ROCHESTER, N.Y. (WROC) — Remember this past week back from Sunday to Wednesday when the weather seemed like it wasn’t changing at all, but rather staying in the same cloudy pattern?
While you’d be right about that, we also have some interesting numbers to back up a fairly impressive streak for Rochester.
Typically when we do a write-up about any notable weather, it’s about the “extremes” whether that be the record high or low temperature recorded for that day, a record-setting amount of rain, or abnormally dry conditions.
This story is a little bit different, but still very cool.
Our very own Meteorologist James Gilbert asked our friends over at the National Weather Service to compile some data regarding the latest lack of diurnal temperature change.
What is a diurnal temperature change? It’s the variation between the highest and lowest air temperature that occurs throughout the same day. For example, on a “normal” day we typically see a diurnal temperature change of around going from the 50s in the morning to the 70s during the afternoon.
Instead, 5 days ago on September 4th at 1:54 am the temperature dropped from 70° to 64°. It wasn’t until September 7th at 11:54 a.m. when the thermometer finally broke out of the 60s and back into the 70s.
This put Rochester at a streak of 82 consecutive hours spent in the 60s if you include the first and last hours of the streak (81 at official count according to the National Weather Service).
That may not seem very intriguing at first thought, but historically on record, there have only been two longer such streaks. The second longest consecutive stretch spent in the 60s was 83 hours from September 13th to the 16th in 2006. The longest streak goes from September 19th to September 23rd in August of 1961.
How does that happen?
It all depends on the weather setup at play and how long it sticks around. This was a unique situation for sure, but not one that we don’t see every so often around here in western New York.
Variables like clouds, sun angle, albedo, pressure rises and falls, and even precipitation or lack thereof all work together to cause temperature fluctuations throughout the day.
The most common setup to get the least amount of temperature change between the daytime and nighttime occurs when an area of low pressure is located overhead for a long period of time resulting in a blanket in cloud cover, and that’s exactly what happened earlier this week.
The area of low pressure was essentially caught in an atmospheric “blocking” pattern that allowed the low to move very little over a span of 3 days. The constant cloud cover produced as a result acted like a blanket or an insulator.
While temperatures fell into the 60s the cloud cover kept the sun from warming things up much further and kept the temperature from dropping during the night as well.
Pretty cool, right?