Good evening everyone. In my last article here - I talked about the potential for a bigger storm system to develop and affect Illinois on Sunday. We're still seeing this system appear on the models, and others have taken notice too.
In fact, I've already noticed a couple social media posts calling for a big snowstorm. While the system certainly carries the potential, there are a couple noteworthy things to point out at this time.
1 - Models still disagree on the placement and timing. Ill show below, but models still aren't in agreement on when this potential system will arrive. Some show Sunday, others Monday.
2 - The track could change drastically. One thing thats so hard about forecasting winter storms is even a 10 mile shift in the storm center can change the amount of snow someone receives by a great deal, or even mean the difference between seeing any snow at all VS just rain.
3 - It could still be too warm to snow. Ahead of the system, rapid warm air advection will take place. In fact, if certain forecasts pan out, much of IL could see temperatures in the 50s and 60s the day before. Cold air will filter around the backside, but will it be cold enough to snow? Some models say yes, others say barely.
So at thit, we continue to closely monitor the evolving forecast to get a better idea of what may happen. All we need for you to know is that something still appears to be brewing in the Sunday/Monday timeframe.
A first guess by me? Illinois will see mostly a rain event from this one, but these systems have a history of appearing too far to the north and west on the models when we are 5-7 days away, and a southward shift in the forecast track - which would put us at a bigger risk for snow - would not surprise me at all.
So lets take a look at some models and what we are seeing. First the GFS which has been pretty consistent in showing Sunday development. This seems like a good bet at this time.
But then we have the GDPS which shows a Monday system. At least they are both consistent in the strength and location, so there is that.
Here is a look at what we call an ensemble plot. Basically the model, in this case the GEFS is ran multiple times to see what the outcomes are. Here we can see many of them develop a storm, but with varying intensity and location. At this range this is pretty good agreement actually and confidence begins to increase.
And last but not least, everyone's favorite. A snowfall map. Given the current expected track it would seem most of the heavy snow targets Iowa and Wisconsin, but it is pretty close to our border. This is why we'll be watching the storm track closely. Shift it south or east by 25 miles and at least northwest Illinois could be in for a heavy snow. Unfortunately given the warm, wet nature of this system it could be that slushy heart attack type snow. This will not be a particularly cold system.
So like we always say everyone, stay tuned for the ever changing updates to the forecast! Especially as the days draw near.
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Once again a Happy Thanksgiving and safe travels to all!
Thanksgiving week will start out featuring mostly quiet weather for Illinois. A couple weak weather disturbances will move through the state Monday and Tuesday morning. The first will breeze through southern Illinois early Monday, bringing some light mixed precipitation. Another will drop south Monday night and early Tuesday morning bringing a shot at some light snow across mostly northeastern Illinois. Right now any snow accumulation looks to be minor at best - 1" or less.
Temperatures will quickly moderate in the middle of the week as southerly flow returns. By Thanksgiving we should see temperatures at a comfortable seasonal level. Mid 40s north and 50s south. With the sun coming out if should feel nice - especially when compared to our recent cold snap.
Medium range models hint at things switching to the more active side Friday and beyond - but with typical track and timing differences. One potential weather maker arrives Friday bringing mostly a light rain threat due to temperatures returning to the mild side.
Afterwards, a stronger low pressure system may develop bringing a chance for a heavier, wind driven rain. If enough cold air wraps around the back side we could be talking about our next snow maker by the weeks end. That system is still 7+ days out though, so we will see how things continue to evolve.
Here are the highlights mentioned above as seen on some of the models.
Potential for light snow on Tuesday - not looking like too big a deal right now.
Approximate highs for Thanksgiving - with mixed sun and clouds!
Friday weather maker - right now temperature profiles support mainly a light rain threat.
Models hinting at a stronger low pressure system to develop around Sunday. We will see if this becomes anything.
So right now there isn't too much to be concerned about - but we do have a couple systems to monitor, especially towards the later part of the week.
From all of us here at ISC we hope you have a wonderful Thanksgiving and safe travels to all your families!
Good afternoon, Illinois residents. Our first significant winter storm of the upcoming winter season is about to get underway. Watches have been upgraded to Advisories and Warnings (see graphic below) in advance of the wintry precipitation.
'Overall, not much has changed from yesterdays forecast. Trends have shown a slight shift west with the storm center track, and much of the model guidance has shifted the snow potential a little further north and west than compared to yesterday.
Forecast amounts haven't changed much, with 4-6" expected across areas that are in a winter storm WARNING. Locally higher amounts are possible in these areas depending on the strength of any convective snow bands.
The below model plot, taken from the hi-res NAM shows the precip potentially reaching further north and west than we saw yesterday, and trends seem to support this. This will not occur until Thursday morning however, when the storm is in a weakening phase. We are not expecting any serious accumulations across northern Illinois but some areas could see an ill-timed inch of snow during the morning commute, just enough to create some road hazards, so be prepared for that.
Our latest TAM has been adjusted to reflect these new developments. We should see a healthy 3-6" swath of snow across much of central and southern Illinois. The areas that should see the most snow will Southwest Illinois, near the St Louis area. These are the areas that are currently under winter storm warnings.
While far from the worst snowstorm we've dealt with across this region. The early timing and location makes it somewhat unusual given the strength and amounts forecast. Safe travels everyone!
Winter is making an early presence across our state this fall (yes technically it is still fall.) We've been dealt abnormally cold temperatures and a couple early season snows. These snows were relatively minor - as early season snows tend to be. That will change Wednesday night as the first real winter storm potential targets parts of southern Illinois. Early indications are some areas could pick up as much as 4-6 inches of snow with locally potential higher amounts.
The National Weather Service has issued winter storm watches for the areas where the heaviest snow may fall. Mainly across Southern Illinois. We expect most of these areas to be upgraded to advisories as warnings as early as Wednesday morning.
Wintry precip, perhaps mixed with sleet and rain at first, should begin entering southern Illinois late Wednesday evening
As temperatures fall during the night and the associated surface low strengthens, any mixed precip should change to all snow, and come down in moderate rates overnight Wednesday into Thursday morning. The Thursday morning commute could be heavily impacted.
The entire system will move northeast, with lighter snow and accumulations spreading as far north as Chicago and Peoria. In those places, much less snow is expected, perhaps a dusting to an inch. The areas downstate will experience heavier snow for a much longer duration and that is why we anticipate the heaviest snow there. The entire system should exit Illinois by Thursday evening, say around 8pm.
SNOWFALL TAM: First Look
Below is our first TAM outlook for the upcoming event. An area of heavier snowfall will likely be added as trends continue to be monitored. Stay tuned for more updates as the event gets underway
(2:00PM - 8/6/18) A brief update on the severe weather potential across portions of the state today...
In the wake of early day scattered showers and thunderstorms across portions of Northern and Central Illinois, areas of clearing are occurring, which is allowing for some destabilization. By mid-afternoon an environment should be in place featuring moderate to high instability levels, ample shear and good moisture.
As a disturbance moves in from the west, scattered thunderstorms are expected to develop this afternoon across portions of Western Illinois. This activity will pose a severe risk as it pushes eastward across portions of Northern and much of Central Illinois. Damaging winds and hail will be the biggest threats, though and isolated tornado can’t be ruled out. It appears there may be an area of where the severe threat is the highest, in and around a box from Peoria to Springfield to Champaign to Kankakee. Across this area some significant severe may occur. This is represented by the orange area on our TAM map below. While this scenario is not fully likely, it is possible given the environment in place, and worth a mention.
The severe threat will greatly diminish by early tonight, with only an isolated severe threat overnight with general showers and thunderstorms across portions of Central and Southern Illinois
(4:15PM - 8/3/18) After more seasonal temperatures to end July and begin August, hot temperatures are once again making a return the next several days across the state...
Another mini-heat wave is settling in across portions of the region, and will be affecting the state today through Monday. Ridging ahead of an incoming series of disturbances is transporting hotter temps into the area from the Plains. This will lead to high temps into the 90's for much of the state the next several days.
Things have started today with high temps around and into the low 90's across portions of West-Central and Southern Illinois. High temps on Saturday and Sunday will likely be around and into the low 90's for much of the state...With mid 90's likely for portions of Western and Southwest Illinois, closer to the Illinois/Missouri and Illinois/Iowa borders, as well as the Chicago, St. Louis and Quad City metro areas. High temps Monday will likely be around and into the low 90's once again for much of the state, with mid-90's possible for portions of Western and Southwest Illinois. Low temps across the state during the period will range from the mid 60's to low 70's, with mid 70's possible in Chicago and St. Louis.
The good news is unlike all of the other heat waves this summer, this one will lack high dew points. This means humidity and heat indices will be held in check, and will not be too much higher than the actual temperature is.
There is the potential for some cloud debris each day, and thunderstorm potential across Northern Illinois on Monday, which could temper the heat for some areas.