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:

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…….

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.

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:

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.

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:

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.

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!

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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.

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.

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