Mild For March Now But Snow Could Be Coming
So Long 60s But Still Above Average
After four straight days with highs in the 60s we will fall back into the 50s for highs today with just 40s along the lakefront. 45° is the average high for this time of the year so we will still be around 5° to nearly 10° above average. March has gotten off to a rather mild start with temperatures now running 9° above average overall. 9 out of 11 days this month have been above average so far.
Highs today should reach into the lower to middle 50s but cooler along the lakeshore with middle 40s there and a light breeze off the lake.
The unusually mild March air that was responsible for record or near record temperatures earlier this week has shifted to the east. Several locations from the eastern Great Lakes to New England and as far south as Virginia saw record warm temperatures on Thursday.
Wind Brings Waves & Keeps Us Cool
We will have a light breeze off the lake today and tomorrow with the wind strengthening Sunday into Monday. That wind could whip up fairly big waves late Sunday into early Monday that might produce at least some minor lakeshore flooding, especially along Lake County's shoreline in Illinois and Wisconsin's southern lakeshore.
Whenever that wind blows off the lake this time of the year it tends to keep us cooler at the lakeshore compared to areas further inland. Lake Michigan's water in the southern part of the lake is now a chilly 36° to 39°.
Falling Back Below Average
We'll fall from the 50s to 40s for highs by Sunday with just 30s expected on Monday. Gusty winds on Sunday will make it feel like the 30s and wind chills by Monday will drop into the 20s for most of the day.
Snow Still In Question
The GFS model has been going back and forth with the possibility for snowfall early next week. The latest GFS model's meteogram shows a wintry mix turning to rain on Sunday. Earlier runs of the model suggested this would be mainly snow. The slow moving system that gives us the chance for snow next week is still a few days away and this type of system is notoriously hard to forecast this far out. In other words, stay tuned.
The models giveth and taketh away. The latest GFS model snowfall accumulation forecast Wednesday morning now scoots all the snow up to our north. Most of that snow would fall later Monday into Tuesday.
The European model has changed places with the GFS model. Yesterday the Euro was keeping the snow to our north but now it has a swath of snow forecast across northern and central Illinois. Most of this would fall later Monday into Tuesday. So again there is no model consensus and for now, low confidence in the snowfall forecast for early next week.
The models are in agreement that a major snowstorm will pound portions of Colorado and Wyoming. Snow will begin there today and this slow moving system could dump on them all the way into early next week. Models are suggesting snowfall will be measured in feet in some areas.
Milder By The End Of March
The long range temperature probability forecasts flip us from a cooler than average pattern to a milder than average pattern. The latest 6-10 day temperature probability forecast has us outlooked for below average temperatures overall from March 17th through March 21st. We are on the low end of the probabilities though. The longer range 8-14 day has us favored for above average temperatures overall from March 19th through March 25th. We are again on the low end of probabilities so the signals aren't very strong.
The even longer range Subseasonal Experiment (SubX) forecast brings a milder end to March. The temperature anomaly forecast for the weekend ending March 26th has us outlooked to be around average for the week. The forecast that looks at the end of March and the start of April has us returning to above average temperatures overall for the week ending on April 2nd.
The longer range precipitation probability forecasts have us generally drying out towards the end of the month. The latest 6-10 day forecast has us outlooked for below average temperatures overall from March 17th through March 21st. The longer range 8-14 day forecast has northern Illinois outlooked for below average average precipitation overall from March 19th through March 25th. The risk for spring flooding is above average for many area rivers. More on that below.
The Climate Prediction Center's seasonal forecast for spring suggests a mild and moist pattern overall here. The temperature probability forecast for the months of March, April and May have us outlooked for above average temperatures overall. The precipitation probability forecast for the same period has us outlooked for above average precipitation overall.
Spring Flood Risk Forecast
The National Weather Service considers many risk factors for spring flooding. They include snow cover, soil moisture, and current river conditions.
"A significant snow cover with high water content can increase the chances of flooding once warmer weather melts the snow. Elevated soil moisture conditions reduce the amount of rainfall that is soaked up by the ground and increase the amount of water that then runs off into area streams. Above average river levels reduce the river rise required to reach flood stage, while below average river levels would require an increased amount of river rise to reach flood stage."
Their latest forecast suggests the flood risk is above average for many of our area rivers. The Des Plaines and Fox rivers in particular need to be watched closely.
Here is my 7 day forecast:
Today: Partly to mostly sunny (cloud build late) High: 54 (45 lakefront)
Saturday: Partly to mostly sunny Low: 30 High: 55 (cooler near the lake)
Sunday: Mostly cloudy, becoming windy Low: 36 High: 47 (cooler near the lake)
Monday: Cloudy, chance of rain and snow Low: 32 High: 39
Tuesday: Partly to mostly cloudy Low: 32 High: 46
Wednesday: Partly to mostly sunny Low: 32 High: 48
Thursday: Partly to mostly sunny Low: 31 High: 45