Cold Rain Coming Then Weekend Warm Up
Blustery Through Thursday
Tuesday was just the 4th day so far this month to come in below average. The high of 38° was the coldest we had seen in just over two weeks. It will be blustery for the next few days with gusty winds off of Lake Michigan. The water temperature in the southern part of the lake is in the lower to middle 30s. More clouds with eventually rain falling from them along with that brisk breeze of the chilly water will keep us below average through Friday.
Average highs for this time of the year are around 47°. Highs today will fail to get above the lower 40s with even upper 30s right along the lakeshore.
By late today winds will gust to near 30 mph. Thursday's gusts may exceed 40 mph. The combination of temperatures and wind will make it feel like the lower 30s most of today with wind chills dipping into the 20s this evening and staying there through Thursday.
60° By Sunday
While it was colder than average on Tuesday we are still enjoying a relatively mild March overall. The month is now running about 7.2° above average. After a couple of blustery and raw days our temperatures really bounce back this weekend. Saturday's highs will be in the 50s for most of us and lower 60s are in sight for Sunday. Those 60s will probably stick around at least through Tuesday.
The GFS model's temperature anomaly forecast for Sunday afternoon has us around 10° to 15° above average. That means highs in the lower 60s here. This milder March pattern could hang around through the end of the month. More on the long range temperature forecasts below.
A Cold Rain Coming
The GFS model is suggesting some light to moderate rainfall here beginning late today and into the morning Thursday. It looks like the heaviest rain will steer south of the city. A more active pattern may kick in next week with two rounds of showers and possible thunderstorms possible. The first would be late Tuesday into Wednesday followed by the next round on Friday.
The GFS model has moved the heavier band of rain further south of the city. It is suggesting most of us will see around a quarter of an inch of rain but well south of the city up to nearly two inches may fall in total through Thursday.
There is still the possibility that early Thursday some of the rain may mix with or change over to some wet snow north & northwest of the city. The accumulated snowfall forecast meteogram considers several different computer models. Just two of them actually squeeze out some measurable snow. The snow they do squeeze out is very light. I'm not expecting anything more than a dusting of some wet snow on some grassy surfaces well north and northwest of Chicago if we see anything at all.
Lakeshore Flooding Possible
Strong winds on Thursday could whip up some big waves and lead to some lakeshore flooding. A lakeshore flood advisory goes into effect at 4 a.m. Thursday and continues until 11 a.m. Friday for Lake and northern and central Cook county.
Here are the National Weather Service concerns for those areas:
* IMPACTS...Some water on low lying roads and property along the lakeshore. * ADDITIONAL DETAILS...Large waves combined with high lake levels will lead to minor flooding of lakeshore parks, trails, parking lots, and other low-lying areas along the immediate lakeshore. This includes portions of the Chicago Bike Path and Whiting Lakefront Park.
Lakeshore flood advisories have also been issued for Lake and Porter counties in Indiana.
Mild Signal For End Of Month
The signals from the latest long range temperature probability forecasts still suggest a milder than average end to the month. The latest 6-10 day temperature probability forecast has us outlooked for above average temperatures overall from March 22nd through March 26th. The signal is strongest from the Midwest through the Great Lakes all the way to the New England area. The longer range 8-14 day has us favored for above average temperatures overall from March 24th through March 30th 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.
Trending Towards Dryer Pattern?
The longer range precipitation probability forecasts have us moving from a moist pattern to a near normal pattern by the end of the Month. The latest 6-10 day forecast has us favored for above average precipitation from March 22nd through March 26th. The longer range 8-14 day forecast has northern Illinois outlooked for around average average precipitation overall from March 24th through March 30th. 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: Cloudy, becoming blustery, rain developing late High: 43 (colder near the lake)
Thursday: Rain mainly early possibly mixed w/snow northwest, windy Low: 37 High: 40
Friday: Sunny, a bit breezy Low: 29 High: 46 (colder near the lake)
Saturday: Mostly sunny Low: 29 High: 55 (cooler near the lake)
Sunday: Partly to mostly sunny Low: 36 High: 62
Monday: Partly to mostly sunny Low: 43 High: 62
Tuesday: Mostly cloudy, chance of light rain Low: 42 High: 60