Variable weather for CPW
Boston experienced unusually warm weather this week, most notably on Wednesday when the record high of 86°F set in 1991 was smashed by a high of 90°F. Expect more seasonable weather to return for the weekend, which will be dry except for a chance of rain today.
How to listen to warnings
The National Weather Service in Taunton has declared this week as severe weather preparedness week in southern New England, and will be issuing informational statements each day of this week on their website. On that note, it is important to be aware of severe weather in the Boston area, which does occur in the summer months. Commonly, lighting, hail, tornadoes, and flash flooding are associated with severe weather. On days in which conditions are favorable for the development of severe thunderstorms or tornadoes, the Storm Prediction Center in Norman, OK issues a watch.
Warmth as spring begins
The temperature again today will soar to pleasantly warm levels, thanks to the absence of any major cloud cover. A combination of sunshine and a southwesterly flow will create an even warmer day on Saturday, with the high reaching 70°F (21°C). This type of setup is often seen during the spring months in Boston, where a high pressure center off the coast of the Carolinas sets up a flow from the southwest that draws much warmer air into our region. An approaching cold front will bring cloud cover on Sunday and not allow the temperature to become as warm.
Early Sunday morning marks the beginning of Daylight Saving Time (not Daylight “Savings” Time), when we move our clocks one hour forward. Eastern Standard Time (EST), five hours behind Greenwich Mean Time (GMT), gives way to Eastern Daylight Time (EDT), four hours behind GMT. The good news is that the sun will set an hour later, but at the price of one hour less of sleep on Saturday night.
Heat Wave This Weekend
High pressure remains in control over the eastern part of the country, giving us a period of quiet weather through the end of the weekend. Plenty of sunshine will be available, giving some of the snow in the area a chance to melt, although this might be bad news for those who enjoy skiing and snowboarding. A “heat wave” slides in on Friday, with a high of 47°F, which is over 10°F above average for this time of year. Long range forecasts show the possibility of a winter storm Monday and Tuesday, but at this point the weather then is rather uncertain.
Ahh, Winter in New England
Do you like cold, rain, and wind? You’re in luck! An intense low pressure system moving through the Great Lakes will trigger a secondary storm that will affect our region tomorrow. Precipitation may start out as sleet or snow due to the cold air currently in place, but will soon change over to rain as warm air is advected in the area. Rain may be heavy at times during the day tomorrow. The wind will also be an issue tomorrow and Thursday, with very blustery conditions much like what we have been seeing recently. After the storm exits, cold air from Canada digs into the region, with lows in the 20s°F and highs in the 30s°F Friday and Saturday.
Sun, Sun, Sun
High pressure builds into the area today, providing light winds and a sunny sky and letting meteorologists let down their guard for a few days. Light winds and a lack of clouds is a win-win combination for winter cold at night, since these are the circumstances that allow the ground to radiate heat efficiently to space once the sun goes down.
69 On Halloween
A tight pressure gradient will be in place this weekend between a high pressure system off the coast of Nova Scotia and a strong low pressure system over southwestern Ontario. This will cause a strong flow from the southwest, bringing hot, steamy air to our region. High temperatures on Saturday will top out around 69°F (21°C), well above average, so no need to cover up your Halloween costume. The remainder of the weekend will be dry with the next chance for rain on Sunday night.
Grab Your Blanket
As winter approaches, the days and nights grow colder and colder as the sun’s position above the horizon gets lower and lower. At night, the temperature is also dependent on the presence of clouds. On a clear night, radiation from the earth’s surface escapes efficiently to space. On a cloudy night, the clouds act as a blanket that traps radiation. Tonight, as the clouds clear out, temperatures will plummet into the upper 30s°F, the coldest night we have seen yet this fall. Temperatures this week will be generally colder than average, as cold air from the north dominates our region.
Many people are often foiled by the assumption that today’s weather will be the same as yesterday’s weather, finding themselves wearing shorts when things suddenly take a turn for the cooler side. Such quickly changing weather is a consequence of living in the midlatitudes, where the circulation pattern is dominated by what meteorologists call eddies.
Just What Season Is It Anyway?
Many people consider Labor Day as the last weekend of the summer, signaling the end of hot weather and the beginning of the school year. Climatologists define their seasons to be three months long, so that autumn starts on September 1 and ends on November 30, summer starts on June 1st and ends on August 31st, etc. The astronomical first day of autumn starts at the precise moment of the autumnal equinox, which in the Northern Hemisphere can either occur on September 22nd or 23rd. Likewise, the first day of summer starts at the summer solstice (June 20 or 21).
Sixth Coldest June on Record
As you are well aware, June was unseasonably cold. The mean temperature for June was 63.3°F, which ties it with June 1982 as the sixth coldest June on record in Boston since records began in 1872. Average temperatures of various sorts are often reported by meteorologists, such as the average high or low for a particular day of the year. A statistical quantity that is often overlooked is the standard deviation. That is, when a record occurs, how statistically unlikely is that event compared with the mean?
Record Warmth This Weekend
It’s that time of year again, when you no longer need your coat outside, but instead must wear it inside. I am referring to a series of warm, summer-like days, followed by the inevitable switch from heat to air conditioning in MIT’s buildings. This weekend looks to do the trick, with Saturday’s forecasted high of 82°F approaching the record high of 83°F (set in 1982), and Sunday’s high of 85°F challenging the current record of 85°F (set way back in 1872).
April Showers, Rain, or Drizzle?
Meteorologists have many words for water falling from the sky. The most general term is precipitation, which includes liquid and solid water.
Just When You Thought Winter Was Over…
The classic nor’easter swept through New England Monday morning, dumping 7.5 inches of snow at Logan airport (as of Monday afternoon).
A Break From the Snow, But Not From the Cold
After receiving 12.4 inches of snow at Logan Airport this past Sunday and Monday, Boston could use a break from the snow. Luckily, the weather looks free of precipitation over the next week. Friday will be the warmest day in two weeks, with the high temperature looking to reach 40°F (4°C). Otherwise, temperatures will remain below freezing, not giving the snow already on the ground any chance to melt. Another shot of cold air invades us on Sunday, with a forecasted high of around 10°F (-12°C).
Warm Advection to the Rescue
Everybody knows it gets warmer when the sun is out, but sometimes we get some help from the wind. Normally people associate a winter wind with cold, since the flow of air removes heat generated by the body. However, when a strong, persistent wind blows from the southwest, the wind may transport warm air from the southern part of the country to New England. Meteorologists call the transport by wind of an atmospheric property (in this case heat) advection.
Rain Tuesday and Wednesday
An intensifying low pressure system moving into our area from the Ohio Valley will bring numerous rain showers, possibly heavy at times, Tuesday afternoon through Wednesday afternoon. The storm center is predicted to track to our west, which means we will experience relatively warm air.
Prepare for a Deep Freeze
High temperatures this week will struggle to get to 40°F, as a cold pattern dominates our weather this week. Lows will reach the mid 20s°F. While these temperatures are 10 degrees below normal, perhaps “deep freeze” is too strong a word, since in February we will look upon this month and remember how warm it was. Luckily (unluckily for snow sports enthusiasts), no snow is forecasted for this week.
Good for You, Bad for Me
High pressure builds in from the west today, giving us a weekend of full of sunny weather. Temperatures will be slightly above normal with highs in the upper 60s°F and lows around 50°F. And while you are outside enjoying yourself this weekend (or maybe not if you have midterms and psets), meteorologists like me have very little to do.
Cool Pattern Continues
Those without air conditioning may rejoice — high temperatures for this weekend and next week look to remain near or below the average high of 80°F for this time of year. Today, the wind continues to blow from the east, bringing cold air from above the ocean. Temperatures will top out in the low 70s, accompanied by clouds and a chance for more thunderstorms. Saturday looks to be quite pleasant, as winds change to westerly and we get the warmer inland air. We should finally get some sunshine, as well as lower dew points (the dew point is a measure of the absolute moisture content of the air). The chance for thunderstorms returns Sunday night, with a chance of showers each day next week.
Standard Deviation Forecast: High
As you’re recovering from Monday morning’s low of 14°F (normal low: 30°F), take comfort in the fact that Wednesday’s high temperature is forecasted to approach 60°F (normal high: 43°F). Often the media quotes the climatological average highs and lows as part of their statistics, but an often overlooked piece of information is the standard deviation, especially in mid-latitude climates like Boston. You may have noticed that the variation in temperature during the winter season is quite high. For example, in January of this year, the lowest temperature for the month was 7°F, and just five days later, the high temperature was 67°F! Yet during the summer, the temperature stays within a narrower range. This difference between the season has to do with the temperature gradient that exists between the equator and the poles. During the winter, the gradient is the strongest in a tight band that weaves across the U.S. Depending on the north-south position of that band near Boston, we may see very cold weather (if it is south of us), or very warm weather (if it is north of us).
Sunny and Mild Days Ahead
September continues to live up to its expectation of being a month of calm, pleasant weather (don’t worry skiers, it’s only three months until snow). The next seven days look to be filled with sunshine, except for a few clouds here and there. High temperatures Sunday will be in the mid 70s, but otherwise highs will be in the low to mid 60s through the beginning of next week. Tropical activity in the North Atlantic is quiet for the moment, though we may see the development of a storm off the coast of Africa or in the Caribbean early next week.
Martian Weather Report
You may have heard in the news about the Mars Phoenix Lander, currently taking soil samples near the Martian north pole. A somewhat less publicized fact is the temperature data being taken by its weather sensor. At the lander site, yesterday’s high temperature was -17°F (-27°C) while the low temperature was -117°F (-83°C). And this is in the middle of summer! It is estimated that the record maximum temperature on Mars, say, on the hottest summer day at the equator, would be around 70°F (21°C). The coldest day at the winter pole can only fall to the carbon dioxide frost temperature of -190°F (-123°C), since then Mars’ carbon dioxide atmosphere begins to sublimate. No equivalent exists on Earth, since it never gets cold enough for our predominately nitrogen atmosphere to freeze out. At least there’s no rain, but you might get stuck in a dust storm that can last for several months!
Dry Week Ahead
This week, an area of high pressure will dominate the eastern third of the country. This high pressure region is forecasted to move very slowly from west to east, which means we will see an extended period of dry weather. A low pressure system that might graze us Thursday night is the only chance we have for rain through Friday. Today will be sunny with perhaps a few fair weather cumulus clouds. Even though the sun will be shining, the wind will blow in cold air out of the north. On Wednesday and Thursday, the winds shift and come from the west, which will result in temperatures in the low to mid 60s. Evenings will still be chilly, since the lack of cloud cover lets thermal radiation escape easily into space.
Coastal Storm Brings Friday Rain
Monday’s snow storm brought seven inches of snow to Boston, which also happened to tie the record maximum snowfall for that date set in 1982. The city was lucky, since some numerical weather forecast models were predicting as much as 14 inches. An unusual event that occurred briefly with this storm was a report of thunder early Monday morning. Thunder and snow do not usually happen at the same time.
A Spectrum of Precipitation
This month Mother Nature has provided us with the full range of winter precipitation, including snow, rain, sleet, and freezing rain. And she’s not done yet. Another weak round of wintry mixed precipitation is expected Tuesday night, followed by a more intense storm Thursday night. High temperatures for the rest of the work week will be in the mid-30s to mid-40s, with lows in the mid-20s to mid-30s.
Sunny Days Ahead
As the Boston Red Sox return home for their victory parade today, nature will treat them to a beautifully sunny sky and relatively mild October temperatures. Expect a high around 60°F (16°C) today and an even warmer 65°F (18°C) tomorrow. Make sure your Halloween costume is well attached tomorrow evening as it could get rather windy. Look for a chance of a sprinkle on Thursday with a high of 61°F (16°C). Night-time temperatures, as you may have noticed, are beginning to get on the chilly side, so if you plan to be out late a coat and perhaps some gloves or a hat might be a good idea.
Head to the Beach
My advice to you: head to the beach if you can. Today and tomorrow will be very hot and humid, making the frigid waters of the Atlantic Ocean feel downright pleasant. Watch out for possible thunderstorms, some of which could be severe. If you plan to be outside, drink plenty of water to prevent heat exhaustion and remember the sunscreen. Sunday’s forecast shows some relief from the heat, and a passing high pressure system will ensure a sunny day.
Unseasonably Warm Weather Continues
Boston continues to be treated to unseasonably warm autumn temperatures. In fact, yesterday’s high temperature of 86°F (30°C) at Logan Airport (where official weather measurements for Boston are taken) exceeded the previous record high of 85°F (29°C) set in 1983. The average high temperature for the first week of October is 66°F (19°C). Our warm trend will continue with pleasantly warm temperatures Friday and Saturday. A weak cold front will move through the region on Saturday night, bringing cooler temperatures and a slight chance of showers. No heavy rain is expected at least through the beginning of next week. In terms of precipitation, Boston has been on the dry side the past month, with September seeing only half of its normally measured rainfall.
Wind and Weather
Wind is an important parameter in determining the weather. Not only is the wind strength a factor (as it turns out, Boston is the windiest major city in America), but so is the wind direction. As you might expect, when the wind blows from the north or south, the temperature becomes colder or warmer, respectively.
Cooler Weekend Ahead
Unstable air associated with a cold front to the west will give us a chance for an isolated shower or thunderstorm today. Temperatures will remain unseasonably warm for one last day, as part of our mini-heat wave of this past week. As the high pressure over central Canada moves to our southwest, the associated clockwise circulation will bring in cooler air from the north. This will bring the weekend’s high temperatures back to the mid-60s, which is more normal for this time of year. The good news is that the friendly high pressure will bring sunny conditions Saturday through Monday, continuing the dry pattern we have been in for the past two weeks.
Dry Weekend Ahead
Perhaps the most startling weather event of the past week was the batch of heavy snow that paid us a visit Wednesday afternoon. Fortunately, it was too warm for any significant accumulation or ice hazards. As it turns out, April snowfalls are not uncommon in Boston. The average total snowfall for April is around 1.5 inches, which accounts for a little under 4 percent of the seasonal total. The record monthly snowfall for April is 22.4 inches, which occurred in 1996 (and is more than we've gotten for the entire year). Surprisingly, the latest snowfall ever was on June 17 in 1952! (Source: <i>http://www.erh.noaa.gov/box/AveragesTotals.shtml</i>)
Winter Hangs On
Despite the approach of the first day of climatological spring on March 1, winter conditions continue to stay with us. As of yesterday evening, Logan Airport had received 1.6 inches of snow from the most recent snowstorm, bringing the seasonal total to 6.4 inches. On this day last year the total was 39.9 inches. It looks like we will have another chance to increase the total late this week and into the weekend, as a low pressure system over the Rockies moves eastward and intensifies. This system brings a whole bag of goodies in terms of precipitation — everything from snow to rain and freezing rain. High temperatures this week will be in the upper 30s°F, while lows will be in the upper 20s°F.