Monday, October 31, 2011

What to expect for November in the way of weather!

Ah yes, November! A most interesting month. In many ways it's like March only November comes in like a lamb and can leave like a lion! Expect pretty nice and warmish temperatures through the first two weeks of this month and then watch out as the night times get seriously cold just before the end of the month (see graph of Nov 2010). 

 The average high is 57F and the average low is 33F where I live in southwest Missouri. However, that figure is skewed somewhat with the warmer stuff coming early on, followed by rapidly cooling conditions late. The reason; more and more aggressive incursions of cold air from the northwest in the form of fronts that also bring moisture as a consequence. Expect rainfall to be close to four inches as a result. Note: Last year was a little dry at about 2.50 inches!

So, think cold and damp as one way to characterize November. Ergo, not my most favorite month, but still way out ahead of the evil trio that is December through February. Please remember though, that just as as this month is often humid, so it is that cold dry air will soon follow. Time to make sure you have a humidifier in good working order. I have an old Duracraft DH799 unit that uses three filters that have to be replace every year. I also need to remember to order a bottle of anti-bacteria solution. Sometime in early December, I'll have this unit running pretty much full time to help keep the air in my home moist. This actually helps my heat pump out as the air will hold heat better if the humidity is at 40% or there about. For more on that, please see my article on moisture control.

Sunday, October 30, 2011

Freak East Coast storm or part of a pattern?

October 29, 2011 - The northern section of the east coast was slammed with what they termed a ‘rare nor’easter’ that killed three people and left millions without power.  But was it really? Or, was this the opening shot of what could be a very strange winter for North America?

Read more on this story here!

Sunday, October 16, 2011

Like a Yo-Yo, the weather will be up and then down and then…!

After hearing the words ‘unseasonably warm’ for the better part of a week, get ready for the warm part to become the unseasonably cold part.

The National Weather Service has announced ‘colder than normal conditions’ can be expected starting about Wednesday of the coming week as a Canadian air mass makes an incursion into the Midwest. Morning temperatures on Thursday may be below freezing, especially in low lying areas. So, be prepared!

Saturday, October 15, 2011

First two week weather recap for October 2011!

The month of October averaged about 4 degrees F. warmer than what is the historical standard. This made it a great month to be outdoors as most days were clear, dry and pleasantly warm. Yet, we also had enough rain to keep us about where we need to be in that department. The month of October normally sees about 3 1/3 inches of rain, so we need only about two more inches to make that target.

This trend for warmer than normal weather should continue until about Tuesday, October 17th when colder conditions will begin to take hold. The weather service is predicting highs in the fifties and lows approaching the freezing mark.

I also thought to include the current Arctic Oscillation Index (AO) for informational purposes:

 I've noted that all the models are trending towards a negative index. This would seem to indicate the potential for colder than normal conditions coming in the near future.

Friday, October 14, 2011

Overnight temps to hit freezing mark for the first time!

As early as Tuesday, Oct the 18th or as late as Thursday, the National Weather Service expects to see the outside overnight temperatures to get close to or at the 32F mark for the first time this fall. Last year in 2010, this did not happen until the 29th.

While there is no significance to this, it will be interesting to follow the mean weekly temperatures as we get into the month of November.

In the meantime, anyone who wants to protect cold sensitive plants may want to cover them by the 18th .

Wednesday, October 12, 2011

October 12, 2011 dawns with the crack of thunder and lots of rain!

Starting at around 5:30 AM in the Forsyth, Missouri area loud and sharp air to ground lightening strikes intensified as they responded to a frontal trough. I have to say that the thunder had a real hard sounding quality to it and, as is normal around here, we lost power for about half a minute. Actually, make that twice as a close lightening strike knocked it out again for a second as I was writing this post. Shocking enough to make your heart stop!! This sort of thing happens with regularity as the local coop, Empire Electric, seems to have only the most tenuous grasp on its electric grid. (When I lived in Chicago with Com Ed, it would take a blizzard to kill the power). Thinking of which, should we experience a hard winter, I cannot imagine this utility working all the time and so would urge everyone to go out and buy a good backup generator.

Along with the thunder came rain, with a real downpour occurring at about 6AM. This didn't last long as the severe part of the system moved quickly on through the area. Behind it were occasional short-lived downpours interspersed with light periods of rain that continued on into the morning hours.

The rainfall for the month, as of noon, amounted to 2 inches in a month that normally sees 3.4 inches. We still have a couple of weeks to go, so I'm hoping we'll hit that mark. This was good to see as I think most everyone would prefer a wet fall over a dry one. I'm not as sure, however, if that would be a good thing should it get carried into the coming winter period as that could easily spell ice! (Note: Last October saw just .56 of an inch of rain and most of that fell on the 26th of the month).

Temperatures during this storm hovered at around 60F. Temperatures for this date expected to get up to 70F or so before a cold front makes it appearance later in the week.

Sunday, October 9, 2011

Winds of Change?

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I’m not sure what it is about this Sunday, but I can feel a definite change. Yes, the winds are a blowing as rain heads in our general direction for Monday, but it’s more than that. Somehow the sunlight feels less intense than what I had been used to. The length of the day is now about 11 ½ hours and this will continue to shorten considerably over the next thirty days. Also, as the arch of the sun gets lower and lower in the sky, less thermal heat energy reaches the surface; a key reason why the nights gets colder this time of year.

As I look out over my yard, I can see it is full of leaves, courtesy of a lone maple tree. Maple trees lose their leaves early and so my yard already has the look of fall to it while the other yards are mostly leaf free. It’s too bad my religion prohibits me celebrating Halloween as the yard would be well suited for a pumpkin or two, right about now!

The high pressure ridge which has acted as a blocker for the rains out west have had a good effect on states like Texas, bringing some of the central parts of the state well over four inches of rain; perhaps a little payback for the folks living there!

Now, as the area of high pressure moves off to the east, that same area of rain will invade the middle states. Right behind this is a shot of colder air which will also act to bring the unseasonable warm temps we’ve been getting back down to more normal (read as colder) levels.

Saturday, October 8, 2011

Texas may see some relief!

 click on image to animate

I'm not positive, but it seems that the high pressure ridge may be doing some good for states that really need some rain. This time loops indicates moisture may be feeding into the Texas panhandle region. One can only hope!

Friday, October 7, 2011

Weather map for Oct 7 2011

This first week of October was a keeper! Warm days and cool nights with trees just now beginning to show a change of color. And, while we could have used some rainfall, I wouldn't mind this kind of weather lasting the whole year! The effects of this high pressure ridge will persist at least through the middle of the coming week with dry, warm weather the norm.

Sunday, October 2, 2011

The difficulty in predicting a coming winter!

When I've done searches on the net for what kind of winter we will have in North America for any particular year, I get mostly prediction based on the Farmer's Almanac. There's very little in the way of scientific papers that address the physics of meteorology. Perhaps there is a good reason for this. Weather systems on a global scale dwarf even the most powerful computers ability to crunch. Too many variable that replicate themselves to infinity even a week or more out.

So it is then, that virtually anyone (me?) with limited or no experience can post a 'Theory of the Coming Winter', without much in the way of credible certifications. What follows then are a couple of theories that may impact the kind of winter that may occur.

Theory of Progressive Ground Cooling (TPGC)

This theory is the manner in which the ground over a particular region of North America is cooled in the early fall months. In general, as one proceeds from the Canadian border to the south, the surface four to six inches of the soil warms. Snow packs cause a dramatic cooling and can affect large geographical areas. As a region becomes cool, it has less impact on warming the air above it, so that any future incursions of cold air become less affected in their passage to the southern states. Once established, such a 'cool' regions can in turn affect weather pattern and result in reinforcing incursions of subarctic and arctic air from more northern latitudes.

Therefore, one of the first things to look out for would be an early and persistent snowfall in key states in the upper Midwest. Two states I pay particular attention to are North and South Dakota, situated as they are between two elevated ranges of land to the west and east. They form the center of a funnel as it were. In addition, both states will tend to be impacted before the other states to the south and east in the event of an outbreak of cold polar air. When night time temperature get into negative digits with daytime highs never breaking the freezing mark, the stage is set for the rapid conveyance of frigid air from north to south. The end result can be a record cold winter for much of the United states. A record that stretches back through time.

The winter of 1917-18

Meteorologist Preston C. Day (1859-1931) wrote in December 1918, “The severity of the weather experienced during December and January of the winter of 1917-1918 over the greater part of the United States east of the Rocky Mountains, and also over much of Canada and Alaska during the early part of the period, was so unusual as to the length of time the low temperatures persisted, the great area involved, and the degree of cold maintained, that some discussion of the contributing factors, and comparison with similar occurrences of previous years, seems desirable.”

Climatologist Charles F. Brooks (1891-1958) wrote in June 1918, “Even though summer is upon us, it is not difficult to recall that last winter in the United States east of the Rockies was remarkably cold and snowy. The first killing frosts of autumn came early, and nipped crops which had started late and grown slowly in the cold spring and early summer. The South had a real winter, much to the detriment of fruit and truck crops which were caught by frost.”

Brooks continued, “By far the most intense winter conditions occurred in the regions from the Ozarks to New England, where low temperatures brought snow with passing cyclones, and the snow cover in turn cooled the air excessively whenever the sky was clear…In the eastern United States it was not surprising that autumn months which in many regions were the coldest on record, should be followed by a December and a January that defied the memories of the oldest inhabitants. For example, in Ohio, a 64-year record fails to show a colder December, and in New England, January seems to have been the coldest month at least since 1836, if an Amherst record may be considered as representative.”

The cycle of clear skies followed by intense cyclones that Charles Brooks alludes to caught my interest. What begs the question is whether the pattern was coincidental or due to some re-enforcing pattern that escaped the notice of the weather forecasters of the time.

Arctic Oscillation

The second causal effect is what is known as the Arctic Oscillation or AO. This is a little understood tendency for low or high pressure to build over the North Pole during the winter months. When a low builds, the AO is said to have a positive aspect and North America will generally experience a mild winter with little snowfall. When high pressure builds, however, this is known as a negative AO and with it comes very cold, snowy winters across the Ozarks and east coast.

The AO can be thought of as a fluctuation in the shape of the global circulation. The strength of the oscillation, as defined by the AO index, measures the awkwardness of the circulation's geometry by contrasting the weather in polar regions from that observed in more temperate latitudes like ours. Often times when the AO index is negative, frigid air typically found at far northern latitudes has been displaced southward, while at the same time warm air has been moved northward toward the pole. As the graph below shows, last winter was definitely a negative AO season. In fact, the AO index measured during much of last winter was "off the charts" low. It bottomed out at values not reached since record keeping began in the middle of the last century.

The big question that comes to the fore at this juncture in early Fall 2011 will be whether the trend seen last year will persist or even amplify going into December and January of 2012.

Wx Summary for September 2011

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Note: The table above depicts data for the entire year thru the first day in October (yellow area).

September 2011 started warm but ended with temperatures a little cooler that is the norm. According to historical averages the average or mean temperature for this month in SW Missouri is 68F. I recorded an average of 65F. Is that significant? I’m not sure.

As far a precipitation went we were on the comfortable side of average at 4.61 inches versus and average of 4.02 (data obtained from West Plains Mo.).

Below is how the Hemisphere looked as of the morning of October 1, 2011.

 Click on picture to animate