Could this next storm be the one?

11am Update:  The latest morning runs of the NAM and GFS are beginning to come in.  From last night to this morning the NAM has shifted the track of the low further south from its previous position (which had it moving through the Quad Cities to Dubuque with all rain falling).  If this track were to verify precip would begin as rain Wednesday night with a change over to snow Thursday.  The American GFS has maintained its track from Sunday evening but has had a slight shift further west.  This, too, would keep precip in the form of rain Wednesday night with a possible mix or change over by Thursday afternoon.  Bottom line, the highest snowfall totals will occur where snow falls during the whole duration of the storm and that might just be north and west of here.  It will interesting to see the morning run of the European model.  I wouldn't be surprised to see that shift further north as well.


Sunday tied the record for the longest stretch without measurable snowfall in Rockford...a whopping 287 days!  The previous record was set back in 1922.  Another snow less day is expected this afternoon so look for that old record to be surpassed, although, we may not remain snow less for long.

A few systems moving within the jet stream will traverse across the Midwest today and tomorrow but the one that has everyone asking "Will this be the one?" is now just moving onshore in the Pacific Northwest and is expected to be here by Wednesday night.  Even though Wednesday night doesn't seem that far away there remains a bit of uncertainty as to where exactly this storm system will track.  After all, a matter of 50-80 miles north or south would be the difference between a foot of snow or an inch of rain.  Before we get too excited about this next system I want to break down a few of the possible tracks and scenarios that may play out by Thursday night.  With this storm just beginning to move onshore there will be shifts in the track until it's sampled for about a day or so with the upper air network.  In fact, we've already seen a shift in the track within the past 24 hours.  The majority of the reliable weather models we look at have a general track from around Oklahoma to central Missouri by Wednesday night to central Illinois by Thursday morning and into Michigan by Thursday night.  Usually the band of heaviest snow will fall just north of where the surface low tracks and with this projected path it would place areas from Des Moines, IA to Freeport, IL to Madison, WI in a swath possible to receive nearly six inches of snow!  East and southeast of the track a rain/snow mix or just rain would fall leaving snowfall totals a little less near Chicago.



January 1996 Snowfall

It's important to look at what will occur at the surface but to gain a better understanding of the storm system we have to look at what's occurring above our heads.  A dip in the jet stream out west will allow for not only a surface low to develop in the central/southern Plains but also an upper level low in the southwest.  This low will become a closed circulation as it moves northeast into the Great Lakes.  When we see this happen in the flow aloft it means the low will strengthen as the jet stream develops a negative tilt and will usually slow down.  As is typical with systems that slow down we usually tend to see a slight shift of the surface low to the north and west; which was already observed from the American GFS model from Sunday morning to Sunday night as well as a slight shift north from the European model.  So I wouldn't be surprised if this general trend towards a more north and west track continues. 



January 1996 Snowfall

To also aid in trying to forecast potential significant storm systems we look back at previous events that have had a similar track as to the one we're expecting.  One such past storm occurred back on January 1996 which dumped a significant amount of snow from Iowa to southern Wisconsin while northern Illinois received only a few inches.  Should the track of this storm shift further north and west the heaviest snow band would shift as well and further away from the Stateline.


   


By Tuesday morning we should have a pretty good idea of just where this low will track and how much snow or rain we should receive.  Stay tuned!