Excessive rain threatens the Finger Lakes with flash flooding Sunday

Rain Storm Set-Up and Timeline

A long duration weather event will unfold tonight and persist into Monday morning with very heavy rain likely in the Finger Lakes.

Saturday Daytime

During the daytime hours Saturday, a slow moving cold front will enter Western New York with a band of light rain.

Here in the Finger Lakes, this band of rain should remain to the west until late in the afternoon or evening hours. Most areas should remain completely dry through 4 pm, with rain overspreading the region between then and 7 pm.

Out ahead of this rain, some sun will shine this morning though clouds will gradually increase.

Winds will gust between 25-35 mph with the strongest winds over higher elevations of the eastern Finger Lakes.

Temperatures will top out in the mid 60s.

Saturday Evening-Sunday Midday

The cold front will make slow progress into the Finger Lakes before stalling over Central New York by Sunday afternoon.

A widespread, steady light rain is expected throughout this time period. There may be a few periods where the rain lets up or even briefly stops.

Still, over the course of 12-18 hours, by the early afternoon Sunday, rainfall amounts of 1-1.5″ will have already fallen.

This will not be enough to cause any flooding issues. Winds will remain generally light, though they will begin to increase across areas east of Cayuga Lake Sunday morning.

Temperatures will fall from the 50s into the low and mid 40s as the front moves through.

Sunday Afternoon-Monday Morning

A rapidly strengthening area of low pressure will race up the East Coast on Sunday. This low will be an offshoot of what should become Tropical Storm Philippe later today near Cuba.

Therefore, this low will have plenty of tropical moisture to work with, as well as a very favorable atmospheric set up for heavy rain.

Rain should increase in coverage and intensity Sunday afternoon and will become rather heavy by Sunday evening.

As the low lifts north into eastern New York and Canada, rain on the backside of the system should continue through Sunday night and into Monday morning before it finally pulls out.

An additional 1.5-4″ is possible, especially east of Cayuga Lake and into the I-81 corridor.

With this heavier rain will come strong winds Sunday night and into Monday, with wind gusts of 35-45 mph widespread and some gusts reaching 50-60 mph over higher elevations.

Temperatures will generally remain in the 40s, keeping the threat for a changeover to snow almost nil.

Key Points

There are a number of key points to consider with this event. Please read and share these:

• Confidence is growing that a significant, even excessive rainfall event will unfold over at least a portion of the Finger Lakes. The exact location is still a bit uncertain, but the highest rain totals are likely over the eastern Finger Lakes with lesser amounts further west.
• Widespread rain amounts of 2-4 inches are likely for most of the Finger Lakes. Localized areas could see even more.
• Flash flooding is a risk region-wide but will be most likely in localized bands of heavy rain that set up Sunday afternoon into Monday morning.
• Minor to moderate river flooding could occur later Sunday night through Monday, even after the rain ends.
• Fallen leaves may quickly clog storm drains, increasing the likelihood of urban flooding. Pay attention to your drains and clear them often.
• Strong winds are likely, especially over higher elevations, with some gusts over 50 mph. Combined with the saturated soil, trees and power lines may come down, resulting in some power outages.
• The rain Saturday night into midday Sunday will be steady but does not pose a direct flooding threat. It will, however, set the stage for flooding later as the second part of the storm moves in.
• Temperatures will remain mostly in the 40s, keeping the region too warm for snow.

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