1/20 - 7pm - Another Week of Snow Forecast Drama

It's cold. We hit 27 degrees for a high today and most of the snow has melted. President Obama's inauguration in Washington had about the same weather as we did, so you can bet it was uncomfortable to be among the crowds in attendance. A warm up is on the way, but a storm lurking in the shadows will cause quite a stir in the forecast.

Tomorrow will nudge above freezing for a high and temperatures should top out in the mid 40s for Thursday and Friday. The models continue to show a couple snow showers around for Friday, but they won't be anywhere near the magnitude of Sunday night's snow event. Temperatures will hold below freezing for the weekend with sunny skies.

Then the "fun" begins.

I've been watching this Monday-Wednesday storm for a couple days now. Over the weekend it looked impressive, but I didn't like where the models were taking the area of low pressure. Yesterday we saw a southward shift in this storm, which piqued my interest and made me a little more optimistic.

Today we saw more southern movement on the models, especially in the GFS. That prompted the Louisville NWS office to put this statement in their forecast discussion:

FORECAST CONFIDENCE ON HAVING A MAJOR PRECIPITATION EVENT IS ABOVE AVERAGE. HOWEVER...THERE ARE MAJOR QUESTIONS REGARDING THE OVERALL THERMAL STRUCTURE WHICH WOULD RESULT IN DIFFERENT P-TYPES. WE WILL BE RAISING POPS SIGNIFICANTLY FOR MON-TUE AND FOR NOW WILL SIMPLY MENTION A MIX OF RAIN/SNOW AND ADDRESS THE ONGOING P-TYPE ISSUES IN LATER FORECASTS. STAY TUNED!

After looking at the 12z and 18z GFS, I agree that this will be very difficult to pin down in terms of precipitation type. Right now this looks rather icy for us, but a slight shift south would give us quite a snowstorm. Then again, it could shift north and become a rainy washout. To illustrate how close we are to the freezing mark, here's the surface pressure map from the 18z GFS for late Monday night:



That blue line straddling the Ohio River is the freezing line at the surface, which is a stone's throw away from town. This line along with the low was south of here for the duration of the storm on the 12z GFS, but the 18z (one above) took it just a hair north of town. I also noticed an increase in precipitation in the 18z as well, so we're really going to have to watch this one. My best guess right now is a mix of ice and snow. It's too early to call for snow amounts (if any) at the moment, but that looks like the task at hand for this weekend. This should be interesting!