Snow Event Summary and Forecast

After a very neat snowstorm yesterday and last night, I would like to give a summary of the storm system.  This system developed from a strong wave of North Pacific low pressure systems that have been pounding the West for days on end.  Here is an analysis image of the jet stream configuration on Wednesday, January 18, 2012.  As you can see in the analysis, an incredibly strong polar jet stream is making its way from the North Pacific to the United States, with the jet streak itself containing winds of almost 200 mph or 180 knots.  This jet streak is what produced the first clipper system that brought 1-2 inches of snow to the area (officially it brought 2 inches of snow to Fort Wayne.).  As the day progressed Wednesday, subtropical moisture from the subtropical jet stream was pouring into the Pacific Northwest, creating heavy snowfall, heavy icing and heavy rain, along with high winds and thunderstorms to some areas.  Seattle during this time frame had record amounts of snowfall.  Below is an image of the 700 millibar relative humidity values on Wednesday.  As you can see, there was plenty of moisture with the system in the Northwest.

By early Thursday morning, a shortwave, along with low level frontogenesis generated an area of light to moderate snow over Iowa, Illinois and Indiana, which eventually spread over the area by late morning.  That night, the clipper system that brought the snow, pushed a strong cold front through the area, causing temperatures to drop down to 2 degrees by the early morning hours of Friday.  Here is an analysis image of the 850 millibar level Friday morning.

Again, you can see that there was a strong baroclinic zone (note: a baroclinic zone is an area in which temperatures vary drastically, which can lead to the development to the develop of a major storm system if conditions are right.  Temperatures on this map are in degrees Celsius) which was draped across the Midwest.  This baroclinic zone lead to the development of this 850 millibar low, located over the lee side of the Rocky Mountains, causing an intensification of heavy snow over Iowa and Illinois, later spreading eastward into Indiana, Ohio, and Michigan by mid afternoon.  As you can see warm moist flow from the Gulf of Mexico over the very cold surface air was causing heavy snow to break out over the Great Lakes and Ohio Valley.  Frontogenesis is the intensification of a baroclinic zone, which causes strong upward motion and the intensification of bands of precipitation.  These two maps below show that strong frontogenesis was occuring over the main heavy snow area over Illinois, Iowa, and Wisconsin, with frontogenesis also occuring over the Ohio Valley as well.

This also caused the intensification of heavy snow bands, leading to widespread amounts of over 8 inches in Iowa and Illinois.  The storm headed eastward by late Friday afternoon, intensifiying at the same time, but also causing snow to change over to sleet and freezing rain in Southern Indiana.  After that, heavy bands of snow moved through Northeast Indiana and Northwest Ohio, causing near whiteout conditions at times.  By 8:00 p.m. last night, increased frontogenesis and uplift caused even heavier bands of snow to develop but they were developing near Indianapolis.  Surprisingly, even though radar indicated heavy snow south of here, our snowfall was coming down just as heavily, because they had larger flakes of wet heavy snow, rather than small, dry flakes of snow.  This still allowed the heaviest snowfall totals to fall from Fort Wayne to Paulding, with a general 4-7 inches falling in these areas.  Snow tapered off over the entire area by 3:00 a.m. last night, leaving many areas with over 6 inches on the ground.  Officially, in Antwerp, I have recorded an average of 6 inches, with some drifts deeper than that.  In Fort Wayne, official snow totals from yesterday was 3.8 inches (before midnight), with probably an additional inch or two falling after midnight.  This brings Fort Wayne's seasonal snowfall total to exactly 24 inches, which is 7 inches above normal for this time of year.  Surprisingly enough, you may have thought this winter was relatively snowless in the area, but we have actually had more snowfall than last year's snowfall total by this time, and we thought last year was really snowy!  The monthly snowfall for January 2012 is 12 inches which is 5 inches above normal.  With the long-range looking like it is right now, we may see at least one more snowstorm before the month of January ends. 
As for the forecast for the next three days, expect much below normal temperatures today, with highs in the low 20's and upper 10's.  By tonight, strong warm air advection will take place aloft, caused by another strong storm system moving out of the Rockies.  As warm air rides up and over the arctic air at the surface, expect an increase in clouds and possibly freezing drizzle tomorrow morning.  Warm air will then begin mixing down to the surface, causing temperatures to rise.  This warming will be strongly offset by cooling with the frigid ground, which will only allow the warm up to cause temperatures to climb into the mid and upper 30's.  By Sunday, significant cyclogenesis will occur with a strong cyclone in the plains states, causing an intensification of the low level jet stream, which will pump warm, moist air into the region.  On the nose of the LLJ (low level jet), widespread heavy rain and thunderstorms will develop late Sunday Night, with the possibility of a QLCS squall line moving through with strong winds and possibly a tornado (right now the threat for severe weather is low, but there is that little chance that conditions will come together just right to form a major severe weather event.).  Heavy rain, combined with rapid melting of the snow cover, will allow for the possibility of widespread flooding to take place across the area.  By later Monday afternoon, temperatures will drop drastically behind the cold front, but they will not be as cold as it was last week.  Continue to read my updates for further forecasts.