Sun-Mon, March 6-7th Snow/Severe T'Storm/Heavy Rainfall Event Update #3

(10:15PM Sunday - 3/6/22) A storm system will continue to impact the region and state, through midday Monday. This storm system is expected to produce a swath of accumulating snow/sleet, heavy rainfall with localized to scattered flooding potential, and an isolated to scattered (levels 1-3) severe t'storm risk across the region and state during this time.

Summary...
Model guidance and real time observations continue to support the going forecasts, thus little to no change is needed with this update.

​A storm system developed across the Southern Plains during the day today, with it set to track through he Ohio Valley tonight into Monday morning, and eventually into the Northeast by Monday night. This storm system is expected to produce a swath of accumulating snow/sleet, heavy rainfall with localized to scattered flooding potential, and an isolated to scattered (levels 1-3) severe t'storm risk across the region and state during this time.

​Wintry (Snow/Sleet) Aspect Forecast...
Tonight - Monday Afternoon, March 6-7th ~ Snow/Sleet Event:
Precipitation in the from of a snow/sleet/rain mix has moved into Western and Central Illinois late this evening and early tonight. This precipitation is continue to expand across Northern and Central Illinois tonight. With colder air filtering in on the north side of the storm system and some dynamic cooling taking place, precipitation will steadily turn to all snow with time across the northern half of the state. Periods of snow will then continue through mid to late Monday morning, before ending by midday Monday or early Monday afternoon. Snow will vary in intensity, with moderate to heavy snow being possible at times along with with snowfall rates of 0.5-1.0" an hour at times. A transition zone is also expected to set up, from roughly the southern Chicago metro area down into Western Illinois. In the vicinity of this transition zone, precipitation types may vary.

​Below is the snow/sleet forecast for this event.

​Severe T'Storm Risk/Heavy Rain/Flooding Aspect Forecast...
Tonight - Monday Afternoon, March 6-7th ~ Severe T'Storm Event:
​The main risk for an isolated to scattered (levels 1-3) severe t'storm risk will continue to exist across the southern half of the state, through Monday morning. As a storm system develops and moves into the region, a warm front has slowly lifted northward into the southern half of the state this evening and early tonight. This frontal boundary will continue to be a focal point of potential severe t'storm activity. Additionally, as the storm system moves through and passes the region, a cold front will then move southward across the southern half of the state overnight tonight into early Monday morning. This frontal boundary will also be a focal point of potential severe t'storm activity. In all, periods of rain and t'storms are expected across the southern half of the state, through early Monday morning. An environment will be in place supportive of some severe t'storm risk with this activity. This environment will feature low instability of up to 1,500J/KG, dew points in the mid 50's to mid 60's, good shear, good forcing, and good lapse rates of 5.5-7.5C. This environment will be supportive of upwards of an isolated to scattered severe t'storm risk (levels 1-3) across the southern half of the state. Damaging winds, hail and an isolated tornado will be the severe weather threats.

Tonight - Monday Afternoon, March 6-7th ~ Heavy Rain/Flooding Event:
Multiple periods of rain and t'storms are expected across the southern half of the state, through early Monday morning. Heavy rainfall will be possible at times, with widespread rainfall totals of 1-3" expected in a corridor across Southern Illinois during this period of time, with locally higher amounts likely. Due to the combination of recent heavy rainfall/flooding during mid-late February and the expected rainfall, localized to scattered flooding is expected.

Below are the severe t'storm and heavy rain/flooding forecast for this event.

​Impacts...
-Snow/sleet accumulation of 1-3" across the northern half of the state, through midday Monday.
​-An isolated to scattered (levels 1-3) severe t'storm threat across the southern half of the state, through early Monday morning.
-Widespread heavy rainfall across the southern half of the state, with a corridor of widespread rainfall totals of 1-3" (Locally higher) expected through early Monday morning. These rainfall totals could cause localized to scattered flooding potential for affected areas.
-Travel impacts likely both for the northern half of the state due to the snow/sleet and across the southern half of the state due to the heavy rain/flood potential.

JP