The deep snow left behind by February storms has been melting in the warmth of recent springlike temperatures, saturating the ground and raising waterway levels. Combined with the 2-4 inches of rain expected this weekend, the remaining snow melt could send already swollen streams over their banks.
National Weather Service forecasters early Friday issued a flood watch for Carbon and Schuylkill counties from tonight through Sunday morning, said metrologist Jim Poirier of NOAA's Mount Holly, New Jersey, office.
A watch means the conditions will allow for the potential of a certain thing happening - whether it's heavy snow or rain," he said. 'But it's not necessarily going to happen. A warning means those conditions are occurring or they are imminent and expected."
Poirier said our area can expect a "2-4 inch total, with a possibility that local spots may get as much as 5 inches. Ground water is already high, and with the addition of any snow melt that will act as if there is even more rain occurring. Recent snow melt has raised levels of waterways."
Poirier cautioned people who live in low-lying areas "to be aware that flooding can occur quickly. Be prepared. Move things to upper floors, and be ready to evacuate to high ground if flooding does occur."
About an inch of rain is expected to fall from late tonight through Saturday morning. The heaviest rainfall, about 2 inches, is expected Saturday morning through Sunday morning.
"The Saturday period is especially critical - that's when you'll get the most snow melting and heavy rain," NOAA metrologist Barry Lambert of the State College office.
Carbon County Emergency Management coordinator Mark Nalesnik said the county is ready should the need arise.
"It's a watch-and-see. We will react to circumstances of the severe weather as we see it develop," he said. "We have a lot of things we can do and activate if the need arises."
That includes activating the Emergency Operations Center to guide communities in whatever needs to be done. The Emergency Management center will keep a close eye on waterways.
But an ounce of prevention is worth a pound of cure.
"Municipalities need to be sure their storm drains are open and cleared and ready to receive large amounts of water," he said.
The rain will result from what NOAA is calling a "complex storm." According to NOAA, "an area of low pressure over the central portion of the nation will move eastward through Saturday. A second low pressure system is forming off the South Carolina coast and will move slowly north into the Delmarva Peninsula on Saturday before heading offshore."
The deluge could cause flooding of underpasses and poor drainage areas.
NOAA advises people to allow extra time if they are traveling, and not try to drive through flooded areas.