More heavy rain heading our way

A widespread heavy rain event is set to impact the entire region tonight into Friday as a slow moving cold front creeps east.An already moisture-rich atmosphere will only become more saturated as southerly winds pump moisture up from the Atlantic ahead of the cold front. This, along with support from the jet stream, will produce heavy rain.The rain will start in the west this evening and gradually spread east. For much of the Finger Lakes, it will not taper off until the late morning or early afternoon on Friday.It looks like the best chance for rain amounts over 2″ will be in the eastern two-thirds of the Finger Lakes and along the I-81 Corridor. Amounts of 2″ or more are possible outside of this area, but less likely.The flood threat along larger rivers is fairly low. The primary concern will be small stream and urban flash flooding. Predicting when and where this will happen is next to impossible due to the localized nature of flash flooding, but there are two areas I am particularly watching.First, of course, is the Penn Yan area. Thankfully there was little additional rainfall yesterday in the area and none is expected during the day today. That will help reduce the flood risk, but if another 2-3″ fell in that area, it would bring rain totals from Tuesday evening to Friday into the 6-8″ range.The other area of concern is in Cortland and Chenango counties. The terrain and numerous small and medium sized streams in this area make it historically prone to flash flooding. Also, the Flash Flood Guidance put out by a division of the National Weather Service shows these areas are currently less capable of handling heavy rain and could exceed the guidance values listed.Please continue to monitor the situation for updates. I suspect 99% of the area will make it through this problem free. But prepare as if you will be in the 1%.