Seattle Chill

Although most of the United States is experiencing a warmer than average summer, there has been one notable exception.  The west coast has been having a cool summer.  From California to Washington, the temperatures have been persistently below average for the past few months.

Seattle, for instance, recorded just their 4th 80 degree day of the year this past Sunday.  Previous to that high temperature, the University of Washington reported just 78 minutes with a temperature at or above 80 degrees on their Seattle campus.  There has been a trough of low pressure along the west coast of the country for the past several weeks with an upstream ridge of high pressure centered over Texas.  This has brought a very consistent weather pattern over the North American continent.

It keeps the west coast cool, the southern plains hot and dry, and our area with above average temperatures with frequent disturbances moving along the jetstream enhancing thunderstorms development.  This pattern looks to be holding for at least another week.

Humidity

Humidity is best quantified by the dew point temperature.  Higher dew point temperatures express increasing mugginess in the air.  For about four hours last Tuesday, the dew point temperature was above 80 degrees and peaked at 83 at the official instrument site at Fargo’s Hector Airport.

Such high humidity is rare in our region, occurring only once in a while every few years or so.  It is not easy for our weather to get so humid and you might be surprised by the process.  The source region for this high humidity is the Gulf of Mexico.  But the dew points along the Gulf in high summer usually hover in the 70s, not the 80s.  But as that humid air gets drawn northward, its humidity is increased by Midwestern agriculture.  Millions of acres of corn and soybean plants actually add to the humidity by their respiration processes.

And the result, under the right weather conditions, humidity in Fargo Moorhead can go higher than in either Miami or Houston.

Jumpy Red

The Red River jumped over a foot right after our Tuesday morning thunderstorm.  It had already risen almost three feet since last weekend due to heavy rainfall here and upstream.  So the river is high again.  It has been above flood stage since for all but a couple of days since the end of March.

Rainfall this summer has been above average, but not so heavy as other recent summers.  So why won’t the river ever go down?  It is because the sponge is full of water.  The ongoing two-decade wet period, and the last three years in particular, have filled every lake, slough, and reservoir to capacity.  Soils are saturated.  There is no room to store any more water.  So it takes much less rain to cause the river system to rise, suggesting that it would require less of a torrential rain to cause a major flood.

There is no immediate threat, of course, but there is enough reason to remain watchful and concerned.

Stormy July

This summer has been a very stormy one in our area.  Every week since Memorial Day, there have been two or three severe weather outbreaks somewhere in eastern North Dakota or northwestern Minnesota.  It is common for June to be very stormy, but usually the frequency of the storms decreases some in July.

Not this year. The summer of 2010 also brought a high frequency of severe storms.  Last summer actually had more tornadoes than this year.  This year, it has been primarily straight line winds doing most of the damage.  People have begun to ask if our weather is actually getting stormier due to some aspect of climate change.  I am quick to point out that 2008 and 2009 were summers with relatively little stormy weather, so it is probably not a climate trend but just normal variability in our weather.

Earlier in the summer, we predicted that the summer would likely begin stormy but turn hot and fairly dry.  We got the hot part right.  Hopefully, the storminess will diminish during August.

Lake Champlain

Devils Lake was not the only big lake in the United States to reach record levels this spring.   Lake Champlain which straddles the border between New York and Vermont broke the old high water mark by nearly two feet, causing lake side homes to be inundated and damage to the many parks in Burlington, Vermont and the islands that dot the lake.

The melting of a deep mountain snow pack combined with record setting precipitation in April and May are to blame. On a recent trip to Burlington, water was still over part of the dock for the ferry that travels to Plattsburgh, New York.  Workers were also trying to clean up the state parks on the lake in time for them to open for the Fourth of July.  The lake is now down 5 feet from the record, and while wave action is still a problem, water no longer threatens any properties.

Unlike Devils Lake, Lake Champlain has an outlet that can remove excess water.

Exaggerated Dew Point

Tuesday evening, the automatic sensor at the Moorhead Airport reported a dew point temperature of 88 degrees.  This was prematurely reported by a number of local and national media as a new state record.

It was premature because the quality of the reading must be evaluated before it can be proclaimed a record, and it appears that the reading had a few problems.  We went out to the site on Wednesday and found the sensor surrounded by moisture-producing corn, sugar beets, and very tall clover without a buffer as is required.  Also, the field had standing water all around which doubtlessly added greatly to the humidity and would not be considered representative of the surrounding countryside as a whole.

Finally, the sensor at Fargo’s Hector Airport was simultaneously registering a dew point of 83 which, although very high, was five degrees lower than the Moorhead reading.  Just like when track and field records do not count if they are wind aided, this dew point record will also fail to qualify as a record.

A couple of links you may want to read:

Hottest Place on Earth?

Unreliable Dew Points

 

It’s the Cold, Not the Heat

With much of the country experiencing above average temperatures with high dew points, there have been many stories presented by the media giving beneficial tips on keeping cool and hydrated.  On occasion, some of these stories will mention that heat is the #1 weather related cause of death.

It is undeniable that excessive heat, if not taken seriously can cause serious medical complications and death among people of any age.  Therefore, precautions need to be taken, yet the data does not support the notion that heat is the #1 weather related killer.  In fact, it is cold weather that is the most harmful to the human body.  Research has shown that death rates increase as the temperature drops because of increased stress in maintaining body heat and the raise in air born diseases, along with other factors. Nearly twice as many people perish in extreme cold than they do in extreme heat.

Of course it really does not matter the rankings, all deaths are tragic, especially the ones that can be prevented which is the case with many weather related fatalities.

Extreme 70s

This week’s stretch of humid weather brought with it some extremely warm low temperatures.  On July 17 the morning low was 79 degrees, and then two days later, on July 19, the morning low was 80 degrees.  There have been only three days since 1881 with a low temperature of 80 degrees or higher.

Therefore, those morning lows of 79 and 80 degrees would have been some of the warmest lows ever recorded.  Although the morning lows were exceptionally high, an official low is over a period from midnight to midnight and on both of those mornings the temperature did drop well below those levels by the end of the day.  In fact, neither of those days ended up even breaking a record for the high minimum as the temperature dropped to 73 and 70 degrees on those two days for the official low.

We may not have recorded any historically high low temperatures, but we did have five straight days with a low of 70 degrees or higher which is the 3rd longest such period on record.