Cooler Tuesday, Tranquil Weather Continues

Tomorrow marks the 1st day of April (April Fool's Day). With all jokes aside, it was a very wet month of March in Rockford. Saturday's two inches of rain pushed the monthly rainfall total to just over five inches. A surplus over two and a half inches. This puts March 2020 as the fourth wettest March on record, following 1961 when 5.62 inches of rain fell. In fact, the wettest March on record was back in 1944 where the airport observed 6.20" of rainfall.

Fortunately, the dry spell we were subjected to yesterday is going to continue into our Tuesday, minus the abundance of sunshine. An area of high pressure has settled to the north of the region, and in doing so, changing our surface winds to the northeast. These winds are crossing over the waters of Lake Michigan dragging moisture onshore. All of this moisture will result in mostly cloudy skies for our Tuesday, and also much cooler highs this afternoon. Highs later on will top out around the mid to upper 40s, landing about 10-15° cooler than highs yesterday. A sprinkle or two is also possible, especially in our eastern areas. Depending on how far west the cloud cover stretches, areas to the west and southwest could see a decent amount of sunshine today.

Thankfully, the chilly weather doesn't last long, as today is going to be the coolest day of the 7 day forecast. Wednesday brings a return to more seasonable temperatures as a ridge of high pressure begins to build into the mid-levels of the atmosphere. This will allow for warmer air to slide northward. Highs for most locations will climb into the mid 50s with a mix of clouds and sunshine expected. Cloud cover will continue to increase into Thursday ahead incredibly slow-moving system. This system will bring rain chances for the end of the week, but also the return of 60° temps!

Month to Date: Fourth Wettest March on Record

Even though the clouds stuck around during the afternoon Monday, skies remain dried and will stay dry for at least the next couple of days. This is some welcomed news after a very rainy weekend for most in northern Illinois and southern Wisconsin. Over two inches of rain came down in Rockford between Friday night and Saturday night, pushing the monthly rainfall total to just over five inches. This also put March as the fourth wettest month to date on record, following 2009 when 5.39 inches of rain fell through the 30th.

March will end dry, but cloudy, as winds shift more off Lake Michigan Tuesday afternoon. A push of cooler air aloft will help lock in the cloud cover for much of the afternoon, keeping temperatures in the mid 40s area wide. A return to southerly winds Wednesday and Thursday will bring temperatures back up into the 50s, and even up near 60 degrees by Thursday and Friday.

Rain chances will remain limited as our upper level flow in the atmosphere remains split and

blocked. The sub-tropical branch of the jet stream will remain active but positioned more across the southern states, while the northern branch remains focused more near the U.S./Canadian border. This jet stream will also be a little 'blocky' through the week, meaning little opportunity for active weather as low pressure remains centered over the Northwest and Northeast. By Thursday the pattern will gradually begin to break down and this will bring our next chance for rain by the end of the week, at the earliest.

Sunshine Returns Ahead of Tuesday's Cool Down

Did anything in your yard blow away yesterday? It wouldn't surprise me if you said yes to that question because Sunday was a very windy day across the region. Under yesterday's Wind Advisory, wind gusts all across northern Illinois topped out between 40 to 50 mph.

Our top observed wind gusts came out of the Rockford, Savanna, and Hebron areas with a wind gust of 49 mph. A breeze does hang around with us for our Monday. But thanks to an area of high pressure, the forecast is definitely going to be something to smile about.

Temperatures were a bit chilly to start thanks to a northwesterly breeze that lingered into this morning. This was the reason behind wind chills across the area registering in the upper 20s and low 30s to start. Thankfully, the cooler weather doesn't hang around long today, as highs climb into the low to mid 50s this afternoon. Winds throughout the rest of the morning and early afternoon could manage to gust up to 20 mph at times. But, I am happy to report that our Monday is going to be filled with sunny weather. An area of high pressure that has taken over much of the plains this morning will shift eastward this afternoon. This will keep the atmosphere above us pretty dry through the day allowing for a partly sunny afternoon. In other words, take anytime today to get outside and grab some much needed fresh air.

The sunshine we see today will be replaced by partly to mostly cloudy skies and below average temperatures. In fact, highs will end up about ten degrees below average by tomorrow afternoon, as highs climb into the mid to upper 40s. Skies Tuesday morning will start off partly cloudy, but then cloud cover will quickly increase area-wide as northeast surface winds helps drag in a bit of moisture off of Lake Michigan. The cloud cover along with these northeasterly winds will be the main factors in Tuesday's cool down. This cool down however is short lived as temperatures for many across the area climb back into the mid 50s by Wednesday afternoon. 

EF-1 Tornado Reported in Ogle County Saturday Evening

The National Weather Service has rated the tornado that moved through central Ogle County Saturday night as an EF-1, with peak winds estimated at 100mph. The tornado touched down two miles east of Oregon around 9:13pm and was on the ground for 7 miles as it traveled to the northeast, just before lifting southwest of Stillman Valley around 9:24pm.

The tornado traveled mostly over rural areas damaging trees and power lines, but did damage

Damage to building on German Church Road in Ogle County

 

a few outbuildings and barns. This tornado originated from a severe storm that had produced several tornadoes earlier in the evening across western Illinois, before moving into Whiteside County and producing an EF-1 tornado southwest of Tampico. A Tornado Warning was issued for Whiteside County around 8:30pm Saturday evening, and then for Lee and Ogle counties shortly before 9pm. The warning was then extended into Winnebago County and included the city of Rockford, however, the stronger rotation of the storm just passed southeast of the downtown area. Rotation continued to weaken allowing the tornado warning to expire at 9:45pm.

Wind Advisory through Sunday Evening

A Wind Advisory remains in effect for northern Illinois through 7pm Sunday evening. Winds were quick to increase following the passage of a strong storm system Saturday night. That same storm brought severe weather and numerous tornadoes across the Midwest, including reported tornadoes in Ogle and Whiteside counties.

Winds Sunday afternoon have been gusting close to 45 mph, with a few gusts topping close to 50 mph. Wind speeds will gradually subside

through the late evening, but remain breezy through the night. Northwest winds will pick back up Monday, gusting 20-25mph before relaxing Monday late afternoon. 

Potentially Severe Weather Nears Stateline

A strong midlatitude cyclone pushing across the Plains at the time of publication is expected to have significant impacts on the Stateline late Saturday afternoon and evening.

As of 2:00 PM on Saturday, the storm in centered over northeastern Nebraska with its cold front extending eastward across northwestern Missouri, southeastern Iowa, and central Illinois. This warm front is expected to be the initiator of strong to severe weather across north and northcentral Illinois. As the system propagates northeastward through central Iowa, the advancing warm front will lift warm, moist air from the surface into a rapidly destabilizing atmosphere. Ample vertical wind shear and strong vorticity streams closer to the storm’s triple point promote long-lived, rotating updrafts and, thus, supercell development.

Diabatic heating will play a big role in the severity of the thunderstorms. Significant warm air advection will be present with the approaching warm front which should pull temperatures in the Stateline into the lower to middle 60’s by late in the afternoon. Although additional sunlight could bring temperatures closer to, and possibly exceeding, the 70’s. This slight increase in temperature could help destabilize the atmosphere even further thus raising the probability for supercells including tornadoes and hail. Skies will remain mostly cloudy for the remainder of the afternoon, but notable clearing is possible at times.

 

All criteria for severe weather are possible including strong winds, sizable hail, and tornadoes. With significant low-level wind shear expected, organized vorticity streams promote the development of lengthy and strong low-level helicity swaths. This increases the probability of long-lived tornadoes. With an environment able to sustain strong updrafts, large hail is also a big concern with the approaching storm system.

The primary time frame for severe weather in the Stateline is between the hours of 4:00 PM and 8:00 PM, though the greatest chance for severe weather looks to arrive closer to 5:00 PM and lasting through around 7:30 PM. The Storm Prediction Center has issued a moderate risk, category 4 of 5, for severe weather for much of central and northcentral Illinois. The moderate risk encompasses Whiteside and Lee Counties, reaches into far southern Carroll and Ogle Counties, and includes the southern half of DeKalb County. This includes the cities of DeKalb, Sterling, and Amboy. An enhanced risk stretches nearly to the Illinois-Wisconsin stateline and includes the cities of Rockford, Freeport, and Galena. The Storm Prediction Center has also issued a 10 to 15% hatched probability for tornadoes as well as a 30% hatched probability for hail for majority of the Stateline. A “hatched” a probability is a 10% or greater probability for significant impacts. For hail, significant would mean two inches in diameter or larger and a significant tornado is an EF-2 tornado or stronger.

Have a plan in place for when severe weather, particularly a tornado, threatens your immediate area. Have a predetermined storm shelter that is easily and quickly accessible to you. Have multiple ways of receiving the most up-to-date weather information, one of these means should still be available to you should you lose power (weather radio, cell phone, etc.).