Weather items on the ‘Early Spring’ checklist; what do they say?
Feb 19, 2020 10:22AM
By Mark Torregrossa of mlive.com - February 19, 2020
There are three weather conditions I would put at the top of a checklist that points or doesn’t point toward an early spring. Let’s take a look at those three indicators, and which way they are pointing.
How much winter we have to burn off is the premise behind two of these weather factors affecting an early spring. The amount of ice on the Great Lakes and the amount of snow on the ground are two factors standing between us and early springs.
This year we don’t have much Great Lakes ice to get rid of before Great Lakes waters start to warm. The graphs below show how the ice cover now compares to the long-term average.
Current ice cover percentage (red line) versus the long-term average (blue line) on Lake Superior.
The current ice cover on Lake Superior is only about half the normal ice cover at this time. Cold spring winds coming from the northwest across Lake Superior are even colder if Superior is covered in ice. Put a checkmark in the early spring column based on Lake Superior’s ice cover.
Current ice cover percentage (red line) versus the long-term average (blue line) on Lake Michigan.
Lake Michigan has half the normal ice cover.
Current lake ice percent(red line) versus long-term average (blue line) on Lake Huron.
Lake Huron has less than half the normal snowfall.
Lake Huron is a key lake for delivering cold air. The raw northeast winds that blow over Lake Huron in March and April can put the big chill on Lower Michigan.
Snow on the ground across the U.S. is also a big factor in the fight for an early spring. Deep, compacted snow chews up a lot of heat over the Plains. Without much snow, the heat makes it to the Great Lakes and starts to warm up Lake Michigan.
How does this year’s snow cover stack up? At first look, the amount of snow is about normal for this time of year.
Current snow cover on February 17 is shaded in white.
Above is the current snow cover.
Snow cover anomaly for January 2020 shows areas around Michigan having less snow than average. Image: Rutgers Snow Lab
The brown areas south of Michigan are areas with less snow cover than average. Put another checkmark in the early spring category.
I’ll admit the snow cover could change dramatically with one big storm. But we will have a tough time building a solid shield of thick, compacted snow going into March.
The final thing on my list for an early spring is just the overall weather pattern. Has the upper-air flow fallen easily into a colder than normal pattern or a warmer than normal pattern or a normal pattern? You know the answer to that question. Our flow has been warmer than average. December averaged around six degrees warmer than average. January was also around six degrees warmer than average. February is pacing at three to four degrees warmer than average.
Now we all know Great Lakes weather can change on a dime. We could have a warm winter and then flip-flop to colder than normal temperatures. Is there any sign of that happening?
Upper-air flow for the next 10 days. Red shows flow that is warmer than average. (weathermodels.com)
The animation above is the forecasted upper-air flow for the next 10 days, through February 28, 2020. While we will have a couple of one to two day cooldowns, you don’t see anything that looks like a full-scale weather pattern change.
Put our final checkmark in the early spring column.
Right now everything is pointing toward an early spring. But just what is an “early spring?” I wrote about early springs here.
To read the original article and related weather reporting, follow this link to the mlive.com website. https://www.mlive.com/weather/2020/02/3-weather-items-on-the-early-spring-checklist-what-do-they-say...