After several weeks of recurring sunny skies and unseasonably warm temperatures, it appears Boston will finally get a taste of typical New England winter this weekend. A low pressure system is forecast to develop tonight off the coast of the Carolinas, moving up the East Coast in the classic pattern of a Nor’easter storm. As the storm intensifies and passes to the southeast of the Massachusetts coast tomorrow, the Boston area is likely to receive at least 2-4 inches of snow accumulation. The snowstorm could be the largest of the season to date this season, with the largest previous accumulation clocking in on January 21st at 2.9 inches. However, as the surface low has yet to develop, there is still considerable uncertainty in the projected track of the storm, and relatively small perturbations in its track could end up resulting in vastly different snow totals here.

Tomorrow is Groundhog Day, the annual holiday on which the most famous rodent resident of Punxsutawney, Pennsylvania predicts whether winter will last another six weeks, or yield to an early spring. The groundhog, known as Punxsutawney Phil, emerges from his burrow each February 2nd. According to legend, if he sees his shadow upon emerging, he will be frightened into running back underground for six more weeks of hibernation. However, cloudy weather is expected for Punxsutawney tomorrow, meaning the groundhog will stay above ground, thereby predicting an early spring. Of course, the official Groundhog Day prediction has only been correct 39% of the time historically, so Phil may not be the best medium-to-long range forecaster.

This year, the Boston area has been experiencing a very anomalously mild winter. The brief snow showers that passed through the area on Monday night constituted our first measurable snowfall since October. This is rather extraordinary, considering that Boston normally records a total of over 10 inches of snow by the end of December. However, the winter is far from over, and the relative lack of snowfall so far does not necessarily mean that the rest of the season will be as mild.

While many people will be celebrating Halloween this weekend, Mother Nature may have a trick (or treat) of her own up her sleeve. A storm currently centered over Georgia is forecast to develop and move up the Atlantic coast Saturday, potentially leading to some stormy conditions here in the Boston area on Saturday night. Depending on the exact track the storm takes off the New England coast, rain showers on Saturday evening may turn to snow showers overnight.

Although the weather has been a bit chilly this week, owing to the beginning of our annual plunge into New England autumn, we will get a reprieve this weekend from the recent crisp fall weather. A high pressure system will strengthen and stay in place over the northeast United States, leading to clear skies and warm temperatures. Today will be among the least windy days of the year, with abundant sunshine raising the temperature to a downright pleasant 64°F. This trend is set to continue through the long weekend, with sunny days and clear nights resulting in summerlike weather. In fact, Boston is actually likely to be warmer than San Diego, CA this weekend! It is sure to be a good opportunity to go outdoors and enjoy the beautiful weather before it gets too cold.

Just days after Hurricane Irene killed at least 54 people and caused widespread flooding in the northeast United States, another tropical cyclone is brewing in the tropical Atlantic Ocean. Tropical Storm Katia, which last night was downgraded from hurricane status, is expected to reattain that status today, and is forecast to intensify in the next few days as it moves westward toward the North American continent. In fact, Katia could become a major hurricane by early next week. Whether or Katia will threaten the U.S. will depend on the strength of the subtropical ridge several days out, which will dictate whether the storm turns to the north, or continues westward toward land. Still, Katia will not begin to near land for more than a week.

After a passing low pressure system brought thunderstorms and torrential downpours to our area yesterday evening, a cooler air mass is now settling over the region. The cold front with which yesterday’s storms were associated has brought an end to the uncomfortably hot temperatures of the past few days. Instead, a more pleasant weather pattern will be in place for the remainder of the week, with overnight lows in the mid 60s, and afternoon highs in the mid to upper 70s. Skies will be mostly sunny, and an afternoon seabreeze will keep things from getting too hot.

Spring is the peak season for severe weather in the southern United States, and that fact has been quite apparent over the past week. Last Thursday, a deep low pressure system over the southern Great Plains began to spawn severe thunderstorms and tornadoes in that region. As the storm tracked eastward over the next two days, a major tornado outbreak occurred, with at least 138 tornadoes touching down in 15 states. Forty-three people were killed as a result of tornadoes and high winds associated with thunderstorms during this outbreak.

Although spring officially started more than 10 days ago, we have not yet quite escaped the grasp of wintry weather. A nor’easter storm coming up the coast will bring a mix of snow and rain as well as blustery winds and chilly temperatures today, making for a rather miserable first day of April. The wintry mixture began yesterday evening, and it will intensify as the center of the storm passes over eastern Massachusetts. The heaviest precipitation will likely fall as rain this morning, but rain and snow could continue to fall all day, potentially putting a damper on the Red Sox’s scheduled opening day.

Every year, one of the early signs that spring is on the way is the thawing of the Charles River. That sign has arrived this week as the layer of ice covering the river has melted away from most of the river’s surface. As of Monday evening, the only sections of the river close to MIT with remaining ice cover were near the Harvard Bridge, and the total frozen area appeared to be decreasing throughout the day.