Autumnal Equinox is here!

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While Autumn started for Meteorologists back in the beginning of September, today marks the Autumnal Equinox! What is the Autumnal Equinox you ask?? To start, Equinox finds its roots in Latin, meaning Equal Night. Here’s a quick look at the science behind it:

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The Earth is always tilted, with the tilt fluctuating between 22.1°and 24° (which the change in the tilt angle occurs over thousands of years). Currently the Earth is tilted at an angle of 23.5° towards the sun. When the Equinox occurs, the way the Earth is tilted and its position in the orbit cause it to be almost perpendicular to the incoming rays from the sun.

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Now even though equinox means, equal night, the earth is not entirely perpendicular to the solar rays at all points due to its spherical nature. We can also look at the spherical nature and the nature of the atmosphere causing the light from the sun to refract and keep most areas light for more than half of the day. The equator never sees equal day and night due to this fact, but areas north and south of there see these days occur at different times after the equinox. The furthest points from the equator see the equal day and night closer to the equinox and points closer to the equator see equal day and night further away from the equinox.

This may seem a bit confusing as we traditionally think of the equinox as 12 hours of sunlight and 12 hours of darkness, but the Equinox also plays a big role for our seasons. After the Equinox, the Earth begins to move further on in its orbit, so that the Northern Hemisphere becomes tilted away from the sun.

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This brings shorter days and longer nights due to less solar radiation in the Northern Hemisphere. This brings us our Autumn and Winter Climate as the reduced amount of solar radiation plays a role in keeping temperatures cooler in the Northern Hemisphere. There is also much more interaction in the atmosphere that also affects the temperatures changes.

So what will this Autumn bring to us? Hopefully more rain as the summer was too dry and the drought in the area keeps getting worse!

 

Tropical Storm Hermine: Impacts on New England

Hurricane Hermine was downgraded yesterday after it passed over Florida to a Tropical Storm. It inundated Florida with torrential rains (up to 10″ in some areas) and flooding (thanks in part to a storm surge of up to 12′ on the coast) and broke a streak that saw the state go almost 10 years without seeing a hurricane hit! Now that it is out into the Atlantic Ocean waters again, what does that mean to us in New England?? Here is a current look at the storm:

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Right now the Carolinas and Virginia are seeing the worst of the winds and the rain from the storm, but this storm is projected to stay near the East Coast for the next few days. Here’s a look:

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Right now the cone of uncertainty is very high for the end of the week, but for the most part, it seems the storm will take a slow trek up the east coast and track further east as each day goes along. This does bring it close enough to New England for us to see some of the aftereffects of the storm, but the question is how much will we see? Our Ocean temperatures are still warm due to summer just ending, so the storm can still churn out some good rain as it won’t run into the cold water that usually kills hurricanes, but it is unlikely that the storm would strengthen any more.

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First off is the rain situation. Looking at the projected radar image, we can see that bands will keep flowing into New England throughout the day Tuesday and Wednesday and even into Thursday on the coast. This will bring some much needed rainfall to the area, with areas along the coast seeing the most rainfall (around 1-3″), while areas further to the North and West see less rainfall (anywhere from .05″ to 1). This unfortunately will not bring much relief to the droughts in the area, but any rain is good rain in our books.

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A look at the current probabilities for Tropical Storm force winds puts the best chance for strong winds off the coast of New England with coastal areas seeing between a 40-50% chance of those winds. Areas over the whole of Southern New England should expect to see gusty winds between 20-40mph with stronger winds along the coastlines. This is not too dangerous usually, but as we have had such a drought this summer, the trees are dry and can easily break apart and be pushed over by gusty winds, so caution needs to be taken. Any boats or small crafts off the coast of Connecticut and Rhode Island need to dock and take caution as the gusty winds out there will cause rough surf for the area.

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This is further exacerbated by the GIF above showing the storm sitting and spinning right off the coast of Connecticut and Rhode Island for a good two days before finally moving out to sea. This is just a preliminary analysis and does not represent what actually will happen by Thursday. Looking at the 10m winds, there are strong winds around 35-50 kts along the coastlines, meaning that there is a good chance for some strong surf in the areas as well as some minor storm surge along the coastline. REMEMBER: Storm surge is not a wave, it is water that is raised to a higher level due to the winds of a storm. This water will not just hit an area and go away as it keeps the depth that it had when it hits the land, unlike a wave, so areas that get hit by it will remain flooded with the extra water for awhile. It is not safe and anyone affected by it should stay out of the water as it could be dangerous.

Overall, New England is going to be spared from the brunt of Tropical Storm Hermine, but we still will see some of the winds and the rain from the storm over the coming week.

 

 

 

Hot and Humid with a chance of Storms

So how about those thunderstorms last night?? Finally we saw some much needed rain along with some of the best thunderstorms that we have had in the area in years. Here is a look at what most communities saw via the CoCoRaHS

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We see that many towns to our west reported seeing rainfall amounts over 2″! Most places in the Merrimack Valley saw around .5″-1.5″ at most. This is much needed especially for the Northeast part of Mass (just take a look at the latest drought monitor!)

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But sadly this will only make a tiny dent in a severe drought that has been with us for the whole Summer. The next question is if there is any relief in sight for this rainfall. The answer to that is the same as always: we do not know for sure.

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The latest prediction from the Climate Prediction Center gives us equal chance for above or below average rainfall for the next month. So it will all depend on the patterns that we see and how they transition between each other. With each of these continuing hot and humid days, we get another chance for some thunderstorms to break out in the afternoon and evening hours, which will bring us some much needed relief. Right now though, the best chance for some actual steady rain looks to be at the end of the week when we begin to see a pattern transition to some cooler and less humid weather for next weekend. Let’s take a look at the upper air maps for the end of the week:

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We have had a consistent, high ridge over the Northeast for the past week with some short waves briefly bringing slight troughing to the region at times. This has been an anomalously high ridge though, so temperatures have been well above average, so much so that even when a trough came, it barely was able to bring the usual cooler air with it to the region. Looking at the end of this week, we see the ridge begin to break down and more short waves appear in the northern stream. This will bring much cooler weather to the Northeast as the warm air retreats southward. This also suggest there could be more rain in store for the pattern, but that is tough to say this far out. But, and I say but, we have another week of hot and humid temperatures to go through before we get there!

Sunday will be the worst that we see for the week in terms of temperature and humidity. Highs in the afternoon could reach the mid to upper 90s and Dew Points will be oppressive in the low to mid 70s! This will make temperatures feel in the 100s for most of the afternoon and early evening hours, so make sure to stay hydrated.

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Monday sees things get slightly better with Highs in the upper 80s to low 90s and some relief with Dew Points reaching the mid 60s. It will still feel warm and there will always be the ever present chance for thunderstorms in the afternoon. Tuesday is when we start to see a shift as we get a good chance for showers each day from Tuesday to Thursday and Highs all three days will only be in the mid 80s, could reach upper 80s if the sun comes out long enough.

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Then by next weekend the big relief hits with Highs only reaching the upper 70s to low 80s both days! Dew Points remain relatively cool in the upper 50s as projected right now. This suggests a pattern shift for us to some a more rain-filled and cooler period, but the question is how long will this last? That is the question and one we will continually be keeping an eye on!

It’s Dry as a Bone, But is There Relief in Sight???

Taking one look at the rainfall totals so far this summer will tell you a story: it has been extremely dry. June didn’t seem too bad:

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Climatology data for Lowell for June painted a typical summer-like picture: dry and beginning to get hot at the end of the month.

We were only around an inch and a half below the monthly average rainfall totals.Temperatures weren’t that warm either, so the danger of wildfires starting was low. Then came July…….

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There was some rainfall to begin the month and it looked like we would finally catch up with our lack of rainfall that we had for the past few months. This much needed rain came just in time too as we began to see Highs reach the upper 80s to 90 degrees. A few cool days mixed in when the rain occurred, but then a pattern shift happened after the 11th, and that’s led us to what we are seeing today.

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500mb height anomalies in the United States starting from July 22, 2016.

Anomalously High heights took over in the Central U.S. and this spread all the way to the East Coast. This brought in much warmer, drier air with only one day since July 11th having seen Highs below 80 degrees! Also with this pattern change came a lack of precipitation. We have seen only three days have rain and a total of 0.11″ since July 11th! That gives us a meager total of 1.35″ for the month of July, which is almost on par with what we saw in June, but leaves us with this for the year:

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Another year of bone dry weather.

We are now 7.83″ below average for rainfall for the year and the U.S. Drought Monitor now has us under a Severe Drought.

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We need water and we need it now!

The question is will this get any better any time soon? The long answer is that we do not know what the rest of the summer holds in respect to precipitation amounts, but the short term answer is a bit easier. We have a couple chances for some much needed rain this weekend thanks to this setup of moisture:

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There is a large amount of water vapor in the atmosphere for some rain tomorrow

 

This will lead us to periods of rain throughout the day tomorrow (Friday). The biggest question the models have for tomorrow is where the heaviest bands will set up. The current two American Models have this to say:

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The NAM keeps the heaviest of the rain to our South over Southern MA, Connecticut and Rhode Island. The GFS however wants the heaviest rain to extend from Southern MA all the way up into Southern New Hampshire. The heaviest rains for the NAM look to bring about 0.5″-0.75″ to our area and around and 1″-1.5″ to the areas to our South. The GFS brings much more torrential rains with increased moisture from ocean enhancement bringing totals across the state into the 2″-2.5″ range. This seems very excessive and we will most likely be in the lower end of around 0.5″-1″ by the end of the day tomorrow, but small changes can make big differences like the models show.

Saturday looks to be clear and sunny, but then we see another chance for rain on Sunday.

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This looks to be a much more scattered showers event for the state and most areas will see periods of on and off rain beginning in the morning and ending in the evening. Most areas look to pick up between 0.1″-0.25″ when all is said and done.

Temperatures this weekend look to be much more manageable with Highs all three days in the low to mid 80s! Humidity will be a factor though as there is a lot of moisture in the atmosphere.

So will this rain cure our drought??? Nothing except for a good weeks worth of rain could do that, but anything that we can get will help!

The Heat is On, But is It a Heat Wave?

A Heat Wave. Triple H weather.Bad Hair Days. The Dog Days of Summer. Whatever you like to call it, it’s something we have to deal with every year, though not nearly as much in New England as other parts of the country.

According the American Meteorological Society’s Glossary of Meteorology, the official definition of a heat wave is :”A period of abnormally and uncomfortably hot and usually humid weather.

The glossary adds further:

To be a heat wave such a period should last at least one day, but conventionally it lasts from several days to several weeks. In 1900, A. T. Burrows more rigidly defined a “hot wave” as a spell of three or more days on each of which the maximum shade temperature reaches or exceeds 90°F. More realistically, the comfort criteria for any one region are dependent upon the normal conditions of that region. In the eastern United States, heat waves generally build up with southerly winds on the western flank of an anticyclone centered over the southeastern states, the air being warmed by passage over a land surface heated by the sun.

How often do we have an actual heat wave here in New England? For Lowell, we average 2 heat waves per year. The most common time for one is between the middle of June and middle of August, but they have occurred as early as the middle of April and as late as late September. In the summer of 1955, we actually had 8 separate heat waves between the end of June and late August. The worst of the bunch was 9-day heat wave that started on June 30 and ended on August 7. On 3 of the 9 days (July 31, August 4, August 5), the high temperature was 100 degrees.

So far, we have not had a heat wave in Lowell in 2016. We had one in 2015, a 3 day stretch from September 7-9, but 2014 also did not feature a 3-day stretch of temperatures above 90.

While a 3-day stretch of 90-degree weather isn’t that uncommon around here, a string of 7 or more days in a row is. In fact, in the 125 years of climate data we have for Lowell, we’ve had a stretch of 7 consecutive days above 90 degrees just 20 times. The last time it happened was just 3 summers ago – July 14-20, 2013. Longer stretches are even rarer. We had a 10-day stretch of 90-degree temperatures from August 27 through September 5, 1953. This occurred just one year after a brutal 13-day stretch from July 11-23, 1952 that featured 4 days with highs above 100 degrees. The worst heat have in Lowell though was a 15-day stretch from August 1 through 15, 1988 which capped off one of the hottest summers in Lowell history.  As if having 15-days of 90-degree weather isn’t tough enough, 11 of those days featured highs of 96 or higher, one (August 3) had a high of 100, and most of those days were accompanied by high humidity, with dewpoints well into the 60s and 70s.

While there have been many memorable heat waves in New England, there’s only one day that is known simply as “The Hot Day”. On August 2, 1975, a ridge of high pressure settled into the Northeast. August 1 was hot in its own right, reaching 102 for a high here in Lowell. Temperatures didn’t drop much that night, with the stifling airmass in place. The low temperature on August 2 here in Lowell was only 79, the warmest low temperature on record here. With temperatures already starting the day so warm, and plenty of sunshine, it didn’t take much to send temperatures to levels that had never been seen around here before. On Nantucket, the high hit 100 for the only time on record. Providence, Rhode Island reached 104, setting a new state record. In Massachusetts, a new state record of 107 was set in both Chester and New Bedford. Here in Lowell, our records show a high of 108 was recorded that day, but this seems suspect. High temperatures from other nearby spots that day included 105 in Reading, 103 in Pepperell, 103 in Haverhill, 101 in Lawrence, 100 in Nashua, and 99 in Dracut.

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Daily Weather Map for August 2, 1975. Image provided by NOAA.

Luckily, 100-degree heat isn’t common around here. On average, we hit 100 here in Lowell about once every 4 years.  The last time it occurred was on July 22, 2011, when we reached 102. In both 1911 and 1952, we reached 100 degrees 5 separate times. 90-degree days occur an average of 14 times per year.  So far in 2016, we’ve had 4 days with highs of 90 or higher.  1932 is the only year on record in Lowell where the high temperature failed to hit 90 degrees.  On the other hand, 1955 saw an incredible 46 days with highs of 90 or higher, just ahead of the 45 such occurrences in 1983.

Whether we hit 90 or not today is still to be determined (the temperature in Lowell was 87 at the time of this being written), but it certainly seems like there are more 90-degree days in our immediate future. The GFS model is showing the possibility of high temperatures in the lower to perhaps middle 90s Sunday and Monday ahead of a cold front, then the possibility of more heat late in the week.

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High temperature forecast for Monday July 18 based on the GFS model. Image provided by WeatherBell.

Summer is Here!

Yesterday marked the beginning of summer with the Summer Solstice (our Meteorological Summer technically began the beginning of this month).  So far this month we have seen a good mix of above and below average High temperatures for each day, with this past week seeing the longest string of above average temperatures we have seen this month.

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Climatology data for Lowell so far this month has us around average for the average High temperature and well below average yet again for precipitation.

The CPC put out there new report for the rest of summer last week and it looks like the trend will continue with above average temperatures for the rest of summer for the region.off01_temp

There is also an above average chance over the Southwest U.S., which correlates with the extreme High temperatures that region has been seeing over the past week with Highs well into the low 100’s! This is really going to hurt the Southwest yet again as they are still in drought conditions even after all the rainfall they saw due to the El Nino last year.

We can see above the latest reports for drought conditions and precipitation chances over the next three months. For our region we have an equal chance of seeing either above or below average precipitation, but we are not in any drought danger and actually the Northeast part of MA and the Southeast part of NH are likely to see some drought mitigation. The Southwest U.S. is going to see more trouble as the drought is likely to persist through the region. This combined with the chance for above average temperatures could likely lead to dangerous living conditions for people in the Southwest and an increased risk for wildfires. This is only an outlook so time will tell whether or not this will come to fruition this summer.

The other news is that there are already signs that a transition to a La Nina could occur over the next few months, which will have to be monitored to see what effects this could have on the atmosphere in time for the Northern Hemisphere Autumnal and Winter seasons.

May Retrospective

What a month we saw in May! Some of the coldest temperatures we had seen all spring started the month and quickly gave way to a few weeks of summer-like weather, all thanks to our good old friend the omega block.

 

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Remember this guy?? The one that brought us all the rain?

Now that we have entered June, let’s take a look at the climatological numbers for May for Lowell.

CaptureWe saw an average high temperature of 66.6° and an average low temperature of 47.69° for the month. These are both slightly below the average, with the average high being 69.2° and the average low being 48.7°, making this one of the few months we have seen in the past year that was cooler than average in Lowell. However, we did set one record High on May 28th with a temperature of 95°! This beat the old record High of 93° set in 1978.

The one remaining issue though is that we were well below average yet again for precipitation for the month. On average, we see 3.66″ of rain for the month of May, which puts us 1.79″ below the average for the month

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Another month of below average precipitation puts us further into our drought for the year.

So what does this bode for June? So far we can see that we have been around to slightly below average for High temperatures and above average for low temperatures. Our precipitation has been well above average, but we will have to wait and see whether it continues to trend that way. As we saw in May, the month started out with a lot of precipitation, but we ended up below average as a dry pattern set in.

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The current climatological outlook from the CPC shows us to have  above average temperatures for the summer months as well as a chance for above average precipitation. We will have to continue to wait and see if and when this pattern will set in as the next week looks to see temperatures below average yet again.off01_temp