Weekend Storm Fizzles; Monday Night Storm Strengthens

For the meteorologically impatient, like my friend John Urban, my 6pm Monday to Noon Tuesday snowfall forecast is divided into two predictions:

Madison airport: 3.8 inches (up slightly from the 3.4 I projected Friday)
Platteville: 5.6 inches 

I'm including Platteville here because it appears to be in the heaviest band of snow for this Monday night Alberta Clipper.

A quick look back at the weekend storm: we fell far short of the precipitation projection (I had 3.1 inches; the Madison total that will be released later today will probably be between 1.0 and 1.5).  I'm pleased that other elements of my forecast -- the two rounds of precipitation, the temperatures, the wind -- were spot on.

On Thursday, I mentioned 4 components of a winter storm that I watch for:

Storm Track: very favorable
Storm Intensity: moderately favorable
Surface Temperature: very favorable
Speed of Track: somewhat favorable

"Storm Intensity" ended up being the downfall of last night's forecast.  The low didn't deepen nearly as much as projected (pressure is 29.80 as of this moment), which means it didn't have the strength to produce significant snow on the back (northwest) side of it.  Thus is the peril of winter forecasting for southern Wisconsin.

On Friday, I predicted a second storm for Monday night, and that storm still appears likely.  The National Weather Service has issued a Winter Storm Watch for far southwestern Wisconsin (Iowa, Lafayette, Green and Rock Counties).  The Watch runs 6pm Monday to Noon Tuesday.

The bulk of the snow will fall in the overnight hours Monday into Tuesday.  A few maps:

The MeteoEarth projection, just after midnight Monday night (click to enlarge)

NOAA probability of 4"+ of snow in the 24-hour period ending Noon Tuesday.

NWS precipitation model for 3am Tuesday.

In the last 24 hours, models have ticked the center of the storm further south and west, which is why I place Platteville roughly in the heaviest snow band.

As I mentioned Friday, the weather story behind this storm will be temperatures.  An arctic blast means that after sunset tonight, our temperatures will range from -15 to +10 through Thursday.  Tuesday and Wednesday will feel especially cold because of wind, as wind chills dip to -25 to -40.

Because of the Monday night snow and Tuesday morning wind/cold, don't be surprised if schools either delay or close on Tuesday.  The morning commute on Tuesday won't be fun, as wind whips the new snow.

Temperatures will be close to normal again by Sunday, with only slight chances of snow during the day Thursday and late Saturday.

I'll update the Monday night snow total if conditions change.