Snow accumulations of from four to seven inches are now forecast from a storm that will begin tonight and last through most of the day tomorrow, according to the National Weather Service in Upton.
A winter storm warning has been issued for eastern Suffolk County and is in effect from 10 p.m. tonight through 4 p.m. tomorrow.
Visibilities during the storm will be reduced to one-quarter to one-half mile.
A winter storm warning for heavy snow means severe winter weather conditions are expected or occurring. Significant amounts of snow are forecast that will make travel dangerous. Only travel in an emergency, the weather service said.
Forecasters are keeping an eye on the expected development of a coastal storm that may bring even greater snowfall amounts to the East End Tuesday into Wednesday next week.
