Friday, January 30, 2015

Latest on the Weekend Winter Storm

Yesterday I said that there will likely be some shifts in the model guidance today as our weekend storm gets fully sampled.  That has indeed been the case.  The data coming in continues to trend farther north and warmer for our weekend storm.  

Precipitation will push in Saturday evening around or just after sunset.  This will likely fall as mostly snow, with some rain possibly mixed in across southern Indiana.  Here is the 12-km NAM for 10pm Saturday, showing that push of snow moving in ahead of the main system.

Nam 12-km courtesy of tropicaltidbits.com


That shield of precipitation will work northward through the night, with a lull likely across the I-70 area southward later in the night.  As we head into Sunday morning, the main system is approaching with widespread precipitation moving in.  The area of low pressure will work through southern Indiana throughout the day Sunday, bringing heavy precipitation across the state.  Likely falling as snow along/north of I-70, rain across southern Indiana.  


NAM 12-km courtesy of tropicaltidbits.com


As we head into Sunday evening, the system pushes off to our east with precipitation diminishing.  However, check out that deformation band across northern Indiana.  Northern portions of the state are in the prime spot for heavy snowfall.  It is not out of the question that locations up there could see as much as 10-12" of snow.  This is where snow will be falling for the longest duration.  


NAM 12-km courtesy of tropicaltidbits.com
  
I think this model may have the track of the low pressure just a little too far north.  However, the other models have trended closer to this more northern solution.  The BIG question is how far north will the rain/snow line get????  Some of the models now try to take it as far north as Indy on Sunday.  I want to have a good look at the 0z data that comes in tonight before making any changes to my forecast.  Just know that the TREND for this storm is farther north which brings warmer air farther north into the state.  Could it still shift a little farther south with new data tonight?  It is still possible.  Here is MY current thinking on snow totals.... 


I have a feeling there will be a sharper range in totals south of Indy than I have, but I want to see some new data tonight before making any changes.  Here are the NOAA Weather Prediction Center probability maps for at least 4" (image on the left) and the probability for at least 8" (image on the right).  


I will post updates on my Twitter and Facebook pages once some new data comes in tonight to see if there are any big changes.  

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