Buffalo Braces: From epic snow to flood in 72 hours?

For many residents just south of Buffalo, New York, the worst may be yet to come.

Epic snowfall totals of up to 88 inches have shut down entire towns, as residents desperately try to dig out and get to nearly empty stores for basics like bread and milk. Some homes have simply buckled under the incredible weight of several feet of snow.

So just how much weight does 5 to 7 feet of heavy wet snow put on your rooftop? CNN has an eye opening graphic on why many roofs around south Buffalo are straining under roughly 50,000 pounds of snow.

https://twitter.com/CNNweather/status/535769973369868288

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Just add water?

The reason the Buffalo mega storm snow is so heavy is simple. Water.

The recorded snowfall totals up to 88 inches contain an incredible amount of water. Anywhere from 4 to 10 inches of liquid "snow water equivalent" is trapped in snowfall just sitting on rooftops and the ground.

That's the equivalent of a hurricane's worth of rainfall.

Here's a look at the modeled snow water equivalent swath running just south of Buffalo from the National Operational Hydrologic Remote Sensing Center.

1121 Buffalo SWE
NOAA/National Operational Hydrologic Remote Sensing Center

The snow has stopped. The big threat now?  Warmer temperatures and rainfall.

Buffalo is on the verge of a rapid thaw and rainfall event over the next three to four days. Rainfall totals of .5 to 1 inch are forecast over the next five days in the Buffalo area.

1121 Buf rain
NOAA GFS model 5-day rainfall output via wxcaster.com

The deep snowpack still sitting on many roofs will quickly absorb incoming rainfall, and rapidly add additional weight loads to roofs, making collapses more likely.

To add to the problem, a rapid thaw is headed for the Buffalo area this weekend. Temps will surge into the 50s, and may push close to 60 degrees by Monday afternoon.

1121 kky Buf
European Model (ECMWF) output for Buffalo, New York. Weatherspark

The combination of a rapid thaw and rainfall will produce a rapid melt of the deep snow, and release a significant portion of the 4 to 10 inches of water stored in the snowpack.

1121 buf fcst
Buffalo NWS

The result? Significant flooding of creeks, rivers and basements is likely as the water has nowhere to go near homes.

The National Weather Service Office in Buffalo has already issued flood watches based on the expected rapid snowfall melt and incoming rain event.

FLOOD WATCH

NATIONAL WEATHER SERVICE BUFFALO NY

1159 AM EST FRI NOV 21 2014

...SIGNIFICANT FLOODING POSSIBLE EARLY NEXT WEEK...

TWO SIGNIFICANT LAKE EFFECT SNOW EVENTS THIS WEEK HAVE BROUGHT A VERY DEEP SNOWPACK ACROSS PORTIONS OF WESTERN NEW YORK. THIS SNOWPACK NOW STORES A LARGE QUANTITY OF WATER. AFTER THE LAKE EFFECT SNOW ENDS...A WARMING TREND WILL START EARLY THIS WEEKEND. BY SATURDAY AFTERNOON AIR TEMPERATURES WILL REMAIN ABOVE FREEZING THROUGH TUESDAY NIGHT. DAYTIME HIGHS WILL RISE TO NEAR 50 F DEGREES ON SUNDAY...AND NEAR 60 F DEGREES ON MONDAY. IN ADDITION TO THE WARMING AIR TEMPERATURES...A SOUTHERLY BREEZE AND RISING DEW POINTS WILL MAKE FOR A MORE EFFICIENT MELTING OF THE SNOWPACK.

AT FIRST THE SNOWPACK WILL ABSORB MUCH OF THE WATER FROM THE SNOW MELT. HOWEVER AS THE SNOWPACK RIPENS...AND WITH THE ADDITION OF A HALF INCH OR SO OF RAINFALL SUNDAY NIGHT AND MONDAY...THE POTENTIAL FOR FLOODING WILL RAPIDLY INCREASE.

PEOPLE LIVING IN AREAS PRONE TO FLOODING...AND WHERE SIGNIFICANT AMOUNTS OF SNOW FELL SHOULD TAKE TIME IN ADVANCE OF THE WARMING TO PREPARE FOR THE POTENTIAL FOR SIGNIFICANT FLOODING EARLY NEXT WEEK. IN ADDITION TO CREEKS AND SMALL STREAMS FLOODING THEIR BANKS...WIDESPREAD FLOODING IS POSSIBLE ACROSS TOWNS WHERE SEVERAL FEET OF SNOW FELL.

Buffalo's epic snowfall event is already deadly and has caused some damage to homes and businesses. The damage may actually increase as snow turns to flood waters in the coming days.

This latest extreme weather event is not over yet.