|
(2:00PM - 4/29/20) The storm system that brought severe t'storms to the state yesterday is now wrapping up across the Great Lakes, and will be bringing a period of heavy rainfall and high winds to portions of the state, today into Thursday morning.
A very March-like late April day is currently ongoing across much of the state. As a storm system wraps up over the Great Lakes, a large area of rain has been pin-wheeling over Northern and Central Illinois this morning into this afternoon. While rain will come to an end for much of Northwest and Central Illinois this evening, periods of rain will continue across Northeast and Eastern Illinois through Thursday morning. Upwards of 0.50-2.00" of rain will be likely for a good portion of Northeast Illinois, between this morning through Thursday morning. Upward of 0.50-3.00" of rain fell across Northeast Illinois yesterday afternoon into last night. The additional heavy rainfall of 0.50-2.00" on top of what already occurred could lead to minor flood potential for some areas, especially prone areas.
In addition to the heavy rainfall, windy conditions will be likely from this later this afternoon through Thursday morning. During this time, wind gusts of 30-50mph will be likely across Northeast Illinois. Higher wind gusts of 50-60mph likely for areas along the Lake Michigan shore, with isolated higher wind gusts in excess of 60mph possible. This could lead to some tree damage and power outages where the highest winds are expected, near the Lake Michigan shore areas. There will also be high waves of 5-15ft and 0.5-1.5ft surge along the Lake Michigan shore, which will lead to widespread lakeshore flooding and erosion. 
0 Comments
(11:45AM - 4/28/20) A storm system moving through the region today will bring the chance for severe t'storms to the state.
The previous forecast continues to look on track, with no real changes needed with this update.
Synopsis...
An area of showers and t'storms has been ongoing this morning across portions of Iowa and Minnesota, ahead of an advancing cold front, associated with a storm system moving through the region. Ahead of this cold front and associated activity, some heating and destabilization is and will continue to occur across the state. However, expansive cloud cover and debris showers will likely move across Northern Illinois this afternoon, which puts into questions the amount of heating and destabilization that will occur cross this area. In any case, new and re-newed development of showers and t'storms will likely occur during the afternoon, from Eastern Iowa/Northwest Illinois on down into Missouri, near the morning activity that will have pushed eastward from Iowa and Minnesota. This activity will then spread eastward across much of the state, from this afternoon into tonight. An environment in place featuring low to moderate instability, mediocre to decent moisture, good forcing and good shear will be in place. This will help support a minimal to limited severe t'storm threat across much of the state. It should be noted that the risk across Northern Illinois will be more conditional, and dependent on how aforementioned issues work out. All modes of severe weather will be possible with any severe t'storms. Below is the severe t'storm forecast for this event. 
(9:45PM - 4/27/20) A storm system moving through the region on Tuesday will bring the chance for severe t'storms to the state.
The previous forecast continues to look on track, with no real changes needed with this update.
Synopsis...
An area of showers and t'storms will be ongoing Tuesday morning across portions of Iowa and Minnesota, along and ahead of an advancing cold front, associated with a storm system moving through the region. Ahead of this cold front and associated activity, some heating and destabilization will occur across the state. However, there is the potential for expansive cloud cover and debris showers, which puts into questions the amount of heating and destabilization that will occur. In any case, new and re-newed development of showers and t'storms will likely occur during the afternoon, from Eastern Iowa/Northwest Illinois on down into Missouri, near the morning activity that will have pushed eastward from Iowa and Minnesota. This activity will then spread eastward across much of the state, from Tuesday afternoon into Tuesday night. An environment in place featuring low to moderate instability, mediocre to decent moisture, good forcing and good shear will be in place. This will help support a minimal to limited severe t'storm threat across much of the state. All modes of severe weather will be possible with any severe t'storms. Below is the severe t'storm forecast for this event. 
(11:45AM - 4/27/20) A storm system moving through the region on Tuesday will bring the chance for severe t'storms to the state.
The previous forecast looks on track, with no real changes needed with this update.
Synopsis...
An area of showers and t'storms will be ongoing Tuesday morning across portions of Iowa and Minnesota, along an advancing cold front, associated with a storm system moving through the region. Ahead of this cold front and associated activity, some heating and destabilization will occur across the state. However, this early activity across Iowa and Minnesota may limit heat and destabilization across Northern Illinois, with cloud and shower debris possible to move through the area. In any case, new development of showers and t'storms will likely occur in the vicinity of the cold front, from Eastern Iowa/Northwest Illinois on down into Missouri, during the afternoon. This activity will then spread eastward across much of the state, from Tuesday afternoon into Tuesday night. An environment in place featuring low to moderate instability, decent moisture, good forcing and good shear will be in place. This will help support a minimal to limited severe t'storm threat across much of the state. All modes of severe weather will be possible with any severe t'storms. It is possible an upgrade in severe probabilities may be needed in future updates, should some potential issues look to be resolved. Below is the severe t'storm forecast for this event. 
(10:45PM - 4/26/20) A storm system moving through the region on Tuesday will bring the chance for severe t'storms to the state.
An area of showers and t'storms will be ongoing Tuesday morning across portions of Iowa and Minnesota, along an advancing cold front, associated with a storm system moving through the region. Ahead of this cold front and associated activity, some heating and destabilization will occur across the state. However, this early activity across Iowa and Minnesota may limit heat and destabilization across Northern Illinois, with cloud and shower debris expected to move through the area. In any case, new development of showers and t'storms will likely occur in the vicinity of the cold front, from Eastern Iowa/Northwest Illinois on down into Missouri, during the afternoon. This activity will then spread eastward across much of the state, from Tuesday afternoon into early Tuesday night. An environment in place featuring low to moderate instability, decent moisture, good forcing and good shear will be in place. This will help support a minimal to limited severe t'storm threat across much of the state. All modes of severe weather will be possible with any severe t'storms. Below is the severe t'storm forecast for this event. 
(12:00PM - 4/20/20) A late season snowstorm affected portions of the state, Thursday into Friday. This event was significant and even record breaking, for mid-April standards.
A lead disturbance and an associated area of snow pushed across portions of Southern Iowa, Northeast Missouri and West-Central Illinois Wednesday night through Thursday morning. This snow was previously not expected to amount to much of anything...However, like usual the weather always has surprises...As a dusting to 2" of snow occurred across portions of West-Central Illinois, with even upwards of 2-6" having occurred across portions of Southern Iowa and Northeast Missouri. As has been the case much of this winter, model guidance struggled quite a bit with this event. Heading into this event, most guidance was favoring higher snowfall totals much further south. However, we decided to base our forecast on furthest north solution, was was the "Euro" model. This idea was based on history in similar circumstances in the past. However, the axis of snowfall ended up with further north than all model guidance, including the "Euro" model our forecast...This lead to higher snowfall totals than expected across far Northern Illinois, and much lower than expected snowfall totals south of I-80. We played the right card on going north of just about all model guidance, but did not go far enough north...It would have been hard to to push fore forecast much further north though, with absolutely no model guidance support at all.
A mix of rain and snow moved into Western Illinois late afternoon early into early evening on Thursday. This activity will then steadily spread across Northern and Central Illinois Thursday evening into Thursday tonight. This activity then continued overnight and into Friday morning, before ending from west to east across the aforementioned areas by early to mid Friday morning. Precipitation fell as all snow across Northern Illinois, with the rain/snow transition zone setting up across Central Illinois. Periods of moderate to heavy snow with increased snowfall rates upwards of 1"+/hour occurred across portions of Northern and Central Illinois, early Thursday night into early Friday morning.
Final storm snowfall totals ranged from 2-5" across much of Northern and Western Illinois, with a higher corridor of 4-8" totals nosing into Western Illinois. Several snowfall records for the date of April 17th were broken for affected areas, along with this being the biggest snowstorm on record for portions of Western Illinois...for mid-April or beyond. Below are map representations of final snowfall totals across the state and adjacent areas. 
(8:45AM - 4/17/20) A brief update regarding the snowstorm that continues to affect the state this morning.
Snow continues to fall this morning across a good portion of Northern Illinois, while it has come to and end across affected portions of Central Illinois. As is usually the case, some areas over-performed and some areas under-performed with snowfall accumulations. Additionally, this event ended up further north than expected, and given our forecast was already on the north side of model guidance, there was nothing much we could about that.
As of 8AM reports show upwards of 4-8" of snow has occurred across portions of Western Illinois, south of I-80. Additionally, a larger swath of 2-5" has occurred over much of Northern Illinois, with snow still falling across much of this area. A few of the high snowfall reports across the state thus far are: 7.0" Burlington, IA - 6.4" Knoxville, IL - 5.5" Galesburg, IL - 5.0" Altona, IL - 4.6" Milledgeville, IL - 4.3" Streamwood, IL - 4.0" Crystal Lake, IL
Below are two maps; one on the left being our final forecast from yesterday, and one on the right being observed snowfall totals as of 8AM.
(4:00PM - 4/16/20) A significant late season snowstorm will be affecting portions of the state today through Friday, bringing several inches of snow to some areas.
With this update we have increased expected snowfall totals for some areas within the expected snowfall axis. Outside of that change, only minor other changes were needed. This is now looking like a significant/historic snowstorm for the hardest hit areas, by mid-April standards. This will likely be the last full update regarding this snowstorm, with only short term updates expected as needed throughout the event. However, we will be watching trends for if there is the need for another full...Sometimes these events with several meso-scale factors involved can throw wrenches in the the evolution of things A lead disturbance and an associated area of snow pushed across portions of Southern Iowa, Northeast Missouri and West-Central Illinois last night through this morning. This snow was previously not expected to amount to much of anything...However, like usual the weather always has surprises...As a dusting to 2" of snow occurred across portions of West-Central Illinois, with even upwards of 2-6" having occurred across portions of Southern Iowa and Northeast Missouri.
A mix of rain and snow is expected to move into Western Illinois late this afternoonand early this evening. This activity will then spread across Northern and Central Illinois this evening into early tonight...then continuing overnight and into Friday morning, before ending from west to east across the aforementioned areas early to mid Friday morning. Precipitation will fall as all snow across Northern Illinois, with the rain/snow transition zone setting up across Central Illinois. Periods of moderate to heavy snow with increased snowfall rates upwards of 1"+/hour will be likely across portions of Northern and Central Illinois, early tonight into early Friday morning. Additionally, conditions will also be favorable for the occurrence of thundersnow.
Additionally, given this will be a heavy/wet snow, the weight of the snow could cause some tree damage and power line damage in the hardest hit areas, with the potentialf or some power outages
Final snowfall totals within the main axis will likely range from 4-8", with amounts quickly tapering on either side of this axis.
Below is the snowfall forecast for this event. 
(9:45PM - 4/15/20) A storm system set to move through the region Thursday into Friday, will bring yet another late season accumulating snowfall to portions of the state.
Once again there no significant changes are needed with this update, as going forecast continues to be on track. While a few rain/snow showers will be possible into Western Illinois Thursday morning into early afternoon, the main focus will be later... Snow is expected to move into Western Illinois Thursday mid to late afternoon. This activity will then quickly spread across Northern and portions of Central Illinois, Thursday evening...then continuing into Friday morning, before ending from west to east across the aforementioned areas early to mid Friday morning. Precipitation will fall as all snow across Northern Illinois, with the rain/snow transition zone setting up across Central Illinois. Periods of moderate to heavy snow will be likely Thursday evening into Thursday night as well, with increased snowfall rates likely during this time as well. Not surprisingly given it's mid-April, temperatures will be marginal, thus meaning the greatest snowfall accumulation will be on colder surfaces.
Final snowfall totals within the main axis will likely range from 2-5", with amounts quickly tapering on either side of this axis. Below is the snowfall forecast for this event.
Even though the calendar says the middle of April, Mother Nature could not care less and she is going to show why beginning tomorrow evening across portions of the state. Numerical model guidance continues to come into good agreement on a weather system bringing a swath of accumulating snow into portions of the state later Thursday into Friday morning. An update follows below...
Our system of interest has come down from British Columbia early this morning and is now moving south and southeast across the Pacific Northwest. It will then turn more to the southeast over today and tonight, eventually crossing the Rockies and emerging out in the plains by Thursday morning with a rough track shown below in blue.
As the system crosses into the plains, a widespread area of precipitation will develop north of the developing surface low across the central plains before eventually streaking eastward into the Midwest and Illinois, as shown below. Model agreement on this general scenario is quite good but there remains differences in the exact location of the swath of accumulating snow into Illinois. The animation loop below runs from 4am on Thursday to 10am on Friday morning.
Periods of moderate to heavy snow will be possible Thursday evening into Friday morning across portions of northern and central Illinois as things stand now. Not surprisingly given it's mid-April, temperatures will be marginal, thus meaning the greatest snowfall accumulation will be on colder surfaces. The favorable thing going for this event is that the snow will be falling mostly at night and overnight, allowing for maximum accumulating potential vs the snow falling during the day. This can mean a big difference in mid-late April regarding snow accumulations. 
We will continue to ride with this current thinking for expected snowfall totals for now but this is subject to change over the next 36 hours ahead of this incoming system so stay tuned for further updates.
MP
|
Archives
March 2023
categories
All
|
RSS Feed