Most of RI and SE MA is under a Winter Storm Warning for the quick-hitting burst of snow that is likely to bring several inches to Southern New England in a relatively short period of time Saturday afternoon and night. The areas shaded in pink are under a Winter Storm Warning, which generally means that 6 or more inches of snow is imminent. The areas shaded in purple are under a Winter Weather Advisory for less snow as a result of lighter precipitation or some mixing with rain.
The National Weather Service also offers snow probability forecasts for a given amount. The odds of at least 1″ are near certain for most of the area. The odds of 4″ are also quite high. In the areas that are expected to be hardest hit, the NWS is estimating a nearly 50/50 shot of 8″ of snow, and a 1 in 4 chance of a foot.
Overall, I think the odds projected by the NWS are decent. The only thing I would consider is slightly lower odds of reaching 8″ of snow. If the storm travels just a bit quicker than expected, or if the snow isn’t quite as heavy as forecast, than most of the ares will come up shy of 8″. I’d be in the 25-35% range for 8″ totals in the hardest hit areas.
Here is the text from the Winter Storm Warning:
...A DEVELOPING OCEAN STORM WILL BRING A PLOWABLE SNOW TO MUCH OF SOUTHERN NEW ENGLAND THIS AFTERNOON AND TONIGHT... .LOW PRESSURE DEVELOPING OVER THE SOUTHEAST STATES WILL MOVE TO THE CAROLINA COAST THIS AFTERNOON. THE STORM WILL THEN RAPIDLY INTENSIFY AS IT PASSES ABOUT 100 MILES SOUTHEAST OF CAPE COD TONIGHT...THEN INTO NOVA SCOTIA SUNDAY. THIS STORM WILL BRING A LARGE SWATH OF 3 TO 6 INCHES OF SNOWFALL TO SOUTHERN NEW ENGLAND...WITH AN AREA OF 7 TO 9 INCHES ACROSS PORTIONS OF RHODE ISLAND AND EASTERN MASSACHUSETTS. CTZ004-MAZ005>007-012>021-RIZ001>007-291845- /O.CON.KBOX.WS.W.0005.121229T1700Z-121230T1200Z/ WINDHAM CT-CENTRAL MIDDLESEX MA-WESTERN ESSEX MA-EASTERN ESSEX MA- SOUTHERN WORCESTER MA-WESTERN NORFOLK MA-SOUTHEAST MIDDLESEX MA- SUFFOLK MA-EASTERN NORFOLK MA-NORTHERN BRISTOL MA- WESTERN PLYMOUTH MA-EASTERN PLYMOUTH MA-SOUTHERN BRISTOL MA- SOUTHERN PLYMOUTH MA-NORTHWEST PROVIDENCE RI- SOUTHEAST PROVIDENCE RI-WESTERN KENT RI-EASTERN KENT RI- BRISTOL RI-WASHINGTON RI-NEWPORT RI- INCLUDING THE CITIES OF...PUTNAM...WILLIMANTIC...FRAMINGHAM... LOWELL...LAWRENCE...GLOUCESTER...MILFORD...WORCESTER...FOXBORO... NORWOOD...CAMBRIDGE...BOSTON...QUINCY...TAUNTON...BROCKTON... PLYMOUTH...FALL RIVER...NEW BEDFORD...MATTAPOISETT...FOSTER... SMITHFIELD...PROVIDENCE...WEST GREENWICH...WARWICK...BRISTOL... NARRAGANSETT...WESTERLY...NEWPORT 535 AM EST SAT DEC 29 2012 ...WINTER STORM WARNING REMAINS IN EFFECT FROM NOON TODAY TO 7 AM EST SUNDAY... * LOCATIONS...RHODE ISLAND...NORTHEASTERN CONNECTICUT AND EASTERN AND SOUTH CENTRAL MASSACHUSETTS. * HAZARD TYPES...HEAVY SNOW. * ACCUMULATIONS...SNOW ACCUMULATION OF 4 TO 8 INCHES. * UNCERTAINTY...THE RAIN SNOW LINE WILL TRACK ACROSS COASTAL SECTIONS OF RHODE ISLAND AND SOUTHEAST MASSACHUSETTS. THUS THE HIGHEST SNOW ACCUMULATIONS WILL BE AWAY FROM THE COASTLINE. * TIMING...SNOW BEGINS EARLY THIS AFTERNOON WITH THE HEAVIEST SNOW FALLING FROM 5 PM TO 1 AM...THEN SNOW TAPERS OFF TOWARD SUNRISE SUNDAY. * IMPACTS...ACCUMULATING SNOW WHICH MAY MAKE DRIVING DIFFICULT. POOR VISIBILITY AT TIMES. PRECAUTIONARY/PREPAREDNESS ACTIONS... A WINTER STORM WARNING IS ISSUED WHEN AN AVERAGE OF 6 OR MORE INCHES OF SNOW IS EXPECTED IN A 12 HOUR PERIOD...OR FOR 8 OR MORE INCHES IN A 24 HOUR PERIOD. TRAVEL WILL BE SLOW AT BEST ON WELL TREATED SURFACES...AND QUITE DIFFICULT ON ANY UNPLOWED OR UNTREATED SURFACES.