidity Tuesday as more low level moisture streams in to Indiana. Dew points are projected to climb in to the lower 70°s.
Once dew points cross the 60° threshold, it begins to feel a little more uncomfortable. Once dew points cross 65° and 70° it feels.... "yuck". Yeah, that's an un-official/official meteorological term. I like to refer to it as "muggly". It is simple math. Muggy + Ugly = Muggly
So we should see our first taste of the mugglies starting Tuesday and continuing for the rest of the week.
FEAST OR FAMINE
Remember all the rain we had in May? It was the 8th wettest May for Indianapolis in the previous 146 years. The tide has turned. The water spigot has turned off.
Through today, June 11 Indianapolis has only recorded 0.02" of rain. That makes this the driest start to June since 1084 and the 4th driest start to the month since 1871.
SOME RELIEF INSIGHT
There are signs of rain coming our way, albeit the rain will be scattered. Medium-range computer models suggest the chance for rain will start to increase Tuesday, with near daily chances for rain through next weekend. However, it doesn't look like widespread rain (with an exception next Sunday).