|
(6:30PM - 2/22/20) While the weather has generally been quiet for the past week or so, and a push of mild temperatures is occurring across the state this weekend...Winter isn't over yet, as a winter storm is likely to affect the region during the early to middle portion of this upcoming week.
Potential has been growing for a winter storm to affect the region during the early to middle portion of next week, with it looking more and more likely as time has gone on. Model guidance has been honing in on this period for the past several days, some some signs of a potentially major winter storm being possible for the state or very nearby.
As has been the case all of this winter, even though there is high support for a winter storm to affect the region during this period, there has been disagreement regarding track and strength of the storm system...as well as where and how much accumulating snow will occur. However, as time has gone on the range of disagreement has narrowed overall among model guidance. This will be yet another complex scenario, with a few main waves expected to interact with each other during this period. How exactly the waves interact will help determine the outcome of the storm system. The support for more and organized interaction has been a clear trend over the past day or so, which would lead to a stronger and more organized storm system for the region...possibly significant.
As of this moment there is high agreement in a storm system moving through the region Monday-Wednesday...with high agreement on accumulating snow occurring across at least portions of the state during this time, with Northern Illinois being most favored at this time. Where the main snow axis will set up and how much snow will fall will be determined in later updates, given some spread of scenarios at this time. 
0 Comments
(4:00PM - 2/21/20) While the weather has generally been quite for the past week or so, and a push of mild temperatures is expected across the state this weekend...Winter isn't over yet, as there is growing potential for a winter storm to affect the region early-mid next week.
Potential is growing for a winter storm to affect the region during the early to middle portion of next week. Model guidance has been honing in on this period for the past several days, and now that we are only 3 or so days away, it is finally time to start mentioning the potential.
As has been the case all of this winter, even though there is high support for a winter storm to affect the region during this period, there is a large disagreement regarding track and strength of the storm system...as well as where and how much accumulating snow will occur. This will be yet another complex scenario, with a few main waves expected to interact with each other during this period. How exactly the waves interact will help determine the outcome of the storm system.
As of this moment there is high agreement in a storm system moving through the region Monday-Wednesday...with high agreement on accumulating snow occurring across at least portions of the state during this time. Where the snow axis will set up and how much snow will fall will be determined in later updates, given the large spread of scenarios at this time. 
(12:00PM - 2/14/20) Post event wrap up regarding the recent Wed-Thur, Feb 12-13th snow event that affected the state.
As expected, a complex setup unfolded across the region...A disturbance across the Southwestern US ejected out into Central US. As this is happened, a disturbance dropped out of Canada, and into the Central US. Both of these disturbances interacted, leading to the development of a storm system, which will moved through the region Wednesday into Thursday. Precipitation initially pushed into Southwest and Southern Illinois Wednesday morning. This activity then steadily spread across the rest of the state through early to mid afternoon Wednesday. This activity then continued from this Wednesday afternoon into Wednesday night, before ending Thursday morning for most areas. Precipitation was all snow across Northern and Central Illinois, though some mixed precipitation occurred along the snow/rain line in portions of Central Illinois. A general light to moderate snow occurred across Northern and Central Illinois for the duration of this event, with brief and scattered periods of heavy snow. Temperatures and snowfall ratios started off on the marginal side Wednesday morning into Wednesday evening, before growing more favorable Wednesday night into Thursday morning, as colder air filtered in. Across Southern Illinois precipitation was predominantly rain, with upwards of 0.50-1.00" of rain, and a few backside snow showers Wednesday night into Thursday.
Final event snowfall totals of 2-5" were widespread across much of Northern and Central Illinois. Snowfall amounts tapered on either side of this main axis, with a very sharp southern gradient across portions of Central Illinois.
Below is a map representation of final snowfall totals across the state and adjacent areas. 
(12:00PM - 2/13/20) Behind the storm system exiting the region, a brief shot of cold air will settle into the region through Friday.
Synopsis... As the current storm system moving through exits the region, a cold front swept across the state later last night through this morning. Behind this cold front, some of the coldest temperatures of the season will occur across portions of the state, including below zero temperatures and wind chills for many. Today... High temperatures in the low to mid 30's for today occurred just after midnight last night and early this morning for most areas. A cold front quickly swept across the state later last night into this morning. Temperatures have rapidly fallen into the range of 5 to 20 across much of the state, the exception being Southern Illinois, though temperatures continue to fall there as well. Breezy conditions, combined with the cold temperatures, have lead to wind chills of 5 to -20 across Northern and Central Illinois.
Tonight-Friday morning...
As an area of high pressure moves into the region, with the brief cold push firmly entrenched in the area and with a few snow pack in place...the coldest temperatures of this period will occur tonight into Friday morning. Low temperatures will range from the -17 to 0 across Northern Illinois, to the -10 to 5 across Central Illinois, to 0 to 15 across Southern Illinois. While winds will be light to calm, already cold temperatures, combined with any little breeze, will create wind chills of 0 to -20 across Northern and Central Illinois. Friday... High temperatures will range from 8 to 20 Northern Illinois, to 13 to 23 across Central Illinois, to the 20 to 32 across Southern Illinois. Friday night-Saturday morning... Low temperatures will range from 0 to 12 across Northern Illinois, to the 7 to 17 across Central Illinois, to the 17 to 25 across Southern Illinois. 
(9:00PM - 2/12/20) Behind the current storm system moving through the region, a brief shot of cold air will settle into the region Thursday morning through Friday night.
Synopsis... As the current storm system moving through the region continues to move through and then exits the region, a cold front sweeping through the region will usher in a brief push of cold air. This cold front will sweep across the state tonight through midday Thursday. Behind this cold front, some of the coldest temperatures of the season will occur across portions of the state, including below zero temperatures and wind chills for many. Thursday... High temperatures in the low to mid 30's for Thursday will likely occur just after midnight tonight and early Thursday morning for most areas. A cold front will then quickly sweep across the state tonight through midday Thursday. Temperatures will rapidly fall into the 10's through the day on Thursday across much of the state. Breezy conditions, combined with the cold temperatures, will lead to wind chills of 5 to -15 across Northern and Central Illinois.
Thursday night-Friday morning...
As an area of high pressure moves into the region, with the brief cold push firmly entrenched in the area and with a few snow pack in place...the coldest temperatures of this period will occur Thursday night into Friday morning. Low temperatures will range from the -17 to 0 across Northern Illinois, to the -10 to 5 across Central Illinois, to 0 to 15 across Southern Illinois. While winds will be light to calm, already cold temperatures, combined with any little breeze, will create wind chills of 0 to -20 across Northern and Central Illinois. Friday... High temperatures will range from 7 to 17 Northern Illinois, to 17 to 25 across Central Illinois, to the 25 to 33 across Southern Illinois. Friday night-Saturday morning... Low temperatures will range from 0 to 10 across Northern Illinois, to the 7 to 17 across Central Illinois, to the 17 to25 across Southern Illinois. 
(4:30PM - 2/12/20) A brief short term update regarding the snow event currently affecting the state, and will continue to do so into Thursday...
As expected, a large area of snow overspread Northern and Central Illinois this morning and afternoon. Upwards of a dusting to 2" of snow has already occurred across much of Northern and Central Illinois. Steady light to moderate snow has been occurring, and will continue through the evening. After this time, periods of light to moderate snow will continue to be likely tonight through Thursday morning. A brief period of heavy snow will be possible as well. Additional snowfall accumulation of a couple inches are likely across Northern and Central Illinois this evening into Thursday morning. As was depicted by our main update this morning, much of Northern and Central Illinois will finish with 2-5" of snowfall accumulation. 
(11:30AM - 2/12/20) A storm system moving through the region today into Thursday will bring accumulating snow to a large portion of the state.
Synopsis... As expected, a complex setup is unfolding across the region...A disturbance across the Southwestern US has started to eject out into Central US. As this is happening, a disturbance has dropped out of Canada, and into the Central US. Both of these disturbances are interacting, leading to the development of a storm system, which will move through the region today into Thursday. Not surprisingly, model guidance was in some disagreement regarding this period, before honing in an an overall idea. Real-time observations from this morning generally support the previous forecast, with only minor changes needed. The main change with this final update was to tighten the snowfall gradient across Central Illinois, where over a very short distance snowfall totals may range from a dusting to a couple of inches.
Precipitation has started to spread into Southwest and Southern Illinois this morning. This activity will steadily spread across the rest of the state through early to mid afternoon. This activity will then continue from this afternoon into tonight, before ending Thursday morning for most areas. Precipitation will be all snow across Northern and Central Illinois, though some mixed precipitation may be possible along the snow/rain line in Central Illinois. Periods of moderate to heavy snow will be possible at times this afternoon into early tonight, across portions of Northern and Central Illinois...Otherwise generally light snow is expected across Northern and Central Illinois during most of this event. Temperatures and snowfall ratios will start off on the marginal end into this evening, before growing more favorable tonight into Thursday. It should be noted that across Southern Illinois, precipitation looks to stay predominately rain, with just a chance of isolated backside snow showers late tonight or early Thursday morning.
Below are visuals of estimated start and end times of precipitation for this event.
Final snowfall totals in an axis across the heart of the state will be in the 2-5" range, with amounts tapering lower on either side of this main axis. There will be a very sharp gradient on the southern end of the main axis, across Central Illinois.
Below is the snowfall forecast for this event. 
It is a one-two punch from old man winter as we will be getting our widespread accumulating snow today into portions of tomorrow, followed by a short stay of some bitterly cold temperatures and what will be the coldest air of the season for some. A short article follow below...
Below is a good visual animation from this afternoon into Friday morning, showing the marching arctic air as it steadily progresses southeast into the heart of the Midwest over the next 24-36 hours associated with the strong Canadian high pressure system.
The coldest period of this short arctic air outbreak will be Friday morning with the area of high pressure gets nearly overhead Illinois. As you can see in the image below, much of northern Illinois will see temperatures below 0 and central Illinois near 0 or just above in the low single digits.
Below our forecast wind chills valid at 6am on Friday morning, showing the coldest wind chills across the northern portions of the state in the -15 to -25 degree range. Far southern Illinois will escape the worst of it with wind chills likely remaining above 0 degrees.
(9:30PM - 2/11/20) A storm system is expected to move through the region Wednesday and Thursday, with accumulating snow expected across a good portion of the state.
Synopsis... A complex setup is expected the next few days, as a disturbance across the Southwestern US ejects out into the Central US. As this happens, a disturbance is dropping into the Central US, southward from Canada. Both disturbances will interact, leading to the development of a storm system, which will move through the region Wednesday and Thursday. Not surprisingly, model guidance has been in some continued disagreement regarding this period. Track of the storm system, location of the main snowfall axis and snowfall amounts have all been in question, though agreement finally appears to be occurring.
Precipitation is expected to spread into Southwest Illinois Wednesday morning, then across the rest of the state during the rest of the Wednesday morning and afternoon. This activity will then continue from Wednesday afternoon into Wednesday night, before ending Thursday morning. Precipitation will be all snow across Northern and Central Illinois, though some mixed precipitation may be possible across Central Illinois at times. Periods of moderate to heavy snow will be possible at times during across Central Illinois Wednesday afternoon and evening as well...Otherwise generally light snow is expected across Northern and Central Illinois during this event. Temperatures and snowfall ratios will start off on the marginal end Wednesday morning through evening, before growing more favorable Wednesday night into Thursday. It should be noted that across Southern Illinois, precipitation looks to stay predominately rain, with just a chance of isolated backside snow showers late Wednesday night or early Thursday morning.
Below are visuals of estimated start and end times of precipitation for this event.
Final snowfall totals in an axis across the heart of the state will be in the 2-5" range, with amounts tapering lower on either side of this main axis.
Below is the snowfall forecast for this event. 
We are less than 24 hours away now from snow impacting Illinois as model guidance tries to get a better handle on this system as we get closer. We are still expecting widespread snow accumulations across portions of the state, as you'll see below. Let's dig into the latest.
Our two systems of interest our inching closer with the northern stream wave moving through British Columbia this afternoon with its sights set on crossing the Rockies tomorrow morning and afternoon. This will eventually phase with the slowly meandering southern stream upper level low that is still located across southern Arizona and the Baja region of Mexico. This will continue slowly through the southern plains and eventually turn more northeast heading in our direction.
We can see the entire evolution of this system below....widespread precipitation, in the form of snow on the north and northwest side will streak northeast out of the plains into portions of Illinois by tomorrow afternoon, continuing northeast into the rest of central and northern Illinois by early tomorrow evening. Snow will continue much of the night across about the northern half of the state and then slowly winding down from west to east Thursday afternoon. A secondary disturbance associated with the much colder air could aid in snowfall production continuing into the afternoon hours across northern Illinois and near Lake Michigan.
By early Thursday morning, an arctic front will be plowing eastward across much of the state, ushering in much colder temperatures as you can see on the image below. Snow should still be ongoing across northern portions of the state at this time leading to the snow becoming light and fluffy, accumulating easier and also an increasing chance for blowing and drifting snow Thursday morning and afternoon as strong northwest winds arrive behind the frontal passage.
Here is our latest thinking on expected snowfall totals across the state. Stay tuned for continued updates.
|
Archives
February 2020
categories
All
|
RSS Feed