Tuesday will bring a cold front with a few stray showers pushing through during the early part of the day. Temperatures will fall over the course of the day, reaching the 40s by Wednesday morning. High pressure overhead will ease up the winds but also result in a cooler air mass overhead.
Humidity will fall away rather quickly behind the front. Dew point temperatures will fall below 50 degrees by Wednesday afternoon and not rise back above that mark until later Friday. Eventually, a small tug of moisture will return over the weekend with a smaller chance for some showers on occasion. Air temperatures will only rebound to the mid-60s with a pleasantly cool feel both Wednesday and Thursday.
Skies have been dry, but mostly cloudy, for much of our Monday afternoon following showers and thunderstorms earlier this morning. Most of the severe weather remained south of the immediate Stateline, with ongoing severe storms over eastern Michigan. Non-severe showers and thunderstorms have been ongoing downstate.
Conditions will remain mostly dry through the rest of the afternoon and early evening as ongoing severe weather continues across the central Plains. There, numerous severe thunderstorm and tornado warnings have been issued.
The expectation is for those storms to remain well to our west through the evening, forming into a line of storms as they move into western and central Iowa between 9pm and 11pm. Severe weather will still be possible west of the Mississippi River through the late evening, but instability does weaken a bit to the east.
An increasing low-level jet, stronger winds in the lower levels of the atmosphere, will likely help support at least some strength of the thunderstorms through the night, but the strongest of the storms may end up just to our south after Midnight. In fact, there are a few of our forecast models that have the northern edge of the line breaking apart by the time it reaches northern Illinois and southern Wisconsin.
If the northern extent of the line holds together, we should see showers and thunderstorms move in around Midnight, most likely between 1am and 2am. There should be an overall weakening trend but there is a low-end chance for a stronger wind gust or two. This would occur if the line holds together. If it doesn't then the chance for those stronger wind gusts would decrease quite a bit.
We've tracking the leftovers from yesterday's intense severe threat across the plains. The good news is that most of this activity is expected to remain under severe limits, but we are keeping a close eye on one particular storm. The National Weather Service has issued a Special Weather Statement for this cell as it moves into southwest Carroll County. As it tracks to the northeast, it could bring wind gusts up to 40 mph and pockets of small-sized hail.
Monday's Severe Threat:
We're not done yet unfortunately as another chance for strong to severe storms arrives tonight into Tuesday morning. Once this morning's activity clears out, the rest of Monday actually looks dry and warm with highs peaking in the low 80s.
The Storm Prediction Center has the highest risk for severe weather well to our south and west over areas in Kansas, Nebraska, and Missouri. As those storms organize and move east, we'll likely see a similar setup to last night, where storms gradually weaken on approach but still holding together enough to track through after midnight, with a least a chance for a few t-storms into Tuesday's morning commute. Gusty winds and small-sized hail will be the primary concern with any severe thunderstorm but again, instability or storm fuel remains quite as these storms move in from the west.
Cooling Back Down:
Temperature-wise, this incoming cold front will be strong, bringing a noticeable shift in our temperatures as we approach the middle of the work week. After enjoying afternoon highs in the low 80s, we'll take a step back into the 70s tomorrow, followed by a much cooler feel by midweek with highs settling in the 60s for Wednesday. It's a sharp reminder that even as we get a taste of summer warmth, spring can still deliver some quick and noticeable cool-downs!
Widespread severe weather is not expected, but some pockets of the storms could pack a punch. There are a few windows for storms over the next 36 hours, primarily during the overnight windows. Late tonight, storms will arrive from the West primarily after 2AM on a weakening trend but could bring some gusty winds and hail threats. Monday morning may have some carry-over storms from the nighttime window, with some intensification possible as daytime heating builds in. Most of Monday afternoon should end up dry, with another widespread round of storms arriving late Monday evening into the night.
The nighttime arrival of storms will be unfavorable for widespread severe weather, but storms look to hold together some of their strength as they approach the area well after midnight. Storms could arrive for Northwestern Illinois as early as 1-2AM and may be near the I-39 corridor around 4AM. While widespread severe weather is not expected due to the unfavorable diurnal timing, a few pockets of storms may pose a wind/hail risk. If storms maintain a bow echo shape, an isolated tornado cannot be ruled out either.
Those morning storms may linger later into mid-day, especially across Central Illinois. As daytime heating builds in, there may be some strengthening of those storms with another threat for damaging winds and hail. Most of the afternoon will end up dry, but an isolated storm may be possible with high levels of instability building in.
The main wave for Monday will again arrive much later in the evening/night. This time around, storms may arrive around 12AM Tuesday for some of the Western Counties, then push through the rest of the area into the pre-dawn hours of Tuesday. Storms will be in a weakening trend once again, but severe threats may be maintained a bit longer into Tuesday morning compared to Monday mornings risk with a bit stronger low-level winds supporting the line.
Both tonight and tomorrow night will feature scattered storms, with varying trends of severe weather risk. It will largely depend on how much storms are able to maintain their strength as they trek across Iowa into the late evening. Much of the Stateline is under a Level 1/5 Marginal Risk for Sunday night and a Level 2/5 Slight risk for Monday afternoon/night from the Storm Prediction Center outlooks. Be sure to have multiple ways to get warnings the next few nights, including ways to wake you up if a warning were to come in the middle of the night!
A few isolated to storms may begin the day Sunday, but the afternoon will dry out and warm up once again. High temperatures will likely push well into the 80s, similar to if not warmer than Saturday. Once again like Saturday afternoon, the humidity will fuel a lot of storm energy. But storms are unlikely after mid-morning with a lack of a trigger mechanism to initiate storms. Some shower and storm activity is possible to the North along a warm front.
While the afternoon will remain dry, it will be rather humid with dew point temperatures pushing the low to mid-60s: similar to if not a little higher than Saturday. Winds will increase feeding into the aforementioned warm front, with some Southerly gusts pushing 30 mph at times through the day.
Better coverage of rain and storm potential will arrive toward Monday morning. A few of these storms may pose a risk for gusty winds and small hail, but the severe threat early in the morning should be somewhat limited.
Monday afternoon could be a different story, however. Following that morning round of storms, the atmosphere could become primed for more storms with high levels of instability once again. But very similar to Saturday and Sunday, the atmosphere is lacking a trigger mechanism. Storm development during the afternoon will hinge heavily on that forcing (or lack thereof) and how morning storms evolve. Stay tuned!
With as warm and humid of a day it has been, we have remained remarkably dry. This despite a lot of uncapped instability, or storm energy, sitting overhead, fueled by the humidity at the surface. Usually, with an uncapped environment, you would see several storms develop using up all of this fuel.
But moisture and instability are just two ingredients for storm development. Storms also need something to jumpstart the process with a boundary or lifting mechanism along with wind shear to keeps the storms going. We do not have strong lift or shear right now, which is why we have remained dry so far Saturday evening.
But an outflow boundary/weak frontal boundary is sitting nearby with all that instability. That boundary may provide just enough of a trigger to get some isolated thunderstorm development between now and 12AM. Any storm that fully develops may pose a risk for gusty winds and some small hail, but the severe threat is not very high.
Slightly higher coverage of showers and storms may be possible after 12AM, with isolated to scattered activity carrying over into Sunday morning. The severe threat does not appear to be very high with the overnight storms, either. A large majority of the area will likely remain dry through at least most of the night.
Thunderstorm chances persist through much of the weekend, but there will be many dry hours between waves of showers and storms. The outflow boundary from Friday night's storms will be a potential focal point for additional showers and storms Saturday afternoon. The large majority of the area and time will remain dry, but an isolated storm or two remain possible through the day. Higher coverage of storms may be possible toward Saturday evening/night.
The Storm Prediction Center has maintained their Level 1/5 Marginal Risk for severe weather, indicating one or two storms may reach near severe limits. Limited forcing and shear will prevent more widespread and organized severe potential during the daytime. Better organization looks possible with the evening wave.
Another threat for severe weather exists Sunday. This will be more of a "watch and see" event compared to Saturday, as it depends on how Saturday night's storms evolve. Similar to Saturday, the large majority of Sunday should be dry, but any storms that develop from the West may pose a risk for severe weather as they progress East across the area. This may be another late evening risk, like Friday night.
Both days this weekend will be very summer-like with warm and even humid conditions. Afternoon highs will push into the mid-80s. Isolated storms remain possible each day, but both afternoons appear to be relatively dry compared to the evening/nighttime windows.
