A BIG OLD SLOPPY STORM...
A potent winter storm is wrapping up over the Midwest and it's delivered a wide variety of weather conditions overnight that will continue to impact the Midwest into Tuesday night. Advisories are in effect to our NW for winter storm and ice storm warnings while further south tornado watches are in effect as far north as Kansas.
Scattered thunderstorms have been detected in my area with some heavy downpours but considering what's going on around us, we're getting out of this in pretty good shape. We may see some light snow accumulations before its over but nothing that should cause any big disruptions on the roads.
Speaking of travel, that will be highly discouraged in some parts of NW Iowa, Minnesota, and Wisconsin where significant ice accumulations are going to make for extremely dangerous (if not near impossible) travel in spots. Check the road conditions if you are headed that way. The winter storm severity index indicates moderate to major impacts with considerable disruption to travel and daily life with widespread closures of infrastructure.
As is often the case with these big storms the track into eastern Iowa brings warm air aloft into the region setting the stage for rain as opposed to snow. Here's the surface and precipitation depiction off the EURO Tuesday morning. The green denotes rain, pink freezing rain, orange sleet, and blue snow.
As the surface low advances into eastern Iowa from the SW Tuesday a warm front is drawn north into the region. It doesn't get much past HWY 30 before it occludes and stalls. South of it highs south of I-80 have a decent chance of approaching 60. North of the front, east winds in my counties north of HWY 30 will not allow highs to get out of the low to mid 40s creating what looks to be a 20 degree spread from north to south.
As for the rain that's been falling overnight, it gradually ends in the south Tuesday morning behind the warm front. In the north showers and isolated thunderstorms may be scattered around well into the afternoon as the front only slowly creeps toward HWY 30.
Outside of some drizzle, much of Tuesday night and Wednesday morning looks dry as the primary forcing and moisture pivots away. By now a trailing cold front is driving much cooler air back into the region with temperatures Wednesday holding in the low 30s.
The lull in precipitation is expected to end by Wednesday afternoon as the upper air low runs into a block, does a loop de loop and reorganizes directly overhead. As it slowly trudges east renewed vorticity and forcing kicks up a period of light snow. Snowfall rates won't be heavy but it appears an inch or so is possible by Thursday night. The EURO suggests amounts like this.
For the entire storm, snow totals over a foot are possible from the NW tip of Iowa into central Minnesota and NW Wisconsin.
Any lingering snow should be out of the region early Thursday and that leads to chilly but dry weather Friday. Highs both Thursday and Friday will likely remain in the range of 30-35 from north to south.
Another fast moving disturbance is slated to streak across the Midwest late Friday night or early Saturday. Both the EURO and GFS indicate a chance of light snow somewhere in my area. Amounts appear light and models are all over the board so time is a necessary ingredient in resolving the differences. Here's what the EURO is tossing around for potential snow totals at this time.
Despite some opportunities for light snow, I still don't see any strong indications of cold air the next couple of weeks. Considering that's climatologically the coldest time of the year that is a positive. However, I do see a teleconnection that is troubling. It's the MJO (Madden Julien Oscillation). Note what the Australian, EURO, and U.S. based CFSv2 are showing for trends next next couple of weeks.
Within the next few days the EURO has it going into phases 8 and 1. The Australian and CFSv2 phases 8, 1, and 2 the remainder of January. For January that is the holy grail of cold.
So far the deterministic models are not indicating anything resembling those temperature analogs until January 20th at the earliest. The GFS shows these departures January 8-18th. That's a blow torch and far different than what the MJO indicates.
Obviously, one of the two, the EURO MJO or its deterministic model guidance is going to be wrong. Often times the MJO is the teleconnection that beats the models to the punch in seeing a trend. This will be a good case study to see if the MJO (a teleconnection based on convection in the tropical Pacific) can outperform the model output of the big two, that being the EURO and GFS. I will be very surprised if we don't see cold return to dominate the last 10-14 days of January.
Okay, that's it for today. For many of you it's back to the grind after a holiday weekend. Hang in there and roll weather...TS