Starting Week Of With Some Snow
Feeling More Like February Today
We've been spared snow since meteorological spring began back on March 1st. March averages about 5.6" of snow for the month. So far we are running just over 3" below average. We could make up much of that March deficit today. More on the snow below.
It will be cold enough for snow. We have only seen two days this month with below average temperatures. Today could be the third. Highs for today's date average 46°. Today's highs will be around 10° colder than average. Look for highs this afternoon in the middle 30s.
Blustery Beginning To The Week
Highs in the middle 30s combined with gusty winds off the lake will make it feel more like the 20s most of the day. Winds could gust to near 35 mph this afternoon. The winds will finally wind down late tonight.
Today will be the coldest day of the week. Highs most of the rest of the week should be around or above average. We will warm up to near 60° by the end of the weekend.
More Than One Shot At Snow?
There may be another shot at snow after today. A few models are hinting at some snow at least mixing in with rain Thursday. The GFS model keeps most of the next system's precipitation in the form of rain.
The accumulated snowfall forecast meteogram shows several different model solutions for snowfall this week. Today's first round of snow has a model range of as little as a half inch to as much as nearly 5". The second potential round of snow on Thursday shows a range of around an inch to nearly 3". Just a few of the models are squeezing out that much snow though late Thursday. Mostly models have little or no snow with this second system.
The National Weather Service has issued a winter weather advisory for areas along and west of I-39. The counties shaded in blue on this map have an advisory in effect from 10 AM until 7 PM today for 2 to 4 inches of wet snow or more. Snowfall totals for most of us in and around Chicago will be lighter, in the 1 to 3 inch range. While the ground is relatively warm, the high snowfall rates could create slick spots on our roadways. Freezing rain and sleet at the onset of this system mainly south of the city will also make for some hazardous driving conditions.
The latest GFS model snowfall accumulation forecast through early Tuesday morning lays down about 3 to 4 inches of snow in our area today into early tonight. It shows nearly twice that much for the northwestern part of Illinois.
The system is overcoming some dry air that has been in place the past few days. The brisk easterly breeze will initially bring in more dry air early today and undercut the snowfall totals here. I am expecting about 1 to 3 inches in total with a few spots approaching 4" well north and west of the city.
The European model is squeezing out around 1 to 3 inches of new snow today into tonight. It also suggests heavier snowfall for areas along and west of I-39 with up to nearly 8" in the far northwest corner of Illinois.
Mild End To This Month
The long range temperature probability forecasts continue to signal a relatively mild end to March. The latest 6-10 day temperature probability forecast has us outlooked for above average temperatures overall from March 20th through March 24th. The probabilities are high from here through the upper Midwest and Great Lakes. The longer range 8-14 day has us favored for above average temperatures overall from March 22nd through March 28th too.
The even longer range Subseasonal Experiment (SubX) forecast is signaling a mild end to March and above average start to April. The temperature anomaly forecast for the week ending April 2nd has us outlooked to be above average for the period. The forecast for the following week ending on April 9th keeps us above average overall. It suggests the temperatures will be even more above average compared to the forecast for the previous week. Both forecasts have the majority of the country milder than average overall.
Becoming Less Active
After a quiet start to March with nine straight dry days, the pattern gets a bit more active this week. Now the longer range precipitation probability forecasts suggest we may settle into a less active pattern by the end of the month. The latest 6-10 day forecast has us outlooked for above average precipitation overall from March 20th through March 24th but at the lowest range of probabilities. The longer range 8-14 day forecast has northern Illinois outlooked for around average average precipitation overall from March 22nd through March 28th. 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: Rain, freezing ran, sleet & snow becoming all snow, blustery High: 36
1" to 3" accumulation of snow with up to 4" well northwest of the city
Tuesday: A.M. drizzle possible, mostly cloudy Low: 32 High: 46 (cooler near the lake)
Wednesday: Partly to mostly cloudy Low: 32 High: 48
Thursday: Mostly cloudy, on & off rain (possibly mixing with snow at night) Low: 37 High: 47
Friday: Partly to mostly sunny Low: 31 High: 47
Saturday: Mostly sunny Low: 32 High: 52
Sunday: Mostly sunny Low: 36 High: 59